This report describes a novel approach developed at the Oak Ridge National Laboratory
(ORNL) for the estimation of the uncertainty in the prediction of the neutron multiplication factor
for spent nuclear fuel. This technique focuses on burnup credit, where credit is taken in criticality
safety analysis for the reduced reactivity of fuel irradiated in and discharged from a reactor.
Validation methods for burnup credit have attempted to separate the uncertainty associated with

This paper draws on my experience as a reviewer of the scientific programs and performance assessments of the geological repository for transuranic waste at the Waste Isolation Pilot Plant in New Mexico and the proposed repository for spent nuclear fuel and high-level waste at Yucca Mountain in Nevada. In addition, I have served on numerous committees of the National Research Council that have addressed many aspects of nuclear waste management.

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.

Japan’s spent fuel management and fuel cycle programs are now at a critical stage. Its first commercial-scale reprocessing plant, at Rokkasho Village, will soon start full-scale operation.

This report presents the findings and conclusions of OTA's analysis of Federal policy
for the management of commercial high-level radioactive waste. It represents a major update
and expansion of the analysis presented to Congress in our summary report, Managing
Commercial High-Level Radioactive Waste, published in April of 1982 during the
debate leading to passage of the Nuclear Waste Policy Act of 1982 (NWPA). This new
report is intended to contribute to the implementation of NWPA, and in particular to

This report puts forth a number of options and recommendations for how to engage
stakeholders and other members of the public in the storage and management of spent
nuclear fuel and high level waste in the United States. The options are generated from a
scientific review of existing publications proposing criteria for assessing past efforts to
engage publics and stakeholders in decision-making about risky technologies. A set of
nine principles are derived for evaluating cases of public and stakeholder engagement with

In the course of producing electrical power in light water.reactors (LWRs), the uranium
fuel accumulates fission products until the fission process is no longer efficient for power
production. At that point the fuel is removed from the reactor and stored in water basins
to allow radioactivity to partially decay before further disposition. This fuel is referred
to as "spent fuel." Although spent fuel as At is discharged from a reactor is intensely
radioactive, it has been stored safely in moderate quantities for decades. Spent fuel could

he U.S. Nuclear Regulatory Commission (NRC) regulates storage of spent nuclear fuel (SNF) from commercial nuclear power plants. An increasing amount of the SNF in storage is in dry storage systems, mostly at current and decommissioned plants. As directed by the Commission (in SRM-COMSECY-10-0007; December 6, 2010), in expectation of continued use of dry storage for extended periods of time, the NRC staff is examining the technical needs and potential changes to the regulatory framework that may be needed to continue licensing of SNF storage over periods beyond 120 years.

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 Materials Characterization Center (MCC) at Battelle Pacific Northwest Laboratory (PNL) has the responsibility to select appropriate spent fuel Approved Testing Materials (ATMs) and to characterize, via hot-cell studies, certain detailed properties of the discharged fuel. The purpose of this report isto develop a collective description of the entire spent fuel inventory in terms of various fuel properties relevant to ATMs using information available from the Characteristics Data Base (CDB), which is sponsored by the U.S.