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Journal Articles

Systematic measurements and analyses for lead void reactivity worth in a plutonium core and two uranium cores with different enrichments

Fukushima, Masahiro; Goda, J.*; Oizumi, Akito; Bounds, J.*; Cutler, T.*; Grove, T.*; Hayes, D.*; Hutchinson, J.*; McKenzie, G.*; McSpaden, A.*; et al.

Nuclear Science and Engineering, 194(2), p.138 - 153, 2020/02

 Times Cited Count:1 Percentile:0.01(Nuclear Science & Technology)

To validate lead (Pb) nuclear cross sections, a series of integral experiments to measure lead void reactivity worth was conducted systematically in three fast spectra with different fuel compositions on the Comet critical assembly of the National Criticality Experiments Research Center. Previous experiments in a high-enriched uranium (HEU)/Pb and a low-enriched uranium (LEU)/Pb systems had been performed in 2016 and 2017, respectively. A follow-on experiment in a plutonium (Pu)/Pb system has been completed. The Pu/Pb system was constructed using lead plates and weapons grade plutonium plates that had been used in the Zero Power Physics Reactor (ZPPR) of Argonne National Laboratory until the 1990s. Furthermore, the HEU/Pb system was re-examined on the Comet critical assembly installed newly with a device that can guarantee the gap reproducibility with a higher accuracy and precision, and then the experimental data was re evaluated. Using the lead void reactivity worth measured in these three cores with different fuel compositions, the latest nuclear data libraries, JENDL 4.0 and ENDF/B VIII.0, were tested with the Monte Carlo calculation code MCNP version 6.1. As a result, the calculations by ENDF/B-VIII.0 were confirmed to agree with lead void reactivity worth measured in all the cores. It was furthermore found that the calculations by JENDL 4.0 overestimate by more than 20% for the Pu/Pb core while being in good agreements for the HEU/Pb and LEU/Pb cores.

Journal Articles

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

 Times Cited Count:5 Percentile:56.63(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 $$^{238}$$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.

Journal Articles

A Simple and practical correction technique for reactivity worth of short-sized samples measured by critical-water-level method

Kitamura, Yasunori*; Fukushima, Masahiro

Nuclear Science and Engineering, 186(2), p.168 - 179, 2017/05

 Times Cited Count:1 Percentile:15.39(Nuclear Science & Technology)

An inconsistency between the reactivity worth of short-size samples measured by the critical-water-level (CWL) method and that conventionally analysed for validating the nuclear data and the nuclear calculation methods has been known. The present study investigated this inconsistency in terms of a simple theoretical framework and proposed a simple and practical technique for correcting the measured sample reactivity worth without making supplementary experiments. A series of Monte Carlo calculations that simulated typical sample reactivity worth measurement by the CWL method showed that this inconsistency is effectively reduced by the present correction technique.

Journal Articles

Validation of the nuclear design code system for the HTTR using the criticality assembly VHTRC

Fujimoto, Nozomu; Nojiri, Naoki; Yamashita, Kiyonobu*

Nuclear Engineering and Design, 233(1-3), p.155 - 162, 2004/10

 Times Cited Count:1 Percentile:10.51(Nuclear Science & Technology)

The HTTR uses low-enriched uranium fuel with burnable poison rod. For validation of the nuclear design code system for the HTTR, a critical assembly of VHTRC had been constructed. The calculation uncertainties of effective multiplication factor, neutron flux distribution, burnable poison reactivity worth, and control rod worth, temperature coefficients were evaluated. Calculation accuracy of a Monte Carlo code is also evaluated.

Journal Articles

Characteristic test of initial HTTR core

Nojiri, Naoki; Shimakawa, Satoshi; Fujimoto, Nozomu; Goto, Minoru

Nuclear Engineering and Design, 233(1-3), p.283 - 290, 2004/10

 Times Cited Count:11 Percentile:61.05(Nuclear Science & Technology)

This paper describes the results of core physics test in start-up and power-up of the HTTR. The tests were conducted in order to ensure performance and safety of the high temperature gas cooled reactor, and was carried out to measure the critical approach, the excess reactivity, the shutdown margin, the control rod worth, the reactivity coefficient, the neutron flux distribution and the power distribution. The expected core performance and the required reactor safety characteristics were verified from the results of measurements and calculations.

JAEA Reports

Measurement of $$^{238}$$U Doppler Effect using various samples in FCA XVII-1

Ando, Masaki; Okajima, Shigeaki; Oigawa, Hiroyuki

JAERI-Research 2001-017, 20 Pages, 2001/03

JAERI-Research-2001-017.pdf:0.82MB

$$^{238}$$U Doppler effect measurements were carried out using 6 uranium samples with various composition or diameter varying self-shielding factors of $$^{238}$$U. Calculation accuracy of the standard analysis method for fast reactor cores at FCA was investigated.The Doppler effect were measured by the sample-heated and reactivity worth measurement method up to 800 degree in the FCA XVII-1 assembly, which simulated Na-cooled MOX fueled FBR. In the analysis, the Doppler effect was calculated using the effective cross sections obtained by the PEACO-X code. The calculated values based on the diffusion theory agreed well with the experiment for the U-metal and UO$$_{2}$$ samples. The calculation underestimated the experiment from 10% to 30% for the UO$$_{2}$$ samples containing BeO. This underestimation was improved by the use of the transport calculation. The calculation, however, underestimated about 20% for the sample whose background cross section is greater than 300 barns.

JAEA Reports

Preliminary analyses for HTTR's start-up physics tests by HTTR nuclear characteristics evaluation code system

Fujimoto, Nozomu; Nojiri, Naoki; Nakano, Masaaki*; Takeuchi, Mitsuo; Fujisaki, Shingo; Yamashita, Kiyonobu

JAERI-Tech 98-021, 66 Pages, 1998/06

JAERI-Tech-98-021.pdf:2.63MB

no abstracts in English

Journal Articles

The Present active status of domestic critical assemblies and the perspective for their future, 2-4; Very high temperature reactor critical assembly (VHTRC)

Akino, Fujiyoshi; Yamane, Tsuyoshi

Nihon Genshiryoku Gakkai-Shi, 40(4), p.262 - 264, 1998/00

no abstracts in English

JAEA Reports

Measurement of reactivity worths of Sm,Cs,Gd,Nd,Rh,Eu,B and Er aqueous solution samples

Komuro, Yuichi; Suzaki, Takenori; *; Sakurai, Kiyoshi; Horiki, Oichiro*

JAERI-Research 97-088, 19 Pages, 1997/11

JAERI-Research-97-088.pdf:0.86MB

no abstracts in English

Journal Articles

Experimental verification and analysis of neutron streaming effect through void holes for control rod insertion in HTTR

Akino, Fujiyoshi; Takeuchi, Motoyoshi; Ono, Toshihiko; Kaneko, Yoshihiko

Journal of Nuclear Science and Technology, 34(2), p.185 - 192, 1997/02

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

no abstracts in English

Journal Articles

High temperature Doppler effect experiment for $$^{238}$$U at FCA, I; Reactivity worth measurement with a small heated sample up to 1500$$^{circ}$$C

Okajima, Shigeaki; Oigawa, Hiroyuki; Mukaiyama, Takehiko; Ando, Masaki

Journal of Nuclear Science and Technology, 33(3), p.202 - 210, 1996/03

 Times Cited Count:3 Percentile:33.71(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Measurement of reactivity worths of natural Sm, Cs, Gd, Nd, Rh, Eu, B and Er

Komuro, Yuichi; ; Sakurai, Kiyoshi; Yamamoto, Toshihiro; Suzaki, Takenori; Horiki, Oichiro*; Nitta, Kazuo*

PHYSOR 96: Int. Conf. on the Physics of Reactors, 1, p.L120 - L129, 1996/00

no abstracts in English

Journal Articles

Doppler effect measurement up to 2,000$$^{circ}$$C in the fast critical facility FCA

Okajima, Shigeaki; Oigawa, Hiroyuki; Ando, Masaki; Mukaiyama, Takehiko

Proc. of 9th Int. Symp. on Reactor Dosimetry, 0, p.172 - 179, 1996/00

no abstracts in English

Journal Articles

Resonance interaction effect between hot sample and cold core in analysis of Doppler effect measurement

Okajima, Shigeaki; Oigawa, Hiroyuki; Mukaiyama, Takehiko

Journal of Nuclear Science and Technology, 31(10), p.1097 - 1104, 1994/10

 Times Cited Count:7 Percentile:57.56(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Measurement of effective delayed neutron fraction of VHTRC-1 core

Akino, Fujiyoshi; Takeuchi, Motoyoshi; Ono, Toshihiko

Journal of Nuclear Science and Technology, 31(8), p.861 - 863, 1994/08

 Times Cited Count:3 Percentile:50.49(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Whole core calculations of power reactors by use of Monte Carlo method

Nakakawa, Masayuki; Mori, Takamasa

Journal of Nuclear Science and Technology, 30(7), p.692 - 701, 1993/07

 Times Cited Count:32 Percentile:92.67(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Neutronics properties of JMTR LEU core

Nagaoka, Yoshiharu; Saito, Minoru;

Transactions of the American Nuclear Society, 66, p.454 - 455, 1992/11

no abstracts in English

Journal Articles

Selected reactor physics phenomena observed during N.S.Mutsu power-up tests

; Miyoshi, Yoshinori; *; *; ;

Proc. of the Int. Conf. on Nuclear Power Plant Operations; Ready for 2000, p.435 - 441, 1992/00

no abstracts in English

JAEA Reports

Experimental study of power distribution in FCA XV cores with half-inserted B$$_{4}$$C control rod

Oigawa, Hiroyuki; Osugi, Toshitaka; Ono, Akio; ; *

JAERI-M 91-096, 39 Pages, 1991/06

JAERI-M-91-096.pdf:0.85MB

no abstracts in English

Journal Articles

Experimental study on reactivity worth for absorber material in high conversion light water reactor using FCA-HCLWR core fueled with enriched uranium

Okajima, Shigeaki; Osugi, Toshitaka; Sakurai, Takeshi; *

Journal of Nuclear Science and Technology, 27(10), p.950 - 959, 1990/10

no abstracts in English

32 (Records 1-20 displayed on this page)