Neutron Cross Section Covariances for Structural Materials and Fission Products
We describe neutron cross section covariances for 78 structural materials and fission products produced for the new US evaluated nuclear reaction library ENDF/B-VII.1. Neutron incident energies cover full range from 10{sup -5} eV to 20 MeV and covariances are primarily provided for capture, elastic and inelastic scattering as well as (n,2n). The list of materials follows priorities defined by the Advanced Fuel Cycle Initiative, the major application being data adjustment for advanced fast reactor systems. Thus, in addition to 28 structural materials and 49 fission products, the list includes also {sup 23}Na which is important fast reactor coolant. Due to extensive amount of materials, we adopted a variety of methodologies depending on the priority of a specific material. In the resolved resonance region we primarily used resonance parameter uncertainties given in Atlas of Neutron Resonances and either applied the kernel approximation to propagate these uncertainties into cross section uncertainties or resorted to simplified estimates based on integral quantities. For several priority materials we adopted MF32 covariances produced by SAMMY at ORNL, modified by us by adding MF33 covariances to account for systematic uncertainties. In the fast neutron region we resorted to three methods. The most sophisticated was EMPIRE-KALMAN method which combines experimental data from EXFOR library with nuclear reaction modeling and least-squares fitting. The two other methods used simplified estimates, either based on the propagation of nuclear reaction model parameter uncertainties or on a dispersion analysis of central cross section values in recent evaluated data files. All covariances were subject to quality assurance procedures adopted recently by CSEWG. In addition, tools were developed to allow inspection of processed covariances and computed integral quantities, and for comparing these values to data from the Atlas and the astrophysics database KADoNiS.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States). National Nuclear Data Center (NNDC)
- Sponsoring Organization:
- USDOE SC OFFICE OF SCIENCE (SC)
- DOE Contract Number:
- DE-AC02-98CH10886
- OSTI ID:
- 1034734
- Report Number(s):
- BNL-96637-2011-JA; NDTSBA; R&D Project: EST-003-NEFA; KB0301041; TRN: US1200915
- Journal Information:
- Nuclear Data Sheets, Vol. 112, Issue 12; ISSN 0090-3752
- Country of Publication:
- United States
- Language:
- English
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ENDF/B-VII.1 Nuclear Data for Science and Technology: Cross Sections, Covariances, Fission Product Yields and Decay Data
ENDF/B-VII.1 Nuclear Data for Science and Technology: Cross Sections, Covariances, Fission Product Yields and Decay Data
Related Subjects
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
APPROXIMATIONS
ASTROPHYSICS
CROSS SECTIONS
DATA COVARIANCES
ELASTIC SCATTERING
FAST NEUTRONS
FAST REACTORS
FISSION PRODUCTS
FUEL CYCLE
INELASTIC SCATTERING
KERNELS
NEUTRONS
NUCLEAR REACTIONS
ORNL
QUALITY ASSURANCE
RESONANCE
SIMULATION
national nuclear data center