The Hanford Nuclear Reservation, where about two-thirds of the nation’s weapons plutonium was produced from 1944 to 1987, is the site of the largest and most complex nuclear cleanup challenge in the United States. Unlike the Savannah River Site, where the other one-third of U.S. weapons plutonium was produced and which used one reprocessing method to extract plutonium from irradiated nuclear fuels, the Hanford Site used three different methods for plutonium extraction and over time the resulting wastes were commingled and chemically altered in enormous underground tanks. The 177 tanks contain collectively about 211 million liters (about 56 million gallons) of waste (WRPS, 2018). The waste treatment challenge is thus extremely complex, because of the variety of waste matter, the mixing of wastes among tanks from transfers to optimize tank usage, the prior efforts to neutralize or otherwise alter the waste, the recovery of some of the cesium-137 and strontium-90, which were placed in separate metal capsules and stored, and the addition of materials to the tanks from auxiliary processes (Peterson et al., 2018).
The U.S. Department of Energy’s Office of Environmental Management (DOE-EM) is responsible for managing and cleaning up the waste and contamination under a legally binding Tri-Party Agreement (TPA) with the Washington State Department of Ecology (the Department of Ecology) and the U.S. Environmental Protection Agency (EPA). DOE-EM has proposed to retrieve the waste from the tanks to produce two waste streams, high-level waste (HLW) and low-activity waste (LAW), by removing several specific radionuclides that constitute most of the radioactivity from the liquids and dissolved salt cake in the tanks, yielding liquid LAW, and then combining the removed radionuclides with the HLW solids. DOE-EM estimates that the HLW will contain more than 90 percent of the radioactivity and less than 10 percent of the total volume, while the LAW will consist of less than 10 percent of the radioactivity and more than 90 percent of the volume. This is primarily accomplished by removing “key radionuclides to the maximum extent practical” (DOE, 2011) during the processing of the waste streams in the Waste Treatment and Immobilization Plant (WTP), which has been under construction for the past 20 years at the Hanford Site.
To treat these two waste streams, the current plan is to use vitrification, that is, immobilization in glass waste forms, for all of the HLW stream and for at least one-third of the direct (primary) LAW stream. Secondary LAW waste comprised of liquid wastes, off-gas filters, and other internally generated wastes is expected to be grouted, that is, immobilized in a cementitious waste form. Due to capacity limits in the LAW vitrification facility portion of the WTP, which is also under construction, DOE-EM anticipates that there will be substantial amounts of the LAW that the WTP cannot process.
In 2023, DOE-EM is scheduled to begin operations of the Direct Feed Low Activity Waste (DFLAW) facility. DFLAW is being implemented to enable Hanford to process liquid waste as soon as possible due to the projected time needed to resolve the technical issues associated with the HLW facility and the Pretreatment facility. When operational, DFLAW is expected to reduce the risk posed by the Hanford liquid waste by processing and encapsulating the most mobile form of Hanford’s waste. DFLAW is also intended to free up Double Shell Tank (DST) space for operational efficiency, accommodate additional DST tank failures, and reduce the amount of additional Supplemental Treatment needed in the future.
To increase the LAW treatment capacity, DOE-EM intends to decide on a supplemental treatment approach and build another treatment facility to implement it. The supplemental LAW (SLAW) to be treated would be similar in composition to the LAW to be treated in the WTP. The immobilized LAW—whether from the WTP or the SLAW facility—is intended to be disposed of in the existing near-surface Integrated Disposal Facility (IDF) at Hanford, though more recently (see the Sec. 3134 study) preliminary
analysis has been done regarding off-site locations such as the Waste Control Specialists (WCS) facility near Andrews, Texas.
To keep the treatment of the HLW in the WTP on track over time to meet the amended TPA milestones, DOE’s plan is to have a supplemental treatment plant for the portion of the LAW that will exceed the capacity of the WTP (SLAW), because the SLAW must be treated concurrently to allow the HLW to be treated at the WTP’s full potential capacity. In DOE’s 2013 Record of Decision on Hanford tank waste management, DOE stated that it “does not have a preferred alternative regarding supplemental treatment for the LAW; DOE believes it is beneficial to study further the potential cost, safety, and environmental performance of supplemental treatment technologies” (DOE, 2013).
DOE-EM has yet to formally select a supplemental treatment approach, although the Department of Ecology and some stakeholders assert that DOE has previously promised to use vitrification. To help with the selection, Congress directed DOE in Section 3125 of the Fiscal Year 2021 National Defense Authorization Act (Public Law 116-283) (Sec. 3125) to enter a contract with a Federally Funded Research and Development Center (FFRDC) to “conduct a follow-on analysis to the analysis required by section 3134 of the National Defense Authorization Act for Fiscal Year 2017 (Public Law 114–328; 130 Stat. 2769) with respect to approaches for treating the portion of low-activity waste at the Hanford Nuclear Reservation, Richland, Washington, intended for supplemental treatment.” The analysis “shall be designed, to the greatest extent possible, to provide decisionmakers with the ability to make a direct comparison between approaches for the supplemental treatment of low-activity waste at the Hanford Nuclear Reservation based on criteria that are relevant to decisionmaking and most clearly differentiate between approaches.” For the criteria that Congress wants considered, see Appendix A, which provides the complete texts of Sec. 3125 and Sec. 3134.
As specified in Sec. 3134, the SLAW treatment approaches considered should at a minimum include:
- Vitrification, to produce glass waste forms either using Joule-heated melters, which are to be used in the WTP, or bulk vitrification;4
- Grouting, to produce cementitious waste forms; or
- Fluidized-bed steam reforming (FBSR), to produce calcined granules (often analogized to the consistency of dry laundry detergent) or a geopolymer-encapsulated granular mineral product waste form.
Sec. 3125 also asks for additional analysis of the grout treatment options identified in the FFRDC’s report for Sec. 3134.
In the previous Sec. 3134 study, the FFRDC considered in its final report five cases: (1) vitrification for disposal at the IDF, (2) grouting for disposal at the IDF, (3) grouting for disposal at WCS, (4) FBSR for disposal at the IDF, or (5) FBSR for disposal at WCS. In addition, secondary wastes, which were assumed to be grouted in all cases, are produced in amounts that depend on the treatment alternative, and these can contribute significantly to the dose rate to a public receptor. To implement the alternatives, additional waste conditioning (pre-treatment) might be needed, for example, to remove certain radionuclides, or adjust the composition of the waste to make it more suitable or less costly for treatment and disposal.
4 Note that Sec. 3134 does not explicitly mention the specific vitrification methods. The committee’s view is that Joule-heated melters or bulk vitrification could be considered based on the FFRDC analysis from the Sec. 3134 study.
In parallel to selecting an FFRDC, DOE was directed in Sec. 3125 to contract with the National Academies of Sciences, Engineering, and Medicine (the National Academies) to conduct a concurrent, iterative review of the FFRDC report as it develops to inform and improve the FFRDC’s work.5 DOE contracted with Savannah River National Laboratory (SRNL), an FFRDC, and then SRNL formed a team of experts from SRNL and other DOE national laboratories as well as from outside the laboratories’ network. The charge to the FFRDC team from Sec. 3125 is in Appendix A. The Statement of Task for the National Academies committee is in Appendix B.
The FFRDC team’s task is to provide DOE and Congress with a side-by-side comparison of the alternative treatment approaches and disposal options to aid decisionmaking. The committee, as peer reviewer, does not offer or wish to imply a recommendation among alternative approaches.
In this first review report, the committee provides its peer review and discusses its observations of the FFRDC’s draft framework report of 74 pages, titled “Hanford NDAA 3125 FFRDC Working Draft Compilation,” dated September 30, 2021, and a set of 71 slides produced by the FFRDC and presented at the public meeting on October 20-21, 2021.6 The committee also takes into account presentations at the two public meetings and submitted comments by stakeholders and other interested members of the public. Appendix E lists the FFRDC’s presentations at the public meetings.
Sec. 3125 by reference to Sec. 3134 specifies that “the National Academies of Sciences, Engineering, and Medicine shall provide an opportunity for public comment, with sufficient notice, to inform and improve the quality of the review.” Also, Sec. 3134 highlights the necessity of consultation with the State of Washington and an opportunity for it to comment on the FFRDC’s draft reports. The committee appreciates the presentations from the Department of Ecology at the two public meetings.
Table 1-1 shows the current schedule for the FFRDC’s work, the committee’s review, the public meetings, and the briefings to stakeholders. While this schedule is subject to change, it is designed to allow adequate time for the FFRDC and the committee to do their work in the iterative fashion described in the Statement of Task, and for regulators, stakeholders, and the public to provide comments. The next public meeting, in Richland, Washington, and with an online connection option, is planned for April 2022. The National Academies will publicly announce the specific dates for the meeting once these have been determined.
To perform its peer review task, the National Academies formed a committee composed of 14 experts and one technical consultant whose expertise spans the issues relevant for reviewing the FFRDC’s analysis, including risk assessments, cost estimation, cost-benefit analysis, waste processing, supplemental treatment approaches, legal and regulatory requirements, and large scale nuclear construction projects. Several of the committee members have prior experience in studying cleanup activities at the Hanford Nuclear Reservation, as well as at other DOE-EM sites. Appendix F contains biographical information about the committee members’ qualifications and experiences. Any information learned by the committee during additional fact-finding will be made available in the study’s Public Access File.7
5 For clarity, to the extent possible, this review report uses the nomenclature of team for the FFRDC’s investigators, committee for the National Academies committee, draft report for the FFRDC team’s work, and review or review report for the committee’s work.
6 To access all these documents and presentations from the public meetings, please go to nationalacademies.org and enter the search terms “Review of the Continued Analysis of Supplemental Treatment of Low-Activity Waste at the Hanford Nuclear Reservation.” This search will show the hyperlinks to the public meetings and provide access to the recordings of the events as well as the FFRDC draft documents and other presentations.
7 To request information in the Public Access File for this project, see https://www8.nationalacademies.org/pa/managerequest.aspx?key=DELS-NRSB-21-01
TABLE 1-1 Study and Review Schedule
|July 15, 2021||The committee’s first information-gathering meeting convened online. This was the first public meeting.|
|October 5, 2021||The FFRDC sent its draft analytic framework as a document for the committee’s first review.|
|October 20-21, 2021||The committee’s second information-gathering meeting convened online. This was the second public meeting.|
|October-December 2021||The committee’s first review report was prepared and reviewed.|
|January 2022||The committee’s first review report (this report) is published; the FFRDC received this review report to take into account during its continued work on the analysis.|
|April 2022||Anticipated month when the committee will receive the FFRDC’s complete draft analytic report to review. Once the report is posted on the National Academies project website, the Academies will announce the start of the minimum 60-day public comment period and will begin collecting those comments for consideration in the second review report.|
|April 2022||Anticipated third public meeting in Richland, Washington, with online option; the FFRDC will present its work to the committee.|
|May-August 2022||The committee’s second review report will be prepared and reviewed.|
|Late August-Early September 2022||Anticipated timeframe for publication of the committee’s second review report. The FFRDC will receive the committee’s review to take into account during its work on its final report.|
|November-Early December 2022||Public release of the final FFRDC report is expected to be posted to National Academies project website. This release will be followed by a public meeting in Richland, Washington, for presentation of the final FFRDC report. This meeting will also provide an opportunity for hearing perspectives from stakeholders.|
|December 2022- February 2023||The committee’s second review report will be prepared and reviewed.|
|March-April 2023||Final briefings to Congress, DOE, Washington State, and other stakeholders about the results of the FFRDC’s report and the final review report.|
The committee’s review is constrained by the Statement of Task, which expressly calls for the committee to “evaluate the technical quality and completeness” of the FFRDC report on the treatment options for the SLAW. The Statement of Task also requires that the committee’s report be “technical,” and the committee’s scope (along with the FFRDC’s) is the considered treatment approaches to the SLAW.
The remainder of this review consists of the committee’s response to the first two items in the Statement of Task (Chapter 2). In Appendix D, the committee provides additional observations of issues for consideration in the forthcoming FFRDC complete draft report. The committee’s findings and recommendations are in Chapter 2.