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Lessons Learned from the West Valley Spent Nuclear Fuel Shipment within the United States
Lessons Learned from the West Valley Spent Nuclear Fuel Shipment within the United States
This paper describes the lessons learned from the U.S. Department of Energy (DOE) transportation of
125 DOE-owned commercial spent nuclear fuel (SNF) assemblies by railroad from the West Valley Demonstration
Project to the Idaho National Engineering and Environmental Laboratory (INEEL). On July 17, 2003, DOE made
the largest single shipment of commercial SNF in the history of the United States. This was a highly visible and
political shipment that used two specially designed Type B transportation and storage casks. This paper describes
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.
Review of Yucca mountain Disposal Criticality Studies
Review of Yucca mountain Disposal Criticality Studies
Review of Results for the OECD/NEA Phase VII Benchmark: Study of Spent Fuel Compositions for Long-Term Disposal
Review of Results for the OECD/NEA Phase VII Benchmark: Study of Spent Fuel Compositions for Long-Term Disposal
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
Modeling BWR Spent-Fuel Isotopics with SAS2H and CASMO-3
Modeling BWR Spent-Fuel Isotopics with SAS2H and CASMO-3
Effects of Integral Burnable Absorbers on PWR Spent Nuclear Fuel
Effects of Integral Burnable Absorbers on PWR Spent Nuclear Fuel
Spent Fuel Burnup Credit in Casks: An NRC Perspective
Spent Fuel Burnup Credit in Casks: An NRC Perspective
Until now, the Nuclear Regulatory Commission's (NRC) approval of criticality safety evaluations for spent fuel in transport and storage casks has been based on analyzing the fuel as though it were fresh and without burnable poisons. The well-known nuclide composition of fresh fuel has provided a straightforward and bounding approach for showing that spent fuel systems will remain subcritical under normal and accident conditions. Burnup credit refers to the approval of criticality safety evaluations that consider the decrease in fuel reactivity caused by. irradiation in the reactor.
Selection of Reactor Criticals as Benchmarks for Spent Nuclear Fuels
Selection of Reactor Criticals as Benchmarks for Spent Nuclear Fuels
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
Nondestructive Assay of Nuclear Low-Enriched Uranium Spent Fuels for Burnup Credit Application
Nondestructive Assay of Nuclear Low-Enriched Uranium Spent Fuels for Burnup Credit Application
Criticality safety analysis devoted to spent-fuel storage and transportation has to be conservative in order to be sure no accident will ever happen. In the spent-fuel storage field, the assumption of freshness has been used to achieve the conservative aspect of criticality safety procedures. Nevertheless, after being irradiated in a reactor core, the fuel elements have obviously lost part of their original reactivity. The concept of taking into account this reactivity loss in criticality safety analysis is known as burnup credit.
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.
Used Fuel Management System Interface Analyses
Used Fuel Management System Interface Analyses
Preliminary system-level analyses of the interfaces between at-reactor used fuel management, consolidated storage facilities, and disposal facilities, along with the development of supporting logistics simulation tools, have been initiated to provide the U.S. Department of Energy (DOE) and other stakeholders with information regarding the various alternatives for managing used nuclear fuel (UNF) generated by the current fleet of light water reactors operating in the United States.
Categorization of Used Nuclear Fuel Inventory in Support of a Comprehensive National Nuclear Fuel Cycle Strategy
Categorization of Used Nuclear Fuel Inventory in Support of a Comprehensive National Nuclear Fuel Cycle Strategy
A technical assessment of the current inventory [~70,150 metric tons of heavy metal (MTHM) as of
2011] of U.S.-discharged used nuclear fuel (UNF) has been performed to support decisions regarding fuel
cycle strategies and research, development and demonstration (RD&D) needs. The assessment considered
discharged UNF from commercial nuclear electricity generation and defense and research programs and
determined that the current UNF inventory can be divided into the following three categories: