239Pu(n,2n) 238Pu cross section inferred from IDA calculations and GEANIE measurements

Chen, H ; Ormand, W E ; Dietrich, F S

Lawrence Livermore National Laboratory

关键词: Fission;    99 General And Miscellaneous//Mathematics, Computing, And Information Science;    Shape;    Simulation;    Neutrons;   

DOI  :  10.2172/15006166
RP-ID  :  UCRL-ID-141663
RP-ID  :  W-7405-ENG-48
RP-ID  :  15006166

美国|英语

来源: UNT Digital Library

【 摘 要 】

This report presents the latest {sup 239}Pu(n,2n){sup 238}Pu cross sections inferred from calculations performed with the nuclear reaction-modeling code system, IDA, coupled with experimental measurements of partial {gamma}-ray cross sections for incident neutron energies ranging from 5.68 to 17.18 MeV. It is found that the inferred {sup 239}Pu(n,2n){sup 238}Pu cross section peaks at E{sub inc} {approx} 11.4 MeV with a peak value of approximately 326 mb. At E{sub inc} {approx} 14 MeV, the inferred {sup 239}Pu(n,2n){sup 238}Pu cross section is found to be in good agreement with previous radio-chemical measurements by Lockheed. However, the shape of the inferred {sup 239}Pu(n,2n){sup 238}Pu cross section differs significantly from previous evaluations of ENDL, ENDF/B-V and ENDF/B-VI. In our calculations, direct, preequilibrium, and compound reactions are included. Also considered in the modeling are fission and {gamma}-cascade processes in addition to particle emission. The main components of physics adopted and the parameters used in our calculations are discussed. Good agreement of the inferred {sup 239}Pu(n,2n){sup 238}Pu cross sections derived separately from IDA and GNASH calculations is shown. The two inferences provide an estimate of variations in the deduced {sup 239}Pu(n,2n){sup 238}Pu cross section originating from modeling.