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Journal Articles

Nuclear data processing code FRENDY; A Verification with HTTR criticality benchmark experiments

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:0 Percentile:0.01(Nuclear Science & Technology)

Journal Articles

Benchmark models for criticalities of FCA-IX assemblies with systematically changed neutron spectra

Fukushima, Masahiro; Kitamura, Yasunori; Kugo, Teruhiko; Okajima, Shigeaki

Journal of Nuclear Science and Technology, 53(3), p.406 - 424, 2016/03

 Times Cited Count:8 Percentile:71.87(Nuclear Science & Technology)

JAEA Reports

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$$_{2}$$ 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$$_{2}$$ 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.

JAEA Reports

Proposal of new $$^{235}$$U nuclear data to improve k$$_{eff}$$ biases on $$^{235}$$U enrichment and temperature for low enriched uranium fueled lattices moderated by light water

Wu, 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$$_{eff}$$ depending on $$^{235}$$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$$_{eff}$$ 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 $$^{235}$$U and $$^{238}$$U, we propose a new evaluation of $$^{235}$$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 $$^{235}$$U and the $$^{238}$$U data from the preliminary ENDF/B-VII gives quite good results for most of benchmark problems.

Journal Articles

Classification of criticality calculations with correlation coefficient method and its application to OECD/NEA burnup credit benchmarks phase III-A and II-A

Okuno, Hiroshi

Journal of Nuclear Science and Technology, 40(7), p.544 - 551, 2003/07

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

A method for classifying benchmark results of criticality calculations according to similarity was proposed in this paper. After formulation of the method utilizing correlation coefficients, it was applied to burnup credit criticality benchmarks Phase III-A and II-A, which were conducted by the Expert Group on Burnup Credit Criticality Safety under auspices of the OECD/NEA. Phase III-A benchmark was a series of criticality calculations for irradiated BWR fuel assemblies, whereas Phase II-A benchmark was a suite of criticality calculations for irradiated PWR fuel pins. These benchmark problems and their results were summarized. The correlation coefficients were calculated and sets of benchmark results were classified according to the criterion that the correlation coefficients were no less than 0.15 for Phase III-A and 0.10 for Phase II-A benchmarks. When a couple of results were in a same group, one result was found predictable from the other. An example was shown for each of the Benchmarks. The evaluated nuclear data seemed the main factor of errors.

Journal Articles

Burnup importance function introduced to give an insight into the end effect

Okuno, Hiroshi; Sakai, Tomohiro*

Nuclear Technology, 140(3), p.255 - 265, 2002/12

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

In order to facilitate discussions based on quantitative analysis about the end effect, which is often talked about in connection to burnup credit in criticality safety evaluation of spent fuel, we introduced in this paper a burnup importance function. This function shows the burnup effect on the reactivity as a function of the fuel position; an explicit expression of this function was derived according to the perturbation theory. The burnup importance function was applied to the Phase IIA benchmark model that was adopted by the OECD/NEA Expert Group on Burnup Credit Criticality Safety. The function clearly displayed that burnup importance of the end regions increases (1) as burnup, (2) as cooling time, (3) in consideration of burnup profile, and (4) in consideration of fission products.

Journal Articles

Japanese evaluated nuclear data library version 3 revision-3; JENDL-3.3

Shibata, Keiichi; Kawano, Toshihiko*; Nakagawa, Tsuneo; Iwamoto, Osamu; Katakura, Junichi; Fukahori, Tokio; Chiba, Satoshi; Hasegawa, Akira; Murata, Toru*; Matsunobu, Hiroyuki*; et al.

Journal of Nuclear Science and Technology, 39(11), p.1125 - 1136, 2002/11

 Times Cited Count:642 Percentile:96.97(Nuclear Science & Technology)

Evaluation for JENDL-3.3 has been performed by considering the accumulated feedback information and various benchmark tests of the previous library JENDL-3.2. The major problems of the JENDL-3.2 data were solved by the new library: overestimation of criticality values for thermal fission reactors was improved by the modifications of fission cross sections and fission neutron spectra for $$^{235}$$U; incorrect energy distributions of secondary neutrons from important heavy nuclides were replaced with statistical model calculations; the inconsistency between elemental and isotopic evaluations was removed for medium-heavy nuclides. Moreover, covariance data were provided for 20 nuclides. The reliability of JENDL-3.3 was investigated by the benchmark analyses on reactor and shielding performances. The results of the analyses indicate that JENDL-3.3 predicts various reactor and shielding characteristics better than JENDL-3.2.

Journal Articles

Burnup importance function and its application to OECD/NEA/BUC phase II-A and II-C models

Okuno, Hiroshi; Tonoike, Kotaro; Sakai, Tomohiro*

Proceedings of International Conference on the New Frontiers of Nuclear Technology; Reactor Physics, Safety and High-Performance Computing (PHYSOR 2002) (CD-ROM), 8 Pages, 2002/10

As the burnup proceeds, reactivity of fuel assemblies for light water reactors decreases by depletion of fissile nuclides, especially in the axially central region. In order to describe the importance of the end regions to the reactivity change, a burnup importance function was introduced as a weighting function to a local burnup variation contributed to a reactivity decrease. The function was applied to the OECD/NEA/BUC Phase II-A model and a simplified Phase II-C model. The application to Phase II-A model clearly showed that burnup importance of the end regions increases as burnup and/or cooling time increases. Comparison of the burnup importance function for different initial enrichments was examined. The application result to the simplified Phase II-C model showed that the burnup importance function was helpful to find the most reactive fuel burnup distribution under the conditions that the average fuel burnup was kept constant and the variations in the fuel burnup were within the maximum and minimum measured values.

JAEA Reports

OECD/NEA burnup credit criticality benchmarks phase IIIB; Burnup calculations of BWR fuel assemblies for storage and transport

Okuno, Hiroshi; Naito, Yoshitaka*; Suyama, Kenya

JAERI-Research 2002-001, 181 Pages, 2002/02

JAERI-Research-2002-001.pdf:10.89MB

The report describes the final results of the Phase IIIB Benchmark conducted by the Expert Group on Burnup Credit Criticality Safety under the auspices of the OECD/NEA. The Benchmark was intended to compare the predictability of current computer code and data library combinations for the atomic number densities of an irradiated BWR fuel assembly model, which was irradiated under specific power of 25.6 MW/tHM up to 40 GWd/tHM and cooled for five years. The void fraction was assumed to be uniform and constant, at 0, 40 and 70%, during burnup. In total, 16 results were submitted from 13 institutes of 7 countries. The calculated densities of 12 actinides and 20 fission product nuclides were found mostly within a range of +- 10% relative to the average, although some results, esp. 155Eu and gadolinium isotopes, exceeded the band. Pin-wise burnup results agreed well among the participants. The results in the multiplication factor also accorded well with each other for void fractions of 0 and 40%; however some results deviated from the average noticeably for the void fraction of 70%.

JAEA Reports

OECD/NEA burnup credit criticality benchmarks phase IIIA; Criticality calculations of BWR spent fuel assemblies in storage and transport

Okuno, Hiroshi; Naito, Yoshitaka*; Ando, Yoshihira*

JAERI-Research 2000-041, 179 Pages, 2000/09

JAERI-Research-2000-041.pdf:6.11MB

no abstracts in English

Journal Articles

A Proposal to asian countries with operating research reactors for making nuclear criticality safety benchmark evaluations

Komuro, Yuichi

Journal of Nuclear Science and Technology, 37(6), p.548 - 554, 2000/06

no abstracts in English

Journal Articles

International studies on burnup credit criticality safety by an OECD/NEA working group, 2; Calculation benchmarks for BWR spent fuels

; *; Suyama, Kenya; Ando, Yoshihira*

Proceedings of 6th International Conference on Nuclear Criticality Safety (ICNC '99), 2, p.566 - 575, 1999/00

no abstracts in English

Journal Articles

Introduction to ``International handbook of criticality safety benchmark experiments''

Komuro, Yuichi

Nihon Genshiryoku Gakkai-Shi, 40(9), p.697 - 701, 1998/00

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Benchmark problems of start-up core physics of High Temperature engineering Test Reactor (HTTR)

Yamashita, Kiyonobu; Nojiri, Naoki; Fujimoto, Nozomu; Nakano, Masaaki*; Ando, Hiroei; Nagao, Yoshiharu; Nagaya, Yasunobu; Akino, Fujiyoshi; Takeuchi, Mitsuo; Fujisaki, Shingo; et al.

Proc. of IAEA TCM on High Temperature Gas Cooled Reactor Applications and Future Prospects, p.185 - 197, 1998/00

no abstracts in English

Journal Articles

Studies on burnup credit at JAERI

; Nomura, Yasushi; Suyama, Kenya

Proc. of Int. Conf. on the Phys. of Nucl. Sci. and Technol., 1, p.742 - 748, 1998/00

no abstracts in English

JAEA Reports

OECD/NEA burnup credit criticality benchmark; Result of phase IIA

; Okuno, Hiroshi

JAERI-Research 96-003, 170 Pages, 1996/02

JAERI-Research-96-003.pdf:5.24MB

no abstracts in English

Journal Articles

Findings of an international study on burnup credit

M.C.Brady*; ; M.D.DeHart*; Okuno, Hiroshi; A.Nouri*; E.Sartori*

PHYSOR 96: Int. Conf. on the Physics of Reactors, 4, p.L41 - L52, 1996/00

no abstracts in English

JAEA Reports

Calculations for reflector savings of steel and stainless steel

*; Okuno, Hiroshi

JAERI-Research 94-047, 39 Pages, 1994/12

JAERI-Research-94-047.pdf:0.89MB

no abstracts in English

JAEA Reports

Analyses with MCNP code of the criticality experiment of pellet-solution coexisting low-enriched uranium fuel

*; Arakawa, Takuya*; Okuno, Hiroshi

JAERI-Data/Code 94-018, 36 Pages, 1994/12

JAERI-Data-Code-94-018.pdf:1.09MB

no abstracts in English

JAEA Reports

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