Environmental Health & Safety

University of Colorado Boulder


Radiation Safety Handbook Appendix G – Defrosting a Contaminated Freezer

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

Revised as of October 1, 2010

  1. Check to see if appropriate tritium (3H) waste containers (liquid and solid) are available for the waste generated from the freezer. If appropriate waste containers are not available, contact Health Physics at (303) 492-6523. See Waste Chapter.
  2. Open the door and follow manufacturer’s directions for switching to DEFROST mode.
  3. Be sure to place pans and absorbent bench paper around the freezer to catch any water leakage.
  4. Prepare the fume hood by placing absorbent paper with a plastic backing in the bottom of the hood. The fume hood will be used to allow ice to melt in containers and dry out paper towels.
  5. When chunks of ice begin to loosen, put on two pairs of disposable gloves and a lab coat and remove the larger pieces of ice. Change gloves frequently, as tritium (3H) can infiltrate the plastic of the gloves.
  6. Place the ice in large beakers or other containers and let thaw in an adequately ventilated fume hood.
  7. Blot up frost melt with disposable paper towels and place the towels in the hood to dry.
  8. Place liquid frost melt in a tritium (3H) liquid radioactive waste container, noting activity on container contents sheet. Place the dry paper towels and used gloves in a tritium (3H) solid radioactive waste container, noting the approximate activity on container contents sheet.
  9. After all the ice and residual liquid is removed, wash down the interior surfaces with a decontamination solution and disposable paper towels. Rinse and dry. Dispose of paper towels, rinse, and used gloves as in 5 and 6 above.
  10. Check freezer handles, exterior, and area around freezer for contamination
  11. Wash hands.