Radiation Waste Management, Inc.

A large percentage of low-level radioactive waste generated by hospitals, clinics, universities, research labs, etc., contains exclusively nuclides with short half-lives. These wastes can be held in storage while the contained nuclides decay and provide a substantial savings in disposal cost over burial. In addition to being more economical than burial, this practice is also encouraged by regulatory authorities as a means to preserve limited burial space for longer lived nuclides that cannot be reasonably held for decay and release.

While the process of holding radioactive waste for decay and release is simple in concept, it is frequently difficult for waste generators to implement such a plan because of the many details involved in the basic procedure. Also, maintaining a secure location within the facility to store and monitor the decaying containers can present a burden due to the time and space necessary to hold the wastes to maturity. The decay process begins with characterizing the waste to determine the longest-lived nuclide. This knowledge, combined with a calculation to determine an estimated date of maturity, will determine the minimum holding period. The accepted time period by most authorities would be 10 half-lives, but this is also dependent upon the activity of the isotope(s). The waste is then stored for the necessary time period, usually two years or more, and periodicically checked to determine that the integrity of the containers has not been compromised. After the calculated time period has elapsed, the waste must be removed from the containers and surveyed to verify that radiation levels have decayed to levels indistinguishable from background. If the waste shows no evidence of radioactivity above background levels, it may be disposed of as non-hazardous waste at a landfill, or incinerated.


RWM-Utah, Inc., located in Salt Lake City, Utah, is a wholly-owned subsidiary of Thomas Gray & Associates, Inc., and was formed to handle and dispose of short-lived, low-level radioactive waste. Constructed in 1995 specifically for this purpose, RWM offers secure and complete service, handling both aqueous and solid waste. Manifested waste entering the facility is first entered into a computer program which calculates the maturity date. Waste containers are then stored on drum racks in a sprinklered and alarmed warehouse, where they are completely visible for periodic inspection. When the containers reach maturity, they are removed from the drum racks and transferred to a survey area. Upon opening, each container is internally sampled using liquid scintillation to verify the nonexistence of residual activity. Fully decayed wastes are then disposed of. A generator may request a summary of the "cradle-to-grave" documentation of actions taken on his/her waste materials.


To qualify for this "Decay in Storage" service, the waste must contain nuclides with a half-life of 90 days or less. The more typical nuclides would be I125, S35, P32, I131, and Cr51. RWM's "Decay in Storage" service is also available for those generators who manage their own decayed waste but choose not to perform the unpleasant inspection process. Charges for this service are considerably reduced, as no storage time fees are involved.