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Journal Articles

Investigation of thermal expansion model for evaluation of core support plate reactivity in ATWS event

Sotsu, Masutake

Journal of Energy and Power Engineering, 14(8), p.251 - 258, 2020/08

Thermal expansion behavior was investigated for evaluation of the core support plate expansion reactivity in the Unprotected Loss of Heat Sink reactor trip failure event. A possibility of mechanical restraint was investigated in thermal expansion of the core structure for the prototype fast breeder reactor Monju. The reactor core expansion was simulated in a three-dimensional finite element analysis model of the reactor vessel considering detailed temperature distribution of the sodium coolant based on the thermal-hydraulic analysis result of the whole core model. It was found that the thermal expansion of the core was not restrained in the ULOHS evert, although part of the core structure is mechanically restrained.

Journal Articles

Study on cooling process in a reactor vessel of sodium-cooled fast reactor under severe accident; Velocity measurement experiments simulating operation of decay heat removal systems

Tsuji, Mitsuyo; Aizawa, Kosuke; Kobayashi, Jun; Kurihara, Akikazu; Miyake, Yasuhiro*

Proceedings of 2020 International Conference on Nuclear Engineering (ICONE 2020) (Internet), 5 Pages, 2020/08

The water experiments using a 1/10 scale experimental apparatus simulating the reactor vessel of SFR were conducted to investigate the natural circulation phenomena in a reactor vessel. In this paper, the natural circulation flow field in the reactor vessel was measured by the Particle Image Velocimetry (PIV) method. The PIV measurement was carried out under the operation of the dipped-type direct heat exchanger (DHX) installed in the upper plenum when 20% of the core fuel fell to the lower plenum and accumulated on the core catcher. From the results of PIV measurement, it was quantitatively confirmed that the upward flow occurred at the center region of the lower and upper plenums. In addition, the downward flows were confirmed near the reactor vessel wall in the upper plenum and through outermost layer of the simulated core in the lower plenum. Moreover, the relationship between the temperature field and the velocity field was investigated in order to understand the natural circulation phenomenon in the reactor vessel. From the above results, it was confirmed that the natural circulation cooling path was established under the dipped-type DHX operation.

Journal Articles

SAS4A simulations of selected CABRI-1 oxide fuel experiments

Karahan, A.*; Kawada, Kenichi; Tentner, A.*

Proceedings of 2018 ANS Winter Meeting and Nuclear Technology Expo; Embedded Topical International Topical Meeting on Advances in Thermal Hydraulics (ATH 2018) (USB Flash Drive), 4 Pages, 2018/11

Journal Articles

Irradiation performance of sodium-bonded control rod for the fast breeder reactor

Sasaki, Shinji; Maeda, Koji; Furuya, Hirotaka*

Journal of Nuclear Science and Technology, 55(3), p.276 - 282, 2018/03

 Times Cited Count:3 Percentile:47(Nuclear Science & Technology)

Journal Articles

Application of FE-SEM to the measurement of U, Pu, Am in the irradiated MA-MOX fuel

Sasaki, Shinji; Tanno, Takashi; Maeda, Koji

Proceedings of 54th Annual Meeting of Hot Laboratories and Remote Handling (HOTLAB 2017) (Internet), 6 Pages, 2017/00

During irradiation in a fast reactor, the microstructure change of the mixed oxide fuels and the changes of element distributions occur because of a radial temperature gradient. Therefore, it is important to study the irradiation behavior of MA-MOX for advancement of fast reactor fuels. In order to make detailed observations of microstructure and elemental analyses of MA-MOX, irradiated MA-MOX specimens were carried out PIE by using a FE-SEM equipped with WDX. Because fuel samples have high radio activities and emit alpha-particles, the instrument was modified. the instrument was installed in a lead shield box and the control unit was separately located outside the box. The microstructure changes were observed in irradiated MA-MOX specimen. The characteristic X-rays peaks were detected successfully. By measuring the intensities of characteristic X-rays, it was tried quantitative analysis of U, Pu, Am along radial direction of irradiated specimen.

Journal Articles

Development of inspection and repair techniques in reactor vessel of experimental fast reactor "Joyo"; Retrieval of the bent test subassembly

Ashida, Takashi; Ito, Hideaki; Miyamoto, Kazuyuki*; Nakamura, Toshiyuki; Koga, Kazuhiro*; Ohara, Norikazu*; Ino, Hiroichi*

Nihon Genshiryoku Gakkai Wabun Rombunshi, 15(4), p.210 - 222, 2016/12

In the experimental fast reactor Joyo, it was confirmed that the top of the irradiation test sub-assembly of material testing rig named "MARICO-2" had been broken and bent onto the in-vessel storage rack as an obstacle and had damaged the upper core structure (UCS). As the result, for Joyo restart, it was necessary to replace the damaged UCS and to retrieve the bent sub-assembly. This paper describes in-vessel repair techniques performed in the retrieval work of the obstacle inside of the reactor vessel. The devices which were prepared for this work demonstrated expected performance under the environmental conditions of an SFR such as high temperature and radiation dose, and the work was completed in 2014. The successful operation of this retrieval work of the damaged component inside of a reactor vessel will contribute to the development of in-service inspections and repair technics in an SFR.

Journal Articles

Validation of core cooling capability analysis in Monju during guillotine pipe break at primary heat transport system

Yamada, Fumiaki; Arikawa, Mitsuhiro*; Fukano, Yoshitaka

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 7 Pages, 2015/05

In sodium-cooled fast reactor, since the coolant does not need to be pressurized, a pipe break due to the internal pressure does not occur physically. For safety margin in Japanese prototype fast breeder reactor (Monju), the guillotine pipe break accident, i.e., loss of integrity (LOPI) has been analyzed as an extreme assumption for beyond design basis accidents (B-DBAs) in the licensing application for the permit. The cooling capability of the core was re-evaluated in this paper during a large-scale, more specifically guillotine pipe break at the primary heat transport system (PHTS) in Monju, newly considering the following latest findings: (a) Experimental data on sodium boiling in fuel assemblies, (b) Actual PHTS pump coast-down characteristics, and (c) Transient burst test data on irradiated fuel claddings. The analysis models were the validated and simulations were re-performed also using the actual Monju data such as the response time to the trip signals, etc. As a result, it was clarified that the ratio of failed fuel claddings does not exceed around 3% of all of fuel assemblies, as in the past licensing analysis. The safety has been reconfirmed to be secured without significant core damage even under an extreme assumption of a double-ended guillotine pipe break at the PHTS in Monju.

Journal Articles

Effect of physical properties on gas entrainment rate from free surface by vortex, 2

Koizumi, Yasuo*; Ote, Naosuke*; Kamide, Hideki; Ohno, Shuji; Ito, Kei

Proceedings of 22nd International Conference on Nuclear Engineering (ICONE-22) (DVD-ROM), 7 Pages, 2014/07

Journal Articles

Hydrogen production by using the heat from high-temperature gas-cooled reactors

Shiozawa, Shusaku; Ogawa, Masuro; Hino, Ryutaro; Onuki, Kaoru; Sakaba, Nariaki

Karyoku Genshiryoku Hatsuden, 57(1), p.7 - 12, 2006/01

no abstracts in English

JAEA Reports

A Set of ORIGEN2 cross section libraries based on JENDL-3.3 library; ORLIBJ33

Katakura, Junichi; Kataoka, Masaharu*; Suyama, Kenya; Jin, Tomoyuki*; Oki, Shigeo*

JAERI-Data/Code 2004-015, 115 Pages, 2004/11


A set of cross section libraries for ORIGEN2 code, ORLIBJ33, has been produced based on the latest Japanese Evaluated Nuclear Data Library JENDL-3.3. The produced libraries are for LWR's which include PWR, BWR and their MOX fuels. The libraries for FBR's are also produced. Using the libraries for LWR, comparisons with old libraries based on JENDL-3.2 were performed. The comparisons with measured PIE data were also carried out. For the libraries for FBR, the comparisons with the calculations using the old libraries were performed and the effects using different libraries were discussed.

JAEA Reports

Research and development on reduced-moderation light water reactor with passive safety features (Contract research)

Iwamura, Takamichi; Okubo, Tsutomu; Akie, Hiroshi; Kugo, Teruhiko; Yonomoto, Taisuke; Kureta, Masatoshi; Ishikawa, Nobuyuki; Nagaya, Yasunobu; Araya, Fumimasa; Okajima, Shigeaki; et al.

JAERI-Research 2004-008, 383 Pages, 2004/06


The present report contains the achievement of "Research and Development on Reduced-Moderation Light Water Reactor with Passive Safety Features", which was performed by Japan Atomic Energy Research Institute (JAERI), Hitachi Ltd., Japan Atomic Power Company and Tokyo Institute of Technology in FY2000-2002 as the innovative and viable nuclear energy technology (IVNET) development project operated by the Institute of Applied Energy (IAE). In the present project, the reduced-moderation water reactor (RMWR) has been developed to ensure sustainable energy supply and to solve the recent problems of nuclear power and nuclear fuel cycle, such as economical competitiveness, effective use of plutonium and reduction of spent fuel storage. The RMWR can attain the favorable characteristics such as high burnup, long operation cycle, multiple recycling of plutonium (Pu) and effective utilization of uranium resources based on accumulated LWR technologies.

Journal Articles

Damage evaluation techniques for FBR and LWR structural materials based on magnetic and corrosion properties along grain boundaries

Hoshiya, Taiji*; Takaya, Shigeru*; Ueno, Fumiyoshi; Nemoto, Yoshiyuki; Nagae, Yuji*; Miwa, Yukio; Abe, Yasuhiro*; Omi, Masao; Tsukada, Takashi; Aoto, Kazumi*

Transactions of the Materials Research Society of Japan, 29(4), p.1687 - 1690, 2004/06

JAERI and JNC have begun the cooperative research of evaluation techniques of structural material degradation in FBR and LWR, which based on magnetic and corrosion properties along grain boundaries. Magnetic method has been proposed as the one of the non-destructive detection techniques on the early stage of creep-damage before crack initiation for aged structural materials of FBRs. The effects of applied stress on natural magnetization were investigated on paramagnetic stainless steels having creep-damages. On the other hand, corrosion properties and magneto-optical characteristics of ion-irradiated stainless steels in the vicinity of grain boundaries were estimated by AFM and Kerr effect microscope, respectively. These degradations were induced by changes in characteristics in the vicinity of grain boundaries. It is found that the initial level of progressing process of damage can detect changes in magnetic and corrosion properties along grain boundaries of aged and degraded nuclear plants structural materials.

Journal Articles

An Investigation into dissolution rate of spent nuclear fuel in aqueous reprocessing

Mineo, Hideaki; Isogai, Hikaru; Morita, Yasuji; Uchiyama, Gunzo*

Journal of Nuclear Science and Technology, 41(2), p.126 - 134, 2004/02

 Times Cited Count:5 Percentile:37.08(Nuclear Science & Technology)

A simple equation was proposed for the dissolution rate of spent LWR fuel, of which the change in the dissolution area was estimated by taking into account of the area of the cracks occurring due to thermal shrinkage of the pellets during irradiation. The applicability of proposed equation was examined using LWR fuel dissolution test results in the present study as well as the results obtained by other workers. The equation showed good agreements with the dissolution test results obtained from spent fuel pellets and pulverized spent fuel. It was indicated that the proposed equation was simple and would be useful for the prediction of dissolution of spent LWR fuels. However, the initial effective dissolution area, the parameter of the equation, was found to depend on the temperature, which could not be explained by the proposed equation. Further studies on the role of other factors affecting dissolution rate, such as nitrous acid, in the dissolution of spent fuel was required.

Journal Articles

Long-term perspective of nuclear energy supply using uranium extracted from seawater

Uotani, Masaki*; Shimizu, Takao*; Tamada, Masao

Proceedings of 2003 International Congress on Advances in Nuclear Power Plants (ICAPP '03) (DVD-ROM), 8 Pages, 2003/00

The present paper describes the current technology of uranium recovery from seawater by using radiation-induced graft-adsorbent and the utilization scenario of collected uranium from the viewpoint of long-term perspective of nuclear energy demand in Japan. The several thousand tons of uranium will be required in the latter half of 21st century in Japan, even if the plutonium is practically used in fast breeder reactors (FBRs). This demand of uranium can be supplied by the uranium recovered from seawater if the recovery cost is reasonable. In conclusion, the utilization of uranium from seawater will be able to play an essential role of providing enough time to develop safe and economical FBRs.

JAEA Reports

Summary of the 5th Workshop on the Reduced Moderation Water Reactor; March 8, 2002, JAERI, Toaki

Nakano, Yoshihiro; Ishikawa, Nobuyuki; Nakatsuka, Toru; Iwamura, Takamichi

JAERI-Conf 2002-012, 219 Pages, 2002/12


no abstracts in English

JAEA Reports

Published literature on the research activities using the JMTR, 2; Publication as JAERI research reports

Nagao, Yoshiharu; Ishii, Tadahiko; Niimi, Motoji; Fujiki, Kazuo; Takahashi, Hidetake

JAERI-Review 2002-031, 119 Pages, 2002/11


The published reports on the research and development activities using the JMTR since 1971 to date have been surveyed by the search of literature database and questionnaire survey. This report compiles the title lists and abstracts of reports published by JAERI and survey the trend of the research and development in JAERI using JMTR.

JAEA Reports

Research on the behavior of polonium produced in lead-bismuth eutectic irradiated with neutrons, JAERI's nuclear research promotion program, H10-026 (Contract research)

Sekimoto, Hiroshi*; Igashira, Masayuki*; Yano, Toyohiko*; Obara, Toru*; Osaki, Toshiro*

JAERI-Tech 2002-008, 58 Pages, 2002/03


no abstracts in English

JAEA Reports

Published literature on the research activities using the JMTR

Nagao, Yoshiharu; Ishii, Tadahiko; Takeda, Takashi; Fujiki, Kazuo

JAERI-Review 2002-007, 191 Pages, 2002/03


The published reports on the research activities using the JMTR since 1971 to date have been surveyed by the search of literature database and questionnaire survey. This report summarized the result of survey as the title lists by research categories.

JAEA Reports


JNC TN1400 2001-015, 509 Pages, 2001/10


no abstracts in English

JAEA Reports


JNC TN1400 2001-014, 437 Pages, 2001/10


no abstracts in English

740 (Records 1-20 displayed on this page)