²⁴²Pu absolute neutron-capture cross section measurement

Abstract

Abstract. The absolute neutron-capture cross section of 242 Pu was measured at the Los Alamos Neutron Science Center using the Detector for Advanced Neutron-Capture Experiments array along with a compact parallel-plate avalanche counter for fission-fragment detection. During target fabrication, a small amount of 239 Pu was added to the active target so that the absolute scale of the 242 Pu(n,γ ) cross section could be set according to the known 239 Pu(n,f) resonance at E n,R = 7.83 eV. The relative scale of the 242 Pu(n,γ ) cross section covers four orders of magnitude for incident neutron energies from thermal to ≈ 40 keV. The cross section reported in ENDF/B-VII.1 for the 242 Pu(n,γ ) E n,R = 2.68 eV resonance was found to be 2.4% lower than the new absolute 242 Pu(n,γ ) cross section.

Note on the potential to increase the accuracy of source term calculations for spent nuclear fuel

“…Therefore, codes like SCALE or CASMO/SIMULATE have been extensively validated (Rhodes et al, 2009;Saylor et al, 2018;Bahadir, 2020;Eysemans et al, 2022) with regard to factors important for the chain reaction. In particular, this means that cross sections and fission yields of relevant nuclides have been analyzed by dedicated cross section measurements [for example, (Buckner et al, 2017)], by radiochemical analysis [for example, (Govers et al, 2015)] or by criticality experiments [for example, (Sanchez et al, 2021)].…”