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Hanawa, Satoshi; Sumita, Junya; Shibata, Taiju; Ishihara, Masahiro; Iyoku, Tatsuo; Sawa, Kazuhiro
Transactions of 18th International Conference on Structural Mechanics in Reactor Technology (SMiRT-18), p.600 - 605, 2005/08
no abstracts in English
Ishikura, Shuichi*; Shiga, Akio*; Futakawa, Masatoshi; Kogawa, Hiroyuki; Sato, Hiroshi; Haga, Katsuhiro; Ikeda, Yujiro
JAERI-Tech 2005-026, 65 Pages, 2005/03
JAERI-Tech-2005-026.pdf:2.86MB
Failure probability analysis was carried out to estimate the lifetime of the mercury target which will be installed into the JSNS (Japan spallation neutron source) in J-PARC (Japan Proton Accelerator Research Complex). The lifetime was estimated as taking loading condition and materials degradation into account. Considered loads imposed on the target vessel were the static stresses due to thermal expansion and static pre-pressure on He-gas and mercury and the dynamic stresses due to the thermally shocked pressure waves generated repeatedly at 25 Hz. Materials used in target vessel will be degraded by the fatigue, neutron and proton irradiation, mercury immersion and pitting damages, etc. The imposed stresses were evaluated through static and dynamic structural analyses. The material-degradations were deduced based on published experimental data. As results, it was quantitatively confirmed that the failure probability for the lifetime expected in the design is very much lower, 10
in the safety hull, meaning that it will be hardly failed during the design lifetime. On the other hand, the beam window of mercury vessel suffered with high-pressure waves exhibits the failure probability of 12%. It was concluded, therefore, that the leaked mercury from the failed area at the beam window is adequately kept in the space between the safety hull and the mercury vessel to detect mercury-leakage sensors.
Nakamura, Hiroo; Ida, Mizuho*; Matsuhiro, Kenjiro; Fischer, U.*; Hayashi, Takumi; Mori, Seiji*; Nakamura, Hirofumi; Nishitani, Takeo; Shimizu, Katsusuke*; Simakov, S.*; et al.
JAERI-Review 2005-005, 40 Pages, 2005/03
JAERI-Review-2005-005.pdf:3.52MB
The International Fusion Materials Irradiation Facility (IFMIF) is being jointly planned to provide an accelerator-based Deuterium-Lithium (Li) neutron source to produce intense high energy neutrons (2 MW/m
) up to 200 dpa and a sufficient irradiation volume (500 cm
) for testing the candidate materials and components up to about a full lifetime of their anticipated use in ITER and DEMO. To realize such a condition, 40 MeV deuteron beam with a current of 250 mA is injected into high speed liquid Li flow with a speed of 20 m/s. In target system, radioactive species such as 7Be, tritium and activated corrosion products are generated. In addition, back wall operates under severe conditions of neutron irradiation damage (about 50 dpa/y). In this paper, the thermal and thermal stress analyses, the accessibility evaluation of the IFMIF Li loop, and the tritium inventory and permeation of the IFMIF Li loop are summarized as JAERI activities on the IFMIF target system performed in FY2004.
Nakano, Junichi; Miwa, Yukio; Koya, Toshio; Tsukada, Takashi
Journal of Nuclear Materials, 329-333(Part1), p.643 - 647, 2004/08
Times Cited Count：9 Percentile：51.82(Materials Science, Multidisciplinary)To study effects of minor elements on the irradiation assisted stress corrosion cracking (IASCC), high purity Type 304 and 316 stainless steels (SSs) were fabricated and added minor elements, Si or C. After neutron irradiation to 3.5
10
n/m (E
1MeV), the slow strain rate tests (SSRT) for the irradiated specimens was conducted in oxygeneted high purity water at 561 K. Fracture surface of the specimens was examined using the scanning electron microscope (SEM) after the SSRT. Fraction of intergranular stress corrosion cracking (IGSCC) on the fracture surface after the SSRT increased with netron fluence. Suppression of irradiation hardening and increase of peiod to SCC fracture as benefitical effects of the additional elements, Si or Mo, were not observed obviously. In high purity SS added C, fraction of IGSCC was the smallest in the all SSs, although irraidiation hardening level was the largest in the all SSs. Addition of C suppressed the susceptibility to IGSCC.
The Working Team for Examination of the Sample from Core Shrouds and Primary Loop Recirculation Pipi
JAERI-Tech 2004-004, 74 Pages, 2004/02
JAERI-Tech-2004-004.pdf:31.62MB
During the 12th periodical inspection in Fukushima Dai-ichi Nuclear Power Station Unit-4 (BWR, 784MW) of Tokyo Electric Power Company (TEPCO), which has been held from September 1993 to February 1994, cracks were found at welded joints No.H4 in the core shroud middle shell. TEPCO has conducted a material examination with Nippon Nuclear Fuel Development Co. Ltd. (NFD) on the SUS304L specimen including cracks sampled from the inner surface of welded joints (H4) of the middle shell of the core shroud. The present examination has been performed with the objective to independently investigate and evaluate the materials by jointly attending the examination with NFD, receiving the final data given by the examination and providing a JAERI's own evaluation report as a third-party organization for assuring the transparency. Based on the research results described above, presence of tensile residual stress by welding and relatively high dissolved oxygen contents in core coolant, it is concluded that the cracks observed were caused by the stress corrosion cracking (SCC).
Nakano, Junichi; Tsukada, Takashi; Tsuji, Hirokazu; Terakado, Shogo; Koya, Toshio; Endo, Shinya
JAERI-Tech 2003-092, 54 Pages, 2004/01
JAERI-Tech-2003-092.pdf:14.05MB
Irradiation assisted stress corrosion cracking (IASCC) is a degradation phenomenon caused by synergy of neutron radiation, aqueous environment and stress on in-core materials, and it is an important issue in accordance with increase of aged light water reactors. Isolating crack initiation stage from crack growth stage is very useful for the evaluation of the IASCC behavior. Hence facility for in-situ observation during slow strain rate test (SSRT) for irradiated material was developed. As performance demonstrations of the facility, tensile test with in-situ observation and SSRT without observation were carried out using unirradiated type 304 stainless steel in 561 K water at 9 MPa. The following were confirmed from the results. (1) Handling, observation and recording of specimen can be operated using manipulators in the hot cell. (2) In-situ observation can be performed in pressurized high temperature water and flat sheet type specimen is suitable for the in-situ observation. (3) Test condition can be kept constantly and data can be obtained automatically for long test period.
Oku, Tatsuo*; Ishihara, Masahiro
Nuclear Engineering and Design, 227(2), p.209 - 217, 2004/01
Times Cited Count：34 Percentile：87.68(Nuclear Science & Technology)The lifetime of graphite material and/or components has been discussed individually from different concepts, and sometimes gives confusion to material researchers as well as designers. The lifetime of graphite materials is determined based on the dimensional changes due to neutron irradiation, at which they return to their original dimensions after initially contracting. On the other hand, the lifetime of graphite components for HTGRs is defined based on a margin of the specified minimum ultimate strengths of the graphite to the stresses induced in the graphite components. As an example, the stresses induced in the graphite block for the HTTR were, then, compared with the limited stress value determined from the specified minimum ultimate strength, and the lifetime of the graphite component was evaluated and compared with that defined as dimensional changes. As a result, it was found that the lifetime of graphite components for HTGRs should be determined as the shorter one in the two lifetimes defined by the stress-strength relationship and by the dimensional changes.
Tsukada, Takashi
Zairyo To Kankyo, 52(2), p.66 - 72, 2003/02
Irradiation assisted stress corrosion cracking (IASCC) is a potential failure mode suffered by the core-components of austenitic stainless steels in the aged light-water reactor (LWR), which is the intergranular type cracking caused by synergistic effects of neutron/gamma radiation and chemical environment. Effects of radiation on the materials and high-temperature water are discussed in this paper to understand IASCC phenomenon from a mechanistic viewpoint. It is essential to elucidate the radiation-induced microcompositional and microstructural changes in the alloy for mechanistic and predictive investigations of IASCC. Although grain boundary segregations of alloying and impurity elements are significant factors affecting IASCC, it has been considered that the radiation-induced microstructural and mechanical changes of materials play critical roles in IASCC. For mechanistic understanding of IASCC, further fundamental research works with experimental and theoretical approaches are needed. Efforts directed to the researches at the Japan Atomic Energy Research Institute are also described.
Nemoto, Yoshiyuki; Miwa, Yukio; Tsuji, Hirokazu; Tsukada, Takashi
Dai-12-Kai MAGDA Konfarensu (Oita) Koen Rombunshu, p.191 - 196, 2003/00
Development and research about analytical method for the study of corrosion behavior of austenitic stainless steel after irradiation was conducted from the point of view for basic study of IASCC (Irradiation Assisted Stress Corrosion Cracking). Ion irradiations were conducted with several irradiation conditions these were irradiation temperature, radiation damage, the contents of helium (He) implantation. AFM (Atomic Force Microscope) was used to evaluate surface condition of irradiated specimens after corrosion procedure. Corrosion condition was developed to obtain good surface condition of irradiated specimens to evaluate corrosion behavior by AFM. It was succeeded and corrosion behavior at inside of grains and grain boundaries of irradiated specimens was obtained. EBSP (Electron Backscatter Diffraction Pattern) was used to evaluate relation of corrosion behavior with grain boundary character. Moreover, relations of corrosion behavior with irradiation condition were discussed.
Sakuma, Takaaki*; Motohashi, Yoshinobu*; Kobayashi, Tomokazu*; Harjo, S.*; Shibata, Taiju; Ishihara, Masahiro; Baba, Shinichi; Hoshiya, Taiji
Nihon Kikai Gakkai Kanto Shibu Ibaraki Koenkai (2002) Koen Rombunshu (No.020-3), p.125 - 126, 2002/09
no abstracts in English
Tsukada, Takashi; Komori, Yoshihiro; Tsuji, Hirokazu; Nakajima, Hajime; Ito, Haruhiko
Proceedings of International Conference on Water Chemistry in Nuclear Reactor Systems 2002 (CD-ROM), 5 Pages, 2002/00
Irradiation assisted stress corrosion cracking (IASCC) is caused by the synergistic effects of neutron and gamma radiation, residual and applied stresses and high temperature water environment on the structural materials of vessel internals. IASCC has been studied since the beginning of the 1980s and the phenomenological knowledge on IASCC is accrued extensively. However, mainly due to the experimental difficulties, data for the mechanistic understanding and prediction of failures of the specific in-vessel components are still insufficient and further well-controlled experiments are needed [1]. In recent years, efforts to perform the in-pile materials test for IASCC study have been made at some research reactors [2-4]. At JAERI, a high temperature water loop facility was designed to install at the Japan Materials Testing Reactor (JMTR) to carry out the in-core IASCC testing. This report describes an overview of design and specification of the loop facility.
Nemoto, Yoshiyuki; Miwa, Yukio; Tsukada, Takashi; Kikuchi, Masahiko; Tsuji, Hirokazu
JAERI-Tech 2001-079, 25 Pages, 2001/12
JAERI-Tech-2001-079.pdf:6.76MB
Development and research about analytical method for the study of oxide film on austenitic stainless steel had been conducted from the point of view for basic study of IASCC (Irradiation Assisted Stress Corrosion Cracking). Nickel plating and copper plating had been compared as the oxide film protection while the fabrication for cross sectional observation. And thin film specimens for microstructural observation were fabricated using FIB (Focused Ion Beam) technique. Microstructure of oxide film on stainless steel had been observed with FE-TEM (Field Emission gun - Transmission Electron Microscope), and the chemical composition was analyzed with EDS (Energy dispersed X-ray Spectrometer). The oxide film had been formed in high pressure (8MPa) and high temperature (288
) water, contains saturated oxygen. The thickness of oxide film was about 1
m as maximum. Micro grains of Fe oxide with 100nm in diameter were formed in the oxide film. On the boundary with alloy, there was about 10nm thickness of passive film formed with Cr oxide.
Sawa, Kazuhiro; Shiozawa, Shusaku; Minato, Kazuo; Fukuda, Kosaku
Journal of Nuclear Science and Technology, 33(9), p.712 - 720, 1996/09
Times Cited Count：25 Percentile：86.19(Nuclear Science & Technology)no abstracts in English
Hoshiya, Taiji; Goto, Ichiro; Omi, Masao; Ando, Hiroei; ;
Journal of Nuclear Materials, 212-215, p.818 - 822, 1994/00
Times Cited Count：3 Percentile：35.55(Materials Science, Multidisciplinary)no abstracts in English
Iyoku, Tatsuo; Ishihara, Masahiro;
Journal of Nuclear Science and Technology, 28(10), p.921 - 931, 1991/10
no abstracts in English
Hayashi, Kimio; ; ; Shiozawa, Shusaku; Sawa, Kazuhiro; ; Kikuchi, Teruo; Fukuda, Kosaku
JAERI-M 91-111, 38 Pages, 1991/07
no abstracts in English
Minato, Kazuo; ; ; Ikawa, Katsuichi
JAERI-M 83-167, 24 Pages, 1983/10
no abstracts in English
; Harayama, Yasuo; ;
JAERI-M 8468, 77 Pages, 1979/09
no abstracts in English
Harayama, Yasuo; ;
JAERI-M 8407, 75 Pages, 1979/08
no abstracts in English
Ogawa, Yutaka; Kondo, Tatsuo; ;
Proc.of 2nd Japan-US HTGR Safety Technology Seminar,Material Properties and Design Method Session, 9 Pages, 1978/00
no abstracts in English
