Frequent Questions

How long may low-level mixed waste (LLMW) be stored?  Does the facility have to apply for an exemption if they want to store LLMW for longer than one year?

The Federal Regulation provide a conditional exemption for LLMW storage and disposal that allows a facility to store and treat waste within a tank or container in accordance with the terms of the facility’s Nuclear Regulatory Commission (NRC) or NRC agreement state license (40 CFR §266.225). During storage or allowable treatment of conditionally exempted LLMW, the generator is not required to have a RCRA permit or meet other RCRA Subtitle C requirements for the conditionally exempt waste. The Federal Requirements do not impose a time limit on how long conditionally exempt waste can be stored. Generators may store these wastes for as long as they are permitted to do so under their NRC or NRC agreement state license (66 FR 27218, 27225; May 16, 2001). 

However, LLMW is no longer subject to NRC regulation when it meets the requirements of the NRC or NRC Agreement State license for decay-in storage and can be disposed of as non-radioactive waste. On that date the waste is subject to hazardous waste regulation under the relevant sections of 40 CFR Parts 260-271, and the time period for accumulation of a hazardous waste as specified in §262.34. Thus, the RCRA accumulation time for a formerly mixed (now solely hazardous) waste begins when the radionuclide with the longest half-life in a container has decayed as specified in the license (generally ten half-lives) and the radiation emitted from the unshielded surface of the waste is not above background levels as measured by appropriate monitoring equipment as specified by the NRC (66 FR 27218, 27237; May 16, 2001). 

In order to claim this exemption a generator must notify the RCRA regulatory agency. Notification of the claim of the exemption for storage and/or treatment must be sent via certified delivery within ninety days of when a storage unit is first used to store a conditionally exempt LLMW (§266.230(a)). 

The May 16, 2001, Federal Register (66 FR 27218) and additional guidance regarding the LLMW conditional exemption is available at the following URL:

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