The U.S. Department of Energy's Office of Environmental Management is responsible for managing and cleaning up the waste and contamination at the Hanford Nuclear Reservation, the nation's biggest and most complex nuclear cleanup challenge. At the site, 177 underground tanks collectively contain about 211 million liters of waste that includes high-activity and low-activity materials. At the request of Congress, Final Review of the Study on Supplemental Treatment Approaches of Low-Activity Waste at the Hanford Nuclear Reservation: Review #4 focuses on approaches for treatment and disposal of the supplemental portion of the low-activity waste from the tanks. This review report discusses developments since the publication of Review #3 and provides a summary of public comments on the third committee review report. The authoring committee then shares their views on these comments and whether they change any of the findings or recommendations in the third review report.

In 1943, as part of the Manhattan Project, the Hanford Nuclear Reservation was established with the mission to produce plutonium for nuclear weapons. During 45 years of operations, the Hanford Site produced about 67 metric tonnes of plutoniumâ€"approximately two-thirds of the nation's stockpile. Production processes generated radioactive and other hazardous wastes and resulted in airborne, surface, subsurface, and groundwater contamination. Presently, 177 underground tanks contain collectively about 210 million liters (about 56 million gallons) of waste. The chemically complex and diverse waste is difficult to manage and dispose of safely. Section 3134 of the National Defense Authorization Act for Fiscal Year 2017 calls for a Federally Funded Research and Development Center (FFRDC) to conduct an analysis of approaches for treating the portion of low-activity waste (LAW) at the Hanford Nuclear Reservation intended for supplemental treatment. The first of four, this report reviews the analysis carried out by the FFRDC. It evaluates the technical quality and completeness of the methods used to conduct the risk, cost benefit, schedule, and regulatory compliance assessments and their implementations; waste conditioning and supplemental treatment approaches considered in the assessments; and other key information and data used in the assessments.

In 1943, as part of the Manhattan Project, the Hanford Nuclear Reservation was established with the mission to produce plutonium for nuclear weapons. During 45 years of operations, the Hanford Site produced about 67 metric tonnes of plutoniumâ€"approximately two-thirds of the nation's stockpile. Production processes generated radioactive and other hazardous wastes and resulted in airborne, surface, subsurface, and groundwater contamination. Presently, 177 underground tanks contain collectively about 210 million liters (about 56 million gallons) of waste. The chemically complex and diverse waste is difficult to manage and dispose of safely. Section 3134 of the National Defense Authorization Act for Fiscal Year 2017 calls for a Federally Funded Research and Development Center (FFRDC) to conduct an analysis of approaches for treating the portion of low-activity waste at the Hanford Nuclear Reservation intended for supplemental treatment. The third of four, this report provides an overall assessment of the FFRDC team's final draft report, dated April 5, 2019.

In 1943, as part of the Manhattan Project, the Hanford Nuclear Reservation was established with the mission to produce plutonium for nuclear weapons. During 45 years of operations, the Hanford Site produced about 67 metric tonnes of plutoniumâ€"approximately two-thirds of the nation's stockpile. Production processes generated radioactive and other hazardous wastes and resulted in airborne, surface, subsurface, and groundwater contamination. Presently, 177 underground tanks contain collectively about 210 million liters (about 56 million gallons) of waste. The chemically complex and diverse waste is difficult to manage and dispose of safely. Section 3134 of the National Defense Authorization Act for Fiscal Year 2017 calls for a Federally Funded Research and Development Center (FFRDC) to conduct an analysis of approaches for treating the portion of low-activity waste (LAW) at the Hanford Nuclear Reservation intended for supplemental treatment. The second of four, this report reviews the results of the assessments, including the formulation and presentation of conclusions and the characterization and treatment of uncertainties.

The U.S. Department of Energy's Office of Environmental Management is responsible for managing and cleaning up the waste and contamination at the Hanford Nuclear Reservation, the nation's biggest and most complex nuclear cleanup challenge. At the site, 177 underground tanks collectively contain about 211 million liters of waste that includes high-activity and low-activity materials. At the request of Congress, Final Review of the Study on Supplemental Treatment Approaches of Low-Activity Waste at the Hanford Nuclear Reservation: Review #4 focuses on approaches for treatment and disposal of the supplemental portion of the low-activity waste from the tanks. This review report discusses developments since the publication of Review #3 and provides a summary of public comments on the third committee review report. The authoring committee then shares their views on these comments and whether they change any of the findings or recommendations in the third review report.

In 1943, as part of the Manhattan Project, the Hanford Nuclear Reservation was established with the mission to produce plutonium for nuclear weapons. During 45 years of operations, the Hanford Site produced about 67 metric tonnes of plutoniumâ€"approximately two-thirds of the nation's stockpile. Production processes generated radioactive and other hazardous wastes and resulted in airborne, surface, subsurface, and groundwater contamination. Presently, 177 underground tanks contain collectively about 210 million liters (about 56 million gallons) of waste. The chemically complex and diverse waste is difficult to manage and dispose of safely. Section 3134 of the National Defense Authorization Act for Fiscal Year 2017 calls for a Federally Funded Research and Development Center (FFRDC) to conduct an analysis of approaches for treating the portion of low-activity waste at the Hanford Nuclear Reservation intended for supplemental treatment. The third of four, this report provides an overall assessment of the FFRDC team's final draft report, dated April 5, 2019.

The Hanford Nuclear Reservation in the state of Washington produced about two-thirds of the nations plutonium for nuclear weapons from 1944 until the last reactor was shut down in 1987. The U.S. Department of Energy Office of Environmental Management (DOE-EM) manages the ongoing clean-up at Hanford and has built a plant to convert the high-level radioactive waste into a glass form (vitrification) for safe disposal. However, decisions remain about how best to treat and dispose of the low-level waste at Hanford, which comprises over 90% of the volume of waste. To inform its decision, DOE contracted with key Federally Funded Research and Development Centers (FFRDC), led by Savannah River National Laboratory, to carry out an analysis. This final in a trilogy of reports from the National Academies reviews the FFRDC third report released in January 2023. The review finds that the FFRDC team made a strong technical case that converting the supplemental low-level waste from the vitrification process to a grout form (like cement) is the best option in terms of cost-effectiveness and timeliness, and that off-site disposal of that grout is a valid option as it will be away from potable water. The FFRDC provided a useful framework to help decision-makers understand the issues and trade-offs of the disposal options and did an excellent job of isolating specific factual considerations that can be analyzed, often quantified, and compared with each other. The FFRDC chose to provide a purely technical analysis that excluded analysis of two important factors to be considered - securing regulatory permissions and public acceptance - treating them, for now, as uncertainties. Looking ahead, the DOE faces many uncertainties and should emphasize flexibility in its overall approach, allowing for multiple, redundant options and pathways, as well as the ability to change over time.

The Hanford Nuclear Reservation in Washington state, which produced plutonium for nuclear weapons from 1944-1987, is the site of the largest and most complex nuclear cleanup challenge in the United States. The U.S. Department of Energy's Office of Environmental Management (DOE-EM) is responsible for managing the cleanup of the radioactive and other hazardous wastes stored in 177 underground tanks at the site. DOE plans to use vitrification, or immobilization in glass waste forms, for all of the high-level radioactive waste at Hanford. However, because the volume of low-activity waste exceeds DOEs capacity limits for vitrification, DOE must decide how to treat the remaining supplemental low-activity waste (SLAW) so that it can be safely disposed in a near-surface disposal site. To help inform its decision, DOE contracted with a Federally Funded Research and Development Center (FFRDC), led by Savannah River National Laboratory, to analyze and report its findings about three potential alternative technologies. At the request of Congress, the National Academies reviewed the FFRDC report in terms of its value for decision making and how well it meets various Congressional requirements related to Hanford cleanup. The review concludes that the FFRDC report is overall very strong, provides a useful framework for evaluating the technology options, and is responsive to guidance from the first National Academies review. The framework provides for structured side-by-side comparisons, using relevant criteria, of a limited number of alternatives for managing SLAW. Recommendations for strengthening the report include estimating a lifecycle cost profile for constructing and operating each alternative, and providing more in-depth discussion on potential challenges that may need to be addressed in obtaining the necessary various regulatory approvals.