Taking credit for the reduced reactivity of spent nuclear fuel in criticality analyses is referred to
as burnup credit. Criticality safety evaluations employing burnup credit require validation of the
depletion and criticality calculation methods and computer codes with available measurement
data. To address the issues of burnup credit criticality validation, the U.S. Nuclear Regulatory
Commission initiated a project with Oak Ridge National Laboratory to (1) develop and establish

This paper provides insights into the neutronic similarities between a representative high-capacity rail-transport cask containing typical pressurized water reactor (PWR) spent nuclear fuel assemblies and critical reactor state-points, referred to as commercial reactor critical (CRC) state-points. Forty CRC state-points from five PWRs were analyzed, and the characteristics of CRC state-points that may be applicable for validation of burnup-credit criticality safety calculations for spent fuel transport/storage/disposal systems were identified.

Section 208 of the Energy Reorganization Act of 1974, as amended (Public Law 93-438), defines an "abnormal occurrence" (AO) as an unscheduled incident or event that the U.S. Nuclear Regulatory Commission (NRC) determines to be significant from the standpoint of public health or safety. The Federal Reports Elimination and Sunset Act of 1995 (Public Law 104-66) requires that the NRC report AOs to Congress annually.

The purpose of this study is to provide insights into the neutronic similarities that may exist between a
generic cask containing typical spent nuclear fuel assemblies and commercial reactor critical (CRC) state-
points. Forty CRC state-points from five pressurized-water reactors were selected for the study and the
type of CRC state-points that may be applicable for validation of burnup credit criticality safety
calculations for spent fuel transport/storage/disposal systems are identified. The study employed cross-

Spent fuel transportation and storage cask designs based on a burnup credit approach must
consider issues that are not relevant in casks designed under a fresh-fuel loading assumption. For
example, the spent fuel composition must be adequately characterized and the criticality analysis
model can be complicated by the need to consider axial burnup variations. Parametric analyses are
needed to characterize the importance of fuel assembly and fuel cycle parameters on spent fuel

The purpose of this calculation is to demonstrate that the preclosure performance objectives specified in 10 CFR 63.111(a) and 10 CFR 63.111(b) (Reference 2.2.1) have been met for the proposed design and operations in the geologic repository operations area (GROA) during normal operations and Category 1 event sequences, and following Category 2 event sequences. Category 1 event sequences are those natural and human-induced event sequences that are expected to occur one or more times before permanent closure of the repository.

Taking credit for the reduced reactivity of spent nuclear fuel (SNF) in criticality analyses is referred to as burnup credit (BUC). Criticality safety evaluations require validation of the computational methods with critical experiments that are as similar as possible to the safety analysis models, and for which the keff values are known. This poses a challenge for validation of BUC criticality analyses, as critical experiments with actinide and fission product (FP)

The U.S. Department of Energy’s (DOE) Office of Civilian Radioactive Waste Management (OCRWM) is responsible, under the Nuclear Waste Policy Act of 1982, for the transportation of spent nuclear fuel and high-level radioactive waste from point of origin to destination at a federal storage or disposal facility. Section 180(c), written into the Nuclear Waste Policy Act Amendments of 1987, requires OCRWM to prepare public safety officials along the routes for these shipments.

The objective of this safety requirements publication is to set down the protection objectives and criteria for geological disposal and to establish the requirements that must be met to ensure the safety of this disposal option, consistent with the established principles of safety for radioactive waste management.

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.

More than 45 million shipments of radioactive materials have taken place in the United States
over the last three decades, with a current rate of about three million per year. The majority of
these radioactive shipments consist of radiopharmaceuticals, luminous dials and indicators,
smoke detectors, contaminated clothing and equipment, and research and industrial sources.
Fewer than 3,500, or 0.01%, have been involved in any sort of accident, incident, or anything