On June 6, 2017, the National Academies of Sciences, Engineering, and Medicine (NAS) released the final publication, Low-Level Radioactive Waste Management and Disposition: Proceedings of a Workshop.  The publication documents the proceedings from a workshop that was organized by the NAS Nuclear and Radiation Studies Board, Division on Earth and Life Studies, at the request of the U.S. Department of Energy (DOE or Department).  The workshop was held in Washington, DC on October 24-25, 2016.

During the workshop, presenters and attendees provided perspectives from academia, industry, federal agencies (including those outside of DOE), state governments, international organizations, public interest groups, and national laboratories.  The proceedings provide a factual description of the workshop presentations and discussions and are limited to the views and opinions of those participating in the event.  The proceedings do not contain consensus findings or recommendations.

Overview  DOE asked NAS to organize this workshop to discuss approaches for the management and disposition of low-level radioactive waste.  The workshop considered similarities between successful case studies, in which unique disposition pathways have been developed to address low-level radioactive wastes, and explored ways to extend these similar characteristics to problematic wastes—i.e., low-level radioactive wastes currently without a clear disposition pathway.  Specifically, the workshop explored the key physical, chemical, and radiological characteristics of low-level radioactive waste that govern its safe and secure management (i.e., packaging, transport, storage) and disposition, in aggregate and for individual waste-streams; and, how key characteristics of low-level waste are incorporated into standards, orders, and regulations that govern the management and disposition of low-level radioactive waste in the United States and in other major waste-producing countries.

Workshop Structure  The workshop began by defining the “universe” of low-level radioactive waste within the United States and elsewhere—first by introducing the types of waste that exist and then by exploring the standards, orders, regulations, and laws that define and control their disposal.  Case studies were then presented to highlight the successful disposal of a variety of wastes that previously lacked a clear disposition pathway—these case studies are referred to as “success stories.”  The studies were selected from within and outside of the United States.  The participants explored common themes that led to success within the case studies such as: the use of existing regulations and standards (i.e., waste classification) to provide an anchor for disposal decisions; the identification of lessons learned from similar or analogous problems such as Canada’s or France’s approach to managing and disposing of very low-level waste (VLLW); and, the importance of site characteristics for disposal decisions.  These themes were organized into an approach to guide future discussions and disposition decisions for challenging low-level radioactive waste streams—referred to in the proceedings as a “common themes approach.”

Waste Streams  The common themes approach was applied to a set of five pre-selected challenging low-level radioactive waste streams that spanned a variety of waste characteristics including Greater-Than-Class C (GTCC) and commercial transuranic waste (TRU) waste in excess of 100 nCi/g; sealed sources; VLLW and very low-activity waste; incident waste; and, depleted uranium.  One leader from each breakout group introduced a specific challenging low-level radioactive waste stream to the full workshop and later summarized the breakout group’s results of applying the common themes approach to the issues associated with the disposal of this waste stream.  Several participants identified short-term actions or next steps that could be taken to show progress in addressing each challenging waste stream in the final session of the workshop.

Challenges  Each of the waste streams discussed at the workshop presents a unique set of challenges for disposal.  For example, GTCC waste and commercial TRU waste in excess of 100 nCi/g lack a clear disposition pathway, while VLLW and very low-activity waste have a disposition pathway in which the level of protection may be considered incommensurate with the hazard, or a potentially non-optimal disposition pathway.  According to NAS, the application of the common themes approach to these diverse waste streams was intended to explore how adaptable this approach would be as a tool in discussing or presenting a variety of disposal options.

Background  The Department’s Office of Environmental Management (DOE-EM) is responsible for the cleanup of the sites used by the federal government for nuclear weapons development and nuclear energy research.  DOE-EM cleanup involves retrieval, treatment, storage, transportation, and disposition of hundreds of different radioactive and hazardous solid and liquid wastes.  Low-level radioactive waste—which is defined by exclusion as waste that does not meet the statutory definitions for spent nuclear fuel, high-level radioactive waste, or transuranic waste—is physically and chemically diverse, ranging from lightly contaminated soils and building materials to highly irradiated nuclear reactor components.  It is the most volumetrically significant waste stream (millions of cubic meters) being generated by the cleanup program.

The NAS proceedings are available to interested stakeholders for free download at https://www.nap.edu/catalog/24715/.  For additional information, please contact Jennifer Heimberg, Senior Program Officer, Nuclear and Radiation Studies Board (NRSB), Board on Life Sciences (BLS), Board on Environmental Change and Society (BECS), NAS at (202) 334-3293 or at jheimberg@nas.edu.