Understanding the changing nuclear and mechanical characteristics of used nuclear fuel (UNF) over time and how these changing characteristics affect storage, transportation, and disposal options can require many tools and types of data. To streamline analysis capabilities for the waste management system, a comprehensive, integrated data and analysis tool has been assembled—UNF-Storage, Transportation & Disposal Analysis Resource and Data System (UNF-ST&DARDS).

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.

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.

In response to the remand of the U.S. Court of Appeals for the District of Columbia Circuit (Minnesota v. NRC, 602 F.2d 412 (1979)), and as a continuation of previous proceedings conducted in this area by NRC (44 Fed. Reg. 61,372), the Commission initiated a generic rulemaking proceeding on October 25, 1979.

The success of the Civilian Radioactive Waste Management Program of the U.S.
Department of Energy (DOE) is critical to U.S. ability to manage and dispose of
nuclear waste safely--and to the reestablishment of confidence in the nuclear energy
option in the United States. The program must conform with all applicable standards
and, in fact, set the example for a national policy on the safe disposal of radioactive
waste.
The Secretary of Energy has recently completed an extensive review of the

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?”

Since a 1985 decision by President Reagan that a separate permanent repository for disposal of
defense high level waste was not required1, DOE has planned for disposal of all high-level waste
and spent fuel from national defense activities and DOE’s own research activities in a repository
for commercial waste developed under the Nuclear Waste Policy Act (NWPA). The Commission
has heard recommendations from some commenters2 that this decision be revisited, or even

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

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