The preclosure criticality analysis process described in this technical report provides a systematic approach for determining the need for criticality controls and for evaluating their effectiveness during the preclosure period of the Monitored Geologic Repository at Yucca Mountain, Nevada.

The Analysis of the Total System Life Cycle Cost (TSLCC) of the Civilian Radioactive Waste Management Program represents the Office of Civilian Radioactive Waste Management's most recent estimate of the costs to dispose of the Nations's spent nuclear fuel (SNF) and high-level radioactive waste (HLW). This TSLCC analysis projects all Program costs through 2119 for a surrogate, single potential repository. The design and emplacement concepts in this TSLCC analysis are the same as those presented in the Monitored Geologic Repository Project Description Document.

This analysis is prepared by the Mined Geologic Disposal System (MGDS) Waste Package Development Department (WPDD) in response to a request received via a QAP-3-12 Design Input Data Request (Reference 5.1) from Waste Acceptance, Storage, & Transportation (WAST) Design (formerly MRSMPC Design). This design analysis is an answer to the Design Input Data Request to provide: Specific requirements for long-term criticality control.

The Monitored Geologic Repository (MGR) Waste Package Operations (WPO) of the Civilian Radioactive Waste Management System Management & Operating Contractor (CRWMS M&O) performed calculations to provide input for disposal of spent nuclear fuel (SNF) from the Emico Fermi Atomic Power Plant (Ref. 1). The Fermi fuel has been considered for disposal at the potential Yucca Mountain site.

The issue of interim storage of used (spent)1 fuel is dependent on a number of key factors, some
of which are not known at this time but are the subject of this study. The first is whether or not
the Yucca Mountain Project continues or is cancelled such that it may be able to receive spent
fuel from existing and decommissioned nuclear power stations. The second is whether the United
States will pursue a policy of reprocessing and recycling nuclear fuel. The reprocessing and

This new report from the National Research Council’s Nuclear and Radiation Studies Board (NRSB) and the Transportation Research Board reviews the risks and technical and societal concerns for the transport of spent nuclear fuel and high-level radioactive waste in the United States. Shipments are expected to increase as the U.S. Department of Energy opens a repository for spent fuel and high-level waste at Yucca Mountain, and the commercial nuclear industry considers constructing a facility in Utah for temporary storage of spent fuel from some of its nuclear waste plants.

The purpose of this calculation is to estimate the probability of criticality in a pressurized water reactor (PWR) uncanistered fuel waste package during the postclosure phase of the repository as a function of various waste package material, loading, and environmental parameters. Parameterization on the upper subcritical limit that is used to define the threshold for criticality will also be performed. The possibility of waste package misload due to human or equipment error during preclosure is also considered in estimating the postclosure criticality probability.

This analysis provides information necessary for total system performance assessment (TSPA) for the license application (LA) to include the excess U.S. Department of Energy (DOE) plutonium in the form of mixed oxide (MOX) spent nuclear fuel and lanthanide borosilicate (LaBS) glass. This information includes the additional radionuclide inventory due to MOX spent nuclear fuel and LaBS glass and the analysis that shows that the TSPA models for commercial spent nuclear fuel (CSNF) and high-level waste (HLW) degradation are appropriate for MOX spent nuclear fuel and LaBS glass, respectively.