A Pseudo-material method for graphite with arbitrary porosities in Monte Carlo criticality calculations

Okita, Shoichiro; Nagaya, Yasunobu; Fukaya, Yuji

Journal of Nuclear Science and Technology, 58(9), p.992 - 998, 2021/09

https://doi.org/10.1080/00223131.2021.1899997

Lead void reactivity worth in two critical assembly cores with differing uranium enrichments

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

https://doi.org/10.1080/00295639.2017.1373520

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.

Analyses of iron and concrete shielding experiments at JAEA/TIARA with JENDL/HE-2007, ENDF/B-VII.1 and FENDL-3.0

Konno, Chikara; Ochiai, Kentaro; Sato, Satoshi; Ota, Masayuki

Fusion Engineering and Design, 98-99, p.2178 - 2181, 2015/10

https://doi.org/10.1016/j.fusengdes.2014.12.034

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.

Benchmark analysis of KRITZ-2 critical experiments

Okumura, Keisuke; Kawasaki, Kenji*; Mori, Takamasa

JAERI-Research 2005-018, 64 Pages, 2005/08

JAERI-Research-2005-018.pdf:3.26MB

In the KRITZ-2 critical experiments, criticality and pin power distributions were measured at room temperature and high temperature (about 245 degree C) for three different cores loading slightly enriched UO or MOX fuels. For nuclear data testing, benchmark analysis was carried out with a continuous-energy Monte Carlo code MVP and its four nuclear data libraries based on JENDL-3.2, JENDL-3.3, JEF-2.2 and ENDF/B-VI.8. As a result, fairly good agreements with the experimental data were obtained with any libraries for the pin power distributions. However, the JENDL-3.3 and ENDF/B-VI.8 give under-prediction of criticality and too negative isothermal temperature coefficients for slightly enriched UO cores, while the older nuclear data JENDL-3.2 and JEF-2.2 give rather good agreements with the experimental data. From the detailed study with an infinite unit cell model, it was found that the differences among the libraries are mainly due to the different fission cross section of U-235 in the energy rage below 1.0 eV.

Integral validation of minor actinide nuclear data by using samples irradiated at dounreay prototype fast reactor

Tsujimoto, Kazufumi; Oigawa, Hiroyuki; Shinohara, Nobuo

Proceedings of International Conference on Nuclear Data for Science and Technology (ND 2004), 4 Pages, 2004/09

Japan Atomic Energy Research Institute (JAERI) has been developing technologies for partitioning and transmutation of long-lived nuclides in high-level radioactive waste. In the dedicated transmutation systems, reliable neuclear data of minor actinide (MA) are indispensable to obtain a reliable design of a transmutation system. Present status of MA nuclear data is not so satisfactory. To obtain reliable nuclear data of MA, radiochemically analyzed data of the actinide samples irradiated at the Dounreay Prototype Fast Reactor (PFR) were used in this study. The samples were actinide oxides of 21 different isotopes from thorium to curium. The burnup calculations were performed and the calculated results were compared with the experimental data to validate the neutron cross section data of MA in an evaluated nuclear data file JENDL-3.3, ENDF/B-VI, and JEFF-3.0. The results for uraniumu and plutoniumu samples show good agreements with experimental data. On the other hand, in the results for americium and curiumu, relatively large disagreement with experimental data are showed.

Analysis of the TRIGA MARK-II benchmark IEU-COMP-THERM-003 with Monte Carlo code MVP

Mahmood, M. S.; Nagaya, Yasunobu; Mori, Takamasa

JAERI-Tech 2004-027, 30 Pages, 2004/03

JAERI-Tech-2004-027.pdf:2.26MB

The benchmark experiments of the TRIGA Mark-II reactor in the ICSBEP handbook have been analyzed with the Monte Carlo code MVP using the cross section libraries based on JENDL-3.3, JENDL-3.2 and ENDF/B-VI.8. MCNP calculations have been also performed with the ENDF/B-VI.6 library for comparison between the MVP and MCNP results. For both cores labeled 132 and 133, which have different core configurations, the ratio of the calculated to the experimental results (C/E) for keff obtained by the MVP code is 0.999 for JENDL-3.3, 1.003 for JENDL-3.2, and 0.998 for ENDF/B-VI.8. For the MCNP code, the C/E values are 0.998 for both the Core 132 and 133. All the calculated results agree with the reference values within the experimental uncertainties. The results obtained by MVP with ENDF/B-VI.8 and MCNP with ENDF/B-VI.6 differ only by 0.02% for Core 132, and by 0.01% for Core 133.

Measurements of neutron induced fission cross-section for Am from 0.003eV to 10keV using lead slowing-down spectrometer, thermal neutron facility and time-of-flight method

Kai, Tetsuya; Kobayashi, Katsuhei*; Yamamoto, Shuji*; Cho, H.*; Fujita, Yoshiaki*; Kimura, Itsuro*; Okawachi, Yasushi*; Wakabayashi, Toshio*

Annals of Nuclear Energy, 28(8), p.723 - 739, 2001/05

https://doi.org/10.1016/S0306-4549(00)00086-4

no abstracts in English

Problems on ENDF/B-VIII.0 and JEFF-3.3 copper nuclear data above a few MeV

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.