In this appendix, the committee provides its observations of additional issues that the FFRDC might consider as it develops its forthcoming analytic report and then gives comments on particular items of text in the FFRDC’s draft framework.
Additional Issues for Consideration
Word usage in the draft framework: The word usage in some places is confusing and is not clearly defined at this early stage: for example, “implementability,” “successful completion,” and “likelihood and consequences of failing to complete for technical reasons.”
Overall waste treatment design goal: At multiple points during the presentations at the October meeting, the FFRDC team stated that the overall design goal was to enable full-capacity operation of HLW vitrification to lead to the most rapid risk reduction at the Hanford site. The corollary to this is full-capacity operation of WTP LAW vitrification would be required. The next corollary is that SLAW has to process the WTP LAW excess on an as-needed basis. Further, large oscillations in the SLAW processing rate have been estimated (see FFRDC slide 11),9 which implies the need for a SLAW technology that accommodates oscillations to the maximum extent possible. Because about 90 percent of the retrieved waste volume will go into the LAW stream, the ability to treat LAW in the WTP and separated SLAW treatment facilities will be the limiting factor in the rate at which tank wastes can be retrieved. In addition, one of the ways to evaluate the technologies is on the ability of the technologies to handle the diverse waste streams.
Apparent Unequal Evaluation of the Treatment Alternatives: The draft framework’s introduction appears to have only one subheading, and it is about grout alternatives. The paragraphs before this subheading are devoted to pre-treatment of the LAW for SLAW and as such appear to be a preamble to “allow grout” to be the favored alternative. In that respect, it is important at this stage not to appear to favor one treatment alternative over another, although Sec. 3125 does call for additional study for the grout option. In particular, while the FBSR alternative is mentioned in the draft framework, the tables for FBSR (pp. 30-33 in the framework document) are all blank at this stage in comparison to the many filled in cells for the tables on vitrification and grout alternatives and their variants. Moreover, in the last sections of the draft framework (see p. 53 and later pages), the measures of effectiveness are given, but they are only given for grout and vitrification; thus, by default, the FFRDC has not yet given equal consideration to FBSR. Two important theoretical benefits of FBSR are that it needs no pretreatment for technetium, cesium, or iodine and can readily accommodate substantial feed rate variations or even complete shutdown. These would obviously require validation in the Hanford environment, which the committee recognizes is considerably more complex than the Idaho National Laboratory environment, which itself has had major challenges in implementing FBSR.
Grout treatment: Grout is treated in the draft framework as if it were a single material/formulation/process. The committee observes that more thought appears to be needed about which key objectives need to be achieved by the grout (as opposed to any pre-treatment or
9 This slide is available in the file labelled, “FFRDC Presentation,” from the October 2021 public meeting at the following URL: https://www.nationalacademies.org/event/10-20-2021/review-of-the-continued-analysis-of-supplemental-treatment-of-low-activity-waste-at-the-hanford-nuclear-reservation-meeting-3-open-session
supplementary processes) and then provide—at least in concept—information about which types of grout are envisaged to meet these needs.
Vitrification treatment: For the vitrification option, the question of secondary waste streams becomes important, and there is a significant chance that a grout plant smaller than the all grout option would be needed to treat these wastes. This could mean that there is a slightly artificial dichotomy between the two technologies.
Off-site communities: In the most recent public meeting and in the previous related study and review, the committee devoted a significant amount of its time to hear from interested and affected local stakeholders in the Hanford region. The committee notes that it has not heard from any similar parties relevant to the options for off-site disposal. While it is perhaps not surprising that there is local support around Hanford for sending the wastes to other locations, the committee has no basis for judging how such a decision would be seen by communities near the off-site disposal locations.
Comparisons of on-site and off-site disposal options: The FFRDC presentations touched upon issues related to on-site and off-site disposal of treated SLAW. The FFRDC team made reference during the October meeting to the non-ideal nature of the Hanford IDF site location and to the superior characteristics of some off-site disposal site locations. Ultimately, a decisionmaker would want reliable information that can provide answers to these questions: (1) Which sites are most likely to be protective of groundwater resources and least likely to negatively impact human health and the environment, and why? (2) Are risks reasonably well quantified for all potential disposal sites based on a common set of analyses, e.g., out to 1,000 years or to 10,000 years? (3) What if SLAW disposal is not permitted for the Hanford IDF? (4) How do transportation risks to humans (including potential transportation accidents) compare to risks associated with disposal site performance? (5) What are the risks associated with local community and host state acceptance, including transportation corridors? (6) How might long-term climate change potentially affect disposal site performance? The committee suggests considering these questions in the next FFRDC report.
Transportation issues: The FFRDC draft framework says almost nothing about transportation. It is hoped that this topic will be addressed in the complete draft report. Transportation is not only relevant for off-site disposal but also for on-site movement of wastes. In addition, the draft framework mentioned an option of shipment of LAW off-site for treatment; this could raise additional transportation risks attendant to the transport of liquid LAW. Moreover, indigenous populations may be impacted by transportation of wastes and their perspectives would have to be considered in any planning for waste shipments.
Another set of issues relevant for transportation is the testing, certification, and control of the containers used for transport, both off-site and on-site. In particular, the waste transfer lines will need to be tested and presumably certified for use in that the substance being transported is “dangerous.” Presumably, local populations would want an assurance that leaks will not occur and want to have evidence, like testing results, to assure them that leaks are not possible.
The FFRDC might benefit from considering the experience at the West Valley Demonstration Project in West Valley, New York. One of the objectives of this DOE-managed project was to convert ~600,000 gallons of HLW (from fuel reprocessing) into a vitrified waste form suitable for disposal at Yucca Mountain. The HLW was pretreated with zeolite ion exchange and the decontaminated supernatant (low-activity waste) was solidified into ~20,000 71-gallon square drums for optimum storage in an on-site above grade drum cell. In 2006 and 2007, ~14,000 drums were shipped by rail to the Nevada National Nuclear Security Site for disposal in the Area 5 of the Radioactive Waste Management Site. These were commercial rail shipments conducted in compliance with Department of Transportation and U.S. Nuclear Regulatory Commission regulations.
Cost estimation: The materials provided by the FFRDC on how it will approach costs is silent on the matter of whether the FFRDC is discussing real or nominal costs. The distinction is very important. For example, using a real zero discount rate when evaluating the relative societal costs of alternative public policy choices implies that society has a zero rate of time preference—a situation that is unsupported by empirical evidence. Using a nominal zero discount rate is even less realistic, in that it
implies either that the societal rate of time preference is negative or that there is no inflation and a zero societal rate of time preference. The FFRDC needs to clarify whether its discount rate choices are real or nominal and to ensure that the future costs to which it will be applied are in the same terms as the discount rate. It is likely that the escalation rates presented (during the October meeting) are real rates (4 percent and 2.4 percent), i.e., escalation above the rate on a long-term Treasury bond. (The California Public Utilities Commission uses a real escalation rate of 3 percent for nuclear power plant decontamination and demolition expenses.) Larger positive discount rates would bring down the present value of large capital expenditures in the medium- and long-term future. It would be useful for the FFRDC to document the DOE guidelines on escalation rates for capital (4 percent/yr) and operating costs (2.4 percent/yr) in the nuclear waste industry. Are these nominal or real rates of escalation?
What programs are being used for the Life Cycle Cost (LCC) component of the cost estimation? It would be helpful for the FFRDC to document these programs and explain the routines and sub-routines in these programs. Will System Plan 9 be the basis of the LCC cost estimates? What (other) programs are being used for System Planning in the cost estimation? Also, it would be helpful to describe the Work Breakdown Structure (WBS) for the Direct Feed Low-Activity Waste (DFLAW) facility, which is under construction. How will DFLAW cost data be incorporated into the LCC estimate? What is the algorithm used to constrain a “flat funding scenario”?
Graphical display of comparisons: For the importance of graphical display of comparisons useful for decisionmakers, the committee notes that Stephen Weigman, Chair of the Hanford Advisory Board, specifically mentioned at the October meeting that pictorial depictions would be particularly helpful for decisionmaking. The committee observes that the draft framework and the FFRDC presentations do not show examples of graphical or pictorial displays of potential evaluation results other than tabular formats.
Comments on Particular Items in the Draft Framework Report
Here are additional observations on specific statements in the draft framework report:
General: the terms variant, option, alternative, and scenario are all used. While the committee believes it understands the difference between variant and alternative based on the presentations, are the other terms really different or a different label for the same thing? Definitions are needed early-on in the FFRDC report.
p. 2: “After TFPT, the liquid will be evaporated to remove excess water; with many of the organic species in the waste expected to partition to the condensate during that evaporation.” It is stated that the waste will be Class A with strontium-90 removal, but will this still be the case after evaporation?
p. 3: “The status of the technology maturation for pretreatment processes discussed here is mixed. A tank-side treatment system for cesium removal is currently deployed at [Savannah River Site] SRS (TCCR) and is in startup testing at Hanford (TSCR), so is mature.” This could be an overstatement. One deployment does not qualify for “mature,” and Hanford waste is more difficult than SRS waste.
p. 3 “While not a specific technology, the ability of a SLAW immobilization process to have flexible processing rates and easy idling periods is important.” It is not clear what “easy idling periods” mean.
p. 4: “Additional measures, such as barriers and getters, may be taken as options to provide defense-in-depth of contaminant release. The details of those options are described in section X.X of this report.” This implies that grouted SLAW alone will meet requirements and the additional measures are inessential additions. Is this the intention? In any case, the next paragraph seems more explicit: “. . . it is assumed that getters are needed to meet the leaching performance criteria for onsite disposal of grout in containers for Alternatives 1-5.”
p. 11: “FBSR has been researched, developed, and used commercially for over two decades for processing low level radioactive wastes.” Is the FBSR being considered for Hanford the same as what has been used commercially for over two decades? Certainly the feed is not.
p. 13: “Since 100% of the spent scrub solution is recycled, there is no liquid secondary process waste from the offgas system.” But isn’t there an off-gas stream?
p. 14 and p. 20: “The waste is assumed to be sampled in the DST [double shell tank] and analyzed and found to be compliant with the pretreatment system such that it would produce an acceptable grout waste form, or it will be staged for vitrification.” Is the proposal to build both a SLAW vitrification plant and a grout plant, or is the FFRDC team suggesting or hoping that LAW vitrification will have the capacity to vitrify the unacceptable LAW?
p. 15: “After grouting the waste, grout containers with lower than a threshold concentration of these radionuclides would be disposed onsite, and those with higher than threshold concentration would be disposed offsite.” Are the polypropylene-encased grout blocks transportable and disposable off-site? The rough order of magnitude size of these is a cube 2 meters on a side weighing approximately 15 tonnes.
p. 18: “Note that the East plant would have to be sized to handle SLAW from the HLW treatment at the WTP, while the West plant would likely be smaller and have a lower capacity requirement.” Isn’t the tank waste from the West plant sent to WTP, so won’t the SLAW be generated in the East plant? How does it get back to the West plant and why?
p. 19: “Geopolymer product has lower free water than cement.” This is not always true, and actually this is quite tricky to achieve a lot of the time. This could be qualified by saying “can be designed to have” instead of “has.” Also, the distinction between geopolymer and grouting (which seems to be implied here) is a fraction artificial; one could view geopolymer as a specific form of grout (applied through similar processes and performing similarly) rather than as a wholly distinct class of materials/processes. Thus, if using FBSR followed by geopolymer grouting, that is a more complex two-stage process.
p. 22: “This alternative utilizes an offsite vendor to immobilize the treated supernate.” How will the liquid SLAW be transported? What will the frequency of shipments be? A cask for off-site transportation of Class A liquid LAW was considered for off-site use at Hanford in 1996. It had a payload of about 1,000 gallons whereas the liquid processing rate in SLAW is in the range of 30,000 to 50,000 gal/day. Perhaps the design can be improved, but they have a long way to go.
p. 53: Clarity is needed on the inclusion of selenium-79 (79Se) as a specific criterion. It is not discussed throughout the draft document, but then it is listed as a specific radionuclide starting in section 188.8.131.52.3. When asked about the importance of 79Se at the October meeting, it was stated that this radionuclide is not an important consideration. If this is not a radionuclide of concern, is it included as a RCRA metal and not called out specifically in the report? If the decision is to include it with the RCRA metals, then it may be important to provide a short justification to address previous concerns that were raised in the Sec. 3134 review (NASEM, 2020).
p. 53 and later instances: For the measures of effectiveness (MOEs), some are likely to be essentially hurdle (pass/fail) criteria for each option, and others are on a continuous scale for comparison between options. It would be helpful to include some clarity on which category each of the MOEs will fall into, as they are being developed and refined.