Decay-In-Storage
Information to be submitted when requesting amendment to dispose of radioactive waste by decay-in-storage method:
1) Please submit a diagram of the area where the waste will be decayed-in-storage. Show the type, location, and thickness of shielding that you will have available in this area of your diagram. Your storage area should be large enough to handle an accumulation of used Tc-99m generators as well as other solid waste. Identify adjacent unrestricted areas located across the walls from the storage area and show that adequate steps have been taken to assure that radiation levels do not exceed the limits specified in OAR 333-120-180 and 333-120-190.
2) Describe your security measures for the decay-in-storage area.
3) Confirm that radiation levels in this area will be surveyed and recorded at least weekly per OAR 333-120-200 (for all licenses) and additionally for medical licenses, OAR 333-116-250.
4) Describe your procedures for monitoring the waste to assure that it has decayed to background levels prior to disposal. As a minimum, your description should include these points:
- Monitor the waste in a low background area.
- Monitor with a low-level GM type survey meter as appropriate for contamination surveys. Use the most sensitive scale.
- Remove all shielding prior to monitoring.
- Maintain records of these surveys as required under OAR 333-120-620.
5) Note that decay-in-storage may not be a practical method of disposal for Tc-99m generators. These generators may contain long-lived radioisotopic contaminants. If you intend to dispose of generators by this method, you should include procedures for segregating the generator columns so that they may be monitored separately.
6) Describe your method for segregating radioactive waste so that materials of variable half-lives are not intermixed (e.g., Iodine-125 and Iodine-131 as well as Tc-99m, etc.) Be certain to submit your amendment request in duplicate. Unless your institution is fee exempt, your request should be accompanied by the appropriate amendment fee. Refer to OAR 333-103