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Takabe, Yugo; Otsuka, Noriaki; Fuyushima, Takumi; Sayato, Natsuki; Inoue, Shuichi; Morita, Hisashi; Jaroszewicz, J.*; Migdal, M.*; Onuma, Yuichi; Tobita, Masahiro*; et al.
JAEA-Technology 2022-040, 45 Pages, 2023/03
JAEA-Technology-2022-040.pdf:6.61MB
Because of the decommission of the Japan Materials Testing Reactor (JMTR), the domestic neutron irradiation facility, which had played a central role in the development of innovative nuclear reactors and the development of technologies to further improve the safety, reliability, and efficiency of light water reactors, was lost. Therefore, it has become difficult to pass on the operation techniques of the irradiation test reactors and irradiation technologies, and to train human resources. In order to cope with these issues, we conducted a study on the implementation of irradiation tests using overseas reactors as neutron irradiation sites as an alternative method. Based on the "Arrangement between the National Centre for Nuclear Research and the Japan Atomic Energy Agency for Cooperation in Research and Development on Testing Reactor," the feasibility of conducting an irradiation test at the MARIA reactor (30 MW) owned by the National Centre for Nuclear Research (NCBJ) using the temperature control system, which is one of the JMTR irradiation technologies, was examined. As a result, it was found that the irradiation test was possible by modifying the ready-made capsule manufactured in accordance with the design and manufacturing standards of the JMTR. After the modification, a penetration test, an insulation continuity test, and an operation test in the range of room temperature to 300
C, which is the operating temperature of the capsule, were conducted and favorable results were obtained. We have completed the preparations prior to transport to the MARIA reactor.
Inaba, Yoshitomo; Ogawa, Mitsuhiro; Yamaura, Takayuki; Tobita, Masahiro
JAEA-Technology 2009-032, 51 Pages, 2009/07
JAEA-Technology-2009-032.pdf:8.74MB
The fuel transient tests for light water reactors are to be carried out in the Japan Materials Testing Reactor (JMTR), and the capsule-type test facilities (fuel transient test capsules) are to be used in the tests. In order to investigate the thermal-hydraulic behavior in the capsules, the multi-dimensional two-fluid model code ACE-3D is used. At first, the functions of ACE-3D were expanded for the pre-process and the post-process. Then, the BWR power calibration test capsule, which had been tested in JMTR, was modeled, and the BWR power calibration tests were simulated numerically for the verification of ACE-3D. The numerical results agreed well with the test data. As a result, it was found that ACE-3D is applicable to the numerical simulation of the fuel transient tests. In addition, the fuel transient tests with a natural convection capsule were simulated numerically with ACE-3D, and the thermal-hydraulic behavior in the capsule was investigated.
Iimura, Koichi; Ogawa, Mitsuhiro; Tomita, Kenji; Tobita, Masahiro
JAEA-Technology 2009-021, 71 Pages, 2009/05
JAEA-Technology-2009-021.pdf:4.34MB
The preparation of a fuel transient test using the JMTR is advanced to conduct its irradiation test from 2011 F.Y. after re-operation of the JMTR. The fuel behavior for high burn-up BWR's under power ramping condition will be evaluated in simulating the BWR environmental condition using the shroud irradiation facility (Oarai Shroud Facility No.1) and 
He power-control type BOCA (Boiling Water Capsule) irradiation facility, which is composed of the capsule control device, He power-control device and boiling water capsule. In order to change the fuel irradiation conditions so as to treat high burn-up fuels (from 50 GWD/t-UO
to 110 GWD/t-U), it is necessary to revaluate the dose for the safety evaluation at the test fuel failure. In this report, evaluations for equivalent dose rate of each device and exposure dose of handling operators when all fission products released in the coolant of the capsule control device and the BOCA at fuel failure in the fuel transient test are summarized.
Ogawa, Mitsuhiro; Iimura, Koichi; Tomita, Kenji; Tobita, Masahiro
JAEA-Technology 2009-017, 254 Pages, 2009/05
JAEA-Technology-2009-017.pdf:15.04MB
In JMTR, upgrade of irradiation facilities is advanced to re-operate from 2011 F.Y. In order to irradiate test fuels of high-burnup, external exposure reassessment by direct and skyshine gamma rays of the nuclear fuel handling facility at JMTR was performed. In evaluation method, radiation source of maximum use of the nuclear fuel was calculated by using ORIGEN2 code. Dose equivalent rate for supervised area boundary was calculated by modeling reactor building at using shielding calculation codes QAD-CGGP2 and G33-GP2. As a result of evaluation, it was confirmed that the effective dose equivalent during year was low enough at supervised area boundary of the JMTR site.
Matsui, Yoshinori; Hanawa, Satoshi; Ide, Hiroshi; Tobita, Masahiro*; Hosokawa, Jinsaku; Onuma, Yuichi; Kawamata, Kazuo; Kanazawa, Yoshiharu; Iwamatsu, Shigemi; Saito, Junichi; et al.
JAEA-Conf 2006-003, p.105 - 114, 2006/05
Irradiation assisted stress corrosion cracking (IASCC) caused by the simultaneous effects of radiation, stress and high temperature water environment is considered to be one of the critical concerns of in-core structural materials not only for light water reactors (LWRs) but also for water-cooled fusion reactors. In the research field of IASCC, post-irradiation examinations (PIEs) for irradiated materials have been mainly carried out, because there are many difficulties on SCC tests under neutron irradiation environment. Hence we have embarked on a development of the test techniques for performing the in-pile SCC tests. In this paper, we describe the developed several in-pile test techniques and the current status of in-pile SCC tests at Japan Materials Testing Reactor (JMTR).
Tobita, Masahiro*; Matsui, Yoshinori
JAERI-Tech 2003-042, 132 Pages, 2003/03
JAERI-Tech-2003-042.pdf:7.19MB
Prediction of irradiation temperature is one of the important issues in the design of the capsule for irradiation test. Many kinds of capsules with complex structure have been designed for recent irradiation requests, and three-dimensional (3D) temperature calculation becomes inevitable for the evaluation of irradiation temperature. For such 3D calculation, however, many works are usually needed for input data preparation, and a lot of time and resources are necessary for parametric studies in the design. To improve such situation, JAERI introduced 3D-FEM (finite element method) code NISA (Numerically Integrated elements for System Analysis) and developed several subprograms, which enabled to support input preparation works in the capsule design. The 3D temperature calculation of the capsule are able to carried out in much easier way by the help of the subprograms, and specific features in the irradiation tests such as non-uniform gamma heating in the capsule, becomes to be considered.
Tobita, Masahiro*; Itabashi, Yukio
JAERI-Tech 2002-042, 40 Pages, 2002/03
JAERI-Tech-2002-042.pdf:2.09MB
In relation to aging of light water reactors (LWRs), Irradiation Assisted Stress Corrosion Cracking (IASCC) has been regarded as a significant and urgent issue for reliability of in-core components of LWRs. It is essential for IASCC studies to irradiate test materials under well-controlled of Boiling Water Reactor (BWR) conditions simulating the in-core environment. Therefore, the study for the design of the new water control unit to supply high temperature water into saturated temperature capsules in the Japan Materials Testing Reactor (JMTR) has been carried out. This report summarizes the results of estimation using ORIGEN-2 and QAD-CGGP2 codes of dose equivalent rate on outer surface of the concrete wall of installation room and dose equivalent rate around the ion-exchangers where the highest dose equivalent rate is expected in the unit after the reactor shutdown.
Tobita, Masahiro*; Matsui, Yoshinori
KAERI/GP-195/2002, p.87 - 95, 2002/00
In the Japan Materials Testing Reactor (JMTR) of Japan Atomic Energy Research Institute (JAERI), the temperature distribution inside of irradiation specimens and capsules structure material are evaluated in the design of irradiation capsules. For the evaluation of detailed temperature distribution, NISA (Numerically Integrated elements for System Analysis) code has been introduced, and subprograms are developed to simplify the input data of the capsules structure and the analysis conditions using the three-dimensional finite element method. By the development of subprograms, prediction of the temperature distribution inside of irradiation specimens and capsules structure material became detailed and more accurate than calculation by one-dimensional code. Also estimation of detail temperature distribution during irradiation became possible based on the indication of thermocouple.
Kanno, Masaru; Nabeya, Hideaki; Mori, Yuichiro*; Matsui, Yoshinori; Tobita, Masahiro*; Ide, Hiroshi; Itabashi, Yukio; Komori, Yoshihiro; Tsukada, Takashi; Tsuji, Hirokazu
JAERI-Tech 2001-080, 57 Pages, 2001/12
JAERI-Tech-2001-080.pdf:2.34MB
no abstracts in English
Kitagishi, Shigeru; Aoyama, Masashi; Tobita, Masahiro; Inaba, Yoshitomo; Yamaura, Takayuki
no journal, ,
For the up-graded use and the lifetime extension of LWRs, the JMTR has a plan of power ramping tests on new design LWR fuels. The purpose of the power ramping tests is to evaluate the fuel behavior during power ramping condition using a capsule inserted into the OSF-1. The design and fabrication of the natural convection capsule used in the power ramping tests has been carried out based on BOCA, which had experience on power ramping tests of 8
8 BWR fuels. The outer cladding diameter of 88 BWR fuels is 12 mm. On the other hand, for a high power, the outer cladding diameter of the new design LWR fuel is changed to 9.5 mm. And, there is potential for transition from nucleate boiling to film boiling because the heat flux of the peak linear power 600 W/cm in the tests approaches the critical heat flux. In this study, prior to the irradiation tests of the fuels, the out-of pile test facility, which had a heater pin instead of a test fuel pin, was designed and fabricated to simulate the capsules used in power ramping tests, and thermal-hydraulic tests were carried out using the out-of pile test facility. In addition, in order to investigate the thermal-hydraulic behavior in the capsule, the out-of pile tests were simulated numerically using the improved analysis code ACE-3D. From these experimental and analytical results, it was found that the power ramping tests with fuels with their outer cladding diameters of 9.5 mm are able to be realized up to linear power 600 W/cm in JMTR.
Hanakawa, Hiroki; Watahiki, Shunsuke; Ide, Hiroshi; Kitagishi, Shigeru; Imaizumi, Tomomi; Araki, Daisuke; Tobita, Masahiro; Yamaura, Takayuki; Kaminaga, Masanori
no journal, ,
On 18th December 2013, the new regulatory requirements for Japanese research reactor were enforced by the Nuclear Regulation Authority in Japan. This new regulatory requirements are also applied to any research reactor in Japan, even if licensed research reactor. Thus the verification of conformity in the JMTR facilities to the new regulatory requirements was carried out. In this reports, the safety assessment against the beyond design basis accident will be described. At first, events tree analyses were carried out to select beyond design basis accidents. From these analyses, it was confirmed that 8 events can be representative cases. These events were analyzed from the viewpoints of public dose exposer. As the result of analysis, it was confirmed that 3 events out of 8 has a possibility to give the considerable public dose exposer so that the counter measerments were taken account to reduce the dose exposer to acceptable limit.
Otsuka, Noriaki; Endo, Yasuichi; Tobita, Masahiro*; Matsui, Yoshinori; Yamaura, Takayuki
no journal, ,
no abstracts in English
Kimura, Nobuaki; Matsui, Yoshinori; Tobita, Masahiro*; Nakamura, Jinichi; Yamaura, Takayuki
no journal, ,
Power transient tests for the fuels of light water reactors were to be carried out in the Japan Materials Testing Reactor (JMTR) using capsule-type irradiation test facilities, and the integrity of the fuels had been to be investigated by the tests. Prior to the irradiation tests of the fuels, evaluation of thermal-hydraulic behavior in the capsule using ACE-3D code were carried out. And more, the out-pile test facility, which had an electric heater pin instead of a test fuel pin, was designed and fabricated to simulate the capsules used in the power transient tests. Using this facility, necessary tests for the realization of the irradiation tests and the planning of the test methods were carried out. From these analytical and experimental results, it was confirmed that the power ramping tests for 1010 BWR fuel are able to achieve linear heat rate of 600W/cm in JMTR.
