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Okita, Shoichiro; Abe, Yutaka*; Tasaki, Seiji*; Fukaya, Yuji
Radioisotopes, 73(3), p.233 - 240, 2024/11
Okita, Shoichiro; Goto, Minoru
Proceedings of 12th International Conference on Nuclear Criticality Safety (ICNC2023) (Internet), 10 Pages, 2023/10
Okita, Shoichiro; Nagaya, Yasunobu; Fukaya, Yuji
Journal of Nuclear Science and Technology, 58(9), p.992 - 998, 2021/09
Times Cited Count：2 Percentile：22.08(Nuclear Science & Technology)Fujimoto, Nozomu*; Tada, Kenichi; Ho, H. Q.; Hamamoto, Shimpei; Nagasumi, Satoru; Ishitsuka, Etsuo
Annals of Nuclear Energy, 158, p.108270_1 - 108270_8, 2021/08
Times Cited Count：3 Percentile：33.11(Nuclear Science & Technology)Fukushima, Masahiro; Goda, J.*; Bounds, J.*; Cutler, T.*; Grove, T.*; Hutchinson, J.*; James, M.*; McKenzie, G.*; Sanchez, R.*; Oizumi, Akito; et al.
Nuclear Science and Engineering, 189, p.93 - 99, 2018/01
Times Cited Count：9 Percentile：61.79(Nuclear Science & Technology)To validate lead (Pb) nuclear cross sections, a series of integral experiments to measure lead void reactivity worths was conducted in a high-enriched uranium (HEU)/Pb system and a low enriched uranium (LEU)/Pb system using the Comet Critical Assembly at NCERC. The critical experiments were designed to provide complementary data sets having different sensitivities to scattering cross sections of lead. The larger amount of the 
U present in the LEU/Pb core increases the neutron importance above 1 MeV compared with the HEU/Pb core. Since removal of lead from the core shifts the neutron spectrum to the higher energy region, positive lead void reactivity worths were observed in the LEU/Pb core while negative values were observed in the HEU/Pb core. Experimental analyses for the lead void reactivity worths were performed with the Monte Carlo calculation code MCNP6.1 together with nuclear data libraries, JENDL 4.0 and ENDF/B VII.1. The calculation values were found to overestimate the experimental ones for the HEU/Pb core while being consistent for the LEU/Pb core.
Fukushima, Masahiro; Tsujimoto, Kazufumi; Okajima, Shigeaki
Journal of Nuclear Science and Technology, 54(7), p.795 - 805, 2017/07
Times Cited Count：13 Percentile：73.88(Nuclear Science & Technology)A series of integral experiments was conducted in FCA assemblies with systematically changed neutron spectra covering from the intermediate to fast ones. The experiments provide systematic data of central fission rates for TRU nuclides containing minor actinides, 
Np, Pu, 
Pu, 
Pu, 
Am, 
Am, and 
Cm. Latest major nuclear data libraries, JENDL-4.0, ENDF/B-VII.1, and JEFF-3.2, were tested using benchmark models regarding the fission rate ratios relative to Pu. For all the libraries, the benchmark tests by a Monte Carlo calculation code show obvious overestimations particularly for the fission rate ratios of Cm to Pu. Additionally, a large discrepancy about by 20% between the libraries is revealed for the fission rate ratio of Pu to Pu measured in the intermediate neutron spectrum. The cause of discrepancy is furthermore clarified by sensitivity analyses.
Konno, Chikara; Ochiai, Kentaro; Sato, Satoshi; Ota, Masayuki
Fusion Engineering and Design, 98-99, p.2178 - 2181, 2015/10
Times Cited Count：8 Percentile：52.78(Nuclear Science & Technology)We have analyzed the iron and concrete shielding experiments with the 40 and 65 MeV neutron sources at TIARA in Japan Atomic Energy Agency with the latest high-energy nuclear data libraries, JENDL/HE-2007, ENDF/B-VII.1 and FENDL-3.0. The Monte Carlo code MCNP-5 and ACE files of JENDL/HE-2007, ENDF/B-VII.1 and FENDL-3.0, which were supplied from JAEA, BNL and IAEA, respectively, were used for this analysis. The followings are found out from the results. (1) The calculations with JENDL/HE-2007 agree with all the measured ones well; (2) Those with ENDF/B-VII.1 tend to overestimate the measured ones with the thickness of the assemblies largely; (3) Those with FENDL-3.0 agree with the measured ones well for the iron experiment, while they overestimate the measured ones well for the concrete experiment largely. Some data in ENDF/B-VII.1 and FENDL-3.0 should be revised.
U nuclear data to improve k
biases on U enrichment and temperature for low enriched uranium fueled lattices moderated by light waterWu, H.; Okumura, Keisuke; Shibata, Keiichi
JAERI-Research 2005-013, 31 Pages, 2005/06
JAERI-Research-2005-013.pdf:3.29MB
The under prediction of k depending on U enrichment in low enriched uranium fueled systems was studied in this report. Benchmark testing was carried out with several evaluated nuclear data files, including the new uranium evaluations from preliminary ENDF/B-VII and CENDL-3.1. Another problem reviewed here was k underestimation vs. temperature increase, which was observed in the slightly enriched system with recent JENDL and ENDF/B uranium evaluations. Through the substitute analysis of nuclear data of U and U, we propose a new evaluation of U data to solve both of the problems. The new evaluation was tested for various uranium fueled systems including low or highly enriched metal and solution benchmarks in the ICSBEP handbook. As a result, it was found that the combination of the new evaluation of U and the U data from the preliminary ENDF/B-VII gives quite good results for most of benchmark problems.
Kwon, Saerom*; Konno, Chikara; Ota, Masayuki*; Sato, Satoshi*
no journal, ,
Our analyses of JAEA/FNS copper benchmark experiment with ENDF/B-VIII.0 and JEFF-3.3 pointed out that the calculation with ENDF/B-VIII.0 underestimated and that with JEFF-3.3 overestimated the measured reaction rate of the 
Nb(n,2n)
Nb sensitive to neutrons above 10 MeV. As a result of our detailed study, we specified that this issue was due to the (n,np) and (n,n') reaction data above a few MeV, etc.
Kwon, Saerom*; Konno, Chikara; Honda, Shogo*; Sato, Satoshi*; Masuda, Kai*
no journal, ,
We examined the accuracy of the iron data in the latest nuclear data libraries (FENDL-3.2b, JENDL-5, ENDF/B-VIII.0 and JEFF-3.3) used in the fusion neutron source design by using QST/TIARA iron experiment with quasi mono-energy neutrons of 40 and 65 MeV and JAEA/FNS iron experiment with DT neutrons. Then we have found the following issues on FENDL-3.2b iron data and specified that the non-elastic, inelastic scattering, (n,2n) reaction and (n,np) reaction data of 
Fe and inelastic scattering data of 
Fe caused the issues.1) The calculation results with FENDL-3.2b underestimate the measured neutron fluxes of the continuous energy range (10-60 MeV) by a factor of 0.6 in the TIARA experiment with 65 MeV neutrons. 2) The calculation results with FENDL-3.2b tend to underestimate the measured neutron flux above 10 MeV by a factor of 0.8 at depth of 70 cm and overestimate the measured ones below 10 keV by a factor of 1.3 up to depth of 40 cm in the FNS experiment.
