Appendix B

Executive Summary from the Federally Funded Research and Development Center’s Report of Analysis of Approaches to Supplemental Treatment of Low-Activity Waste at the Hanford Nuclear Reservation

INTRODUCTION

Section 3134 of the National Defense Authorization Act for Fiscal Year 2017 (NDAA17) stipulates that a Federally Funded Research and Development Center (FFRDC) team conduct an analysis of technologies for treating and solidifying what is generally called “Supplemental Low Activity Waste” at the Department of Energy’s (DOE’s) Hanford Nuclear Reservation. The focus of the analysis is technical, and the FFRDC team is made up of technical experts in appropriate disciplines from the national laboratories. The NDAA17 also requires a concurrent review of the analysis by a committee of technical experts selected by the National Academies of Science, Engineering, and Medicine.

Hanford tank waste processing is currently planned to complete in 2063. Supplemental Low Activity Waste (SLAW) is treated Hanford liquid radioactive waste that cannot be treated and solidified by the currently planned first Low Activity Waste (LAW) systems within the Waste Treatment and Immobilization Plant (WTP) without extension of processing and tank storage durations. Under current planning expectations, the projected volume of SLAW (~54,000,000 gallons) will be similar to the volume of waste currently stored in the tanks due to the need to add water while removing the waste from the tanks, transferring it, and pretreating to remove key radionuclides. A decision on how to treat the SLAW is anticipated in the future and this report is expected to assist in those future decisions.

This report describes the FFRDC team’s analysis results, which are intended to inform the decision-makers who will ultimately select approaches and technologies for the SLAW treatment.

SCOPE & CASES ANALYZED

The NDAA17 section 3134 calls for analysis of further processing of SLAW to remove long-lived isotopes such as technetium and iodine to immobilize with High Level Waste (HLW). It also calls for analysis of vitrification, grouting, and fluidized bed steam reforming and other approaches identified by the DOE for immobilizing LAW. These technologies are described in detail in the report. Each of these technologies was analyzed against the following parameters as specified in the NDAA:

• Risks related to treatment and final disposition
• Benefits and costs
• Anticipated schedules
• Regulatory compliance
• Obstacles that would inhibit pursuit of the approaches

The study developed numerous cases for initial analysis (including off-site out-of-state disposal) and ultimately simplified them to five. These five cases are:

1. Vitrification with On-site Disposal
2. Grouting with On-site Disposal
3. Grouting with Out-of-state Disposal
4. Steam Reforming with On-site Disposal
5. Steam Reforming with Out-of-state Disposal

Off-site disposal was considered because the geology and waste acceptance requirements of the off-site disposal facility are different from those of the on-site disposal facility and offer a disposal path for wasteforms that may be deemed unsuitable for on-site disposal.

The grout process is a room temperature process that is much lower temperature than the other technologies. Low temperature can be beneficial: heating waste to high temperature drives off volatile chemicals, creating liquid secondary waste and air emissions, which are not created in a low temperature process. However, low temperature treatment does not destroy all hazardous organic chemicals that are typically restricted from land disposal.

Without pretreatment, organics present in some of the waste will remain in the grout and some waste may be prohibited from disposal unless granted an exemption. Before grouting, pretreatment to remove or reduce organics would be required on the waste with high organic content. Thus, Pretreatment to remove or destroy these organics prior to grouting was conservatively assumed to be required for the low temperature alternatives.

Each of these five cases addresses primary and secondary wastes. Secondary waste is generated during treatment of primary waste and may include solid and liquid forms. For example, offgas treatment during vitrification produces liquid secondary waste that requires additional treatment and disposal. Grouting and steam reforming produce no liquid secondary waste from the offgas systems. Each technology will produce solid secondary waste.

The study found that disposal of secondary waste generated by these cases may be viable for off-site disposal. There is also potential for “combination” treatment and disposal scenarios, such as disposal of a primary waste on-site and off-site disposal of secondary waste. Such cases were not explored in detail.

HIGH LEVEL RESULTS

Table 1 includes a high level summary of results. There are many details, assumptions, and technical explanations behind this high level summary, which are addressed in this report.

CONCLUSIONS

The following conclusions resulted from the FFRDC analysis of the SLAW treatment technologies:

• A viable SLAW treatment and disposal option can be developed for each of the three technologies evaluated (vitrification, grouting, and steam reforming).
• For grouting, both on-site and out-of-state disposal will likely require treatment of select organics if found in the waste, and additional flowsheet studies will be needed to define that treatment.
• Removal of technetium and iodine is not needed for out-of-state disposal of grouted or steam reformed wasteforms.
• Technetium removal is not needed for on-site disposal of grouted or steam reformed wasteforms, assuming high performing grouted and steam reformed wasteforms.
• Iodine removal is not needed for on-site disposal of grouted or steam reformed wasteforms, assuming best performing grouted and high performing steam reformed wasteforms.
• Grouting and steam reforming offer significant cost benefits over vitrification. Grout is the least expensive option, with FBSR and vitrification options ranging 2.5 to 5× and 4 to 10× higher, respectively, which is comparable to recent Government Accountability Office reporting.

TABLE 1 High-Level Comparison of the Five Representative Cases for Immobilization of Hanford SLAW per the Analysis Criteria Specified in NDAA17

• A near-term decision on SLAW treatment technology is needed to meet DOE mission completion goals.
• Implementing any of the SLAW treatment technologies will exceed current funding levels when combined with required spending for all WTP and tank projects concurrent with SLAW treatment.
• Secondary waste generated from vitrification will require additional wasteform development and treatment capabilities.

Several key aspects of this study may benefit from further verification and technical analysis to increase confidence in several cases. These include the following:

• Treatment of organics restricted from land disposal (on-site and off-site grout cases)
• Treatment of technetium and iodine (on-site grout case)
• Treatment of liquid secondary wastes (vitrification case)
• Performance of grouted waste forms (on-site grout case)
• Performance of steam reformed waste forms (on-site SR case).

It is clear from the analysis that increased levels of funding will be needed in all cases, based on the integration with other Hanford tank waste disposition efforts. It is important that a decision on the SLAW treatment technology (or a baseline/alternate) be made quickly and commencement of technical maturation be started without delay to allow the completion of a facility to treat the SLAW by the time the facility will be needed. If the SLAW facility is not ready when needed, the treatment of tank waste could be delayed, thus extending tank waste storage duration (and resulting in increased storage risks).

The remainder of the FFRDC report is intended to provide a deeper review of each analyzed case by defining it and explaining the risks and the areas recommended for further study and analysis.