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.

The NAS proceedings are available to interested stakeholders for free download at https://www.nap.edu/catalog/24715/.

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.”

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.

Common Themes Approach

The workshop planning committee was not charged with inventing a new regulatory framework for low-level radioactive waste.  Rather, the workshop used case studies to highlight successful examples of low-level radioactive waste management and disposal within existing regulatory frameworks.

Common themes within the case studies that led to successful disposition of the wastes were identified such as:  the use of existing regulations and standards—such as the U.S. Nuclear Regulatory Commission’s (NRC’s) Class A, B, and C classification scheme—to provide an anchor for disposal decisions; the identification of lessons learned from similar or analogous approaches such as Canada’s or France’s approach to managing and disposing of very LLW; and, acknowledgement that the disposal site characteristics are as important for safe disposal as the inherent characteristics of the waste.

These common themes were organized into a common themes approach that could be used within the current low-level radioactive waste regulations as an aid to guide decisions and direct discussions.  The approach includes the following three key elements:

• Anchors: The current regulatory framework that governs low-level radioactive waste disposal provides a starting point for decisions about the disposition of challenging low-level radioactive waste streams.

• Analogies: Learn from successful disposition of similar wastes.  Examples of past decisions for successful disposition of challenging low-level radioactive waste streams offer additional guidance for future waste disposal decisions.

• Adjustments: Use flexibility within current regulatory frameworks for making decisions about disposing of challenging low-level radioactive waste streams.

The common themes approach acknowledges that existing United States’ regulations, as well as regulations and standards from international organizations, offer valuable guidance for making decisions about dispositioning challenging low-level radioactive waste streams.  It also makes use of the roughly proportional relationship between the hazard of a low-level radioactive waste stream and the required protectiveness of the facility that will be used for its disposal.

According to the workshop proceedings, the graphical representation of the common themes approach included in the final document could help guide disposition decisions for wastes without clear or potentially non-optimal disposition pathways and could also help explain disposal decisions to non-experts.  This representation is risk informed—a concept advocated by reports from the NAS and others including the National Research Council—and is relatively easy to comprehend because it uses a small number of readily understood characteristics and shows the relationship between hazard and protection measures.  The workshop proceedings further state that the graphical representation of the common themes approach can also help to improve decision-making consistency for challenging low-level radioactive waste streams.

Major Topics

Several major topics emerged during the discussions throughout the workshop including complexity of regulations; communication among stakeholders; diversity of the type, source and hazard of low-level radioactive waste; and, integration of knowledge gained from operations.

The following is a brief overview of the discussion of the major topics from the proceedings:

• Complexity of Regulations: The complexity of the current low-level radioactive waste regulatory structure in the United States was mentioned in several presentations and discussions.  Participants noted that the current regulatory structure is the result of “tweaks” and “adjustments” to regulations to address unanticipated types of wastes or other challenges.  Several participants argued that the current low-level radioactive waste regulatory system should be thrown out and that a new system should be “developed from scratch.”  This “revolution instead of an evolution” of the low-level radioactive waste regulatory structure was raised several times during the workshop.  Participants also discussed the complexity of the definition and regulation of TRU waste, noting that multiple laws and regulations contain definitions of TRU waste that can be inconsistent with each other.  It was also noted, however, that the current low-level radioactive waste regulatory system has the flexibility to deal with unanticipated waste streams through case-by-case exceptions—which adds to the system’s complexity.  The proceedings state that the unintended impacts of this complex system include the following: potential loss of public trust and confidence; mounting costs for disposal that are passed on to rate payers; and, levels of regulation that are disproportionate to the hazards posed by low-level radioactive waste.

• Communication Among Stakeholders: Several participants noted that the complexity of the current low-level radioactive waste regulatory system leads to communication problems with stakeholders.  Many stakeholders assume that low-level radioactive waste must be dangerous because the regulations are so strict and complex.  Several participants also questioned the appropriateness of the language used when discussing stakeholder or public concerns.  Some favored a move away from the use of the term “stakeholder”—which is a term that is difficult to define—to “concerned” or “interested parties” in order to be inclusive of a wider group including waste producers, academics, and other members of the public.  According to the proceedings, another phrase often used by experts that raises concern is “talking to the public,” which implies a one-way flow of information, instead of “talking with the public.”   In addition, “educating the public,” was identified as denigrating—its use presupposes that the public is uneducated and also that, if given education, the public would agree with the experts doing the educating.  Some participants stated that improving communications among stakeholders involves a change in mindset in addition to a change in language, and that decisions on the final disposition of challenging wastes could be informed by a continuing conversation with stakeholders throughout the lifetime of a project.  The topic of accepting responsibility for the waste streams now to ensure safe disposal for future generations was repeatedly discussed at the workshop.  Several participants noted that discussions with stakeholders on the final disposition of low-level radioactive waste were aided when the origins and social value of the activities that produced the wastes (i.e., medical treatments, electricity generation) were described.

• Diversity of the Type, Source and Hazard of Low-Level Radioactive Waste: Participants noted that the “universe” of low-level radioactive waste in the United States is large due to its definition by exclusion.  In the United States, high-activity wastes such as irradiated metals and sealed sources of high activity are considered low-level radioactive waste.  Also, very low-activity wastes in the United States are subject to disposal requirements that many participants believe exceed the hazard of the waste.  Participants noted that characteristics such as half-life and activity levels (or hazards) of the waste are used in other countries to define waste categories and disposal options.  Participants also noted that other countries have a “cleared” or “exempt” category of waste that allows for less protective disposal—an approach that is commensurate to the hazard of the waste—while there is no low-end threshold of activity for low-level radioactive waste in the United States.   The workshop proceedings point out that, in the United States, the states have regulatory authority for some radioactive wastes and regulations can be inconsistent across state boundaries even though the characteristics and hazard of the waste remain the same.

• Integration of Knowledge Gained from Operations: The United States and other countries have been managing and disposing of nuclear waste for at least six decades.  Several comparisons of early to modern low-level radioactive waste disposal concepts and facilities were presented at the workshop including: the EnergySolutions (Utah), Barnwell (South Carolina), Waste Control Specialists (Texas)—as well as both the Centre de la Manche (CSM) and Centres de stockage de l’Aube (CSA) (France)—disposal facilities.  The workshop proceedings state that these comparisons highlighted the improvements in modern facilities that resulted from applying the knowledge gained from the construction and operation of earlier facilities.  Another point that was repeatedly raised by participants at the workshop was the importance of site characteristics of modern facilities in the United States, many of which are located in arid regions of the country.  Several participants noted that the United States should find a way to integrate this new knowledge into the regulations and rules that govern the management and disposal of low-level radioactive waste.

The above topics are described in detail in the proceedings.

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.

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.