Abstract
The set of 233U resonance parameters of the ENDF/B-VIII.0 nuclear data library was adopted from the previous ENDF/B-VII.1 evaluation using the external levels to update the thermal values. Adoption of IAEA 2017 thermal standards (σf=533.0±2.2 b, σc=44.9±0.9 b, and ν‾tot=2.487±0.011) and of the IAEA-recommended thermal-neutron induced prompt fission neutron spectrum (PFNS) with average PFNS energy of 2.030±0.013 MeV requires a re-evaluation of 233U neutron cross sections in the resolved resonance region. A newly produced evaluation is being tested on benchmarks carefully selected from the Handbook of International Criticality Safety Benchmark Experiments (ICSBEP) which are highly sensitive to 233U data. An important goal of this work was to eliminate the strong negative gradient of the calculated effective multiplication factors with respect to the epithermal fission fraction observed in the validation of the ENDF/B-VIII.0 library for those assemblies. A significant improvement in integral performance of critical 233U solutions is observed for the newly proposed evaluation. Further work addressing the fast neutron region is needed.
| Original language | English |
|---|---|
| Article number | 108595 |
| Journal | Annals of Nuclear Energy |
| Volume | 163 |
| DOIs | |
| State | Published - Dec 1 2021 |
Funding
This work was supported by the Nuclear Criticality Safety Program, funded and managed by the National Nuclear Security Administration for the Department of Energy. The authors would like to acknowledge very useful discussions on 233U benchmarks held with A.C. (Skip) Kahler. To Max Salvatores, MP had the pleasure to meet first Max in 2007 while working on the generation of an extensive set of covariances for future releases of the US ENDF library. This was the beginning of a very fruitful collaboration with Max within projects focusing on data adjustment—such as the Global Nuclear Energy Partnership and programs such as the Nuclear Criticality Safety Program that, at that time, addressed the scarcity of neutron covariance data with the joint efforts of four major US national laboratories (Brookhaven National Laboratory, ORNL, Los Alamos National Laboratory, and Argonne National Laboratory). The collaboration with Max peaked in the use of covariance matrices in a consistent multiscale data assimilation, a project based on Max's idea to use basic nuclear model parameters and related covariance information to improve the agreement with integral data experiments: from meters to femtometers. Particularly important in the early stage of a career in the nuclear data field, Max clearly taught MP the equal importance of the physics that intrinsically supports the applied world, as well as the pragmatism necessary to move forward and make the applied world more and more reliable. This manuscript has been authored by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE). The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan). This work was supported by the Nuclear Criticality Safety Program, funded and managed by the National Nuclear Security Administration for the Department of Energy.
| Funders | Funder number |
|---|---|
| U.S. Department of Energy | |
| National Nuclear Security Administration | |
| Argonne National Laboratory | |
| Oak Ridge National Laboratory | |
| Los Alamos National Laboratory |
Keywords
- Evaluated data
- Fissile nuclide
- Nuclear data
- R-matrix
- U
- Validation