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Journal Articles

Count-loss effect in determination of prompt neutron decay constant by neutron correlation methods that employ two sets of neutron counting systems

Kitamura, Yasunori*; Fukushima, Masahiro; Kitamura, Yasunori*

Annals of Nuclear Energy, 125, p.328 - 341, 2019/01

 Times Cited Count:0 Percentile:100(Nuclear Science & Technology)

It has been taken for granted that the neutron correlation methods that employ two sets of neutron counting systems, e.g., the covariance-to-mean and the cross-correlation methods, are free from the count-loss effect for determination of the neutron decay constant. It was however found in the present study that these methods overestimate the neutron decay constant under high counting rate conditions. New formulae of these methods were hence obtained on the basis of a rigorous theoretical approach for treating the count-loss process. It is expected that the present formulae work better than conventional ones for determination of the neutron decay constant.

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:71.51(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

Benchmark tests of newly-evaluated data of $$^{235}$$U for CIELO project using integral experiments of uranium-fueled FCA assemblies

Fukushima, Masahiro; Kitamura, Yasunori*; Yokoyama, Kenji; Iwamoto, Osamu; Nagaya, Yasunobu; Leal, L. C.*

Proceedings of International Conference on the Physics of Reactors; Unifying Theory and Experiments in the 21st Century (PHYSOR 2016) (USB Flash Drive), p.605 - 619, 2016/05

A nuclear data of $$^{235}$$U has been recently evaluated for the CIELO (Collaborative International Evaluated Library Organization) project. We tested the newly-evaluated data of $$^{235}$$U using integral experiments of the Fast Critical Assembly (FCA) performed at JAEA. We selected two integral data of uranium-fueled FCA assemblies; one is the sodium-void reactivity worth of FCA XXVII-1 assembly and the other is the criticalities of the seven assemblies of FCA IX. The benchmark tests support the evaluation done in the resonance regions. However, the $$^{235}$$U capture cross section above the unresolved resonance range needs further investigation.

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:7 Percentile:22.3(Nuclear Science & Technology)

Journal Articles

Count-loss effect in subcriticality measurement by pulsed neutron source method, 2; Proposal for utilization of neutron detection system operated in current mode

Kitamura, Yasunori; Fukushima, Masahiro

Journal of Nuclear Science and Technology, 52(6), p.801 - 810, 2015/06

 Times Cited Count:6 Percentile:31.94(Nuclear Science & Technology)

JAEA Reports

Establishment of benchmark problems for TRU fission rate ratios of FCA-IX assemblies

Fukushima, Masahiro; Oizumi, Akito; Iwamoto, Hiroki; Kitamura, Yasunori

JAEA-Data/Code 2014-030, 50 Pages, 2015/03

JAEA-Data-Code-2014-030.pdf:10.34MB

In the IX-th experimental series in 1980's at the fast critical assembly (FCA) facility, central fission rate ratios for TRU such as $$^{237}$$Np, $$^{238}$$Pu, $$^{242}$$Pu, $$^{241}$$Am, $$^{243}$$Am and $$^{244}$$Cm to $$^{239}$$Pu were measured in the seven uranium-fueled assemblies with systematically changed neutron spectra. In the present report, benchmark problems with respect to central fission rate ratios were established for the assessment of the TRU's fission cross sections. We reported the sample calculation results on the benchmark problems by using JENDL-4.0.

Journal Articles

Uncertainty analysis of temperature effect on reactivity in very high temperature reactor critical assembly and establishment of biases for benchmark models

Kitamura, Yasunori; Eguchi, Yuta

Nuclear Science and Engineering, 178(3), p.401 - 413, 2014/11

 Times Cited Count:0 Percentile:100(Nuclear Science & Technology)

Journal Articles

Neutronic characteristics of lead-bismuth in KUCA A core for accelerator-driven system

Sugawara, Takanori; Oizumi, Akito; Kitamura, Yasunori; Iwamoto, Hiroki; Yagi, Takahiro*; Pyeon, C. H.*

KURRI Progress Report 2013, 1 Pages, 2014/10

The Japan Atomic Energy Agency (JAEA) has investigated the accelerator-driven system (ADS) to transmute minor actinides discharged from nuclear power plants. The ADS investigated by JAEA is a lead bismuth eutectic (LBE) cooled-tank-type ADS. It has been known that there was a major upgrade for the cross section data of lead isotopes from JENDL-3.3 to JENDL-4.0. Due to this upgrade, the value of $$k_{eff}$$ of the core was significantly changed, from 0.97 calculated by JENDL-3.3 to 1.00 calculated by JENDL-4.0. The difference was mainly caused by the cross section data of the lead isotopes from JENDL-3.3 to JENDL-4.0. This study aims to measure sample worth reactivity from aluminum plates to lead or LBE ones to validate the nuclear data of lead and bismuth isotopes.

Journal Articles

Count-loss effect in subcriticality measurement by pulsed neutron source method, 1; Investigation on count-loss effect in determination of neutron decay constant

Kitamura, Yasunori; Fukushima, Masahiro

Journal of Nuclear Science and Technology, 51(6), p.752 - 765, 2014/06

AA2013-0401.pdf:0.67MB

 Times Cited Count:6 Percentile:39.24(Nuclear Science & Technology)

Journal Articles

Correction of count-loss effect in neutron correlation methods that employ single neutron counting system for subcriticality measurement

Kitamura, Yasunori; Fukushima, Masahiro

Journal of Nuclear Science and Technology, 51(6), p.766 - 782, 2014/06

 Times Cited Count:6 Percentile:39.24(Nuclear Science & Technology)

Journal Articles

Measurement and analysis of reflector reactivity worth by replacing stainless steel with zirconium at the fast critical assembly (FCA)

Fukushima, Masahiro; Kitamura, Yasunori; Ando, Masaki; Kugo, Teruhiko

Journal of Nuclear Science and Technology, 49(10), p.961 - 965, 2012/10

 Times Cited Count:0 Percentile:100(Nuclear Science & Technology)

Journal Articles

Benchmark calculations of sodium-void experiments with uranium fuels at the fast critical assembly FCA

Fukushima, Masahiro; Kitamura, Yasunori; Kugo, Teruhiko; Yamane, Tsuyoshi; Ando, Masaki; Chiba, Go; Ishikawa, Makoto; Okajima, Shigeaki

Progress in Nuclear Science and Technology (Internet), 2, p.306 - 311, 2011/10

Journal Articles

Pulse neutron experiment for accelerator-driven system, 2

Nishihara, Kenji; Sugawara, Takanori; Tsujimoto, Kazufumi; Kitamura, Yasunori; Pyeon, C. H.*

KURRI Progress Report 2009, P. 201, 2010/10

The regression method for pulse neutron source (PNS) experiment has been developed to monitor sub-criticality of an accelerator-driven system (ADS). This method is applicable for PNS experiment with bad experimental conditions, such as high repetition of neutron source that makes the alpha-fitting method difficult to determine delayed neutron level. In the present study, the regression method was verified using the KUCA-A core with various sub-critical levels induced by DT neutrons with several numbers of repetitions. As a result, the discrepancy of $$k$$$$_{eff}$$ and count rates between experiment and the regression method was observed for the low repetitions. Further investigation for background is necessary in next study.

Journal Articles

Benchmark calculations of sodium-void experiments with uranium fuels at the fast critical assembly FCA

Fukushima, Masahiro; Kitamura, Yasunori; Kugo, Teruhiko; Yamane, Tsuyoshi; Ando, Masaki; Chiba, Go; Ishikawa, Makoto; Okajima, Shigeaki

Proceedings of Joint International Conference of 7th Supercomputing in Nuclear Application and 3rd Monte Carlo (SNA + MC 2010) (USB Flash Drive), 6 Pages, 2010/10

Journal Articles

Diagnostics system of JT-60U

Sugie, Tatsuo; Hatae, Takaki; Koide, Yoshihiko; Fujita, Takaaki; Kusama, Yoshinori; Nishitani, Takeo; Isayama, Akihiko; Sato, Masayasu; Shinohara, Koji; Asakura, Nobuyuki; et al.

Fusion Science and Technology (JT-60 Special Issue), 42(2-3), p.482 - 511, 2002/09

 Times Cited Count:6 Percentile:96.97(Nuclear Science & Technology)

The diagnostic system of JT-60U (JT-60upgrade) is composed of about 50 individual diagnostic devices. Recently, the detailed radial profile measurements of plasma parameters have been improved, so that the internal structure of plasmas has been explored. The understanding of plasma confinement has been enhanced by density and temperature fluctuation measurements using a mm-wave reflectometer and electron cyclotron emission measurements respectively. In addition, the real-time control experiments of electron density, neutron yield, radiated power and electron temperature gradient have been carried out successfully by corresponding diagnostic devices. These measurements and the real time control contribute to improving plasma performance. Diagnostic devices for next generation fusion devices such as a CO2 laser interferometer/polarimeter and a CO2 laser collective Thomson scattering system have been developed.

Oral presentation

Criticality administration of ADS

Kitamura, Yasunori

no journal, , 

no abstracts in English

Oral presentation

Development of reactivity feedback effect measurement techniques under sub-critical condition in fast reactor, 1-5; FCA experimental plan

Fukushima, Masahiro; Okajima, Shigeaki; Kitamura, Yasunori; Ando, Masaki; Yamane, Tsuyoshi; Mori, Takamasa; Nishi, Hiroshi; Yamane, Yoshihiro*; Kanemoto, Shigeru*

no journal, , 

no abstracts in English

Oral presentation

Development of reactivity feedback effect measurement techniques under sub-critical condition in fast reactor, 1-1; Purpose and program

Okajima, Shigeaki; Nishi, Hiroshi; Yamane, Yoshihiro*; Kanemoto, Shigeru*; Yamane, Tsuyoshi; Mori, Takamasa; Kitamura, Yasunori; Fukushima, Masahiro; Kitano, Akihiro; Ando, Masaki; et al.

no journal, , 

The program was planned and has been carried out to develop of the reactivity feedback effect measurement techniques under sub-critical condition in the start-up experiment for fast reactors. The program includes the demonstration of the developed technique in fast critical assembly (FCA) and the proposal of the appropriate measurement system based on the results. The background and the purposes of the program and the outline of development subjects are presented.

Oral presentation

Development of reactivity feedback effect measurement techniques under sub-critical condition in fast reactor, 1-2; Development of acquisition system with high time-resolution for long time-series data

Kitamura, Yasunori; Yamane, Yoshihiro*; Okajima, Shigeaki; Fukushima, Masahiro; Ando, Masaki; Yamane, Tsuyoshi

no journal, , 

no abstracts in English

Oral presentation

FCA critical experiment for validation of $$^{235}$$U capture cross section and experimental analysis

Kugo, Teruhiko; Kitamura, Yasunori; Fukushima, Masahiro; Ando, Masaki; Yamane, Tsuyoshi; Okajima, Shigeaki

no journal, , 

Sodium void reactivity experiments were performed at FCA using uranium fueled core to obtain integral data for evaluation of epithermal capture cross section of $$^{235}$$U. Experimental analysis were carried out with use of various nuclear data libraries including JENDL-4.0. The ratio of calculated value to experiment value (C/E) are less than unity with JENDL-3.3, ENDF/B-VII.0 and JEFF-3.1. This tendency of C/E values is similar to those for the sodium void reactivity experiments at BFS. Newly obtained integral data at FCA has a large sensitivity to $$^{235}$$U capture cross section from several hundreds eV to several keV. Thus, the new integral data are useful for validation of epithermal capture cross section of $$^{235}$$U and are used for the re-evaluation capture cross section of $$^{235}$$U in subgroup-29 of OECD/NEWA/NSC/WPEC.

27 (Records 1-20 displayed on this page)