This  report found that the dilute and dispose approach would be significantly  less expensive than the MOX approach and would face fewer technical  risks. DOE’s Revised Cost Estimate for Constructing the MOX Facility Substantially Met Best Practices, but NNSA Has Not Yet Applied Best Practices to the Revised Life-cycle Cost Estimate for Completing the Overall Program

DOE’s revised cost estimate for completing construction of the MOX  facility substantially met best practices and, therefore, we believe it can  be considered reliable because it substantially met all four characteristics  of a high-quality estimate. In contrast, NNSA has not yet applied best  practices when revising its life-cycle cost estimate for the Plutonium  Disposition Program using the MOX approach, as we previously  recommended. DOE’s 2016 revised cost estimate for MOX construction  substantially met all four characteristics of a high-quality, reliable cost  estimate: comprehensive, well-documented, accurate, and credible. This is because, according to NNSA  officials, they developed the $56 billion cost estimate to satisfy an annual  requirement to record the plutonium environmental liability on  departmental financial statements that were due in September 2016. NNSA is currently assessing the extent to which any  new equipment and facilities would be needed to pursue this approach  and, according to NNSA officials, will complete a life-cycle cost estimate  that will follow GAO’s cost estimating best practices, including having the  estimate independently validated. According to the program requirements document that NNSA created to  outline its plans for conducting the dilute and dispose approach and  NNSA officials, NNSA’s life-cycle cost estimate for the program using this  approach will include several program elements: preparing the plutonium  for dilution, diluting the plutonium into waste, and disposing of it at  WIPP. DOE developed this capability as a technology  development project. These officials also said that if  DOE needs to expand the disposal space at WIPP in order to accept all  of the plutonium from the dilute and dispose approach, the costs for such  an expansion would not be part of the life-cycle cost estimate currently  under development for the program using the dilute and dispose  approach. WIPP Will Need to Be Expanded to Dispose of Defense TRU Waste Already Planned for WIPP

DOE does not have sufficient disposal space available in WIPP for the  TRU waste planned for disposal identified in its 2016 annual TRU waste  inventory report, and DOE will need to expand the repository to  accommodate this waste. While DOE officials stated that they  recognize expansion of WIPP’s disposal space may be necessary in the  future, they have not analyzed or planned for expanding the facility  because their focus has been on resuming waste emplacement  operations at WIPP. DOE relies on several types of overpacks for the disposal  of TRU waste. DOE’s most current formal planning document for  WIPP, the TRU waste management plan, covers 5 years. Completion of the new model for WIPP that is needed to begin the  regulatory approval process for expansion is not expected to be ready  until 2024, and then the approval and subsequent construction process  could take another 4 years or longer. Without developing a long-term plan for WIPP that includes the  need for expanding WIPP’s disposal space and an integrated schedule  that describes how DOE will complete the regulatory approval process  and construction of new space before WIPP’s existing space is full, DOE  will not have reasonable assurance that it will be able to expand the  repository in a timely manner. Conclusions

DOE is currently in the process of reevaluating the best approach for  disposing of 34 MT of surplus weapons-grade plutonium. DOE has not adequately planned for all possible waste that it may be  expected to dispose of in WIPP, complicating its ability to determine  whether the waste from the dilute and dispose approach can be disposed  of at WIPP. DOE does not  have plans to show how additional space will be excavated in time to  prevent a disruption in waste shipments after the facility’s existing  disposal space is filled in 2026. Appendix I: Objectives, Scope, and Methodology

Our report examined (1) the extent to which the Department of Energy’s  (DOE) revised cost estimate for completing construction of the Mixed- oxide Fuel Fabrication Facility (MOX facility) and the revised life-cycle  estimate for completing the Plutonium Disposition Program using the  mixed-oxide (MOX) fuel approach met cost-estimating best practices, (2)  the status of the National Nuclear Security Administration’s (NNSA)  development of a life-cycle cost estimate for completing the Plutonium  Disposition Program using the dilute and dispose approach, and (3) the  extent to which DOE has sufficient disposal space and statutory capacity  at its Waste Isolation Pilot Plant (WIPP) to dispose of all defense  transuranic (TRU) waste, including the diluted plutonium resulting from  the dilute and dispose approach.
Why GAO Did This Study

The United States has pledged to dispose of 34 metric tons of surplus, weapons-grade plutonium. The current U.S. approach relies on disposing of the plutonium by irradiating it as MOX fuel—a mixture of plutonium and uranium oxides—in modified commercial nuclear reactors. Due to a significant rise in cost, DOE recently proposed terminating the MOX approach in favor of the dilute and dispose approach, which DOE stated may be less expensive. Under this approach, plutonium would be diluted with inert material and then disposed of in a geologic repository.
GAO was asked to review DOE's planning for both the MOX and dilute and dispose approaches. This report examines: (1) the extent to which DOE's revised cost estimates for completing the construction of the MOX facility and for completing the overall Plutonium Disposition Program met best practices, (2) the status of NNSA's development of a life-cycle cost estimate for the dilute and dispose approach, and (3) the extent to which DOE has sufficient disposal space and statutory capacity at WIPP to dispose of all defense TRU waste, including waste from the dilute and dispose approach. GAO reviewed documents and interviewed DOE and NNSA officials, including officials from five major waste-generating sites.

What GAO Found

In August 2016, the Department of Energy's (DOE) revised cost estimate for completing construction of the Mixed-Oxide (MOX) Fuel Fabrication Facility was approximately $17.2 billion and assumed annual funding of $350 million. This estimate substantially met best practices and can be considered reliable as it substantially met all four characteristics of a high-quality cost estimate: comprehensive, well-documented, accurate, and credible. In contrast, DOE's National Nuclear Security Administration (NNSA) has not yet applied best practices when revising its life-cycle cost estimate of $56 billion for the Plutonium Disposition Program using the MOX approach, as GAO previously recommended. This is because NNSA officials developed the revised life-cycle cost estimate to satisfy an annual requirement to record the plutonium environmental liability on departmental financial statements that were due in September 2016.
NNSA is developing a life-cycle cost estimate for completing the Plutonium Disposition Program using the dilute and dispose approach, which would dispose of diluted plutonium at DOE's Waste Isolation Pilot Plant (WIPP). WIPP is an underground repository for the disposal of transuranic (TRU) nuclear waste, which is waste contaminated by nuclear elements heavier than uranium, such as diluted plutonium. NNSA is currently assessing the extent to which any new equipment and facilities would be needed to pursue this approach, and it expects to develop an independently validated life-cycle cost estimate for the program by late 2018. NNSA has outlined an initial set of milestones for the program using the dilute and dispose approach; these milestones include program elements such as preparing the plutonium for dilution, diluting the plutonium into waste and securely storing it, and disposing of it at WIPP.
DOE does not have sufficient space at WIPP to dispose of all defense TRU waste. DOE's current plan is to fill the existing disposal space in WIPP by 2026, and additional space will need to be excavated to dispose of all the waste included in DOE's current TRU waste inventory report. While DOE officials recognize that expansion of WIPP's disposal space may be necessary in the future, they have not analyzed or planned for the facility's expansion because their focus has been on resuming operations at WIPP, which had been suspended in 2014 after two separate accidents at the facility. Specifically, GAO found the following:
DOE's TRU waste management plan, which includes planning for WIPP, covers a 5-year period and does not address possible expansion. Moreover, DOE's TRU waste management plan does not include a schedule for expanding DOE's disposal space before existing space is full.
Expanding WIPP's disposal space will require regulatory approval that is expected to take several years. However, DOE modeling that is needed to begin the regulatory approval process is not expected to be ready until 2024.
Without developing a plan for WIPP that includes an integrated schedule for completing the regulatory approval process and constructing new space before WIPP's existing space is full, DOE does not have reasonable assurance that it will be able to expand the repository in a timely manner.

What GAO Recommends

GAO is making four recommendations, including that DOE develop a plan for expanding WIPP's disposal space that includes a schedule for completing the expansion before existing space is full. DOE concurs with the recommendations.