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Yanagisawa, Hiroshi

JAEA-Technology 2021-023, 190 Pages, 2021/11

Computational analyses on nuclear criticality characteristics were carried out for heterogeneous lattice systems composed of water moderator and fuel rods utilized in lowpower research and test reactors, in which the depletion of fuel due to burnup is relatively small, by using the continuous-energy Monte Carlo code MVP Version 2 with the evaluated nuclear data library JENDL-4.0. In the analyses, the minimum critical number of fuel rods was evaluated using calculated neutron multiplication factors for the heterogeneous systems of the uranium dioxide fuel rod in the Static Experiments Critical Facility (STACY) and the Tank-type Critical Assembly (TCA), and the uranium-zirconium hydride fuel rod in the Nuclear Safety Research Reactor (NSRR). In addition, six sorts of the ratio of reaction rates, which are components of neutron multiplication factors, were calculated in the analyses to explain the variation of neutron multiplication factors with the ratio of water moderator to fuel volume in a unit fuel rod cell. Those results of analyses are considered to be useful for the confirmation of reasonableness and validity of criticality safety measures as data showing criticality characteristics for water-moderated heterogeneous lattice systems composed of the existing fuel rods in research and test reactors, of which criticality data are not sufficiently provided by the Criticality Safety Handbook.

Okazaki, Yasuyuki*; Hayashi, Hisashi*; Aoyagi, Kazuhei; Morimoto, Shingo*; Shinji, Masato*

Proceedings of 5th ISRM Young Scholars' Symposium on Rock Mechanics and International Symposium on Rock Engineering for Innovative Future (YSRM 2019 and REIF 2019) (USB Flash Drive), 6 Pages, 2019/12

In the design of tunnel support, the behavior of the rock mass around a tunnel and the stress acting on the tunnel support may be predicted using a numerical analysis. However, in such a numerical analysis, it is common to assume that each stratum comprises a homogeneous material, ignoring the heterogeneity of the geomechanical properties inherent to the rock mass. For this reason, it is not unusual for the results of the numerical analysis to differ from the actual behavior. We performed a tunnel excavation analysis considering the heterogeneity of the geomechanical properties in the rock mass to investigate the local increase in the tunnel support stress obtained in the 350 m gallery at the Horonobe Underground Research Laboratory. The results revealed that, in order to predict the locally increased support stress in advance, it is necessary to carry out a tunneling excavation analysis considering the heterogeneity of the geomechanical properties. It was also revealed that the scale at which the geomechanical properties fluctuate is an important factor.

Watanabe, Shoichi; Yamamoto, Toshihiro; Miyoshi, Yoshinori

Transactions of the American Nuclear Society, 91, p.431 - 432, 2004/11

Temperature effect is a main factor which affects the transient characteristics at a criticality accident. A series of reactivity effects due to changes in fuel temperatures were measured for two kinds of STACY heterogeneous lattice configurations. The core was composed of LWR-type fuel rod array and low-enriched uranyl-nitrate-solution concerning the dissolver of the reprocessing facility for LWR spent fuel. The critical solution heights at various solution temperatures were measured. From the change of the critical water height with fuel temperature, the reactivity effect was evaluated by a critical-solution-level worth method. The temperature effect was also calculated by using SRAC and the transport calculation code TWODANT. The experimental value was estimated to be -2.0 cent/C for the case "2.1cm-pitch", and -2.5 cent/C for the case "1.5cm-pitch". The calculated results gave agreement with the experiments within 10%.

Tonoike, Kotaro; Yamamoto, Toshihiro; Watanabe, Shoichi; Miyoshi, Yoshinori

Journal of Nuclear Science and Technology, 41(2), p.177 - 182, 2004/02

Times Cited Count：12 Percentile：64.04(Nuclear Science & Technology)As a part of the development of a subcriticality monitoring system, a system which has a time series data acquisition function of detector signals and a real time evaluation function of alpha value with the Feynman- method was established, with which the kinetic parameter (alpha value) was measured at the STACY heterogeneous core. The Hashimoto's difference filter was implemented in the system, which enables the measurement at a critical condition. The measurement result of the new system agreed with the pulsed neutron method.

Kugo, Teruhiko

Journal of Nuclear Science and Technology, 39(3), p.256 - 263, 2002/03

Times Cited Count：3 Percentile：24.34(Nuclear Science & Technology)Two vector computation algorithms; an odd-even sweep (OES) method and an independent sequential sweep (ISS) method, have been developed for the characteristics method to solve the neutron transport equation in a heterogeneous geometry. They realize long vector lengths without recursive operations for effective use of vector computers. Their efficiency has been investigated to a realistic fuel assembly calculation. For both methods, a vector computation is 15 times faster than a scalar computation. From a viewpoint of a comparison between the OES and ISS methods, the ISS method is superior to the OES method because the ISS method shows a faster convergence and saves a computer memory without reducing a computation speed.

Kugo, Teruhiko

JAERI-Research 2001-051, 39 Pages, 2001/11

Fast computation of the characteristics method to solve the neutron transport equation in a heterogeneous geometry has been studied. Two vector computation algorithms; an odd-even sweep (OES) method and an independent sequential sweep (ISS) method have been developed and their efficiency to a typical fuel assembly calculation has been investigated. For both methods, a vector computation is 15 times faster than a scalar computation. From a viewpoint of comparison between the OES and ISS methods, the ISS method is superior to the OES method because the ISS method shows a faster convergence and saves a computer memory without reducing a computation speed. In the vector computation, a table-look-up method to reduce computation time of an exponential function saves only 20% of a whole computation time. Both the coarse mesh rebalance method and the Aitken acceleration method are effective as acceleration methods for the characteristics method, a combination of them saves 70-80% of outer iterations compared with a free iteration.

; Kaneko, Kunio*

Mathematics and Computation, Reactor Physics and Environmental Analysis in Nuclear Applications, 2, p.2113 - 2122, 1999/09

no abstracts in English

Onishi, Ryoichi*; ; Takemiya, Hiroshi*; Guo, Z.*

Koku Uchu Gjutsu Kenkyujo Tokubetsu Shiryo, (41), p.47 - 52, 1999/02

no abstracts in English

Akino, Fujiyoshi; Takeuchi, Motoyoshi; Ono, Toshihiko; Fujisaki, Shingo

PHYSOR 96: Int. Conf. on the Physics of Reactors, 2, p.E281 - E289, 1996/00

no abstracts in English

Yamane, Tsuyoshi; Akino, Fujiyoshi;

PHYSOR 96: Int. Conf. on the Physics of Reactors, 2, p.E290 - E299, 1996/00

no abstracts in English

Okuno, Hiroshi; Naito, Yoshitaka; *

Journal of Nuclear Science and Technology, 31(9), p.986 - 995, 1994/09

Times Cited Count：2 Percentile：28.77(Nuclear Science & Technology)no abstracts in English

B.P.Kochurov*

JAERI-Review 94-002, 161 Pages, 1994/08

no abstracts in English

*; Okumura, Keisuke;

JAERI-M 92-067, 35 Pages, 1992/05

no abstracts in English

Okumura, Keisuke; ;

Proc. of Int. Conf. on the Physics of Reactors; Operation, Design and Computation, Vol. 4, p.101 - 110, 1990/00

no abstracts in English

; ; *; ; *; *

JAERI-M 86-016, 51 Pages, 1986/02

no abstracts in English

;

JAERI-M 85-218, 20 Pages, 1986/01

no abstracts in English

Journal of the Physical Society of Japan, 53(5), p.1587 - 1589, 1984/00

Times Cited Count：1 Percentile：40.76(Physics, Multidisciplinary)no abstracts in English

; ; ;

JAERI-M 8117, 18 Pages, 1979/03

no abstracts in English

; *

JAERI-M 7763, 60 Pages, 1978/07

no abstracts in English

; *; Takehisa, Masaaki; Machi, Sueo

Journal of Polymer Science; Polymer Chemistry Edition, 12(9), p.2027 - 2033, 1974/09

no abstracts in English