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 Monitored Geologic Repository (MGR) Waste Package Operations (WPO) of the Civilian Radioactive Waste Management System Management and Operating Contractor (CRWMS M&O) performed calculations to provide input for disposal of Pu-ceramic waste forms. The Pu- ceramic (Refs. 1 and 2) is designed to immobilize excess plutonium from weapons production, and has been considered for disposal at the potential Yucca Mountain site.

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.

After more than 20 years of commercial nuclear power, the Federal Government has yet to develop a broadly supported policy for fulfilling its legal responsibility for the final isolation of high-level radioactive waste. OTA's study concludes that until such a policy is adopted in law, there is a substantial risk that the false starts, shifts of policy, and fluctuating support that have plagued the final isolation program in the past will continue.

The purpose of this report, and the information contained in the associated computerized data bases, is to establish the DOE/OCRWM reference characteristics of the radioactive waste materials that may be accepted by DOE for emplacement in the mined geologic disposal system as developed under the Nuclear Waste Policy Act of 1982. This report provides relevant technical data for use by DOE and its supporting contractors and is not intended to be a policy document.

The purpose of this calculation is to develop an estimate of the isotopic content as a function of time for mixed oxide (MOX) spent nuclear fuel (SNF) assemblies in a Westinghouse pressurized water reactor (PWR). These data will be used as source data for criticality, thermal, and radiation shielding evaluations of waste package (WP) designs for MOX assemblies in the Monitored Geologic Repository (MGR).

The Disposal Criticality Analysis Methodology Topical Report (YMP 2003) presents the methodology for evaluating potential criticality situations in the monitored geologic repository. As stated in the referenced Topical Report, the detailed methodology for performing the disposal criticality analyses will be documented in model reports. Many of the models developed in support of the Topical Report differ from the definition of models as given in the Office of Civilian Radioactive Waste Management procedure AP-SIII.10Q, Models, in that they are procedural, rather than mathematical.

The Office of Civilian Radioactive Waste Management (OCRWM) is responsible for all spent fuels and high-level wastes (HLW) that will eventually be disposed of in a geologic repository. The purpose of this document, and the information contained in the associated computerized data bases and supporting technical reports, is to provide the technical characteristics of the radioactive waste materials that will (or may) be accepted by DOE for interim storage in an MRS or emplacement in a repository as developed under the Nuclear Waste Policy Act Amendment of 1987.

The main question before the Transportation and Storage Subcommittee was whether the United States
should change its approach to storing and transporting spent nuclear fuel (SNF) and high-level
radioactive waste (HLW) while one or more permanent disposal facilities are established.
To answer this question and to develop specific recommendations and options for consideration by the
full Commission, the Subcommittee held multiple meetings and deliberative sessions, visited several

The objective of these calculations is to perform intact and degraded mode criticality evaluations of the Department of Energy's (DOE) Three Mile Island- Unit 2 (TMI-2) spent nuclear fuel (SNF) in canisters. This analysis evaluates codisposal in a 5-Defense High-Level Waste (5-DHLW/DOE SNF) Long Waste Package (Civilian Radioactive Waste Management System Management and Operating Contractor [CRWMS M&O] 2000b, Attachment V), which is to be placed in a potential monitored geologic repository (MGR).

The Disposal Subcommittee of the Blue Ribbon Commission on America’s Nuclear Future (BRC) addressed a wide-ranging set of issues, all bearing directly on the central question: “How can the United States go about establishing one or more disposal sites for high-level nuclear wastes in a manner and within a timeframe that is technically, socially, economically, and politically acceptable?”

The Monitored Geologic Repository Waste Package Operations 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 Navy (Refs. 1 and , 2). The Navy SNF has been considered for disposal at the potential Yucca Mountain site. For some waste packages, the containment may breach (Ref. 3), allowing the influx of water. Water in the waste package may moderate neutrons, increasing the likelihood of a criticality event within the waste package.

Presented at the NEI Used Fuel Management Conference, St. Petersburg, FL, May 7-9, 2013

There are more than 250 forms of U.S. Department of Energy (DOE)­owned spent nuclear fuel (SNF). Due to the variety of the spent nuclear fuel, the National Spent Nuclear Fuel Program (NSNFP) has designated nine representative fuel groups for disposal criticality analyses based on fuel matrix, primary fissile isotope, and enrichment. For each fuel group, a fuel type that represents the characteristics of all fuels in that group has been selected for detailed analysis.

An Account of the Programs of Federal Agencies and Events That Have Led to the Selection of a Potential Site for a Geologic Repository for High-Level Radioactive Waste

How to dispose of highly radioactive wastes from commercial nuclear power plants is a question that has remained unresolved in the face rapidly changing technological, economic, and political requirements. In the three decades following WWII, two federal agencies -- the Atomic Energy Commission and the Energy Research and Development Administration -- tried unsuccessfully to develop a satisfactory plan for managing high level wastes.

The effective termination of the Yucca Mountain program by the U.S. Administration in 2009
has further delayed the construction and operation of a permanent disposal facility for used fuel
and high level radioactive waste (HLW) in the United States. In concert with this decision, the
President directed the Energy Secretary to establish the Blue Ribbon Commission on America’s
Nuclear Future to review and provide recommendations on options for managing used fuel and

How to dispose of highly radioactive wastes from commercial nuclear power plants is a question that has remained unresolved in the face of rapidly changing technological, economic, and political requirements. In the three decades following World War II, two federal agencies--the Atomic Energy Commission and the Energy Research and Development Administration--tried unsuccessfully to develop a satisfactory plan for managing high level wastes.

With the passage of the Nuclear Waste Policy Act of 1982 (NWPA), Congress for the first time established in law a comprehensive Federal policy for commercial high-level radioactive waste management, including interim storage and permanent disposal. NWPA provides sufficient authority for
developing and operating a high-level radioactive waste management system based on disposal in mined geologic repositories. Authorization