Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Yonomoto, Taisuke; Nakashima, Hiroshi*; Sono, Hiroki; Kishimoto, Katsumi; Izawa, Kazuhiko; Kinase, Masami; Osa, Akihiko; Ogawa, Kazuhiko; Horiguchi, Hironori; Inoi, Hiroyuki; et al.
JAEA-Review 2020-056, 51 Pages, 2021/03
JAEA-Review-2020-056.pdf:3.26MB
A group named as "The group for investigation of reasonable safety assurance based on graded approach", which consists of about 10 staffs from Sector of Nuclear Science Research, Safety and Nuclear Security Administration Department, departments for management of nuclear facility, Sector of Nuclear Safety Research and Emergency Preparedness, aims to realize effective graded approach (GA) about management of facilities and regulatory compliance of JAEA. The group started its activities in September, 2019 and has had discussions through 10 meetings and email communications. In the meetings, basic ideas of GA, status of compliance with new regulatory standards at each facility, new inspection system, etc were discussed, while individual investigation at each facility were shared among the members. This report is compiled with expectation that it will help promote rational and effective safety management based on GA by sharing contents of the activity widely inside and outside JAEA.
Araki, Shohei; Gunji, Satoshi; Tonoike, Kotaro; Kobayashi, Fuyumi; Izawa, Kazuhiko; Ogawa, Kazuhiko
Proceedings of European Research Reactor Conference 2020 (RRFM 2020) (Internet), 7 Pages, 2020/10
Critical experiments of thermal neutron system are still expected to be playing an important role for wide technical issues. The Japan Atomic Energy Agency (JAEA) is renovating the Static Experimental Critical Facility (STACY) to maintain the experimental capability. The new STACY is designed as a general-purpose criticality facility. Its core mainly consists of low enriched UO
fuel rods, grid plates, and light water moderator. The first experiment campaign in the new STACY aims to obtain criticality characteristics of fuel debris, which will be used in validation of criticality analysis methods. The designs of the experimental core configurations are in progress.
Tonoike, Kotaro; Watanabe, Tomoaki; Gunji, Satoshi; Yamane, Yuichi; Nagaya, Yasunobu; Umeda, Miki; Izawa, Kazuhiko; Ogawa, Kazuhiko
Proceedings of 11th International Conference on Nuclear Criticality Safety (ICNC 2019) (Internet), 9 Pages, 2019/09
Criticality control of the fuel debris in the Fukushima Daiichi Nuclear Power Station would be a risk-informed control to mitigate consequences of criticality events, instead of a deterministic control to prevent such events. The Nuclear Regulation Authority of Japan has administrated a research and development program to tackle this challenge since 2014. The Nuclear Safety Research Center of Japan Atomic Energy Agency, commissioned by the authority, is conducting activities such as computations of criticality characteristics of the fuel debris, development of a criticality analysis code, preparation of criticality experiments, and development of a criticality risk analysis method.
Izawa, Kazuhiko; Ishii, Junichi; Okubo, Takuya; Ogawa, Kazuhiko; Tonoike, Kotaro
Proceedings of 11th International Conference on Nuclear Criticality Safety (ICNC 2019) (Internet), 9 Pages, 2019/09
Japan Atomic Energy Agency, JAEA, is conducting the renewal program of the heterogeneous water moderated critical assembly STACY (Static Experiment Critical Facility) in order to verify the criticality calculation considering fuel debris which have been produced in the accident of Fukushima Daiichi Nuclear Power Station. The first criticality of the new STACY is scheduled at the beginning of 2021. After the first criticality, it is necessary to perform a series of critical experiments with a series of basic experimental core in order to gain a proficiency of operators and grasp the uncertainty that accompanies the result of critical experiments in STACY. Prior to the construction of the new STACY, a series of neutronic calculation was carried out for licensing and planning first series of critical experiment. In this paper, possible core configuration of the basic experimental core and their limitations are discussed and presented.
Izawa, Kazuhiko; Aoyama, Yasuo; Sono, Hiroki; Ogawa, Kazuhiko; Yanagisawa, Hiroshi; Miyoshi, Yoshinori
Proceedings of 9th International Conference on Nuclear Criticality (ICNC 2011) (CD-ROM), 11 Pages, 2012/02
For reactor physics and criticality safety researches, the Static Experiment Critical Facility (STACY) will be modified. In the modification, the present STACY, solution-fuel-type homogeneous cores, will be converted to fuel-pin-type heterogeneous cores moderated by light water. For nuclear safety design of the modified STACY, computational analyses have been carried out by using a Monte Carlo code MVP and a transport code system DANTSYS with cross-section data based on the JENDL-3.3. In the analyses, basic nuclear characteristics have been evaluated, such as criticality, water-level worth and reactor shutdown margin. By the results of these analyses, the feasibility of reactivity control mechanism and the sufficiency of reactor shutdown margin of the modified STACY were confirmed. In addition, temperature and void coefficients of reactivity and kinetic parameters were obtained to comprehend nuclear characteristics of the modified STACY.
Ogawa, Kazuhiko; Kaminaga, Fumito*
Journal of Nuclear Science and Technology, 46(1), p.1 - 5, 2009/01
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)In the safety research regarding a criticality accident in nuclear reprocessing plants, prediction of nuclear fission yields is essential to evaluate its influence on a radiation of neutrons/
-rays to the public. For numerical calculations of the number of fissions in a criticality accident, a void reactivity coefficient due to the formation of radiolytic gas voids in the solution is required to evaluate the negative feedback reactivity. Small oscillations of both the power and the core pressure are measured after the first power pulse in a slow transient operation in TRACY. The small power oscillations are due to the reactivity feedback effect of the change of the volume of gas voids. In this paper, we propose a new estimation method of the void reactivity coefficient and estimate the coefficient using the TRACY transient data. The present estimated void reactivity coefficient is less than the calculated values in the uniform distribution of gas voids.
Ogawa, Kazuhiko; Kaminaga, Fumito*
Journal of Nuclear Science and Technology, 45(10), p.1028 - 1035, 2008/10
Times Cited Count：3 Percentile：23.55(Nuclear Science & Technology)no abstracts in English
Izawa, Kazuhiko; Aoyama, Yasuo; Sono, Hiroki; Ogawa, Kazuhiko; Yanagisawa, Hiroshi
JAEA-Technology 2007-001, 40 Pages, 2007/02
JAEA-Technology-2007-001.pdf:2.73MB
A series of critical experiments is conducted in FY 2006 using a heterogeneous core of the Static Experiment Critical Facility (STACY) in the Japan Atomic Energy Agency (JAEA). In the experiment, the core is composed of uranyl nitrate solution (
U enrichment 6wt%) containing soluble poison (gadolinium) and 333 pins of uranium dioxide (U enrichment 5wt%) loaded at a latticepitch of 1.5cm. Prior to the experiment, the following neutronic characteristics were analyzed to assess safety of the core and operation parametor limits: criticality, reactivity and reactor shutdown margins. In the analyses, a Monte Carlo code, MVP, and a neutronics code system, SRAC, were used with an evaluated nuclear data library, JENDL-3.3. From these analyses, it was confirmed that the reactor shutdown margins would comply with the safety criteria under all conditions of the fuel used in the experiments. Simplified formulas for criticality and reactivity were also evaluated based on the analyzed values which are utilized to confirm the operation parameter limits during operations of the core.
Motegi, Toshihiro; Iigaki, Kazuhiko; Saito, Kenji; Sawahata, Hiroaki; Hirato, Yoji; Kondo, Makoto; Shibutani, Hideki; Ogawa, Satoru; Shinozaki, Masayuki; Mizushima, Toshihiko; et al.
JAEA-Technology 2006-029, 67 Pages, 2006/06
JAEA-Technology-2006-029.pdf:3.07MB
The plant control performance of the IHX helium flow rate control system, the PPWC helium flow rate control system, the secondary helium flow rate control system, the inlet temperature control system, the reactor power control system and the outlet temperature control system of the HTTR are obtained through function tests and power-up tests. As the test results, the control systems show stable control response under transient condition. Both of inlet temperature control system and reactor power control system shows stable operation from 30% to 100%, respectively. This report describes the outline of control systems and test results.
Izawa, Kazuhiko; Seki, Masakazu; Hirose, Hideyuki; Kaminaga, Jota; Aoyama, Yasuo; Yoshida, Hiroshi; Sono, Hiroki; Ogawa, Kazuhiko; Sakuraba, Koichi
UTNL-R-0453, p.9_1 - 9_10, 2006/03
no abstracts in English
Sono, Hiroki; Tsukamoto, Michio; Aizawa, Eiju; Takeuchi, Masaki; Fukaya, Yuji; Iseda, Hirokatsu*; Ogawa, Kazuhiko; Sakuraba, Koichi; Tonoike, Kotaro
UTNL-R-0446, p.3_1 - 3_10, 2005/03
This report describes an investigation and countermeasures of the unexpected reactor shutdown of the TRACY facility at the Japan Atomic Energy Research Institute on June 17, 2004, caused by a malfunction of a safety rod of the facility. As a result of the investigation, the principal cause of the malfunction was ascribed to a drop in attraction of a binding magnet for the safety rod by a small piece of a foreign material. The following countermeasures were taken against its recurrence: prevention of incidence of foreign materials, reduction of the chance of intrusion of foreign materials into devices, and certain detection of foreign materials. This lesson learned through the experience is expected to be shared with the staffs concerned in reactor operation and maintenance.
Aizawa, Eiju; Ogawa, Kazuhiko; Sakuraba, Koichi; Tsukamoto, Michio; Sugawara, Susumu; Takeuchi, Masaki*; Miyauchi, Masakatsu; Yanagisawa, Hiroshi; Ono, Akio
JAERI-Tech 2002-031, 120 Pages, 2002/03
JAERI-Tech-2002-031.pdf:4.32MB
TRACY (Transient Experiment Critical Facility) in NUCEF (Nuclear Safety Research Facility) is the pulse-type critical facility using uranyl nitrate solution which can carry out various supercritical experiments changing reactivity addition up to 3$.TRACY achieved its first criticality on 20th December 1995,and transient operations have been conducted Since1996.This report summarizes the operation data of 176 experiments from the first criticality to FY2000.
Nakajima, Ken; Yamane, Yuichi; Ogawa, Kazuhiko; Aizawa, Eiju; Yanagisawa, Hiroshi; Miyoshi, Yoshinori
JAERI-Data/Code 2002-007, 123 Pages, 2002/03
JAERI-Data-Code-2002-007.pdf:4.34MB
no abstracts in English
Nakajima, Ken; Yamane, Yuichi; Ogawa, Kazuhiko; Aizawa, Eiju; Yanagisawa, Hiroshi; Miyoshi, Yoshinori
JAERI-Data/Code 2002-006, 176 Pages, 2002/03
JAERI-Data-Code-2002-006.pdf:6.33MB
no abstracts in English
Nakajima, Ken; Yamane, Yuichi; Ogawa, Kazuhiko; Aizawa, Eiju; Yanagisawa, Hiroshi; Miyoshi, Yoshinori
JAERI-Data/Code 2002-005, 158 Pages, 2002/03
JAERI-Data-Code-2002-005.pdf:6.55MB
no abstracts in English
Yanagisawa, Hiroshi; Ono, Akio; Ogawa, Kazuhiko; Aizawa, Eiju; Yokoyama, Mitsutaka*
Journal of Nuclear Science and Technology, 38(8), p.591 - 599, 2001/08
Times Cited Count：6 Percentile：44.09(Nuclear Science & Technology)no abstracts in English
Ogawa, Kazuhiko; Morita, Toshio*; Yanagisawa, Hiroshi; Aizawa, Eiju; Sakuraba, Koichi; Sugawara, Susumu; Ono, Akio
Journal of Nuclear Science and Technology, 37(12), p.1088 - 1097, 2000/12
no abstracts in English
; Nakajima, Ken; Yanagisawa, Hiroshi; ; ; *; *; Sakuraba, Koichi; Ono, Akio
Proceedings of 6th International Conference on Nuclear Criticality Safety (ICNC '99), 3, p.1277 - 1285, 1999/00
no abstracts in English
Yanagisawa, Hiroshi; Nakajima, Ken; ; ; Sakuraba, Koichi; ; *; *; Sonoda, Takashi; Ono, Akio
Proceedings of 6th International Conference on Nuclear Criticality Safety (ICNC '99), 2, p.900 - 906, 1999/00
no abstracts in English
Nakajima, Ken; ;
Proceedings of 6th International Conference on Nuclear Criticality Safety (ICNC '99), 3, p.1286 - 1292, 1999/00
no abstracts in English
