Executive Summary

The Further Consolidated Appropriations Act of 2020 (Public Law 116-94) and the Consolidated Appropriations Act of 2021 (Public Law 116-260) mandated that the National Academies of Sciences, Engineering, and Medicine examine the merits and viability of different nuclear fuel cycle options, waste aspects of advanced reactors and their fuel cycles, and nonproliferation and security risks of these technologies.

At the current stage of advanced reactor and associated fuel cycle development in the United States, a vast array of concepts could—if realized—significantly diversify the reactor and fuel cycle technologies used for nuclear power generation in the United States, to a level exceeding the diversity of available technologies for light water reactors. Implementing just a few of the most promising reactor concepts and their associated fuel cycles at a large commercial scale would require substantial government and industry investments well beyond 2050. Most importantly, advanced reactors and their associated fuel cycles would not eliminate the requirement for geologic repositories for some radioactive wastes, because even advanced reactors will require disposal of radioactive fission products. Based on presentations and committee expertise, the committee concluded that the introduction and use of advanced reactors will do little, if anything, to mitigate the need for successful management and disposal of nuclear waste. The present strategy in the United States of a once-through fuel cycle, if completed, could safely dispose of all spent nuclear fuel from commercial power generation, including fission products and all actinide elements, in a system of one or more deep geologic repositories. The following paragraphs present the committee’s key conclusions; the full list of its findings and recommendations can be found in this report’s Summary.

As a top priority, the committee highlights that Congress will need to establish a single-mission entity with responsibility for managing and disposing of commercial nuclear waste. The entity will need continuity of leadership and funding, as well as a consistent disposal strategy; it will also need high technical and scientific competence and the ability to organize and lead research programs and large construction projects. Importantly, such an entity will need to engage the public in a way that engenders trust. Finally, the entity will need to operate effectively over the many decades that will be required to manage the present inventory of nuclear waste, as well as waste generated by future advanced reactors.

The committee also underscores the importance of the U.S. Department of Energy’s (DOE’s) decision making about its advanced reactor technology programs. Using data from the Advanced Reactor Demonstration Program and DOE’s research and development programs over the next several years, DOE will need to select and support, with industry cost sharing, the development of a few promising advanced reactor technologies and fuel cycles, which can be potentially deployed by 2050 and achieve goals described in the Nuclear Energy Innovation Capabili-

ties Act of 2017 (NEICA) (Public Law 115-248). DOE needs to develop a clear and transparent decision-making process based on criteria and metrics that can guide its programs and associated budget decisions. With NEICA’s goals as guidance, DOE’s criteria will need to include (1) science-based estimates of improved fuel utilization and reduced waste yields compared with the existing light water reactor (LWR) fleet, (2) the development of acceptable waste forms and disposal options, (3) the implementation of enhanced safety throughout the entire fuel cycle similar to that demanded for reactor design and operation, and (4) a level of proliferation resistance comparable to the LWR once-through cycle. DOE will also need to factor into its decision-making process the effort and costs required for establishing advanced fuel cycles, including the manufacturing base and supply chain infrastructure required to support these advanced fuel cycles.

While it will be challenging to make cost estimates with small uncertainties, better understanding of costs for various scenarios of reactor deployment and supporting fuel cycle requirements will aid Congress and DOE in their decision making as to what technologies to support in the coming years. Congress and DOE will benefit from obtaining an independent assessment of cost estimates of various scenarios for potential deployment of advanced reactor technologies and related fuel cycle components. The independent assessor should have expertise in evaluating large-scale construction projects, examining project management challenges, and understanding technological and financial risks and their uncertainties.