EXFOR-based simultaneous evaluation for neutron-induced fission cross section of plutonium-242

ABSTRACTThe 242Pu neutron-induced fission cross section was evaluated from 100 keV to 200 MeV. The experimental 242Pu and 235U fission cross sections and their ratios in the EXFOR library were reviewed and analysed by the least-squares method. Additional simultaneous evaluation was performed by including the experimental database of the 233,238U and 239,240,241Pu fission cross sections and their ratios developed for JENDL-5 evaluation. The 242Pu fission cross sec- tions from our evaluation and JENDL-5 evaluation are close to each other below 1 MeV while systematically differ from each other above 10 MeV. The cross section from our evaluation is systematically lower than the JENDL-4.0 cross section in the prompt fission neutron spectrum peak region (∼5% lower around 1 MeV). The newly evaluated 242Pu fission cross section was verified against the cross section measured in the 252Cf spontaneous fission neutron field and criticalities of small-sized LANL fast systems, and demonstrated better performance than the JENDL-4.0 cross section on the same level with the JENDL-5 cross section.KEYWORDS: Plutonium-242fissionsimultaneous evaluationJENDLEXFORDisclaimerAs a service to authors and researchers we are providing this version of an accepted manuscript (AM). Copyediting, typesetting, and review of the resulting proofs will be undertaken on this manuscript before final publication of the Version of Record (VoR). During production and pre-press, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal relate to these versions also. AcknowledgementAntonio Jime´nez-Carrascosa and Oscar Cabellos (Universidad Polite´cnica de Madrid) per- formed criticality calculations by KENO to check if our criticality calculations are reasonable. We thank Melissa Denecke (IAEA) for careful reading of the manuscript. RO would like tothank the members of IAEA Nuclear Data Section for their hospitality during her internship. Her internship was financially supported by “Fundamental Nuclear Education Program by Japanese University Network for Global Nuclear Human Resource Development” entrusted to Tokyo Institute of Technology by Ministry of Education, Culture, Sports, Science and Technology (MEXT).Figure 1 242Pu/235U fission cross section ratios below 1 MeV from evaluations along with the experimental ones used in the present evaluationCitation13, Citation48, Citation52, Citation53, Citation56, Citation57.Display full sizeFigure 2 242Pu/235U fission cross section ratios above 1 MeV from evaluations along with the experimental ones used in the present evaluationCitation13, Citation48, Citation52–57.Display full sizeFigure 3 242Pu fission cross sections from evaluations along with the experimen- tal ones used in the present evaluationCitation12, Citation14, Citation15, Citation50, Citation51. Three datasets excluded from the present evaluationCitation11, Citation16, Citation27 are also plotted by grey symbols.Display full sizeFigure 4 235U fission cross sections from evaluations along with the experimental ones used in the present evaluationCitation62–78. Error bars of the experimental data points are omitted for readability.Display full sizeFigure 5 Difference in 242Pu fission cross sections between evaluations.Display full sizeFigure 6 Ratios of 252Cf spontaneous fission neutron spectrum averaged cross sections from present evaluation, evaluated data librariesCitation17, Citation19, Citation40–42 and Mannhart’s recommendationCitation45 to those measured by AdamovCitation38. The ENDF/B-VIII.0Citation43 and TENDL-2021Citation44 libraries adopt the JENDL-4.0 eval- uation and not shown.Display full sizeFigure 7 C/E values of the LANL small-sized fast system (SPEC-MET-FAST-004-1, 2 and 3) criticalities calculated by ACE-FRENDY-CBZ sequence with the JENDL-4.0 library updated with the present 242Pu evaluation.Display full sizeAdditional informationFundingThe work was supported by the Ministry of Education, Culture, Sports, Science and Technology .