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Validation of important fission product evaluations through CERES integral benchmarks
Validation of important fission product evaluations through CERES integral benchmarks
Optimization of energy resources suggests increased fuel residence in reactor cores and hence improved
fission product evaluations are required. For thermal reactors the fission product cross sections in the JEF2.2 and
JEFF3.1 libraries plus new evaluations from WPEC23 are assessed through modelling the CERES experiment in
the DIMPLE reactor. The analysis uses the lattice code WIMS10. Cross sections for 12 nuclides are assessed. The
thermal cross section and low energy resonance data for 147,152Sm and 155Gd are accurate to within 4%. Similar data
Sensitivity Coefficient Generation for a Burnup Credit Cask Model Using TSUNAMI-3D
Sensitivity Coefficient Generation for a Burnup Credit Cask Model Using TSUNAMI-3D
Validation of SCALE-4 for Burnup Credit Applications
Validation of SCALE-4 for Burnup Credit Applications
In the past, criticality analysis of pressurized water reactor (PWR) fuel stored in racks and casks has assumed that the fuel is fresh with the maximum allowable initial enrichment. If credit is allowed for fuel burnup in the design of casks that are used in the transport of spent light water reactor fuel to a repository, the increase in payload can lead to a significant reduction in the cost of transport and a potential reduction in the risk to the public. A portion of the work has been performed at Oak Ridge National Laboratory (ORNL) in support of the U.S.
PWR Radiochemical Assay Benchmarks Using SAS2H and CASMO
PWR Radiochemical Assay Benchmarks Using SAS2H and CASMO
Issues for Effective Implementation of Burnup Credit
Issues for Effective Implementation of Burnup Credit
In the United States, burnup credit has been used in the criticality safety evaluation for storage pools at
pressurized water reactors (PWRs) and considerable work has been performed to lay the foundation for use of
burnup credit in dry storage and transport cask applications and permanent disposal applications. Many of the
technical issues related to the basic physics phenomena and parameters of importance are similar in each of these
applications. However, the nuclear fuel cycle in the United States has never been fully integrated and the
Sensitivity and Uncertainty Analysis of Commercial Reactor Criticals for Burnup Credit
Sensitivity and Uncertainty Analysis of Commercial Reactor Criticals for Burnup Credit
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.
Actinide-Only Burnup Credit for Pressurized Water Reactor Spent Nuclear Fuel - I: Methodology Overview
Actinide-Only Burnup Credit for Pressurized Water Reactor Spent Nuclear Fuel - I: Methodology Overview
A conservative methodology is presented that would allow taking credit for burnup in the criticality safety analysis of spent nuclear fuel (SNF) packages. The method is based on the assumption that the isotopic concentration in the SNF and cross sections of each isotope for which credit is taken must be supported by validation experiments. The method allows credit for the changes in the 234U, 235U, 236U, 238U, 238Pu, 239Pu, 240Pu, 241Pu, 242Pu, and 241Am concentration with burnup. No credit for fission product neutron absorbers is taken. The methodology consists of five major steps:
Actinide-Only Burnup Credit for Pressurized Water Reactor Spent Nuclear Fuel - III: Bounding Treatment of Spatial Burnup Distributions
Actinide-Only Burnup Credit for Pressurized Water Reactor Spent Nuclear Fuel - III: Bounding Treatment of Spatial Burnup Distributions
A flat, uniform axial burnup assumption, preferred for its computational simplicity, does not always conservatively estimate the pressurized water reactor spent-fuel-cask multiplication factors. Rather, the reactivity effect of the significantly underburned fuel ends, usually referred to as the "end effect," can be properly treated by explicit modeling of the axial burnup distribution based on limiting axial burnup profiles.
Actinide-Only Burnup Credit for Pressurized Water Reactor Spent Nuclear Fuel - II: Validation
Actinide-Only Burnup Credit for Pressurized Water Reactor Spent Nuclear Fuel - II: Validation
The calculation of isotopic concentrations in spent nuclear fuel (SNF) assemblies and the subcritical multiplication factor of SNF packages are two of the essential requirements of the actinide-only burnup credit methodology. To justify the accuracy of the computed values, the code systems used to perform the calculations must be validated. Here, the techniques used for actinide-only burnup credit isotopic and criticality validation are presented and demonstrated.
Use of Reactor-Follow Data to Determine Biases and Uncertainties for PWR spent Nuclear Fuel
Use of Reactor-Follow Data to Determine Biases and Uncertainties for PWR spent Nuclear Fuel
Effects of Integral Burnable Absorbers on PWR Spent Nuclear Fuel
Effects of Integral Burnable Absorbers on PWR Spent Nuclear Fuel
An Empirical Approach to Bounding the Axial Reactivity Effects of PWR Spent Nuclear Fuel
An Empirical Approach to Bounding the Axial Reactivity Effects of PWR Spent Nuclear Fuel
One of the significant issues yet to be resolved for using
burnup credit ~BUC! for spent nuclear fuel ~SNF! is establishing
a set of depletion parameters that produce an adequately conservative
representation of the fuel’s isotopic inventory. Depletion
parameters ~such as local power, fuel temperature, moderator temperature,
burnable poison rod history, and soluble boron concentration!
affect the isotopic inventory of fuel that is depleted in a
pressurized water reactor ~PWR!. However, obtaining the detailed
Investigation of the Effect of Fixed Absorbers on the Reactivity of PWR Spent Nuclear Fuel for Burnup Credit
Investigation of the Effect of Fixed Absorbers on the Reactivity of PWR Spent Nuclear Fuel for Burnup Credit
The effect of fixed absorbers on the reactivity of pressurized water reactor (PWR) spent nuclear fuel (SNF) in support of burnup-credit criticality safety analyses is examined. A fuel assembly burned in conjunction with fixed absorbers may have a higher reactivity for a given burnup than an assembly that has not used fixed absorbers. As a result, 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.
From Integral Experiments to Nuclear Data Improvement
From Integral Experiments to Nuclear Data Improvement
Target accuracy on LWR neutronics parameters is 2 to 5 times lower than the a priori uncertainty (1σ)
due to nuclear data. This paper summarizes the experimental facilities and the integral measurements that are required
for code qualification. The rigorous use of integral information through trend analysis method is described. Trends
on JEF2 data from Keff measurements and P.I.Es are presented. These trends were accounted for in the new JEFF3
evaluations. The role of fundamental experiments, such as worth measurement of separated isotopes, is emphasized.