Environmental Health & Safety

University of Colorado Boulder

Resources

Radiation Safety Handbook

This Environmental Health & Safety guideline documentation is intended for researchers working with radiation.

Revised as of October 1, 2010

General Description

The University of Colorado Radiation Safety Handbook (RSH) is intended to be a user’s guide for anyone working with radioactive materials and/or ionizing radiation. Radioactive materials and ionizing radiation include unsealed sources, sealed sources and x-rays. The RSH is required by the University’s Radioactive Materials License. This chapter will address basic radiation safety concepts including some background information for reference use. It will also address the University’s Radioactive Materials License, regulations, and inspections.

Important Phone Numbers

Boulder Campus
Environmental Health & Safety: (303) 492-6025
EH&S Health Physics (Campus Hours): (303) 492-6523
EH&S Health Physics FAX: (303) 492-1322
EH&S Health Physics e-mail: hpl@spot.colorado.edu

Colorado Springs Campus
EH&S Health Physics (Campus Hours): (303) 492-6523
UCCS Public Safety: (719) 262-3111

Emergency Phone Numbers

To report an emergency situation, please use the following contact information:

Boulder Campus
EH&S Health Physics (Campus Hours): (303) 492-6523
Environmental Health & Safety (Campus Hours): (303) 492-6025
UCB Police Dispatch (After Campus Hours): 911 or (303) 492-6666

Colorado Springs Campus
EH&S Health Physics (Campus Hours): (303) 492-6523
Public Safety (After Campus Hours): (719) 262-3111
UCCS Police Department (After Campus Hours): 9-911

Foreword

The State of Colorado has entered into an agreement with the United States Nuclear Regulatory Commission (U. S. NRC) to govern the safe use of radioactive materials. The Colorado Department of Public Health and Environment (CDPHE) is responsible for implementing this agreement and for developing regulations which are at least as restrictive as those established by the U. S. NRC.

The University of Colorado has a license from the State of Colorado, through CDPHE, to oversee the safe use of radioactive materials on the Boulder and Colorado Springs campuses. This license requires, in part, that the University have a Radiation Safety Committee (RSC) and a Radiation Safety Officer (RSO). The RSC and RSO work together to ensure safety and regulatory compliance for individuals working with radioactive material or radiation; for the faculty, staff, and students of the University; and for members of the public.

The Radiation Safety Committee essentially serves as the on-site regulatory agency for the University, and as such, has the authority to establish policies and procedures, provide enforcement sanctions, and restrict the use of radioactive materials and/or radiation. The RSC and RSO issue, amend, and terminate laboratory licenses, which authorize the specific activities associated with radioactive materials and/or radiation.

The RSC is composed of members of the faculty and staff representing various departments and levels of experience with radioactive materials and radiation, as well as the Radiation Safety Officer. Each member is appointed through the University’s Administration. Every effort is made to maintain representation from each of the departments that actively use radioactive materials in the course of their research and/or academic work. Membership also includes a representative from Administration.

The Radiation Safety Officer is an individual approved by the State of Colorado who has the knowledge, responsibility, and authority to apply appropriate radiation protection regulations.

The Radiation Safety Officer and Health Physics staff are members of the University of Colorado’s Department of Environmental Health and Safety. These individuals provide daily management and support services for the safe use of radioactive materials and radiation. EH&S Health Physics works closely with the RSC to ensure safety and regulatory compliance, while striving to provide customer-friendly services which facilitate continued successful research and academic activities at the University of Colorado. Members of the RSC and the RSO may be contacted through EH&S Health Physics.

We thank you for taking the time to read this Radiation Safety Handbook and hope that it proves to be helpful. We encourage and appreciate your comments and feedback.

Sincerely,

R. Jerome Peterson, Ph.D. Michelle S. Law, M.S.
Radiation Safety Committee Chair Radiation Safety Officer

October 1, 2010

Derrick Watson, Director
Environmental Health and Safety
University of Colorado at Boulder
1000 Regent Drive, 413 UCB
Boulder, CO 80309-0413

Dear Mr. Watson:

Pursuant to Article 3.B.7 of the Laws of the Regents and as chief academic and administrative officers of the University of Colorado at Boulder and Colorado Springs, we have the responsibility to ensure research and instruction which use radioactive materials is done in a safe and compliant manner. To that end, we hereby delegate to you, the Radiation Safety Officer, and the Health Physics staff the authority to act as the custodian for the purpose of enforcing the Laws of the Regents, applicable municipal ordinances, and State and Federal statutes specific to radiation safety. This authority to act shall include, but not be limited to:

  1. Ensuring full compliance with the University’s Radioactive Materials License issued by the State of Colorado through the Colorado Department of Public Health and Environment as well as any other applicable Federal, State, and local regulations;
  2. Supporting the functions of the Radiation Safety Committee with representatives from the Boulder and Colorado Springs campuses;
  3. Developing and issuing policies and procedures that clarify radiation safety issues and responsibilities at the Boulder and Colorado Springs campuses;
  4. Acting in an advisory capacity to students, faculty, and staff in matters pertaining to radiation safety and compliance;
  5. Serving as liaison between the University and Federal, State, and Local agencies in matters pertaining to radiation safety and compliance; and
  6. Suspending activities and/or operations and closing areas where imminently dangerous conditions and/or non-compliance with regulatory requirements exist.

Approved by,

Philip P. DiStefano, Chancellor Pamela Shockley-Zalabak, Chancellor
University of Colorado at Boulder University of Colorado at Colorado Springs

Introduction

1. Purpose of the Radiation Safety Handbook

The University of Colorado Radiation Safety Handbook (RSH) is intended to be a user’s guide for anyone working with radioactive materials and/or ionizing radiation. Radioactive materials and ionizing radiation include unsealed sources, sealed sources and x-rays. The RSH is required by the University’s Radioactive Materials License. This chapter will address basic radiation safety concepts including some background information for reference use. It will also address the University’s Radioactive Materials License, regulations, and inspections.

2. Fundamentals of Radiation Safety

Radioactivity is defined as the spontaneous emission of radiation, generally alpha or beta particles, often accompanied by gamma rays, from the nucleus of an unstable atom. Radiation may be particles [alpha (α), beta (β), neutron (n)] or photons [gamma (γ), x-ray (x)] emitted from an unstable radioactive atom as a result of radioactive decay. All of these types of radiation are represented at the University of Colorado. Each type of radiation has unique safety considerations and handling techniques that will be discussed in this chapter.

Background Radiation

Radiation is part of everyday life. There are many sources of natural “background” radiation, both external and internal. External radiation sources include cosmic (beyond the Earth’s atmosphere) and terrestrial (the Earth’s contribution) radiation. Internal radiation sources include carbon (14C), potassium (40K), numerous other minerals which make up bones and soft tissues, and radon deposited in the lungs through inhalation. The average radiation dose from exposure to natural and man-made background radiation in the United States is approximately 3.6 mSv (360 mrem) per year (see common units below and the glossary for an explanation of these units). As a rough estimate or rule of thumb, this value doubles for each mile of elevation gain. Therefore, living in Boulder, Denver, or Colorado Springs increases the average background dose to approximately 5 – 6 mSv (500-600 mrem) per year. The increase is due to a higher contribution from cosmic radiation at higher altitudes and terrestrial radiation.

Common Units

There are many units used to describe activity, dose, dose equivalent, and exposure. In the United States, conventional units are still being used, although the complete conversion to the Systeme International (SI) units may happen in the future. At the present time, SI units are used in addition to conventional units on packages and radiation sources. At the University of Colorado, subdivisions of units such as millicuries (mCi) and millirem (mrem) are used along with divisions of SI units such as megabecquerel (MBq) and millisievert (mSv). Both conventional and SI are units are acceptable.

The SI unit of radioactivity is the Becquerel (Bq) which is equivalent to one disintegration or decay per second. The SI unit of dose is a Gray (Gy) and the unit of dose equivalent is a Sievert (Sv), both of which are equivalent to 1 Joule per kilogram by definition. As mentioned previously, not all forms of radiation (α, β, γ, n, x) produce the same biological effect. For example, 1 Gray (Gy) of beta radiation is not equivalent to 1 Gray (Gy) of neutron radiation. However, 1 Sievert (Sv) of beta radiation is equivalent to 1 Sievert (Sv) of neutron radiation.

The conventional unit for radioactivity is the Curie (Ci). One Curie is equal to 3.7 x 1010 nuclear disintegrations or decays per second. Other conventional units include the rad for dose and the rem for dose equivalent. Rad is an acronym for Radiation Absorbed Dose and rem is an acronym for Roentgen Equivalent Man. Dose equivalent was developed in an effort to incorporate biology into the physics of radiation exposure. Not all forms of radiation (α, β, γ, n, x) produce the same biological effect. For example, 1 rad of beta radiation is not equivalent to 1 rad of neutron radiation. However, 1 rem of beta radiation is equivalent to 1 rem of neutron radiation. Exposure is defined only for gamma or x-rays in air, not tissue. Roentgen (R) is the unit of exposure. Many radiation survey meters use units of milliroentgen (mR). Please refer to the Glossary for additional clarification of these terms.

Systeme International (SI) Units Conventional Units
Activity Activity
1 Bq = 1 disintegration/second 1 Ci = 3.7 x 1010 disintegrations / second
1 Bq = 2.7027 x 1011 Curies 1 Ci = 1000 mCi
1 kBq = 1,000 Bq = 2.7027 x 10-8 Ci = 2.7027 x 10-5 mCi 1 mCi = 1000 μCi
1 MBq = 1000 kBq = 1,000,000 Bq = 0.027027 mCi 1 mCi = 37,000 kBq = 37 MBq
Dose Dose
1 Gy = 1 J / kg = 100 Rad 1 Rad = 100 ergs / gram = 0.01 J / kg
1 Gy = 100 centigray (cGy) (1 cGy = 1 Rad) 1 Rad = 0.01 Gy
Dose Equivalent Dose Equivalent
1 Sv = 1 J / kg = 100 Rem 1 Rem = 1000 mrem
1 mSv = 0.1 Rem = 100 mrem 1 Rem = 0.01 Sv
1 mrem = 0.01 mSv

ALARA

A common acronym used in radiation safety is ALARA, which stands for As Low As Reasonably Achievable. The ALARA philosophy attempts to incorporate physical, social, and economic factors in reducing doses to individuals. The University of Colorado has an ALARA program which is reviewed each year to evaluate efforts at keeping doses and exposures ALARA. It is the responsibility of each radiation worker to keep the dose to themselves and the people around them ALARA. Refer to Appendix A for a copy of the University’s ALARA program.

Time, Distance, Shielding

Radiation doses may be reduced by taking advantage of time, distance, and shielding. By reducing the time spent working with radioactive materials and/or radiation producing machines, the dose received from the radiation is reduced. Increasing the distance from a source also will reduce the dose because the intensity of radiation decreases at approximately 1/d2, where d is the distance from the source. For example, if the distance (d) is doubled, the intensity is reduced to ¼ (d2) of the original intensity. This is also known as the Inverse Square Law. Shielding can be very effective in reducing the dose received. There are different types of shielding for different types of radiation. Use caution when selecting shielding to reduce the radiation dose. The dose may actually increase by selecting the wrong shielding. Verify radiation levels with a survey meter to ensure that appropriate and/or enough shielding has been used. Health Physics normally does not provide shielding to researchers. However, staff members are available to answer general shielding questions and discuss the efficacy of shielding materials.

Remember: Time, Distance, and Shielding

Doses can be minimized by taking advantage of the following simple methods:

  1. Reduce the amount of time spent near the radioactive material/source
  2. Increase the distance from the source
  3. Use appropriate shielding whenever possible

Laboratory Licensing

1. Introduction

Most of the use of radioactive materials at the University of Colorado occurs in laboratories. Proper laboratory set up and licensing are essential to maintaining a safe working environment for personnel using radioactive materials and/or radiation. This section will address general laboratory safety requirements for unsealed radioactive materials, sealed radiation sources, x-rays, and lasers. It will also address the responsibilities of the Principal Investigator (PI) and individuals using radioactive materials and/or other radiation sources.

2. Laboratory Licensing

The University of Colorado issues Radioactive Materials Licenses (License) to qualified PIs, also known as Authorized Users (AUs) or Licensees. Applications for a new license, license amendment, license renewal, or license termination may be obtained from Health Physics. Sample forms are included in Appendix B. A license must be obtained prior to working with radioactive materials and must be kept current. The Radiation Safety Committee (RSC) has established a renewal frequency goal of three years. A license will be issued with an expiration date reflecting the three year period. Licenses not amended or renewed within the three year period remain valid until an amendment or renewal is issued.

New Licenses

New licenses are approved at quarterly meetings of the Radiation Safety Committee. Applicants should allow at least six (6) weeks should for processing of applications. License requirements include laboratory contact information, radionuclide information and limits, experimental procedures, equipment to be used, waste information, and past training and experience.

Laboratory contact information includes building location, offices, telephone numbers at work and at home, and campus box number. Radionuclide information includes radionuclide(s), amount of activity required for each experiment, and the physical and chemical forms needed. Experimental procedures should describe the experiment, operating procedures to be used for each radionuclide and a statement indicating whether or not biohazardous materials will be used with the radioactive materials. Operating procedures should include information to limit the spread of contamination, frequency of surveys, analysis methods such as liquid scintillation counters, and any special logistics required to complete the experiment.

Equipment item information includes type, make, model, serial number(s), and location. For equipment that requires internal radiation sources and/or calibration sources, information also includes the radionuclide, activity, physical and chemical forms, manufacturer, and assay dates for the sources.

Waste information should be broken into volume, approximate percentage of the total waste, and chemical constituents. All laboratories using unsealed radioactive material must perform contamination surveys, and will, therefore, generate scintillation vial waste upon analyzing the wipe smears. Please refer to the Radiation Survey chapter for more information. Biodegradable scintillation cocktails are strongly recommended whenever possible. Please refer to the Waste chapter for additional information.

The Training, Education, and Experience sections refer primarily to the PI. These sections may be completed for additional laboratory staff if necessary. Dates should be provided as much as possible in these sections. Anyone using radioactive materials in a laboratory also must obtain training specific to the type of radiation used. Training is available by contacting Health Physics. Please refer to the Training chapter for additional information.

A laboratory visit may be scheduled for new licensees upon completion of the application to review equipment, signs, use areas, and waste storage areas. The entire application and results of the laboratory visit are then submitted to the RSC for review and approval. New license applications may not be reviewed or approved by the Committee outside of their meetings, so please plan accordingly when submitting a license application.

License Amendments

Amendments are required for changing radionuclides, experimental procedures, and laboratory locations. When in doubt, contact Health Physics. At least three (3) weeks should be allowed for processing amendment applications. Amendments include verifying and updating laboratory contact information, radionuclide information and limits, experimental procedures, waste information, and past training and experience. See New Licenses section for clarification.

New or different experimental procedures should describe the experiment and operating procedures to be used for each radionuclide. Operating procedures should include information to limit the spread of contamination, frequency of surveys, analysis methods such as liquid scintillation counters, and any special logistics required to complete the experiment.

Waste information should be broken into volume, approximate percentage of the total waste, and chemical constituents for each new radionuclide and/or new procedure. All laboratories using unsealed radioactive material must perform contamination surveys, and will, therefore, generate scintillation vial waste upon analyzing the wipe smears. Please refer to the Radiation Survey chapter for more information. Biodegradable scintillation cocktails are strongly recommended whenever possible. Please refer to the Waste chapter for additional information.

A new type of radiation may require additional training specific to the type of radiation used. Training is available by contacting Health Physics. Please refer to the Training chapter for additional information.

A laboratory visit may be scheduled for amendments involving new or completely different procedures. The entire application and results of the laboratory visit are submitted to the RSC for review and approval.

License Renewal

The Radiation Safety Committee (RSC) has established a renewal frequency goal of three years. A license will be issued with an expiration date reflecting the three year period. Licenses not amended or renewed within the three year period remain valid until an amendment or renewal is issued. The Health Physics office will contact licensees whose licenses need review, typically after a license has been active without amendments for more than three years. License requirements are reviewed and updated including laboratory contact information, radionuclide information and limits, experimental procedures, waste information, and past training and experience.

A laboratory visit may be scheduled for renewals upon completion of the paperwork. The entire application and results of the laboratory visit are then submitted to the RSC for review and approval.

Inactive Licenses

Periodically, research using radioactive materials is put on hiatus but a licensee may wish to keep their laboratory license. In this case, the licensee may request to be placed on inactive status. In this situation, all radioactive materials and waste must be removed from the laboratory through the Health Physics office. A final wipe survey will be performed on laboratory surfaces and equipment. After this, the Radiation Safety Committee will review the request and, if approved, the licensee will be released from regular license requirements such as training and surveying.

If a licensee wishes to become active again within three years of going inactive, the Radiation Safety Committee can approve a re-activation. The license will be reviewed by the Committee as though it was an amendment.

After three years on inactive status, an inactive license will be terminated by the Radiation Safety Committee and the licensee will need to submit a new License application to resume work with radioactive materials.

License Termination

Termination is required for laboratories leaving the University of Colorado. If a laboratory is relocating or closing, the PI should contact Health Physics as soon as possible to facilitate proper relocation or disposal of the radioactive materials and closing of the laboratory. EH&S should also be contacted at (303) 492-6025 to facilitate proper relocation or disposal of non-radioactive materials.

Termination may also be used for laboratories that are discontinuing work with radiation and/or radioactive materials. Contact Health Physics to facilitate proper termination and disposal of radioactive materials.

3. Responsibilities

PIs are responsible for the radiation safety program in their labs, including the following: overall supervision of work with radioactive materials, ensuring completion of basic and refresher training by all personnel, ensuring proper use and exchange of dosimeters when necessary, ensuring that contamination surveys are performed and properly documented, and ensuring compliance with all regulations and license commitments. Additionally, the PI must designate a Laboratory Contact. If the PI elects to be the Laboratory Contact, then an Alternate Safety Contact must be designated for emergencies. The Laboratory Contact is responsible for coordinating activities such as contamination clean-up (See Mishaps and Emergencies Chapter) and radioactive waste disposal (See Waste Chapter). Correspondence from Health Physics regarding lab practices will be sent to both the PI and the Lab Contact.

4. Laboratory Signs & Labels

All entrances and doors to laboratories must have signs posted to warn users of hazardous conditions. For example, Caution Radioactive Materials, Caution X-ray Producing Equipment, Caution Lasers (various classes), and Emergency Notification signs are necessary for doors and entrances as applicable. Each laboratory should have a Notice to Employees posting. Additionally, all areas in a laboratory where radioactive materials are being used must be labeled clearly with Caution Radioactive Materials signs or stickers. This includes labeling equipment in which radioactive materials are used as well as equipment that contains radioactive sources. Equipment and X-ray machines should be labeled clearly. These signs and stickers may be obtained from laboratory safety supply vendors or are available by contacting Health Physics at (303) 492-6523.

5. Laboratory Audits

Health Physics performs periodic audits of each laboratory using radioactive materials. These audits review training, contamination surveys and other safety issues to ensure compliance with the laboratory’s Radioactive Materials License and Federal, State and local regulations. Audits will be unannounced, but laboratories will be given an opportunity to complete a pre-audit checklist which will help reduce the time spent with the auditor in the field. Final audit findings are sent to the Licensee. Items of non-compliance and other concerns identified during the audit require a written response from the licensee which must include planned corrective actions.

6. State Inspections

The University of Colorado is inspected by the State of Colorado to ensure compliance with the Rules and Regulations pertaining to Radiation Control. The inspections may occur at any time, but are usually once every 1-2 years. Most inspections include a review of records, interviews with personnel, and laboratory visits. Items of non-compliance must be corrected and may include enforcement sanctions.

Radioactive Materials Management

1. Introduction

Management of radioactive materials and radiation is the responsibility of the Principal Investigator (PI) under whose license the material/machine is being used. Ultimately, however, it is the responsibility of each member of the laboratory to maintain safe storage and use of the radioactive materials and machines in their area. By using correct procedures to order, store, and dispose of radionuclides, sealed sources, and radiation producing machines, each researcher is helping to implement the ALARA Program and ensure safety at the University of Colorado.

2. Purchasing

To Receive Radioactive Materials and/or Radiation-producing Machines:

  1. Ensure that the Laboratory License is obtained and includes the appropriate authorization for the radionuclide(s) or radiation-producing machine(s)
  2. All deliveries must be through Health Physics (see address below)
  3. All items must be purchased using a Purchase Request (PR) or Standing Purchase Order (SPO)
  4. The University’s Procurement Card or any other credit/debit cards are not permitted for these purchases
  5. Exceptions to the above may be granted with prior approval of the RSO or ARSO on a case-by-case basis

Laboratories wishing to order radioactive materials and/or a radiation-producing machine must first obtain a license for the specific product from the Radiation Safety Officer (RSO) and the Radiation Safety Committee (RSC). Radioactive materials will not be delivered to laboratories if the material will cause the license limit to be exceeded. If a limit is exceeded, a license amendment or disposal/removal of current inventory will be required and may prevent timely delivery. Please refer to the Laboratory Licensing chapter. The PI and laboratory staff members who will be using radioactive materials and/or radiation should complete Radiation Safety Training prior to ordering the product, however, the required training must be completed prior to receipt of the product. Please refer to the Training chapter.

Ordering radioactive materials and radiation-producing machines requires using a Purchase Request (PR)/Standing Purchase Order (SPO). In most cases, these are established by individual departments through the Procurement Service Center. All PRs and SPOs must be approved in advance by Health Physics. The “Ship To” address must be verified on all PRs. See Delivery Address below. The University’s Procurement Card, other credit/debit cards, and other purchasing methods may NOT be used to order radioactive materials or radiation-producing machines unless PRIOR approval is granted by the RSO or Alternate RSO. Exceptions may be granted on a case-by-case basis.

All radioactive materials and sources must be delivered to Health Physics and checked for contamination prior to delivery to the receiving laboratory unless special arrangements have been approved in advance. Radionuclide stock vials contaminated at a level of 1,000 dpm/100 cm2 or less will be delivered to the laboratory. Laboratory personnel will be notified of the contamination. Radionuclide stock vials contaminated at a level of 10,000 dpm/100 cm2 or above will not be delivered to the laboratory. Exceptions may be granted by the RSO or Alternate RSO on a case-by-case basis. In the case of vials contaminated at a level above 1,000 dpm/100 cm2 but below 10,000 dpm/100 cm2, laboratories will be notified of the potential for contamination from the vial and reminded to use safe handing procedures. Laboratories have the right to refuse receipt of a vial contaminated at any level. It is the laboratory’s responsibility to arrange for a replacement from the manufacturer if necessary.

Radioactive materials that are purchased, donated, received as gifts, or transferred from other institutions must be delivered through Health Physics.

Radiation-producing machines that are purchased, donated, received as gifts, or transferred from other institutions may be delivered to the area of use only after prior notification has been made to Health Physics and approval has been granted. In most cases, delivery should be made through the Health Physics office.

Radioactive Materials Delivery “Ship To” Address:

University of Colorado at Boulder
Environmental Health and Safety Center
Health Physics
1000 Regent Drive, 413 UCB
Boulder, CO 80309-0413
ATTN: (PI’s Name)

3. Storage of Radioactive Materials

All freezers and other equipment used to store radioactive materials must have a Caution Radioactive Materials sign or label. Radioactive materials should be stored only in areas properly marked and approved for their use. Please refer to the Laboratory Licensing chapter or contact Health Physics at (303) 492-6523 for further information.

Each laboratory must ensure security of radioactive materials and/or radiation-producing machines. This may require locking of laboratory doors or storage freezers/refrigerators depending on use and accessibility of the area.

Please refer to the Sealed Sources chapter for information on storage of sealed sources.

4. Use of Radioactive Materials

Recommendations for the Safe Use of Radioactive Materials are provided in Appendix C.

Designated Areas

Radioactive materials should be used only in designated areas. All laboratories should designate an area(s) for eating and drinking. This area(s) should be as far as possible from any radiation work and should be the only area(s) in the laboratory where personnel eat or drink.

Shielding

Work with radioactive materials may require shielding. Appropriate shielding should be used for each experiment. For 32P and other strong beta emitters, ¼ inch of Plexiglas is appropriate. The use of lead for 32P is discouraged because it produces Bremsstrahlung x-rays. Contact Health Physics for assistance in selecting appropriate shielding.

5. Radioactive Materials Inventory

Health Physics provides a Radioactive Materials Inventory to users of unsealed radioactive materials. See Appendix D for a sample Radioactive Materials Inventory form. This inventory should be kept on the outside of the main storage freezer/refrigerator/area in each laboratory. As a vial of radionuclide is used and disposed, the identification number on the outside of the pig should be crossed off the inventory. Enter the date and initials of the individual disposing of the item being crossed off the inventory.

At least quarterly, the vials physically present in the freezer/refrigerator/area should be compared with the printed inventory to ensure accuracy. Vials which are no longer being used or have decayed too far for use should be placed in an appropriate waste container and removed from the inventory list. The inventory sheet is collected by Health Physics to update the laboratory’s possession levels.

It is a good practice to dispose of radioactive materials which are more than one or two years old, especially those bound to nuclides and proteins. Some bound radioactive materials and their chemical carriers have an effective “shelf-life” that may be exceeded. With certain long-lived radionuclides, especially tritium, the practice of periodically purging them helps reduce contamination problems in the storage area.

Please refer to the Sealed Sources chapter for inventory of sealed sources.

6. Transfer of Radioactive Materials

Radioactive materials or radiation-producing machines may be transferred to another appropriately licensed laboratory in the same building, following approval from Health Physics. If the recipient is not licensed for the material being received, a license amendment will be necessary prior to the transfer. See the Laboratory Licensing chapter. Transfers between buildings must be arranged through Health Physics to ensure safe handling and transport. The radioactive material, sealed source, or machine must be transferred to the license and included in the Radioactive Materials Inventory of the recipient.

In order to send radioactive materials off-campus, the user should carefully package the material to avoid damage. Health Physics will address the radiation packaging requirements. Include a list of the package contents, name and address of the sender and receiver, Federal Express account number (if necessary), and any special instructions. Health Physics should then be contacted to arrange pick up, testing, and shipping. Radioactive materials are not to be shipped off-campus without prior approval of the RSO or the RSO’s designee. Shipping costs will be paid by the laboratory wishing to ship the material.

Radiation Surveys

1. Introduction

Radiation Surveys are performed in areas where radioactive materials or radiation-producing machines are used to ensure that radioactive contamination and/or exposure levels are as low as reasonably achievable (ALARA).

Contamination surveys are performed with wipe smear samples and are used to detect removable radioactive contamination, for example, radioisotopes such as 32P or 35S. Access to a liquid scintillation counter (LSC) or gamma counter is usually necessary to analyze wipe smear samples. Wipe smear samples analyzed with an LSC must have scintillation cocktail in the vial, preferably a cocktail that is biodegradable. Dry samples are not acceptable for contamination surveys.

Area surveys performed with an appropriate survey instrument such as a Geiger-Mueller counter are used to detect exposure levels from either a removable or fixed source. Area surveys are performed in laboratories using x-ray machines or sealed sources, and should be performed in conjunction with contamination surveys in laboratories using unsealed radioactive materials.

2. Contamination Surveys

All laboratories should be kept clean to avoid contamination. Laboratories using any unsealed radioactive materials are required to survey for contamination using a wipe smear. Surveys should be taken on a regular basis to detect any contamination occurring from radiation work. It is strongly suggested that weekly surveys be conducted, using wipe smears and a LSC. The results should be submitted online monthly. The page should be printed and stored in the Radiation Safety Survey Logbook with the LSC print outs. The printed page can also be submitted by faxing it the Health Physics office at (303)-492-1322. The Radiation Safety Survey Logbook should be stored in an easily accessible location for review by Health Physics and Federal, State, or local Inspectors.

Conducting Contamination Surveys

The laboratory contamination survey should include equipment and work areas used during the experiment. For example, the survey should check floors (especially near waste containers, desks, and doorways); doorknobs; telephone receivers; buttons on equipment; hood sashes, edges, handles and switches; sink handles, edges, and drains; and lab benches. Results should be reviewed when the surveys have finished running so any contamination can be remediated without delay. If a contamination level in an area is more than twice background, e.g. 100 cpm if the background is 50 cpm, decontaminate the area and re-survey. Continue this process until the area is clean (less than twice background). Initial and final results should be included when submitting the Survey Report. Contact Health Physics for assistance with areas that are not able to be decontaminated.

Surveys should be completed each week that radioisotope is used to detect any contamination occurring from radiation work. A week is defined as 7 days beginning Sunday and ending Saturday. Each licensee using a “common room” is responsible for performing and recording surveys of the common room. An exception may be granted by Health Physics staff regarding inter-laboratory agreements to conduct surveys of common rooms. Surveyors should use wipe smears and a LSC with scintillation cocktail or, for certain isotopes, a gamma counter to analyze the results of the survey. Surveyors should complete Radiation Safety training for unsealed isotope users, even if they are not actively working with radioactive materials in other laboratory protocols.

Health Physics may perform secondary contamination surveys as well as exit surveys of laboratory areas where work with radionuclides has been discontinued. The secondary survey may include, but is not limited to, the following areas: floors (especially near waste containers and doorways); doorknobs; telephone receivers; buttons on equipment; hood sashes, edges, handles and switches; sink handles, edges, and drains; and lab bench edges. Laboratories will be notified if contamination levels exceed twice background. If the contamination level in an area is more than twice background, the lab should decontaminate and re-survey the area. Health Physics may re-survey the area, as well. See Appendix F for decontamination procedures.

3. Area Surveys

For high energy β and any γ emitters, area surveys are conducted with a portable (hand-held) radiation survey meter in addition to routine contamination surveys. Area surveys are used to monitor for levels of increased radiation such as in unshielded areas or during relocation of radioactive materials. It is important to document a background radiation survey value for comparison to the measured radiation result.

Laboratories using unsealed radioactive materials should perform area surveys periodically before, during, and after an experiment. A final survey after completion of the experiment may be performed, but does not eliminate the requirements for taking wipe smears for the contamination survey mentioned previously. Results may be recorded in the Radiation Safety Survey Log with the contamination survey results.

Laboratories which use primarily radiation-producing machines and/or sealed sources should perform periodic area surveys using an appropriate survey instrument. This survey should be performed while the radiation-producing machine is “on,” in order to determine if there is leakage of x-rays. The results of the survey should be noted in a log and maintained in an easily accessible location for review by auditors.

4. Survey Instruments

Each laboratory using unsealed radioactive material other than 3H or 14C should either have two portable radiation survey instruments/meters or possess one instrument and have access to a second. This is to ensure availability of a survey instrument if one is damaged, out of calibration, or otherwise unable to be used.

While appropriate survey instruments must be available for activities involving radiation at the University of Colorado, it is the responsibility of each laboratory to supply the instrument. Ideally, the instrument should read out in units of mR/hr and/or counts per minute (cpm) and the probe should be one which is most appropriate for the type of work performed in the laboratory. Health Physics is available to assist with appropriate instrument selection. Health Physics has a limited supply of loaner meters available for temporary use.

Health Physics maintains a database of all survey instruments on campus and provides calibration services for most of the models used at the University of Colorado. Calibration is required at least once each year. Health Physics collects and calibrates the survey instruments every six months to ensure compliance with the annual calibration requirement. If a survey meter has not been calibrated within the last six months, contact Health Physics at (303) 492-6523.

If a new instrument is obtained, contact Health Physics as soon as possible to have it placed on the calibration schedule. If an instrument requires major repairs or more complicated calibration techniques, it will be sent to the manufacturer for these services at the expense of the laboratory. Minor repairs may be provided by Health Physics at little to no charge to the laboratory. Additional repair costs may be recovered from the laboratory.

Survey instruments/meters are calibrated to a National Institute of Standards and Technology (NIST) traceable 137Cs gamma source. Correction factors are indicated on the calibration label for use with beta emitting radionuclides. When using β emitters, multiply the reading on the instrument by this correction factor to obtain an accurate reading.

The following types of instruments are most commonly used on campus:

  • Geiger-Mueller counter with thin-end window probe
    • Used for 32P, 86Rb, 125I
  • Geiger-Mueller counter with “pancake” probe
    • Used for 32P, 33P, 35S

These are available from several companies, including the following (Health Physics has catalogs and price lists available):

Ludlum Instruments
1-800-622-0828
www.ludlums.com

Eberline
1-505-471-3232
www.thermoeberline.com

Victoreen
1-800-850-4608
www.elimpex.com

5. Freezer Frost Surveys

Freezers used to store tritium (3H), may be contaminated by the radionuclide due to hydrogen exchange with water. The escaped tritium (3H) is then incorporated into the freezer frost (or condensation in a frost-free freezer) in the form of tritiated water (HTO). A heavily contaminated freezer could contain several MBq (mCi) of HTO in the frost.

Freezers used to store tritium (3H) are checked every six months by Health Physics personnel. Excessive contamination (10,000 dpm/100 cm2 or dpm/ml) requires defrosting and decontamination of the freezer by laboratory personnel. Any liquid generated by defrosting should be considered radioactive liquid waste and collected for disposal through Health Physics. Paper towels used to blot liquid are considered solid radioactive waste. Please refer to the Waste chapter for additional information.

Health Physics encourages laboratories to dispose of tritium (3H) that is not being used. This will decrease the chances of freezer contamination. If a concern arises about excessive build-up of tritium (3H) contamination in a storage freezer, call Health Physics at (303) 492-6523 to discuss techniques for reducing the contamination. See Appendix G for procedures for defrosting a contaminated freezer.

6. Equipment Transfer / Disposal / Resale Surveys

Equipment such as refrigerators, freezers, centrifuges, and other laboratory items used with radioactive materials must be surveyed prior to transfer or disposal to assure that they are free from radioactive contamination. Refrigerators and freezers used for tritium, which may have become incorporated into the plastic of the unit, are two specific examples. Contact Property Services at (303) 492-6524 to transfer or dispose of equipment associated with radioactivity. A contamination survey of both the inside and outside of the unit will be required. Maintain the survey records, including LSC print-outs, with the contamination survey results in the Radiation Safety Survey Log. Once the unit is determined to be free from radioactive contamination, all radioactive signs and symbols must be obliterated or removed.

Equipment such as liquid scintillation counters which contain radioactive sources should have the source and any lead shielding removed by the manufacturer prior to disposal. Radiation-producing machines should have the x-ray tube removed and/or destroyed prior to disposal. All radioactive signs and symbols must be obliterated or removed. Contact Health Physics at (303) 492-6523 for additional assistance with disposal of these items.

Waste: Radioactive & Mixed

1. Introduction

This Chapter will address the general requirements for handling waste in a radioactive materials laboratory. There are three different types of radioactive waste created in a radiation laboratory: 1) purely radioactive, 2) mixed (radioactive and chemical), and 3) radioactive and biological. Proper handling of wastes is critical for appropriate transportation and disposal. Numerous Federal, State, and local regulations impact waste; the Colorado Department of Public Health and Environment (CDPHE), the Department of Transportation (DOT), the Environmental Protection Agency (EPA) through the Resource Conservation and Recovery Act (RCRA), the University’s Radioactive Materials License, and the City of Boulder. Mixed waste must comply with both radioactive and chemical regulations.

Radioactive wastes are separated by waste type (solid, liquid, and scintillation vial) and by half-life. See section 2 of this chapter. Health Physics provides containers for all radioactive waste. When the containers are full, the laboratory submits a Radioactive Waste Pick-up Request Form to Health Physics. Health Physics then schedules a waste pick-up. See section 5 of this chapter.

Mixed waste is separated by waste type and half-life in the same way as purely radioactive waste. Generation of mixed (hazardous and radioactive) wastes should be avoided whenever possible. Disposal of this type of waste is very difficult and costly. Laboratories should actively seek ways to reduce the amount of mixed waste generated. One example of a way to decrease a laboratory’s mixed waste production is switching to biodegradable scintillation cocktail from flammable scintillation cocktail. Cost for mixed waste disposal may be re-charged to the laboratory.

Mixed waste generators must complete Hazardous Waste Generator Training as well as Radiation Safety Training. Please refer to the Training chapter for more information regarding Radiation Safety Training. More information on Hazardous Waste Generator Training is in the EH&S Generator’s Guide to Hazardous Material/Waste booklet.

Mixing biological wastes and radioactive material should be avoided whenever possible. Any biological material must be rendered non-infectious using bleach or other disinfecting agent prior to disposal with Health Physics. When radioactive material is involved, use of an autoclave is NOT permitted. Once rendered non-infectious, this waste should be segregated from all other radioactive wastes. Do not use biohazard bags for radioactive materials. If this type of waste is expected to be produced in the laboratory, contact Health Physics at (303) 492-6523 for further guidance.

2. Waste Containers

Radioactive waste is separated into three types: solid, liquid, and scintillation vials. Each type has specifically designated waste containers. Solid waste containers are available in two sizes, a twenty-gallon size which looks like a trash can, and a five-gallon size which looks like a covered metal bucket.

Liquid radioactive waste containers are available in two sizes, a five-gallon, round plastic carboy not to be confused with the cube-like carboys used for chemical wastes, and a one-gallon, round plastic bottle. Smaller containers are available upon request for small amounts of liquid waste. Secondary containment tubs are available from Health Physics and are strongly recommended for liquid waste containers.

Scintillation vials have only one size of waste container, a five (5) gallon covered metal bucket. This container looks the same as the small solid waste container. Care must be taken to avoid confusion between these containers. See section 4 of this chapter.

Containers are also provided for sharps, lead pigs, and any other unusual wastes. Empty lead pigs are stored separately and collected upon request by Health Physics for possible recycling. Unlike lead pigs, plastic pigs may be disposed in the appropriate solid waste container. Call Health Physics at (303) 492-6523 for special containers.

Radioactive waste is also segregated by half-life. There are three half-life categories designated by color. The half-life categories are as follows:

Yellow: P-32, P-33, Rb-86 and other radionuclides with half-lives < 60 days
Orange: S-35, I-125 and other radionuclides with half-lives > 60 days but < 90 days
Green: H-3 and C-14 and other radionuclides with half-lives > 90 days

The yellow and orange categories are held for decay by Health Physics. Half-life categories are very important for waste minimization and decreasing disposal costs for the University. Waste should be segregated by half-life category whenever possible and placed in the appropriately colored waste container. If waste is created containing two or more isotopes from different half-life categories, the waste should be disposed in the container for the longest lived isotope in the waste. For example, waste containing S-35 and C-14 should be placed in a C-14 waste container.

Waste containers should be kept closed at all times, unless waste is actively being added.

3. Restricted Materials

Keep in mind the following restrictions when disposing of radioactive waste:

  • Sharps (glass pipettes, needles, scalpels, razor blades) must be placed in sharps containers designated for radioactive sharps and not in any other type of waste container. Sharps do not require segregation by half-life.
  • Lead pigs should be collected in lead pig boxes available from Health Physics.
  • No more than 10 ml of liquid total should be placed in a solid waste container.
  • Scintillation vials (even if empty and “clean”) have their own waste container. Solids other than scintillation vials and/or liquids other than liquid scintillation cocktail should not be placed in the scintillation vial container.
  • Mixed wastes of different types should be segregated and minimized as much as possible to facilitate disposal. Smaller waste containers are available from Health Physics upon request.

Contact Health Physics with questions concerning items not specifically addressed in this list.

4. Container Contents Sheets

Container Contents Sheets are provided with each container from Health Physics and are color coded to correspond with the decay categories used to separate waste by half-life. The color copies were implemented to facilitate identification with a given container in laboratories having multiple decay categories. If you need additional Container Contents Sheets, copies are acceptable and the color coding is not required. Once waste is added to a container, all contents must be recorded on the Container Contents Sheet. Additional copies are available from Health Physics as well as in Appendix H.

The Container Contents Sheet is designed so that an entry can be made on the sheet each time that waste is placed into the container, and the contents can be easily totaled for disposal. The entries should detail the amount added, constituents, radionuclide and activity, and the initials of the waste generator. Full chemical names, in English, should be used for each constituent. Do not use abbreviations.

When the container is full, the individual entries from the waste generators should be totaled and the separate total section of the Container Contents Sheet should be completed by an appropriately trained waste generator. Prior to pick-up by Health Physics, the waste generator must survey the exterior of each container for contamination using a wipe smear and liquid scintillation counter analysis. The result of the wipe smear survey is then recorded on the Container Contents Sheet. Each sheet must be signed by the generator. The Generator Certification is required by regulation and includes confirmation that the generator has completed appropriate Radiation Safety training. Please refer to the Training Chapter.

5. Radioactive Waste Pick-Up Requests

When some or all of the waste containers in a laboratory are full, a pick-up may be requested from Health Physics. To request a pick-up, the generator or laboratory representative completes a Radioactive Waste Pick-up Request Form. Requests must be submitted to Health Physics any time before noon on the day preceding the next scheduled pick-up. The pick-up request forms may be submitted online, by Fax, Campus Mail, U.S. Mail, or in person. Refer to Appendix I for a blank form. Contact Health Physics at (303) 492-6523 for a current waste pick-up schedule. The Radioactive Waste Pick-up Request Form summarizes all of the information for the containers that need to be collected including the total volume of the container, radionuclide, total activity, constituents and total percentages of each constituent (which must total 100%), and pH for liquids. Indicator paper is acceptable for determining the pH value. Unless otherwise requested, each container collected will be replaced with an empty container of the same type and size.

Congruent with submittal of the Radioactive Waste Pick-up Request Form, each Container Contents Sheet must be completed, signed by the generator, and the contamination survey performed and noted on the sheet. Health Physics cannot collect waste containers without properly completed container contents sheets.

6. Sealed Source Disposal

Sealed sources require special provisions for disposal. Some sources may be returned to the manufacturer for reuse/recycling rather than disposed. A completed Container Contents Sheet and Radioactive Waste Pick-up Request Form will be required as mentioned in sections 4 and 5 of this chapter. Contact Health Physics at (303) 492-6523 to dispose of sealed sources or facilitate return to manufacturer.

Training

1. Introduction

The Radiation Safety Committee requires that basic radiation safety training be completed before any person begins working with unsealed sources of radioactive materials, sealed sources, and/or x-ray units. This training must cover the following topics: Basic Units and Concepts, Regulatory Limits and Requirements, Dose and Exposure Control Techniques, and rules specific to the institution. Consequently, training from other institutions cannot be accepted to meet the requirements of the University of Colorado Radioactive Materials License.

Once initial training has been completed, refresher training in basic radiation safety is required every three years in order to continue working with radioactive materials at the University of Colorado. This interval has been established by the Radiation Safety Committee (RSC).

2. Basic Radiation Safety Training

Satisfactory completion of the University of Colorado’s basic radiation safety training is required by everyone planning to use unsealed or sealed radioactive materials and/or x-ray radiation. It is the responsibility of the PI to ensure that radiation safety training is completed by laboratory personnel working with radioactive materials and/or radiation. A final exam must be completed with a score of at least 70% to satisfy this requirement. Researchers requesting dosimeters must complete this training before a dosimeter is issued.

The University’s basic radiation safety training for unsealed radioactive material is offered by Health Physics personnel and consists of computer-based training at the Health Physics Office in the Environmental Health and Safety Center. This training is available by appointment. Please call (303) 492-6523.

The following topics are addressed: Basic Units and Concepts, Dose and Exposure Control, Regulatory Limits and Requirements, Safe use of Radioactive Materials, and a general overview of the University of Colorado Radiation Protection Program. Information and techniques specific to a laboratory or experimental protocol is not covered under this training and should be provided by the Principal Investigator.

Basic Radiation Safety Training for sealed sources and x-ray units is available online.

3. Refresher Training

The Radiation Safety Committee requires all personnel using radioactive materials and/or radiation to complete refresher radiation safety training every three years. A final exam must be completed with a score of at least 70% to satisfy this requirement.

Refresher training may be completed using the Radiation Safety Handbook, and may be submitted online. Alternatively, refresher training may be completed via computer-based training at the Health Physics Office in the Environmental Health and Safety Center or as self-study through campus mail. Computer-based training is available by appointment. Please call (303) 492-6523.

The topics covered by refresher training are the same as those addressed in basic radiation safety training. It is the responsibility of the PI to ensure that refresher training is completed at appropriate intervals by laboratory personnel continuing to work with radioactive materials and/or radiation.

4. Laboratory Contact Training

Laboratory Contact Training is offered periodically by the Health Physics office. Topics include a detailed overview of: Waste management, Dosimetry management, Training requirements, Contamination Surveys, Survey Instrumentation, Inventory and Radioactive Materials Purchasing, Licensing, Storage and Use of Sealed Sources, and Storage and Use of X-ray machines. A one-on-one appointment to discuss these topics is available to new and existing radiation safety laboratory contacts if requested. Call Health Physics at (303) 492-6523 to schedule a training session.

5. Support Staff Training

Custodians and other personnel who may enter radiation laboratories are trained to recognize radioactive materials signs, labels, locations, and working safely in or around these areas. Radiation safety training is provided as part of the initial training by Facilities Management Supervisors.

6. Sealed Source User Training

The Radiation Safety Committee requires that users of sealed sources complete basic radiation safety training for sealed sources using self-study materials specifically addressing the concerns associated with sealed sources. A final exam must be completed with a score of at least 70% to satisfy training requirements. The training packet and quiz should be completed before a dosimeter is issued. Sealed Source Training and the final exam are available online.

7. X-Ray Machine User Training

The Radiation Safety Committee requires that users of radiation-producing machines complete basic radiation safety training for x-ray machines using self-study materials specifically addressing the concerns associated with radiation-producing machines. A final exam must be completed with a score of at least 70% to satisfy training requirements. The training packet and quiz should be completed before a dosimeter is issued. X-ray training and the final exam are available online.

8. Emergency Responder Training

Emergency responders, such as the University of Colorado Police Department, EH&S, and Fire Departments are encouraged to attend a training course addressing radiation emergencies at the University of Colorado. These classes are scheduled upon request.

Sealed Sources

1. Introduction

Sealed sources are radioactive material usually encased in metal or plastic. Sealed sources may present an external exposure hazard, but are not a significant contamination hazard under normal conditions. The basic principles of time, distance and shielding apply to the safe use of sealed sources. Please refer to the Introductory chapter for more information regarding fundamental principles. Basic radiation safety training for sealed sources should be completed prior to using sealed sources. Dosimetry may be required. When planning to use a sealed source, contact Health Physics at (303) 492-6523 to determine the training and dosimetry requirements.

Sealed sources are found in many different sizes and shapes. Some sources may be alpha, beta, gamma, or a combination of these emitters enclosed in metal or plastic. Sealed sources include those found in Electron Capture Detectors (ECDs) and Liquid Scintillation Counters (LSCs). They may also be inert metal onto which a thin film of radioactivity has been attached, known as plated sources. Metals which have been irradiated with neutrons, protons, or other particles, causing them to become “activated” may also be considered sealed sources. Sealed sources may have as little activity as a few Becquerels (Bq) (fractions of a microcurie (μCi)) or many MBq (mCi) and larger. They may be as small as a button, which can easily be lost, or contained in large devices. See Section 3 of this chapter.

2. Storage of Sealed Sources

Possession and use of sealed sources requires a laboratory license. Refer to the Laboratory Licensing chapter for information regarding licensing. Sealed sources are divided into two categories; those that must be leak tested (Tier I), and those that are exempt from leak tests (Tier II).

Tier I Sealed Sources

At the University of Colorado, Tier I sources are defined as α sources with activities greater than 370 kBq (0.010 mCi) and β or γ sources with activities greater than 3.7 MBq (0.10 mCi), as required by regulations. Health Physics performs leak test surveys (also known as “wipe smears”) in accordance with regulations on all Tier I sources at the University of Colorado. Leak tests are performed every three months for α Tier I sources and every six months for β or γ Tier I sources. Health Physics will notify the laboratory if a Tier I source is found to be leaking at a level exceeding regulatory limits, currently 185 Bq (0.005 µCi). All leaking sources must be removed from service for repair or disposal.

Tier II Sealed Sources

At the University of Colorado, Tier II sealed sources are sealed sources with activities less than the Tier I amounts indicated above. There are some radioactive materials which do not have a defined Tier II quantity in the regulations. Health Physics inventories all Tier II sources every six months in accordance with regulations. Health Physics will notify the laboratory if a Tier II source cannot be located.

Generally Licensed Devices

Generally Licensed Devices (GLDs) include sealed sources such as 63Ni electron capture detectors (ECDs), 85Kr aerosol neutralizers and 210Po static eliminators. GLDs are leak tested and tracked as Tier I sources for a sources with activities greater than 370 kBq (0.010 mCi) and β or γ sources with activities greater than 3.7 MBq (0.10 mCi). Generally Licensed Devices with activities less than the above will be treated as Tier II sources. As with Tier I and Tier II sources, a license is required before obtaining a GLD. All GLDs must be received and disposed through the Health Physics Office.

The exception is 210Po static eliminators with an activity of 18.5 MBq (500 μCi) or less. These devices are exempt from licensing, leak testing and inventories. However, labs using such devices should notify the Health Physics Office at (303) 492-6523 and have the devices received and disposed through Health Physics whenever possible.

3. Use of Sealed Sources

Health Physics posts a Sealed Source Inventory on or near each storage location. The Sealed Source Inventory describes the sources stored in each location. Cabinets used to store sealed sources should be kept locked at all times.

If a sealed source is to be used at another location in the laboratory, it must be signed out on the Sealed Source Sign-out Log. This log is generally found near the cabinet where the source is stored and must be completed, regardless of location and duration of use. When the source is returned to storage, this also must be noted on the Sealed Source Sign-out Log. Refer to Appendix J for sample forms.

Contact Health Physics at (303) 492-6523 if sources are to be moved to a location outside of the laboratory’s authorized locations. Proper accountability is essential for sealed sources. If disposal is required, please refer to the Waste chapter or contact Health Physics.

4. Gas Chromatographs & Electron Capture Detectors

Some of the Gas Chromatographs (GCs) at the University of Colorado have Electron Capture Detectors (ECDs) which contain a sealed source, typically 63Ni or 3H (tritium). These machines usually have a radioactive materials sticker or label, identifying the presence of the source. Dosimetry is not required for normal operation of these devices. However, Sealed Source Training is required before using these machines. See Training Chapter.

These sealed sources are inventoried and leak tested periodically by Health Physics staff. If a source is found to be leaking at a level above regulatory limits, it must be taken out of service for repair or disposal.

5. Liquid Scintillation Counters

Many laboratories use liquid scintillation counters (LSCs) to analyze wipe smears and other samples. Machines which calculate H# (efficiency) may also contain a sealed gamma sources, typically 137Cs or 226Ra. These internal sources are managed in the same way as other sealed sources and must be removed from the machine prior to disposal. Please refer to Section 2 of this chapter. Contact Health Physics at (303) 492-6523 for assistance with disposal. Most LSCs have calibration check sources for routine use. These sources usually are 3H or 14C in sealed liquid form and are inventoried regularly by Health Physics.

6. Portable Gauges and XRF Devices

Portable gauges and XRF Devices not in storage must be leak tested by Health Physics and require training of personnel working with the source. When planning to obtain or use such a device, contact Health Physics at (303) 492-6523 for more information on licensing, using, and storing these items safely.

Exposure Control

1. Introduction

Dose Limits

The United States Nuclear Regulatory Commission has established an annual limit on the radiation dose individuals may receive. The limits were developed using international recommendations and risk estimates. The Colorado Department of Public Health and Environment (CDPHE) is responsible for enforcing compliance with these limits in the State of Colorado. Notice that the limits are significantly lower for children and members of the general public than for radiation workers in laboratories.

Individual Annual Dose Limit
Radiation Worker
Whole Body (penetrating radiation) 50 mSv (5,000 mrem)
Lens of the Eye 150 mSv (15,000 mrem)
Skin and Extremeties 500 mSv (50,000 mrem)
Individual Organs (internal dose) 500 mSv (50,000 mrem)
Embryo/Fetus (during gestation period) 5 mSv (500 mrem)
Member of General Public 1 mSv (100 mrem)
Minor (under 18 years old) 1 mSv (100 mrem)

Exposure to radiation does not automatically determine the dose, because of mitigating factors such as:

  • The energy and type of radiation emitted from the source;
  • The amount of time spent near the radioactive source;
  • The distance from the source; and
  • Any shielding used by the individual.

Dose is a measurement of the radiation energy which is absorbed by tissue. Please refer to the Introduction chapter for more information regarding time, distance, and shielding and fundamental principles of radiation safety.

Relative Risk

How will radiation exposure increase the chance (RISK) of cancer death?

The National Research Council established committees on the Biological Effects of Ionizing Radiations (BIER) to prepare a series of reports to advise the U. S. government on the health consequences of radiation exposures. One of these committees, BIER VII, published a report in 2006 titled Health Risks from Radiation. In this report, the BIER VII committee reaffirmed the findings from the BEIR V committee (report published in 1990), which indicated that the risk of cancer death is 0.08% per rem for doses received rapidly (acute exposure). The risk from doses received over a long period of time (chronic exposure) might be as little as 0.04% per rem or 2-4 times lower. These risk estimates are averages considering males and females, all age groups, and all forms of cancer. Significant uncertainty is associated with the estimates. BEIR VII also noted that relatively high levels of radiation exposure increased the risk of heart disease and stroke, but did not give specific risk estimates. The BIER VII committee stated that every exposure to radiation produces a corresponding increase in cancer risk (linear non-threshold, or stochastic, model). Most scientists believe that this is a conservative estimate or model of risk from low doses of radiation.

In the United States, the current death rate from cancer is approximately 20-25%, therefore out of any group of 10,000 United States citizens, about 2,000 will die of cancer. Although about 20% of the population will die from cancer, it is impossible to say which specific individuals will die.

Based on these assumptions, in a population of 10,000 people exposed to one rem (per person to the whole body), approximately eight additional deaths (0.0008*10,000*1 rem) would be due to the radiation exposure. So, instead of the 2,000 people expected to die from cancer naturally, now there are 2,008. This small increase in the expected number of deaths would not be seen in this group, due to natural fluctuations in the rate of cancer.
It is not certain that 8 people will die, but there is a risk of 8 additional deaths in a group of 10,000 people if they all receive one rem instantaneously (acute exposure). If the exposure is received over a long period of time (chronic exposure), the risk would be reduced to less than 4 additional expected fatal cancers.

Relative risk must be balanced with the benefit from the exposure to radiation. The risk is a small increase in developing fatal cancer. Risk comparisons show that exposure to radiation has a small risk relative to risks taken daily including driving a car, eating fatty foods, or smoking cigarettes. Some benefits from radiation include medical diagnosis and treatment, electricity, and results from scientific research.

Personnel Monitoring

Federal and State regulations require that individuals expected to receive more than 10% of the annual dose limits be monitored for occupational dose. At the University of Colorado, very few individuals are likely to exceed 10% of the limits. However, most technicians working in laboratories using radioactivity are monitored with a dosimeter in order to maintain a permanent record of the dose they may receive. Any dose received is recorded in units of mrem, and a record of the dose is maintained for the “life of the institution.” Individuals using significant amounts of radionuclides that are likely to cause internal exposure are monitored periodically using bioassay techniques.

2. Dosimetry

Dosimeters are issued after proper training has been completed and a completed dosimetry application is received by Health Physics. Refer to Appendix K for a blank dosimetry application. By regulation, the University of Colorado is required to request exposure histories from all institutions at which individuals have worked in order to build a lifetime exposure history. Extremity monitoring rings are issued to individuals working with greater than 37 MBq (1 mCi) of high energy radionuclides and at the discretion of the Radiation Safety Officer (RSO), following evaluation of experimental protocol. Extremity rings may be requested by an individual. A dosimeter may be canceled by returning it along with its holder to Health Physics with a note indicating cancellation is needed.

Whole Body

Individuals in laboratories using radionuclides other than 3H or 14C should apply for a whole body dosimeter. This includes individuals using sealed sources and radiation-producing machines.

Whole body dosimeters are designed to measure whole body dose to penetrating (x- and gamma ray) radiation as well as beta particle radiation. Consequently, the badge should be worn on the portion of the body most likely to receive a dose, usually on the front of the chest, anywhere between the neck and the waist. Care should be taken to prevent contamination of the badge. If contamination occurs, the badge should be immediately returned to Health Physics and a replacement will be issued for the remainder of the monitoring period. All dosimeters are assigned to specific individuals and are not transferable.

Extremity

Those individuals using 37 MBq (1 mCi) or more of 32P or other high-energy radionuclides are advised to be monitored with an extremity dosimeter, also known as a ring badge or TLD ring. Individuals performing beam alignments on radiation-producing machines should also be monitored with an extremity ring.

It is the responsibility of the Principal Investigator and/or experimenter to ensure that an extremity ring is worn when 37 MBq (1 mCi) or more of 32P or other high energy radionuclide is used during an experiment, or when completing beam alignments on x-ray machines. Extremity rings are designed to measure extremity dose. They should be worn on the hand most likely to receive a dose. Multiple sizes are available. The labeled section on the ring should be closest to the radiation source, usually facing into the palm.

Embryo/Fetus

If a woman becomes pregnant, it is her choice whether or not to “declare” her pregnancy. A Declared Pregnant Woman has a lower dose limit than a non-pregnant radiation worker due to the embryo/fetus limit. If the pregnancy is not “declared,” the woman continues working under the radiation worker dose limit. She may notify her supervisor and Health Physics that she is pregnant by completing a Fetal dosimeter application. The notification must be in writing in order to implement the lower dose limit. Refer to Appendix L for a blank Fetal dosimeter application. This application includes the signature of the worker affirming that she wishes to fall under the lower dose limit, as well as the estimated conception date. Individuals in the fetal dosimetry program will receive dose reports from Health Physics during the pregnancy.

3. Bioassay

Some radionuclides used at the University of Colorado present an increased risk of internal contamination. Use of unbound forms of radioiodine and 3700 MBq (100 mCi) of 3H (tritium) requires bioassays to monitor internal dose. Prior to working with these radionuclides, each researcher must have “baseline” bioassays to ensure appropriate measurements following the experiments. Any internal dose received will be included in the individual’s dosimetry record. The Total Effective Dose Equivalent (sum of the internal and external doses to an individual) will be determined. If the Total Effective Dose Equivalent (TEDE) exceeds 0.05 Sv (5 rem), CDPHE must be notified within 24 hours. If the TEDE exceeds 0.25 Sv (25 rem), CDPHE must be notified immediately.

Anyone planning to work with unbound radioiodine or large amounts of 3H (tritium) should contact Health Physics to schedule a baseline bioassay. The RSO may require that the experimental work be performed in the Health Physics facility. Follow-up bioassays will be scheduled, taking into account the biological half-life and anatomical target of the radionuclide involved.

Because most iodine in the body accumulates in the thyroid, internal contamination from radioiodine is measured by a non-invasive bioassay of the thyroid. The bioassay requires about 10 minutes.

Tritium (3H) replaces stable hydrogen in the body water of the researcher; therefore urinalysis is necessary to measure the amount of internal (3H) contamination.

Bioassays will be performed at the following intervals:

  • For Radioiodines – Within one week of using more than 1850 MBq (50 mCi) of I-125 or I-131 in a single operation (or within one week of using 37 MBq (10 mCi) in a non-contained form).
  • For Tritium – Within one week of using greater than 3700 MBq (100 mCi) of tritium in a single operation. For a continuous experiment using this amount of tritium, bioassays will be performed weekly (on the same day of each week, if possible) until it can be assessed that urine concentrations do not exceed this level in a calendar quarter. After that, bioassays may be taken monthly (on the same day of each month, if possible) as long as this level is maintained.

4. Environmental Monitoring

As with all hazardous materials, radioactive materials may not be discharged into the sanitary sewer (down the drain) or released in any other way by researchers at the University of Colorado. In the event of a release, alert Health Physics immediately at (303) 492-6523. Refer to the Mishaps and Emergencies chapter for additional information.

Mishaps & Emergencies

If a radiation emergency occurs, notify EH&S Health Physics immediately.

Boulder Campus
EH&S Health Physics (Campus Hours) – (303) 492-6523
Environmental Health & Safety (Campus Hours) – (303) 492-6025
UCB Police Dispatch (After Campus Hours) – 911 or (303) 492-6666

Colorado Springs Campus
EH&S Health Physics (Campus Hours) (303) 492-6523
Public Safety (After Campus Hours) (719) 262-3111
UCCS Police Department (After Campus Hours) 9-911

1. Introduction

In the event of an emergency involving radiation, Health Physics should be notified as soon as possible. If the emergency is life threatening, University Police (911) should be contacted. Be sure to indicate that radiation is involved. The police will contact Health Physics personnel if radiation or radioactive materials are involved. Please have the following information available for emergency personnel:

  1. Your name and the name of the Principal Investigator in charge of the laboratory
  2. Type of radiation incident (i.e., spill, x-ray malfunction, lost sealed source, etc.)
  3. The location of the incident
    1. Building
    2. Room number
    3. Location of a spill or machine within the laboratory
  4. A phone number where you can be reached, as well as the location where you will meet emergency personnel
  5. The radionuclide (or energy if an x-ray machine)
  6. The estimated activity involved
  7. The volume of liquid or solid involved
  8. The chemical form of the labeled compound

2. Unsealed Radionuclide Spill Clean-Up

Contamination in the Laboratory

In the event of a spill involving radioactive materials, immediately notify the other personnel in the immediate area of the spill. All personnel not involved in the spill should vacate the area, avoiding the spill area while leaving. Contact Health Physics at (303) 492-6523 for help cleaning up the spill, especially if it involves mixed radioactive/hazardous materials.

To clean up the spill, use personal protective equipment such as a lab coat, eye protection, disposable gloves, and disposable booties. Be sure to wear appropriate dosimetry and have a survey instrument nearby. See Appendix M For Solid Spill Procedures and Appendix N for Liquid Spill Procedures.

Personnel Contamination

Health Physics should be notified of personal contamination incidents. A dose assessment may need to be performed. The Radiation Safety Officer (RSO) will need to know how much radiation was involved, the radionuclide, and approximately how long the radiation was present on the skin and/or clothing. See Appendix O for Personnel Decontamination Procedures.

Ingestion/Inhalation/Injection of Radioactive Materials

Health Physics should immediately be notified of any ingestion, inhalation, or injection of radioactive materials. Inhalation of radioactive materials may be remedied somewhat by intentional coughing or deep-breathing in a clean area. Injection of radioactive materials may be remedied somewhat by flushing the area thoroughly. In some cases, bioassay tests may need to be performed to determine the amount of radiation ingested, inhaled, or injected. See Exposure Control chapter.

3. Leaking Sealed Sources

Health Physics performs leak tests on sealed sources. If the source is found to be leaking above regulatory levels, it will be taken out of service by Health Physics. Leaking sealed sources can cause contamination hazards, as well as exposure hazards. Please refer to the Sealed Sources chapter for more information.

If a sealed source appears to be leaking, use personal protective equipment and a survey instrument to check the area near the source for evidence of contamination. Contact Health Physics immediately at (303) 492-6523 for help in reducing the contamination hazard.

4. High Radiation Exposure

Certain x-ray machines or areas on campus could result in possible exposure to high radiation levels. If an exposure to high levels of radiation has occurred or is suspected, contact Health Physics immediately at (303) 492-6523. The RSO may need to perform a dose calculation and will need to know the duration of the exposure, the proximity to the radiation source, and the activity or energy of the source.

X-Ray Machines

1. Introduction

Management of x-ray machines is the responsibility of the Principal Investigator (PI) under whose license the machine is being used. For information concerning set up of an x-ray laboratory, see the Laboratory Licensing chapter. It is the responsibility of each member of the laboratory to maintain safe use of the x-ray machine(s) in their area.

X-ray machines are certified periodically by a State Qualified Expert. Additionally, radiation surveys and surveys following repairs or changes are coordinated through Health Physics. See Area Requirements in this chapter. Any new x-ray equipment should be registered with Health Physics to ensure compliance with these inspection requirements.

2. Purchasing

Laboratories wishing to order an x-ray machine should first obtain a license for the device from the Radiation Safety Officer (RSO) and Radiation Safety Committee (RSC). Please refer to the Laboratory Licensing chapter for licensing information. Radiation safety training for x-ray users should be completed by all personnel planning to use the device prior to beginning work with the machine. Please refer to the Training chapter. Whole body dosimeters as well as extremity rings may be issued to personnel using x-ray machines, as determined by Health Physics. Please refer to the Exposure Control Chapter.

X-ray machines should only be ordered using a Purchase Request (PR)/Standing Purchase Order (SPO) through the Procurement Service Center. The PRs and SPOs must be approved in advance by Health Physics. The University’s Procurement Card, other credit/debit cards, and other purchasing methods may NOT be used to order radiation-producing machines unless PRIOR approval is granted by the RSO or the Alternate RSO. Exceptions may be granted on a case-by-case basis.

X-ray machines may be delivered to the area of use as long as prior notification has been made to Health Physics.

3. Analytical X-Ray Devices

Analytical x-ray systems and equipment are groups of components utilizing x-ray or gamma radiation to determine the elemental composition or examine the microstructure of materials using diffraction or fluorescence analysis. Analytical x-ray devices are regulated under Part 8 of the Rules and Regulations Pertaining to Radiation Control issued by the State of Colorado. A summary of Part 8 requirements is included in this chapter.

Analytical x-ray devices have the potential for significant radiation exposure to personnel. Therefore, the restrictions outlined in the regulations and by the RSC must be followed. Contact Health Physics at (303) 492-6523 to review these regulations. Analytical x-ray devices are certified once every two years by a State Qualified Inspector.

Summary of Part 8 Requirements

Equipment Requirements

Each x-ray unit must have a safety device which prevents the entry of any portion of an individual’s body into the primary x-ray beam path, or which causes the beam to be shut off upon entry into its path. This may also be known as an interlock. The x-ray unit must also have a readily discernible indication of x-ray tube “on-off” status; shutter “open-closed” status; and an easily visible warning light labeled with the words X-RAY ON, or similar words. Any equipment installed after October 1, 1978 shall have fail-safe characteristics in the warning devices.

Any unused ports shall be secured in the closed position, in a manner which will prevent casual opening. All analytical x-ray equipment shall be labeled with a readily discernible sign or signs bearing the radiation symbol an the words: Caution High Intensity X-ray Beam on the source housing; Caution Radiation – This equipment produces Radiation When Energized near any switch that energizes an x-ray tube; or Caution Radioactive Material if the radiation source is a radionuclide. If the source is a radionuclide, refer to the Laboratory Licensing chapter for licensing of sealed sources.

Any x-ray unit installed after October 1, 1978 shall be equipped with a shutter for each port on the radiation source housing that cannot be opened unless a collimator or a coupling has been connected to the port. Each source housing shall be equipped with an interlock that shuts off the tube if it is removed from the radiation source housing, or if the housing is disassembled. Each radioactive source housing, or port cover or each x-ray tube housing shall be constructed so that, with all shutters closed, the radiation measured at a distance of 5 cm from its surface is not capable of producing a dose in excess of 0.025 mSv (2.5 mrem) in one hour. For systems utilizing x-ray tubes, this limit shall be met at any specified tube rating. These requirements should be met by the manufacturer. Contact Health Physics for assistance.

Each x-ray generator shall be supplied with a protective generator cabinet which limits leakage radiation measured at a distance of 5 cm from its surface such that it is not capable of producing a dose in excess of 2.5 μSv (0.25 mrem) in one hour.

Area Requirements

The local components of an analytical x-ray system shall be located and arranged and shall include sufficient shielding, or access control such that no radiation levels exist in any surrounding local area which could result in a dose to an individual present in excess of the public dose limits. Public dose limits are 1 mSv (100 mrem) per year and 0.02 mSv (2 mrem) in any one hour.

Radiation surveys shall be performed upon installation of the equipment, and at least once every 12 months thereafter; following any change in the initial arrangement, number or type of local components in the system; following any maintenance requiring the disassembly, or removal of a local component in the system; during the performance of maintenance and alignment procedures if the procedures require the presence of a primary x-ray beam when any local component of the system is disassembled, or removed; any time a visual inspection of the local components in the system reveals an abnormal condition; and whenever personnel monitoring devices show a significant increase over the previous monitoring period, or the readings are approaching occupational (radiation worker) dose limits. Occupational dose limits include 0.05 Sv (5 rem) per year whole body dose, 0.15 Sv (15 rem) per year eye dose, and 0.5 Sv (50 rem) per year shallow dose to the skin or to any extremity.

Each area or room containing analytical x-ray equipment shall be conspicuously posted with a sign, or signs bearing the radiation symbol and the words Caution X-Ray Equipment. Each area should also have Emergency Notification signs which include telephone numbers for the PI and/or other emergency contact designee. These signs may be obtained free of charge from Health Physics.

Operating Requirements

Normal operation procedures shall be written and available to all analytical x-ray equipment workers. No individual shall be permitted to operate analytical x-ray equipment in any manner other than that specified in the procedures unless such individual has obtained the written approval of the RSO.

No individual shall bypass a safety device or interlock, unless such individual has obtained the written approval of the RSO. Such approval shall be for a specified period of time. When a safety device or interlock has been bypassed, a readily discernible sign bearing the words Safety Device Not Working, or similar words, shall be placed on the radiation source housing.

Except as described in the previous paragraph, no operation involving removal of covers, shielding materials, or tube housings, or modifications to shutters, collimators, or beam stops shall be performed without ascertaining that the tube is off and will remain off until safe conditions have been restored. The main switch, rather than interlocks, shall be used for routine shutdown in preparation for repairs.

If the x-ray device contains a radioactive source, replacement, leak testing, or other maintenance or repair procedures shall be conducted only by individuals specifically authorized under the University’s Radioactive Materials License. For information concerning these tasks, contact Health Physics at (303) 492-6523.

Personnel Requirements

Individuals must complete x-ray training through Health Physics and on-the-job training in the laboratory prior to operating or maintaining analytical x-ray equipment. This training will include identification of radiation hazards associated with the use of the equipment; significance of various radiation warning, safety devices and interlocks incorporated into the equipment; proper operating procedures for the equipment; recognition of symptoms of an acute localized exposure; and proper procedures for reporting an actual or suspected exposure. Please refer to the Training chapter.

Personnel dosimeters issued by Health Physics shall be used by analytical x-ray equipment workers using systems having an open-beam configuration and not equipped with a safety device; and personnel maintaining analytical x-ray equipment if the maintenance procedures require the presence of a primary x-ray beam when any local component in the analytical x-ray system is disassembled or removed.

4. Medical (Human Use) X-Ray Devices

Medical x-ray devices (healing arts or veterinary medicine) are regulated under Part 6 of the Rules and Regulations Pertaining To Radiation Control issued by the State of Colorado. PIs using a medical x-ray device for human use must be licensed by the Medical Licensing Board of the State of Colorado. These devices are inspected every year by a State Qualified Inspector. Contact Health Physics at (303) 492-6523 for assistance with licensing a medical x-ray device.

5. Security and Storage

Each laboratory must ensure security of x-ray machines. This may require locking of laboratory doors and/or locking the device. All laboratory areas in which x-ray machines are used should have a sign displayed on all entrances as indicated under Area Requirements described above. Health Physics may supply appropriate signs and stickers. Operating keys should not be kept in the machine when the machine is not in active use.

6. Transfers

X-ray machines may be transferred to another licensed laboratory with prior approval from Health Physics. Transfers between buildings should be arranged through Health Physics to ensure safe handling and transport. The machine will be transferred to the laboratory license of the recipient through a license amendment. Please refer to the Laboratory Licensing chapter.

Glossary

Absorbed Dose
The energy imparted to matter by ionizing radiation per unit mass of irradiated material at the place of interest. The SI unit is the gray (Gy); 1 Gy = 1 Joule/Kg, or 100 rads. The conventional unit of absorbed dose is the rad; 1 rad = 100 ergs/g. See also Dose, Absorbed.

Activated Metal
A metal that has been made radioactive through the process of activation. For the purpose of the University of Colorado, an activated metal is considered a sealed source and is usually a small metal disc. See also Activation.

Activation
The process of making a radionuclide by bombarding a stable element with neutrons, protons, or other nuclear radiation.

Activity
Time rate of nuclear transformations. The conventional unit of activity is the curie, Ci and the SI unit of activity is the Becquerel, Bq. See also Radioactivity and Decay, Radioactive.

ALARA
Acronym for “As Low As Reasonably Achievable.” An approach to radiation protection which has the objective of attaining individual and collective doses as far below regulatory limits as is reasonably achievable. ALARA considers the state of technology, the economics of improvements in relation to the state of technology and benefits to the public health and safety, and other societal and socioeconomic considerations, and in relation to utilization of nuclear energy and radioactive materials in the public interest.

Alpha Particle
A positively charged particle ejected spontaneously from the nuclei of some radioactive elements. Identical to a helium nucleus having a mass number of 4 and an electrostatic charge of +2, it has low penetrating power and a short range. The most energetic alpha particle generally fails to penetrate the dead layers of cells covering the skin. Alphas are hazardous when an alpha-emitting radionuclide is inside the body.

Analytical X-ray
An x-ray producing device used to determine elemental composition, or to examine the microstructure of materials using diffraction or fluorescence analysis. See also Medical X-ray and X-ray.

Annual Limit on Intake (ALI)
The derived limit for the amount of radioactive material taken into the body of an adult worker by inhalation or ingestion in a year. An ALI is the smaller value of intake of a given radionuclide in a year by the reference man that would result in a committed effective dose equivalent of 0.05 Sv (5 rem) or a committed dose equivalent of 0.5 Sv (50 rem) to any individual organ or tissue.

Area Survey
A survey using a portable radiation survey meter to determine the dose rate in a given area. Most radiation survey meters have scales of mR/hr or counts per minute (cpm). See also Contamination Survey.

Atom
The smallest particle of an element that cannot be divided or broken up by chemical means. It consists of a central core of protons and neutrons, called the nucleus. Electrons revolve in orbits in the region surrounding the nucleus.

Atomic Number
The number of positively charged protons in the nucleus of an atom.

Attenuation
The process by which the number of particles or photons entering a body of matter is reduced by absorption and scatter.

Audit, Laboratory
See Laboratory Audit.

Authorized User
An individual who uses radioactive materials and/or radiation unsupervised, or supervises their use and is issued a University of Colorado Radioactive Materials License. See also Principal Investigator and Licensee.

Background Radiation
Radiation from cosmic sources; naturally occurring radioactive Radiation materials, including radon and global fallout as it exists in the environment from the testing of nuclear explosive devices. It does not include radiation from source material, byproduct material, or special nuclear materials. The typically quoted average individual exposure from background radiation is 360 millirem per year.

Becquerel (Bq)
The unit of radioactive decay equal to 1 disintegration per second. 3.7 x 1010 Bq = 1 Curie.

Beta Particle
A charged particle emitted from a nucleus during radioactive decay, with a mass equal to 1/1837 that of a proton. A negatively charged beta particle is identical to an electron. A positively charged beta particle is called a positron. Large amounts of beta radiation may cause skin burns, and beta emitters are harmful if they enter the body. Beta particles may be stopped by thin sheets of plastic, wood, or metal.

BIER VII
The National Research Council’s committee on the Biological Effects of Ionizing Radiations (BIER). Committee VII published a report in 2006 titled Health Risks From Radiation which suggested levels of risk associated with radiation exposure.

Bioassay
The determination of kinds, quantities or concentrations, and in some cases, the locations of radioactive material in the human body, whether by direct measurement (in vivo) or by analysis and evaluation of materials excreted or removed from the human body (in vitro).

Biohazardous Waste
For the purposes of this handbook, biologically active waste material that has not been rendered non-infectious using bleach or other disinfectant. Reminder – Autoclaves are NOT PERMITTED for use with radioactive materials.

Biological Half-life
The time required for a biological system, such as that of a human, to eliminate, by natural processes, half of the amount of a substance (such as a radioactive material) that has entered it.

Calibration
The act or process of tuning an instrument by determining the deviation from a standard to ascertain the proper correction factors. Refers to radiation survey meters for the purposes of this handbook. Radiation survey meters are calibrated at least annually by Health Physics.

CDPHE
Acronym for the “Colorado Department of Public Health and Environment” which establishes and enforces the regulations relating to radiation and radioactive materials in the State of Colorado.

Container Contents Sheet
A sheet of paper near or attached to a waste container which describes the waste material inside the container. Each sheet must be completed properly for the container to be collected for disposal.

Contamination
The deposition of unwanted radioactive material on the surfaces of structures, areas, objects, or personnel. It may also be airborne or internal (inside components or personnel).

Contamination Survey
A survey using a wipe smear and liquid scintillation counter (LSC) or gamma counter to determine the radioactive contamination in a given area. Most LSCs and gamma counters provide results in counts per minute (cpm) which are converted to decays per minute (dpm) using the efficiency of the instrument. See also Area Survey.

Cosmic Radiation
Penetrating ionizing radiation, both particulate and electromagnetic, originating in outer space. Secondary cosmic rays, formed by interactions in the earth’s atmosphere, account for approximately 0.45 to 0.5 mSv (45 to 50 mrem) of the 3.6 mSv (360 mrem) background radiation that an average individual receives in a year.

Curie (Ci)
The conventional unit used to describe the intensity of radioactivity in a sample of material. The curie is equal to 37 billion disintegrations per second, which is approximately the rate of decay of 1 gram of radium. A curie is also a quantity of any radionuclide that decays at a rate of 37 billion disintegrations per second or 37 billion Becquerels. Named for Marie and Pierre Curie, who discovered radium in 1898.

Decay, Radioactive
The decrease in the amount of any radioactive material with the passage of time, due to the spontaneous emission from the atomic nuclei of either alpha or beta particles, often accompanied by gamma radiation. See also Activity and Radioactivity.

Declared Pregnant Woman
A woman who has voluntarily informed her employer, in writing, of her pregnancy and the estimated date of conception. For the purposes of this handbook, informing the employer means informing Health Physics.

Decontamination
The reduction or removal of contaminating radioactive material from a structure, area, object, or person.

Dose
The absorbed dose, given in grays (Gy) or rads, that represents the energy absorbed from the radiation in a gram of any material. Furthermore, the biological dose or dose equivalent, given in sieverts (Sv) or rem, is a measure of the biological damage to living tissue from the radiation exposure.

Dose, Absorbed
The amount of energy deposited in any substance by ionizing radiation per unit mass of the substance. It is expressed numerically in grays (Gy) or rads. See also Absorbed Dose.

Dose Equivalent
A term used to express the amount of biologically effective radiation dose when modifying factors have been considered. The product of absorbed dose multiplied by a quality factor multiplied by a distribution factor. It is expressed numerically in sieverts (Sv) or rems. If the dose is in Gray (Gy), the dose equivalent is in sieverts (Sv). If the dose is in rads, the dose equivalent is in rems.

Dose Limit
A limitation on the legal amount of dose allowed during a given period, usually one year. The values are established in regulations and enforced by CDPHE. Dose limits vary depending upon the classification of the individual of concern; for example, a radiation worker, a member of the public, a minor, or an embryo/fetus.

Dosimeter
A portable instrument for measuring and registering the total accumulated dose to ionizing radiation.

Dosimetry
The theory and application of the principles and techniques involved in the measurement and recording of radiation doses.

Dose Rate
The radiation dose delivered per unit time, e.g. rem per hour or mrem per hour. In practice, it may also be expressed as mR/hr. New meters also reflect SI units of Sieverts per hour (Sv/hr) or millisieverts per hour (mSv/hr).

Effective Dose Equivalent
The sum over the tissues of the product of the dose equivalent in a tissue, the weighting factor representing its proportion of the risk resulting from irradiation of tissue to the total risk when the whole body is irradiated uniformly.

Effective Half-life
The time required for the amount of a radioactive element deposited in a living organism to be diminished 50% as a result of the combined action of radioactive decay and biological elimination.

Electron
An elementary particle with a negative charge and a mass equal to 1/1837 of the proton. Electrons surround the positively charged nucleus and determine the chemical properties of the atom.

Element
One of the 103+ known chemical substances that cannot be broken down further without changing its chemical properties. Some examples include: Hydrogen, Nitrogen, Gold, Lead, and Uranium.

Emergency Responder
For the purposes of this handbook, anyone responding to an  emergency involving radioactive materials. These individuals may include EH&S, Police, and Fire personnel.

Environmental Monitoring
Monitoring conducted to evaluate radioactive material and/or radiation released to the environment to ensure compliance with applicable regulations. Monitoring may include area dosimetry, air samples, and water samples.

Equipment Survey
A contamination survey conducted to ensure that an instrument or piece of equipment is not contaminated prior to transfer and/or disposal.

Exposure
Being exposed to radiation or to radioactive material. Also that amount of γ or x-radiation that produces one electrostatic unit of charge in air at standard temperature and pressure. This concept applies only to electromagnetic radiation in air.

External Radiation
Exposure to ionizing radiation when the radiation source is located outside the body.

Extremity Dosimeter
An instrument used to measure and register the accumulated dose received by an extremity. Generally associated with radionuclides emitting high energy beta particles or gamma rays. See also Dosimeter, Fetal Dosimeter, Ring Badge, and Whole Body Dosimeter.

Extremity (-ies)
The hands, forearms, elbows, feet, knee, leg below the knee, and ankles. Permissible radiation exposures in these regions are generally greater than the whole body because they contain less blood forming organs and have smaller volumes for energy absorption.

Fetal Dosimeter
An instrument used to measure and register the accumulated dose received by an embryo/fetus. See also Declared Pregnant Woman, Dosimeter and Whole Body Dosimeter.

Freezer Frost
The frost created in a freezer that can be potentially contaminated with radioactive materials, especially tritium (H-3).

Gamma Ray
High-energy, short wavelength, electromagnetic radiation emitted from the nucleus. Gamma radiation frequently accompanies alpha and beta emissions and always accompanies fission. Gamma rays are very penetrating and are best stopped or shielded by dense materials, such as lead or uranium. Gamma rays are similar to X-rays.

Geiger-Mueller Counter
A radiation detection and measuring instrument. It consists of a gas-filled tube containing electrodes, between which there is an electrical voltage, but no current flowing. When incoming radiation ionizes the gas in the tube, a short, intense pulse of current passes from the negative electrode (cathode) to the positive electrode (anode) causing an electrical pulse which is measured or counted by the meter. The number of pulses per second measures the intensity of the radiation field. It was named for Hans Geiger and W. Mueller, who invented it in the 1920s. It is sometimes simply called a Geiger counter or a GM Counter.

Generator
For the purposes of this handbook, anyone who handles or produces hazardous waste.

Generator Cabinet
A protective cabinet surrounding each x-ray generator which limits leakage radiation measured at a distance of 5 centimeters from its surface such that it is not capable of producing a dose in excess of 0.25 mrem (2.5 μSv) in one hour.

Genetic Effects
Those effects of radiation that may be transmitted to the progeny of exposed individuals.

Gray (Gy)
The System International (SI) unit of absorbed radiation dose equal to 1 Joule per Kilogram. 1 Gy = 100 rad.

Half-life
The time in which one half of the atoms of a particular radioactive substance disintegrates into another nuclear form. Measured half-lives vary from millionths of a second to billions of years. Also called physical or radiological half-life.

Half-life, Biological
The time required for the body to eliminate one half of the material taken in by natural biological means.

Half-life, Effective
The time required for a radionuclide contained in a biological system, such as a human or an animal, to reduce its activity by one half as a combined result of radioactive decay and biological elimination.

Half-life Categories
The categories used by Health Physics to separate wastes for decay-in-storage prior to disposal. There are three categories, identified by the colors yellow, orange and green, representing the half-lives less than 60 days, between 60 and 90 days, and greater than 90 days.

Health Physics
The science concerned with recognition, evaluation, and control of health hazards from ionizing radiation. The group in Environmental Health and Safety that is responsible for Radiation Safety.

High Radiation Area
Any area with dose rates greater than 1 mSv (100 mrem) in one hour at 30 cm from the source or from any surface through which the radiation penetrates. These areas must be posted as “high radiation area” and access into these areas is maintained under strict control.

Hot
A colloquial term meaning highly radioactive.

Hot Spot
The region in a radiation / contamination area in which the level of radiation / contamination is noticeably greater than in neighboring regions in the area.

Interlock
For the purposes of this Handbook, a safety device used to prevent an operator from inadvertently placing any portion of their body in the direct beam of an x-ray device.

Internal Radiation
Nuclear radiation resulting from radioactive substances in the body. Some examples are Iodine-131 (found in the thyroid gland) and Strontium-90 and Plutonium-239 (found in bone).

Inventory
See Radioactive Materials Inventory.

Inverse Square Law
A result of geometry, this law shows that the radiation intensity is inversely proportional to the square of the distance from the source. Therefore, if the distance is increased from 1 meter to 2 meters, the intensity will be only one fourth of the original intensity, 1/22.

Ionization
The process of adding one or more electrons to, or removing one or more electrons from, atoms or molecules, thereby creating ions. High temperatures, electrical discharges, or nuclear radiations can cause ionization.

Ionizing Radiation
Any radiation capable of displacing electrons from atoms or molecules, thereby producing ions. Some examples are alpha, beta, gamma, X-ray, neutrons, and ultraviolet light. High doses of ionizing radiation may produce severe skin or tissue damage.

Isotope
One of two or more atoms with the same number of protons, but different numbers of neutrons in their nuclei. Thus Carbon-12, Carbon-13, and Carbon- 14 are isotopes of the element carbon, the numbers denoting the approximate atomic weights. Isotopes have very nearly the same chemical properties, but often different physical properties. For example, Carbon-12 and Carbon-13 are stable, but Carbon-14 is radioactive.

Label
A sticker, sign, tape, or posting which provides identification or description.

Laboratory Audit
An audit of a laboratory’s procedures and use of radioactive materials under the University of Colorado Radioactive Materials License issued to a Principal Investigator. Usually conducted at least annually and usually unannounced.

Laboratory Contact
An individual designated on the University of Colorado Radioactive Materials License who is the liaison between the laboratory and the Health Physics staff. This person usually receives mailings, exchanges dosimeters, and handles waste pick-up requests.

Leak Test
A wipe smear test similar to a contamination survey which verifies the integrity of a sealed source. If the results of the survey indicate more than 185 Bq (0.005 μCi) of contamination, the sealed source is considered leaking, taken out of use, and either repaired or disposed of promptly.

License
A document authorizing a Principal Investigator to use radioactive materials and/or radiation for specific purposes in specific locations. Officially referred to as the University of Colorado Radioactive Materials License. See also Authorized User, Licensee, and Principal  Investigator.

Licensee
An individual who uses radioactive materials and/or radiation unsupervised, or supervises their use and is issued a University of Colorado Radioactive Materials License. See also Authorized User and Principal Investigator.

Licensing
The review process and paperwork necessary to obtain a University of Colorado Radioactive Materials License.

Liquid Scintillation Counter (LSC)
Instrument used to measure radiation and/or contamination levels by utilizing a liquid solution which fluoresces, or emits light, when interacting with radioactive material. LSCs are primarily used in association with beta emitters; however, they can also detect some alpha particles and most gamma emitting radiation.

Medical X-ray Device
A device used to irradiate human beings for the purpose of diagnosis or treatment. See also Analytical X-ray and X-ray.

Microcurie
One millionth of a Curie. Abbreviated μCi.

Millisievert
One thousandth of a Sievert. Abbreviated mSv.

Milligray
One thousandth of a Gray. Abbreviated mGy.

Millicurie
One thousandth of a Curie. Abbreviated mCi.

Millirad
One thousandth of a rad. Abbreviated mrad.

Millirem
One thousandth of a rem. Abbreviated mrem.

Milliroentgen
One thousandth of a Roentgen. Abbreviated mR.

Mixed Waste
Waste that has both radioactive and chemical constituents. This waste must comply with regulations governing both hazards.

Natural Uranium
Uranium as found in nature. It contains 0.7% Uranium-235, 99.3 % of Uranium-238, and a trace of Uranium-234.

Neutron
An uncharged elementary particle with a mass slightly greater than a proton, and found in the nucleus of every atom heavier than hydrogen.

Non-Ionizing Radiation
Radiation not having enough energy to ionize atomic or molecular systems with a single event. Characterized by frequencies below the far ultraviolet region of the electromagnetic spectrum and includes ultraviolet (UV), visible light, infrared (IR), microwave, and other radio-frequency (RF) radiation. It is also found in the acoustic spectrum and includes sonic and ultrasonic radiation.

Nucleus
The small, central, positively charged region of an atom that carries essentially all of the mass. Except for the nucleus of ordinary hydrogen, which has a single proton, all atomic nuclei contain both protons and neutrons. The number of protons determines the total positive charge, or atomic number. This is the same for all the atomic nuclei of a given chemical element. The total number of neutrons and protons is called the mass number.

Nuclide
A general term referring to all known isotopes, both stable (279) and unstable (about 5,000), of the chemical elements.

Over Exposure
An exposure to radiation which leads to a dose in excess of the regulatory limits.

Pancake Probe
A thin paddle-like probe used to detect high energy alpha, beta and gamma radiation. See also Geiger-Mueller Counter.

Personnel Monitoring
The use of survey meters to determine the amount of radioactive contamination on an individual, or the use of dosimetry to determine an individual’s radiation dose.

Photon
A quantum (or packet) of energy emitted in the form of electromagnetic radiation. Gamma rays and X-rays are examples of photons.

Pick-up Request
See Radioactive Waste Pick-up Request Form.

Pig
A container (usually lead or plastic) used to ship or store radioactive materials. The thick walls protect the person handling the container from radiation. Large containers are commonly called casks. (The word may have originated from the use of “pig iron” in the early days of handling radioactive materials.)

Plated Source
Generally considered a sealed source for the purposes of this handbook. A source which has radioactive material bound to its surface by electroplating. The material cannot be removed from the surface under normal conditions.

Port
An opening on an x-ray device which allows the primary beam to pass out of the device to irradiate an object of interest. Sometimes used to mount a camera or other analytical device.

Positron
Particle equal in mass, but opposite in charge, to the electron (a positive electron).

Principal Investigator
An individual who uses radioactive materials and/or radiation unsupervised, or supervises their use and is issued a University of Colorado Radioactive Materials License. See also Authorized User and Licensee.

Procurement Card
The University’s Master Card obtained through the Procurement Services Center. Reminder – the Procurement Card CANNOT be used for purchasing radioactive materials.

Proton
An elementary nuclear particle with a positive electric charge located in the nucleus of an atom.

Purchase Request
A form used to request a purchase and designate a shipping address. Normally available in each department, these forms are approved by Health Physics for purchasing radioactive materials and radiation producing machines. If used without a Standing Purchase Order, they must be signed by Health Physics.

Quality Factor
The factor by which the absorbed dose (e.g., ergs/g or rad) is to be multiplied to obtain a quantity that expresses, on a common scale for all ionizing radiation, the biological damage (e.g., Sievert or rem) to exposed persons. It is used because some types of radiation, such as alpha particles, are more biologically damaging than other types.

Rad
Acronym for Radiation Absorbed Dose, the basic unit of absorbed dose of radiation. A dose of one rad means the absorption of 100 ergs (a small but measurable amount of energy) per gram of absorbing tissue. 100 rad = 1 Gray.

Radiation, Nuclear
Particles (alpha, beta, neutrons) or photons (gamma) emitted from the nucleus of an unstable radioactive atom as a result of radioactive decay.

Radiation Area
Any area with radiation levels greater than 0.05 mSv (5 mrem) in one hour at 30 cm from the source or from any surface through which the radiation penetrates.

Radiation Producing Machines
Machines designed to produce radiation, usually x-rays, when operating.

Radiation Safety Committee (RSC)
The on-site regulatory Committee for the University’s Radioactive Materials License. This committee has the authority to establish policies and procedures, provide enforcement sanctions, and restrict the use of radioactive materials and/or radiation. The RSC issues, amends, and terminates laboratory licenses, which authorize the specific activities associated with radioactive materials and/or radiation. It is composed of faculty and staff members representing various departments and levels of experience with radioactive materials and radiation, as well as a representative from Administration.

Radiation Safety Handbook
A user’s guide for the University of Colorado’s laboratory licensees that includes topics such as the safe use of radioactive materials and radiation, licensing, and waste disposal. This document becomes regulation through the Radiation Safety Committee (RSC) and the State of Colorado. Amendments are reviewed and approved by the RSC.

Radiation Safety Officer
An individual approved by the State of Colorado who has the knowledge, responsibility, and authority to apply appropriate radiation protection regulations. The University of Colorado must have a Radiation Safety Officer (RSO) in order to have its Radioactive Materials License.

Radiation Safety Survey Log
A logbook of contamination survey results for each laboratory. This log may also contain room diagrams and results of area surveys. It should be kept in a central location for review during laboratory audits and inspections by Federal, State, or local agencies.

Radiation Safety Training
The basic radiation safety courses offered by Health Physics to fulfill the training requirements of the University’s License for users of unsealed isotope, sealed sources, and radiation-producing machines.

Radiation Shielding
Reduction of radiation by interposing a shield of absorbing material between any radioactive source and a person, work area, or radiation-sensitive device.

Radiation Source
Usually a manmade sealed source of radiation used in various types of instruments and industrial gauges. Machines such as accelerators and natural radionuclides may be considered sources.

Radiation Source Housing
The material surrounding the x-ray tube that restricts physical proximity and radiation released from the radiation producing machine.

Radiation Standards
Exposure standards, permissible concentrations, rules for safe handling, regulations for transportation, regulations for industrial control of radiation, and control of radioactive material by legislative means.

Radiation Warning
An officially prescribed symbol (a magenta or black trefoil) on a Symbol yellow background that must be displayed where certain quantities of radioactive materials are present or where certain doses of radiation could be received.

Radioactive
Exhibiting radioactivity or pertaining to radioactivity.

Radioactive Materials
Any solid, liquid, or gas which emits radiation spontaneously. Sometimes abbreviated as RAM.

Radioactive Materials Inventory
A list of radionuclides in a laboratory. The inventory includes the date of receipt, an unique identification number, the radionuclide, and the activity. Reminder – laboratories should keep this list updated at all times. Health Physics updates each laboratory’s inventory on a quarterly basis.

Radioactive Waste Pick-Up Request
A form used to request a radioactive waste pick-up. It summarizes for each container: the container type(s), volume, radionuclide(s), total activity, constituents, pH, and location. This form is used to properly manifest the waste for transportation and to ensure appropriate replacement containers are issued.

Radioactive Waste
Unwanted radioactive material or items that are contaminated with radioactive material.

Radioactivity
The spontaneous emission of radiation, generally alpha or beta particles, often accompanied by gamma rays, from the nucleus of an unstable atom. See also Activity and Decay, Radioactive.

Radioisotope
An unstable form of an element that decays or disintegrates spontaneously, emitting radiation. Approximately 5000 natural and artificial radioisotopes have been identified. See also radionuclide.

Radionuclide
An unstable form of an element that decays or disintegrates spontaneously, emitting radiation. Approximately 5000 natural and artificial radioisotopes have been identified. See also radioisotope.

Radiosensitivity
The relative susceptibility of cells, tissues, organs, organisms, or other substances to the injurious action of radiation.

Relative Risk
The ratio of risk from radiation in an irradiated population to the risk in a comparable non-irradiated population.

Rem
The special unit of dose equivalent. The dose equivalent equals the absorbed dose multiplied by the quality factor. 100 Rem = 1 Sievert (Sv).

Restricted Materials (Waste)
Items that should be segregated from each other and include sharps, lead pigs, liquids, solids, and scintillation vials.

Ring Badge
See Extremity Dosimeter.

Roentgen
An unit of exposure to ionizing radiation. It is the amount of gamma or X-rays required to produce ions resulting in a charge of 0.00258 coulombs/kilogram of air under standard conditions. Named after Wilhelm Roentgen, German scientist who discovered X-rays in 1895.

Safety Devices
When used in conjunction with radioactive material or x-ray devices, these may be interlocks, physical barriers, or other engineering controls.

Scattered Radiation
Radiation that, during its passage through a substance, has been changed in direction. It may also have been modified by a decrease in energy. It is one form of secondary radiation.

Sealed Source
Radioactive material that is permanently bonded or fixed in a capsule or matrix designed to prevent release and dispersal of the radioactive material under the most severe conditions which are likely to be encountered in normal use and handling.

Sealed Source Inventory
A list of sealed sources in a laboratory. The inventory includes the date of receipt, an unique identification number, the radionuclide, and the activity.

Sealed Source Sign-out Log
A record of source use including the date when it is removed from storage, the date it is returned to storage, and the location in which it is being used. Generally found on or near the storage location.

Secondary Radiation
Radiation originating as the result of absorption of other radiation in matter. It may be either electromagnetic or particulate in nature.

Shielding
Any material or obstruction that absorbs radiation and thus tends to protect personnel or materials from the effects of ionizing radiation.

Shutter
An automatic closure device on x-ray machines that cannot be opened unless a collimator or coupling has been connected to the port.

Sievert (Sv)
The System International (SI) unit of dose equivalent equal to 1 Joule per Kilogram. 1 Sv = 100 rem.

Spill
An unintentional release or spread of radioactive materials.

Standing Purchase Order
A form/system used to request multiple purchases from the same supplier. Normally available in each department, these forms are approved by Health Physics for purchasing radioactive materials and radiation producing machines for a period of one year. They are established through the Procurement Service Center (PSC).

Storage Cabinet
A cabinet used to hold radioactive materials not in use in a laboratory. Generally used for sealed sources of radioactive material.

Storage Freezer
A freezer used to hold radioactive materials not in use in a laboratory. Generally used for unsealed radioactive sources.

Storage Refrigerator
A refrigerator used to hold radioactive materials not in use in a laboratory. Generally used for unsealed radioactive sources.

Support Staff
University of Colorado staff members and others involved in service functions in relation to administration of laboratories using radioactive materials. Custodians and facilities management trades people are examples of support staff.

Survey
A study to find the radiation or contamination level of specific objects or locations within an area of interest, or to locate regions of higher-than-average intensity, i.e., hot spots.

Survey Meter
Any portable radiation detection instrument adapted for inspecting an area to establish the existence and amount of radioactive material.

Terrestrial Radiation
The portion of natural radiation (background) that is emitted by naturally occurring radioactive materials in the earth.

Thermoluminescent Dosimeter (TLD)
A device used to measure radiation by evaluating the amount of visible light emitted from a crystal in the detector after being exposed to radiation. See also Extremity Dosimeter.

Thin-end Window
A small cylinder-like probe used to detect high energy beta and Probe gamma radiation. See also Geiger-Mueller Counter.

Tritium
A radioactive isotope of hydrogen (3H, one proton, two neutrons). Because it is chemically identical to natural hydrogen, tritium can be taken into the body by any ingestion path. It decays by beta emission. It has a radioactive half-life of about 12.5 years.

Unstable Isotope
A radioisotope.

Unsealed Radionuclide
Radioactive materials which do not meet the definition of sealed sources. Generally, these are in liquid form in laboratories.

Uranium (U)
A radioactive element with the atomic number 92 and as found in natural ores, an atomic weight of approximately 238. The two principle natural isotopes are U-235 (0.7% of natural Uranium) and U-238 (99.3% of natural Uranium). See also Natural Uranium.

Urinalysis
An analysis and evaluation of urine used to determine kinds, quantities or concentrations, and in some cases, the locations of radioactive material in the human body. A form of bioassay used for individuals working with large amounts of tritium.

Very High Radiation Area
An area in which radiation levels exceed 5 Gy (500 rads) in one hour at 1 meter from the source or from any surface that the radiation penetrates.

Warning Device(s)
Lights, sounds, signs, or barriers which indicate an existing hazard.

Waste, Radioactive
Materials from radioactive materials operations that are radioactive or become radioactive and for which there is no further use. Wastes are generally classified as high, low, or intermediate levels based on activity per gallon or per cubic foot. The University generates low level radioactive waste.

Waste Container
For the purposes of this handbook, containers used to hold waste items. These are color coded for half-life categories and are specific to the type of waste generated. See also Container Contents Sheet and Radioactive Waste Pick-up Request Form.

Whole-Body
For the purposes of external dose; head, trunk including male gonads, arms above the elbow, or legs above the knee.

Whole-Body Dosimeter
An instrument used to measure and register the accumulated dose received by the whole body. See also Dosimeter and Extremity
Dosimeter.

Whole-Body Exposure
An exposure of the body to radiation, in which the entire body, rather than an isolated part, is irradiated. Where a radioisotope is uniformly distributed throughout the body tissues, rather than being concentrated in certain parts, the result can be considered as whole-body exposure.

Wipe Sample (a.k.a. Wipe Smear, Swipe, etc.)
A sample made to determine the presence of removable radioactive contamination on a surface. It is done by wiping, with slight pressure, a piece of soft filter paper over a representative type of surface area, usually 100 cm2.

X-ray
Penetrating electromagnetic radiation (photon) having a wavelength that is much shorter than that of visible light. These rays are usually produced by excitation of the electron field around certain nuclei. In nuclear reactions, it is customary to refer to photons originating in the nucleus as gamma rays, and to those originating in the electron field of the atom as X-rays. See also Analytical X-ray and Medical X-ray.

Appendices