Radiological Waste

Radioactive Waste consists of any waste that contains or is contaminated with radioactive materials. At St. John’s University, radioactive waste consists of the following nine radioactive isotopes:

  • TRITIUM
  • CARBON-14
  • IODINE-125
  • PHOSPHORUS-32
  • PHOSPHORUS-33
  • CALCIUM-45
  • IODINE-131
  • CHROMIUM-51
  • SULFUR-35

The radioactive waste generated at St. John’s comes in two forms: scintillation vial waste, and solid waste (both of which may contain any of the four radioactive isotopes mentioned previously). The composition of the solid waste may includes pipettes, pipette tips, absorbent padding, wiping rags, mops, filters, residues, swabs, or syringes.

Generators of radiological waste should review procedures for disposal of materials with the University’s Radiation Safety Officer (RSO), during the early stages of experimental design. RSO contact information can be found in Appendix A.

Storage, Handling & Disposal

Radiological Waste Containing Only Phosphorus-32
Radioactive waste samples containing phosphorus-32 should NOT be disposed via the drain. Wash water (that which is used to wash out the empty containers) may be put down the sanitary drain. In no case should the amount exceed 0.01 mCi without first consulting the RSO. Generators must keep a log of the amount of radioactive wash water that is disposed of down the drain on a daily basis. This log is submitted to the RSO each month.

Phosphorus-32 (P-32) radioactive waste must be placed in yellow bags that are imprinted with the word “Radiation.” These bags are available from the EH&S Department. Once a bag is full of P-32 waste, the Principal Investigator (PI) dates the bag, and stores it for a period of ten (10) half-lives (140 days) by placing the bag in a Plexiglas container that acts as a radiation shield. After ten half-lives, the PI checks the contents of the bag for radioactivity. If no radioactivity is detected, the contents are removed from the bag, and are discarded as regular trash after all radioactive labels have been removed. If radioactivity is detected after ten half-lives, the bags are stored for a longer period of time, and tested periodically until no radiation is detected. The final container must show the date that the material was placed into the container to ensure that the ten half-life period has elapsed.

Radiological Waste Containing Tritium, Carbon-14, Iodine-125, Phosphorus-33, Calcium-45, Iodine-131, Chromium-51, OR Sulfur-35
Radioactive waste must NOT be disposed via the drain. Only wash water (that which is used to wash out the empty containers) may be put down the laboratory drain. In no case should amount exceed 0.01 mCi without first consulting the RSO. Generators must keep a log of the amount of radioactive wash water that is disposed of down the drain. This log is submitted to the RSO each month.

Radioactive waste must be placed in yellow bags that are imprinted with the word “Radiation.” These bags are available from EH&S. The filled bags must then be placed in special Plexiglas containers that act as a radiation shield. Radioactive waste must be shielded such that radiation levels do not exceed 0.5 millirem/hr. within one foot of the surface of the waste. These containers must be purchased by the generator of the radiological waste in consultation with the RSO. Once placed in the container, the radiological waste is brought to the central storage area, where the waste is removed from the container and placed in drums for disposal by an EH&S approved contractor.