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Introduction

As the committee has mentioned in its three previous review reports, the nation’s biggest and most complex nuclear clean-up challenge is at the Hanford Nuclear Reservation. While the Hanford site has several clean-up challenges, the focus of this congressionally mandated study is approaches for treatment and disposal of the supplemental portion of the low-activity waste (LAW) from the tanks, as defined in the following section. At the site, 177 underground tanks collectively contain about 211 million liters (about 56 million gallons) of waste (WRPS, 2018) that includes high-activity and low-activity materials. This diverse waste is incompletely documented and characterized, chemically complex, and difficult to manage and dispose of safely due to many factors. These include the use of three different methods for plutonium extraction from irradiated nuclear fuel, the mixing of wastes among tanks from transfers over decades to optimize tank usage, the prior efforts to neutralize or otherwise alter the waste, the (incomplete) recovery of cesium-137 and strontium-90, which were placed in separately stored capsules, 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 at the Hanford site 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).

This review report, the final of four to be issued by the National Academies to address the congressional mandate, focuses on the Statement of Task’s study charge for the committee to provide a summary of public comments on the third committee review report, which was published on August 15, 2019, and the committee’s views, if any, on these comments and whether they change any of the findings or recommendations in the third review report (see Appendix D).

As in the previous review reports, the committee in this introductory chapter describes the context and tasks of the congressional mandate in Section 3134 (Sec. 3134) of the National Defense Authorization Act of Fiscal Year 2017 (see Appendix C). This chapter also introduces the study process for this final review.

PROPOSED TREATMENT PLAN AND CONGRESSIONAL MANDATE TO ANALYZE AND REVIEW THE ANALYSIS OF SUPPLEMENTAL TREATMENT APPROACHES

DOE-EM has proposed to retrieve the waste from the tanks to produce two waste streams, by removing several specific radionuclides that contain 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 remaining solids to yield high-level waste (HLW). 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 accomplished by removing “key radionuclides to the maximum extent practical” (DOE, 2011a) during the initial processing of the waste streams in the Waste Treatment and Immobilization Plant (WTP), which is already under construction at Hanford. Of particular concern are the long-lived radionuclides iodine-129 (half-life of 15.7 million years) and technetium-99 (half-life of 210,000), and these radionuclides are problematic because of their high mobility in an oxidizing environment as compared to most other radionuclides and more than 90 percent of iodine-129 and technetium-99 could end up in the LAW stream.

To treat these two waste streams, the baseline plan is to use vitrification, that is, immobilization in glass waste forms, for all of the HLW stream and for about 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, DOE-EM anticipates that there will be substantial amounts of the LAW that the WTP cannot process. 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 consideration has been given to an off-site location such as the Waste Control Specialists (WCS) facility near Andrews, Texas.

DOE-EM has yet to formally select a supplemental treatment approach, though the Department of Ecology and some stakeholders believe that DOE has previously promised to use vitrification. To help with the final selection, Congress directed DOE-EM in Sec. 3134 to contract with a Federally Funded Research and Development Center (FFRDC) to perform analysis on treatment approaches. According to Sec. 3134, the treatment approaches considered should at a minimum include:

1. Vitrification, to produce glass waste forms either using Joule-heated melters, which are to be used in the WTP, or bulk vitrification;
2. Grouting, to produce cementitious waste forms; or
3. Fluidized bed steam reforming (FBSR), to produce a calcined powder or a monolithic crystalline ceramic waste form.

Sec. 3134 also asks for identification by DOE of additional alternative treatment approaches, if appropriate. At this final stage of the study, neither DOE nor the FFRDC has identified additional alternative primary approaches, though the FFRDC has identified some variants of the primary approaches. As discussed in the FFRDC’s final draft report, dated April 5, 2019, as well as the final report, dated October 18, 2019, the FFRDC team narrowed its consideration of alternatives to five SLAW treatment 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. (If the waste is vitrified, there would be little purpose to shipping it off-site, so only the IDF is considered for vitrified waste.) The vitrification method being considered is use of Joule-heated melters. 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. Also, to implement the five currently identified alternatives, additional waste conditioning (pre-treatment) might be needed, for example, to remove certain radionuclides, or to adjust the composition of the waste to make it more suitable or less costly for treatment and disposal. Notably, Sec. 3134 requires an analysis of “further processing of the low-activity waste to remove long-lived radioactive constituents, particularly technetium-99 and iodine-129, for immobilization with high level waste.”

In parallel to selecting an FFRDC, DOE was directed in Sec. 3134 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.¹ 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. The charge to the FFRDC team from Sec. 3134 is in Appendix C. The Statement of Task for the National Academies committee is in Appendix D. For both the FFRDC team and the National Academies’ committee, the charge is limited to analysis of methods for the

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¹ 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, final draft report or final report for the FFRDC team’s work, and review or review report for the committee’s work.

treatment of SLAW, considering disposal location and possible pre-treatment as needed for that analysis. Neither the FFRDC nor the committee is to make a recommendation regarding the treatment or disposal of SLAW, and certainly neither is a decision-maker.

The FFRDC team’s task is to provide DOE and Congress with facts and analyses regarding treatment approaches, but not a recommendation concerning a preferred alternative. Likewise, the committee, as peer reviewer, does not offer or imply a recommendation among alternative approaches in its reviews. The committee’s role as peer reviewer, though, did involve two iterations before the committee’s comprehensive report (its third), as envisioned by Sec. 3134.

This congressionally mandated study has come about in part due to a 2017 U.S. Government Accountability Office (GAO) report that indicated significant cost savings if a grout treatment approach were to be used as compared to vitrification, based on the experience of the Savannah River Site’s (SRS’s) use of grout for about 4 million gallons (as of the date of that report) of LAW (GAO, 2017). Because the LAW at the SRS is not as chemically complex as the LAW at Hanford, however, the cost and performance of using grout treatment at Hanford could differ significantly from the cost at the SRS. The GAO report, therefore, recommended:

In its report, GAO noted that “DOE agreed with both recommendations.”

Additionally, the committee notes another very recent GAO report on risk-informed decision making (GAO, 2019). In that report, the GAO writes:

Performing such trade-offs and prioritization of federal funding is particularly relevant to the Hanford situation, as will be discussed in Chapter 5. The GAO report outlines the essential elements of a framework for making risk-based clean-up decisions.

The congressional charge, reflected in the Statement of Task, is very specific to treatment options for SLAW; moreover, neither the FFRDC nor the committee was charged to select, reject, or recommend any particular supplemental treatment approaches. Thus, the scope of this review report is very limited by comparison to the many, much larger, elements of the overall Hanford clean-up. SLAW, indeed, is the “tail” element of the treatment sequence. In particular, several important questions for the Hanford site were not within the scope of the FFRDC’s analysis (and thus not in the scope of the committee’s review). Those not within the scope include, tank waste management, HLW processing and treatment, treatment and disposal of LAW not considered SLAW, the proper definition or interpretation of high-level waste or other legal agreements or requirements, and the WTP’s design, construction, and operations. In addition, while the committee specifically references the overall funding (Finding 2-2) and length of the Hanford clean-up (Finding 3-4, Recommendation 4-1), the Statement of Task clearly does not permit a comprehensive analysis of the clean-up process.

Clearly, there is solid logic to limiting the FFRDC and committee’s scope: the SLAW infrastructure has yet to be built; it makes for a manageable task for the FFRDC in the time allotted; and it avoids further delays in progress toward completing the infrastructure that would result from having to perform a comprehensive analysis. Nevertheless, as the committee has previously observed (Reviews #2 and #3), decisions about the SLAW “tail” are unavoidably part of a larger, interdependent system: upstream decisions frame the options for SLAW; decisions about the SLAW “tail,” even if made independently, have upstream implications; and SLAW decisions themselves have downstream implications for disposal, and disposal options have implications for SLAW. As ecologists say, everything is connected to everything; at Hanford this is literally true, and the interactions and total system will ultimately need to be addressed. Consequently, the limited scope means that very consequential upstream elements (such as tank management, HLW-LAW separation, and pre-treatment) and downstream elements (such as expected future use of the site) of the treatment process are clearly beyond the scope of the FFRDC study. DOE and Congress may ultimately decide, therefore, that a broader view of the treatment and disposal system is desirable to achieve their goals of an effective, thorough, safe, and efficient clean-up of the Hanford site.

STUDY PROCESS

In this fourth review report, according to the Statement of Task, the committee is required to “provide a summary of public comments on the third committee report and the committee’s views, if any, on these comments and whether they change any of the findings or recommendations in that report.” In other words, the committee is to summarize, and consider as appropriate, comments on the committee’s review, not the FFRDC’s report. Importantly, the committee is not expected to perform a further peer review of the FFRDC’s final report.² Rather, the committee’s peer review of the FFRDC analysis formally concluded with its assessment of the FFRDC’s final draft report, dated April 5, 2019.³ At the public meeting preceding the present (fourth) review, on October 31, 2019, in Richland, Washington, members of the FFRDC team presented the main results in their final report and also discussed how they addressed several of the committee’s findings and recommendations in Review #3. Table 1-1 lists the FFRDC’s presentations from this meeting.⁴ The webcast videos of the public meetings are archived and available for viewing.⁵ During the most recent public meeting in Richland, Washington, several stakeholders presented their views to the committee (see Appendix E for a list of those presentations).

Throughout the study, in addition to comments received during the public meetings, the National Academies has received comments submitted via e-mail and mail as well as most recently during the congressionally mandated comment period, via a Web survey form. All comments are available in the study’s Public Access File.⁶ 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

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² To access the FFRDC’s final report, see http://dels.nas.edu/resources/static-assets/nrsb/miscellaneous/SRNL-RP-2018-00687-Final-Report-Hanford-SLAW.pdf.

³ To access the FFRDC’s final draft report, see http://dels.nas.edu/resources/static-assets/nrsb/miscellaneous/ffrdc2019-4.pdf.

⁴ For the FFRDC’s presentations and other presentations from the October 31, 2019, public meeting, see http://dels.nas.edu/Past-Events/Meeting-Supplemental-Treatment/DELS-NRSB-17-02/11480.

⁵ For the first public meeting’s video recording, see https://livestream.com/NASEM/DELS-NRSB; for the second public meeting’s video recording, see http://www.tvworldwide.com/events/nas/180228; for the third public meeting’s video recording, see http://www.tvworldwide.com/events/nas/180723; for the fourth public meeting’s video recording, see http://www.tvworldwide.com/events/nas/181129; for the fifth public meeting’s audio recording (no video was recorded), see http://www.tvworldwide.com/events/nas/190108; for the sixth public meeting’s video recording, see http://www.tvworldwide.com/events/nas/190516; and for the seventh public meeting’s video recording, see http://www.tvworldwide.com/events/nas/191031.

⁶ To request information in the Public Access File for this project, see https://www8.nationalacademies.org/pa/ManageRequest.aspx?key=49905.

and an opportunity for it to comment on the FFRDC’s draft report and the committee’s review of that report. The committee received invited presentations during the second, third, fourth, sixth, and most recent seventh public meetings from the Department of Ecology and has considered these presentations in its reviews.

Table 1-2 shows the study’s schedule, including the FFRDC’s work, the committee’s reviews, the public meetings, and the briefings to stakeholders. While the last activity in this schedule is subject to change, it was 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.

TABLE 1-1 List of the FFRDC’s Presentations, Given on October 31, 2019, in Richland, Washington

TABLE 1-2 Study Schedule

To perform the peer review task, the National Academies formed a committee composed of 13 experts and one technical adviser 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. A majority of the committee members have prior experience in studying clean-up activities at the Hanford Nuclear Reservation and at other DOE-EM sites. Appendix F contains biographical information about the committee members’ qualifications and experiences. The committee also has found it necessary to perform additional fact finding, for example, by receiving briefings from experts outside the FFRDC team about aspects of the supplemental pre-treatment, treatment, or analysis approaches. Any information learned by the committee during additional fact-finding is available in the study’s Public Access File.

The FFRDC team was assigned a very large task to be accomplished in a short period of time, that is, to review a long history and large technical literature on three or more very different treatment technologies and, as the analysis developed, the permanent disposition of waste material in two (or potentially three) very different disposal sites. (As the committee has noted in previous reports, the choice among treatment approaches cannot meaningfully be made without consideration of the disposal environment and transporting the waste to the disposal site.) The FFRDC team has, as the committee has also noted, worked very hard to grapple with the task it was assigned. It has gathered a large amount of information, performed analysis on it, and improved its approach and presentation of results in response to comments. Importantly, the FFRDC is not in the role of a decision-maker in selecting one treatment approach over another.

REVIEW REPORT ORGANIZATION

The remainder of this review report proceeds in four parts. In Chapter 2, the committee discusses developments since publication of Review #3, in particular, the availability of the performance assessment (PA) for the IDF, and the publication of the FFRDC’s final, revised report and FFRDC comments on Review #3. In Chapter 3, the committee provides a summary of comments received during the comment period and categorizes the comments by themes or groupings. In Chapter 4, the committee responds to comments according to the ground rules described at the start of Chapter 3. Finally, Chapter 5 provides the committee’s conclusions about this study.