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Recommendations on the Credit for Cooling Time in PWR Burnup Credit Analyses
Recommendations on the Credit for Cooling Time in PWR Burnup Credit Analyses
The U.S. Nuclear Regulatory Commission's guidance on burnup credit for pressurized-water-reactor (PWR) spent nuclear fuel (SNF) recommends that analyses be based on a cooling time of five years. This recommendation eliminates assemblies with shorter cooling times from cask loading and limits the allowable credit for reactivity reduction associated with cooling time. This report examines reactivity behavior as a function of cooling time to assess the possibility of expanding the current cooling time recommendation for SNF storage and transportation.
Screening Analysis of Criticality Features, Events, and Processes for License Application
Screening Analysis of Criticality Features, Events, and Processes for License Application
An Approach for Validating Actinide and Fission Product Burnup Credit Criticality Safety Analyses-Criticality (keff) Predictions
An Approach for Validating Actinide and Fission Product Burnup Credit Criticality Safety Analyses-Criticality (keff) Predictions
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)
CSNF Loading Curve Sensitivity Analysis
CSNF Loading Curve Sensitivity Analysis
The purpose of this scientific analysis report, CSNF Loading Curve Sensitivity Analysis, is to establish the required minimum burnup as a function of initial enrichment for both pressurized water reactor (PWR) and boiling water reactor (BWR) commercial spent nuclear fuel (CSNF) that would allow permanent disposal of these waste forms in the geologic repository at Yucca Mountain. The relationship between the required minimum burnup and fuel assembly initial enrichment forms a loading curve.
DOE SNF Phase I and II Summary Report
DOE SNF Phase I and II Summary Report
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.
SAS2H Generated Isotopic Concentrations for B&W 15xl5 PWR Assembly (SCPB: N/A)
SAS2H Generated Isotopic Concentrations for B&W 15xl5 PWR Assembly (SCPB: N/A)
This analysis is prepared by the Mined Geologic Disposal System (MGDS) Waste Package Development Department (WPDD) to provide pressurized water reactor (PWR) isotopic composition data as a function of time for use in criticality analyses. The objectives of this evaluation are to generate burnup and decay dependant isotopic inventories and to provide these inventories in a form which can easily be utilized in subsequent criticality calculations.
OECD/NEA Burnup Credit Criticality Benchmarks Phase IIIB: Burnup Calculations of BWR Fuel Assemblies for Storage and Transport
OECD/NEA Burnup Credit Criticality Benchmarks Phase IIIB: Burnup Calculations of BWR Fuel Assemblies for Storage and Transport
The report describes the final results of the Phase IIIB Benchmark conducted by the
Expert Group on Burnup Credit Criticality Safety under the auspices of the Nuclear Energy
Agency (NEA) of the Organization for Economic Cooperation and Development (OECD).
The Benchmark was intended to compare the predictability of current computer code and
data library combinations for the atomic number densities of an irradiated BWR fuel
assembly model. The fuel assembly was irradiated under specific power of 25.6 MW/tHM
Summary Report of Commercial Reactor Criticality Data for Crystal River Unit 3
Summary Report of Commercial Reactor Criticality Data for Crystal River Unit 3
The "Summary Report of Commercial Reactor Criticality Data for Crystal River Unit 3" contains the detailed information necessary to perform commercial reactor criticality (CRC) analyses for the Crystal River Unit 3 (CR3) reactor.
Summary Report of Commercial Reactor Critical Analyses Performed for the Disposal Criticality Analysis Methodology
Summary Report of Commercial Reactor Critical Analyses Performed for the Disposal Criticality Analysis Methodology
The "Summary Report of Commercial Reactor Critical Analyses Perfonned for the Disposal Criticality Analysis Methodology" contains a summary of the commercial reactor critical (CRC) analyses used to support the validation of the criticality models for spent commercial light water reactor (LWR) fuel.
Calculation of Upper Subcritical Limits for Nuclear Criticality in a Repository
Calculation of Upper Subcritical Limits for Nuclear Criticality in a Repository
The purpose of this document is to present the methodology to be used for development of the Subcritical Limit (SL) for post closure conditions for the Yucca Mountain repository. The SL is a value based on a set of benchmark criticality multiplier, keff> results that are outputs of the MCNP calculation method. This SL accounts for calculational biases and associated uncertainties resulting from the use of MCNP as the method of assessing kerr·
Why DOE's Messages on Transportation Don't Resonate with the Public (and What DOE Can Do to Fix the Problem)
Why DOE's Messages on Transportation Don't Resonate with the Public (and What DOE Can Do to Fix the Problem)
Geochemistry Model Validation Report: Material Degradation and Release Model
Geochemistry Model Validation Report: Material Degradation and Release Model
The purpose of the material degradation and release (MDR) model is to predict the fate of the waste package materials, specifically the retention or mobilization of the radionuclides and the neutron-absorbing material as a function of time after the breach of a waste package during the 10,000 years after repository closure. The output of this model is used directly to assess the potential for a criticality event inside the waste package due to the retention of the radionuclides combined with a loss of the neutron-absorbing material.
The Effect of Half-life and Branching Fraction Uncertainties on the Effective Neutron Multiplication Factor
The Effect of Half-life and Branching Fraction Uncertainties on the Effective Neutron Multiplication Factor
This calculation demonstrates how uncertainties in half-life and branching fraction affect postclosure isotopic concentrations and the quantification of those effects in terms of reactivity.
Preliminary Criticality Analysis of Degraded SNF Accumulations External to a Waste Package (SCPB: N/A)
Preliminary Criticality Analysis of Degraded SNF Accumulations External to a Waste Package (SCPB: N/A)
This study is prepared by the Mined Geologic Disposal System (MODS) Waste Package Development Department (WPDD) to provide input to a separate evaluation on the probablility of criticality in the far- field environment. These calculations are performed in sufficient detail to provide conservatively bounding configurations to support separate probabilistic analyses.
U.S. Regulatory Recommendations for Actinide-Only Burnup Credit in Transport and Storage Casks
U.S. Regulatory Recommendations for Actinide-Only Burnup Credit in Transport and Storage Casks
In July 1999, the U.S. Nuclear Regulatory Commission (NRC) Spent Fuel Project Office
(SFPO) issued Interim Staff Guidance 8 Revision 1 (ISG8R1) to provide recommendations for the use
of burnup credit in storage and transport of pressurized-water reactor (PWR) spent fuel. Subsequent to
the issuance of ISG8R1, the NRC Office of Regulatory Research (RES) has directed an effort to
investigate the technical basis for extending the criteria and recommendations of ISG8R1 to allow
Criticality Analysis of Pu and U Accumulations in a Tuff Fracture Network
Criticality Analysis of Pu and U Accumulations in a Tuff Fracture Network
The objective of this analysis is to evaluate accumulations within the thermally altered tuff surrounding a drift. The evaluation examines accumulation of uranium minerals (soddyite), plutonium oxide (Pu01), and combinations of these materials. A hypothetical model of the tuff is used to provide insight into the factors that affect criticality for this near-field scenario. The factors examined include: the size of the accumulation, the fissile composition of the accumulation, the water or clayey material fraction in the accumulation and the water fraction in the tuff
Laboratory Critical Experiment Reactivity Calculations
Laboratory Critical Experiment Reactivity Calculations
The purpose of this calculation is to perform the same reactivity calculations as performed in Reference 7.1 and Reference 7.2 for a set of Laboratory Critical Experiments (LCE) except to change some of the cross section libraries as specified here, and to perform sixteen additional calculations for U233 LCEs.
LCEs for Naval Reactor Benchmark Calculations
LCEs for Naval Reactor Benchmark Calculations
The purpose of this engineering calculation is to document the MCNP4B2LVevaluations of Laboratory Critical Experiments (LCEs) performed as part of the Disposal Criticality Analysis Methodology program. LCE evaluations documented in this report were performed for 22 different cases with varied design parameters. Some of these LCEs (10) are documented in existing references (Ref. 7.1 and 7.2), but were re-run for this calculation file using more neutron histories.
Commercial Spent Nuclear Fuel Waste Package Misload Analysis
Commercial Spent Nuclear Fuel Waste Package Misload Analysis
The purpose of this calculation is to estimate the probability of misloading a commercial spent nuclear fuel waste package with a fuel assembly(s) that has a reactivity (i.e., enrichment and/or burnup) outside the waste package design. The waste package designs are based on the expected commercial spent nuclear fuel assemblies and previous analyses (Macheret, P. 2001, Section 4.1 and Table 1). For this calculation, a misloaded waste package is defined as a waste package that has a fuel assembly(s) loaded into it with an enrichment and/or burnup outside the waste package design.
Sensitivity and Uncertainty Analysis of Commercial Reactor Criticals for Burnup Credit
Sensitivity and Uncertainty Analysis of Commercial Reactor Criticals for Burnup Credit
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-
Long-Term Criticality Control Issues for the MPC (SCPB: N/A)
Long-Term Criticality Control Issues for the MPC (SCPB: N/A)
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.
CRC Reactivity Calculations for Crystal River Unit 3
CRC Reactivity Calculations for Crystal River Unit 3
The purpose of this calculation is to document the Crystal River Unit 3 pressurized waste reactor (PWR) reactivity calculations performed as part of the commercial reactor critical (CRC) evaluation program. CRC evaluation reactivity calculations are performed at a number of statepoints, representing reactor start-up critical conditions at either beginning of life (BOL), beginning of cycle (BOC), or mid-cycle when the reactor resumed operation after a shutdown.
Isotopic Analysis of High-Burnup PWR Spent Fuel Samples from the Takahama-3 Reactor
Isotopic Analysis of High-Burnup PWR Spent Fuel Samples from the Takahama-3 Reactor
This report presents the results of computer code benchmark simulations against spent fuel radiochemical assay
measurements from the Kansai Electric Ltd. Takahama-3 reactor published by the Japan Atomic Energy
Research Institute. Takahama-3 is a pressurized-water reactor that operates with a 17 × 17 fuel-assembly design.
Spent fuel samples were obtained from assemblies operated for 2 and 3 cycles and achieved a maximum burnup
of 47 GWd/MTU. Radiochemical analyses were performed on two rods having an initial enrichment of
Study of the Effect of Integral Burnable Absorbers for PWR Burnup Credit
Study of the Effect of Integral Burnable Absorbers for PWR Burnup Credit
The Interim Staff Guidance on burnup credit issued by the U.S. Nuclear Regulatory Commission's Spent Fuel Project Office recommends restricting the use of burnup credit to assemblies that have not used burnable absorbers. This restriction eliminates a large portion of the currently discharged spent fuel assemblies from cask loading, and thus severely limits the practical usefulness of burnup credit.