Re-evaluation of the thermal neutron scattering law for light water in JENDL-5

Tada, Kenichi   ; Abe, Yutaka*; Watanabe, Tomoaki  

In the previous meeting, the authors explained that the effective multiplication factor using thermal neutron scattering law (TSL) data for light water in JENDL-5 oscillated with moderator temperature. We found that the cause of this problem was the number of trials of the molecular dynamics (MD) simulation, i.e., the statistical uncertainty of the simulation. The previous MD simulation results were insufficient for the evaluation of the TSL data. The number of trials was significantly increased to reduce the effect of the statistical uncertainty of the MD simulation. The k-effective trend with moderator temperature using the re-evaluated TSL data for light water was similar to that with the other nuclear data libraries, e.g., ENDF-B/VIII.0 and JENDL-4.0.