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Journal Articles

Improvement of symbiotic performance of ${it Sinorhizobium}$ with ${it Vigna marina}$ under high salt conditions using the ion beam mutation breeding

Maruyama, Yudai*; Takeda, Kiyoko*; Tomooka, Norihiko*; Sato, Katsuya; Ono, Yutaka; Yokoyama, Tadashi*

JAEA-Review 2015-022, JAEA Takasaki Annual Report 2014, P. 99, 2016/02

Journal Articles

RELAP5/MOD3.2 sensitivity analysis using OECD/NEA ROSA-2 project 17% cold leg intermediate-break LOCA test data

Takeda, Takeshi; Watanabe, Tadashi; Maruyama, Yu; Nakamura, Hideo

NEA/CSNI/R(2013)8/PART2 (Internet), p.173 - 183, 2013/12

An experiment simulating a PWR cold leg IBLOCA with 17% break at cold leg was conducted. The post-test analysis by RELAP5/MOD3.2.1.2 code revealed that cladding surface temperature was underpredicted due to later major core uncovery. The post-test analysis conditions were considered as Base Case assuming the discrepancies were caused by uncertainties in the code predictability and input data. Key phenomena and related important parameters, which may affect the cladding surface temperature, were selected based on the LSTF test data analysis and post-test analysis results. Sensitivity analyses were performed by changing the parameters relevant to the key phenomena within the ranges to investigate influences of the parameters onto the cladding surface temperature. It was confirmed that both constant C of Wallis CCFL correlation at the core exit and inter-phase drag in the core are more sensitive to the cladding surface temperature.

Journal Articles

RELAP5 analyses of OECD/NEA ROSA-2 project experiments on intermediate-break LOCAs at hot leg or cold leg

Takeda, Takeshi; Maruyama, Yu; Watanabe, Tadashi; Nakamura, Hideo

Journal of Power and Energy Systems (Internet), 6(2), p.87 - 98, 2012/06

Journal Articles

Insights from review and analysis of the Fukushima Dai-ichi accident

Hirano, Masashi; Yonomoto, Taisuke; Ishigaki, Masahiro; Watanabe, Norio; Maruyama, Yu; Shibamoto, Yasuteru; Watanabe, Tadashi; Moriyama, Kiyofumi

Journal of Nuclear Science and Technology, 49(1), p.1 - 17, 2012/01

 Times Cited Count:63 Percentile:87.5(Nuclear Science & Technology)

An unprecedented earthquake and tsunami struck the Fukushima Dai-ichi Nuclear Power Plants on 11 March 2011. Although extensive efforts have been continuing on investigations into the causes and consequences of the accident, and the Japanese Government has presented a comprehensive report on the accident in the IAEA Ministerial Conference held in June 2011, there is still much to be clarified on what happened during the accident and why. This article aims at identifying what should be clarified further about the progression of the accident at Units 1-3 through the review and analysis of information released from Tokyo Electric Power Company and government authorities. It also discusses the safety issues raised by the accident based on the insights gained, in order to contribute to establishing a new framework that pursues continuous improvement toward the highest standards of safety that can reasonably be achieved.

Journal Articles

RELAP5 analyses of OECD/NEA ROSA-2 project experiments on intermediate-break LOCAs at hot leg or cold leg

Takeda, Takeshi; Maruyama, Yu; Watanabe, Tadashi; Nakamura, Hideo

Proceedings of 19th International Conference on Nuclear Engineering (ICONE-19) (CD-ROM), 9 Pages, 2011/10

Experiments simulating PWR intermediate-break loss-of-coolant accidents (IBLOCAs) with 17% break at hot leg or cold leg were conducted in OECD/NEA ROSA-2 project using LSTF. In the hot leg IBLOCA test, core uncovery appeared simultaneously with loop seal clearing (LSC). Water remained on upper core plate in upper plenum due to CCFL. In the cold leg IBLOCA test, core dryout took place before LSC. Liquid was accumulated in upper plenum, SG U-tube upflow-side and SG inlet plenum before the LSC due to CCFL. The RELAP5/MOD3.2.1.2 post-test analyses were performed. In the hot leg IBLOCA case, cladding surface temperature was underpredicted due to overprediction of core liquid level after the core uncovery. In the cold leg IBLOCA case, the cladding surface temperature was underpredicted too due to later core uncovery than in the experiment. These may suggest that the code has remaining problems in proper prediction of primary coolant distribution.

Journal Articles

Neutron-coupled thermal hydraulic calculation of BWR under seismic acceleration

Satou, Akira; Watanabe, Tadashi; Maruyama, Yu; Nakamura, Hideo

Proceedings of Joint International Conference of 7th Supercomputing in Nuclear Application and 3rd Monte Carlo (SNA + MC 2010) (USB Flash Drive), 5 Pages, 2010/10

In the BWR subjected to an earthquake, the oscillating acceleration attribute to the seismic wave may cause the variation of the coolant flow rate and void fraction in the core, which might result in the core instability due to the void-reactivity feedback. Therefore, it is important to properly evaluate the effect of the seismic acceleration on the core stability from a viewpoint of plant integrity estimation. In the present study the numerical code analyzing the behavior of nuclear power plant under the seismic acceleration is developed based on the 3-D neutron-coupled thermal hydraulic code, TRAC/SKETCH. The coolant flow is simulated with introducing the acceleration attributed to the earthquake into the motion equation of the flow as external force terms. The analyses are performed on a real BWR4-type nuclear power plant with the sinusoidal acceleration and the acceleration obtained from the response analysis to an actual earthquake. The behaviors of the core and coolant are calculated in the various parameters of acceleration. The effects of the frequency, amplitude and direction of the oscillating acceleration are discussed.

Journal Articles

Interpolation and Extrapolation method to analyze irradiation-induced dimensional change data of graphite for design of core components in Very High Temperature Reactor (VHTR)

Shibata, Taiju; Kunimoto, Eiji*; Eto, Motokuni*; Shiozawa, Shusaku; Sawa, Kazuhiro; Oku, Tatsuo*; Maruyama, Tadashi*

Journal of Nuclear Science and Technology, 47(7), p.591 - 598, 2010/07

 Times Cited Count:9 Percentile:56.9(Nuclear Science & Technology)

no abstracts in English

JAEA Reports

Draft of standard for graphite core components in High Temperature Gas-cooled Reactor

Shibata, Taiju; Eto, Motokuni*; Kunimoto, Eiji*; Shiozawa, Shusaku; Sawa, Kazuhiro; Oku, Tatsuo*; Maruyama, Tadashi*

JAEA-Research 2009-042, 119 Pages, 2010/01

JAEA-Research-2009-042.pdf:26.28MB

For the design of the graphite components in the High Temperature Engineering Test Reactor (HTTR), the graphite structural design code for the HTTR etc. were applied. However, general standard systems for the High Temperature Gas-cooled Reactor (HTGR) have not been established yet. The authors had studied on the technical issues which is necessary for the establishment of a general standard system for the graphite components in the HTGR. The results of the study were documented and discussed at a "Special committee on research on preparation for codes for graphite components in HTGR" at Atomic Energy Society of Japan (AESJ). As a result, "Draft of Standard for Graphite Core Components in High Temperature Gas-cooled Reactor" was established. In this draft standard, the graphite components are classified three categories (A, B and C) in the standpoints of safety functions and possibility of replacement. For the components in the each class, design standard, material and product standards, and in-service inspection and maintenance standard are determined. This draft standard is the first standard in the world which shows the concept of standard for the graphite core components in HTGR.

JAEA Reports

Expansion of irradiation data by interpolation and extrapolation for design of graphite components in high temperature gas-cooled reactor; Evaluation on IG-110 graphite irradiation data for component design

Kunimoto, Eiji; Shibata, Taiju; Shimazaki, Yosuke; Eto, Motokuni*; Shiozawa, Shusaku; Sawa, Kazuhiro; Maruyama, Tadashi*; Oku, Tatsuo*

JAEA-Research 2009-008, 28 Pages, 2009/06

JAEA-Research-2009-008.pdf:4.6MB

The VHTR is being focused and developed internationally. In Japan, the HTTR of the JAEA is in operation, and research and development for the development of commercial HTGRs are carried out. Nuclear graphites are used for core components of the HTGRs and expansion of irradiation data is necessary when enough irradiation data are not established, because the graphite components in the HTGRs are used at severer condition than that in the HTTR. The necessary database can be established by expansion of existing irradiation data with appropriate interpolation and extrapolation methods. This paper shows the reasonable interpolation and extrapolation method for IG-110 graphite which is used for the HTTR and a major candidate for the VHTR. The interpolation and extrapolation method was developed so as to be general by using the irradiation data of the other graphites. As a result, irradiation properties of the IG-110 graphite were successfully expanded to the VHTR condition for the first time and the irradiation properties being necessary for the design could be developed.

Journal Articles

Neutron irradiation effect on isotopically tailored $$^{11}$$B$$_{4}$$C

Morohashi, Yuko; Maruyama, Tadashi*; Donomae, Takako; Tachi, Yoshiaki; Onose, Shoji

Journal of Nuclear Science and Technology, 45(9), p.867 - 872, 2008/09

 Times Cited Count:9 Percentile:56.05(Nuclear Science & Technology)

JAEA Reports

Development of cavity length control system for high repetition rate Nd:YAG laser oscillator (Joint research)

Maruyama, Yoichiro; Kubomura, Hiroyuki*; Kasamatsu, Tadashi*; Matsuoka, Shinichi*; Nakano, Fumihiko*; Kan, Hirofumi*

JAERI-Tech 2004-056, 14 Pages, 2004/09

JAERI-Tech-2004-056.pdf:3.49MB

A high average power tunable solid state laser is pumped by the second harmonic of LD-pumped high repetition rate Nd:YAG laser consisting of a single-longitudinal-mode oscillator and amplifiers. To operate the Nd:YAG laser oscillator with a single-longitudinal-mode by injection seeding, the cavity length control is required to coincide the resonant frequency of Nd:YAG laser oscillator with the frequency of seeder. For this purpose, a cavity length control system of the Nd:YAG laser oscillator is developed and the characteristics are studied. With this system, the cavity length is controlled at the pulse repetition rate of 0.5 kHz and the single frequency operation for more than three hours is realized.

JAEA Reports

Basic Research on Radiation Effects of Ceramics (5)

Maruyama, Tadashi*

JNC TJ4420 2004-001, 76 Pages, 2004/03

JNC-TJ4420-2004-001.pdf:15.02MB

Ion irradiation ezperiment was carried out to elucidate microstructural change of neutron-irradiated B4C. The materials used in this investigation were boron carbides made of carbothermi-reduction method. The specimens were irradiated with helium ions having 15 MeV and 100 to 200 keV, to the fluences of 1$$times$$10$$^{13}$$ to 2$$times$$10$$^{8}$$/cm$$^{2}$$ at temperatures from room temperature to 1000$$^{circ}$$C. After ion irradiation, the microstructure of specimens was analyzed by transmission electron microscopy (TEM). The difference in maicrostructures disappeared among different B$$_{4}$$C pellets after ion irradiations. The ion-irradiation by 15 MeV helium ions produced a radiation-induced amorphization in the matrix. A radiation-enhanced precipitation of micro-crystals which consists of Fe-rich composition was observed in the materials irradiated below 800$$^{circ}$$C. High temperature helium ion irradiation created a number of He bubbles which is associated with strain fields. When irradiation temperature was increased to 1000$$^{circ}$$C, extended planer bubbles were formed on the (001) plane of B$$_{4}$$C, Extremely higher helium irradiation lead to initiation of itragranular clarks. We have also carried out studies of method for measurement of isotopic content was accurately measured when recovery of boron from irradiated B$$_{4}$$C was higher than 60%. Since ICP-MS is rather cheap and easy to measure isotopic content of materials, we studied the feasibility of using ICP-MS for measurement of 10 B in B$$_{4}$$C.

JAEA Reports

Research on adsorption and desorption properties of activated charcoals, 3

Maruyama, Tadashi*; Nagatomo, Jinro*

JNC TJ2410 2004-005, 157 Pages, 2004/03

JNC-TJ2410-2004-005.pdf:6.01MB

From these investigation ,it was recommended that when we make enrichment of noble gases by using adsorption bed of activated charcoals,it is desirable to provide two adsorption beds;one for enrichiment and other for separation of noble gases from Ar base gas.

JAEA Reports

Research on adsorption and desorption properties of activated charcoals (2)

Maruyama, Tadashi*; Nagatomo, Jinro*

JNC TJ2410 2003-001, 170 Pages, 2003/08

JNC-TJ2410-2003-001.pdf:6.32MB

The results of measurement showed that anomalous breakthrough curves were observed at -180$$^{circ}$$C which is effect of condensation of noble gas. However, the amomalous breakthrough curves was not observed at -170$$^{circ}$$C. It was shown that the activated good performances. The effect of materials propertied on the absorption and the desorption properties is summarized as follows: The longer breakthrough time and the steeper break through curves were obtained as the grain size became smaller and the specific surface area gets larger. Further studies are needed to elucidate effect on enrichment of experimental conditions by varying such as the heating rate,sweep gas velocity,and the onset tempertuer of heating

JAEA Reports

None

Maruyama, Tadashi*

JNC TJ4400 2001-007, 169 Pages, 2002/03

JNC-TJ4400-2001-007.pdf:33.79MB

no abstracts in English

JAEA Reports

Research on adsorption and desorption properties of activated charcoals

Maruyama, Tadashi*; Nagatomo, Jinro*

JNC TJ2410 2001-030, 265 Pages, 2002/02

JNC-TJ2410-2001-030.pdf:6.1MB

no abstracts in English

JAEA Reports

Investigation of Radiation Effects on Ceramics (2)

Maruyama, Tadashi*

JNC TJ4420 2001-012, 100 Pages, 2001/03

JNC-TJ4420-2001-012.pdf:15.53MB

no abstracts in English

JAEA Reports

None

Maruyama, Tadashi*

JNC TJ4420 2000-005, 101 Pages, 2000/03

JNC-TJ4420-2000-005.pdf:3.49MB

no abstracts in English

Journal Articles

Effect of Fast Neutron Irradiation on the Properties of Boron Carbide Pellet

Maruyama, Tadashi; Onose, Shoji; Kaito, Takeji; Horiuchi, Hiroto

Journal of Nuclear Science and Technology, 34(10), p.1006 - 1014, 1997/10

None

JAEA Reports

Postirradiation examination of JOYO MK-II control rods; Irradiation performance of absorber pins

Maruyama, Tadashi; ; ; Onose, Shoji;

PNC TN9410 97-077, 177 Pages, 1997/07

PNC-TN9410-97-077.pdf:9.84MB

Postirradiation examinations of JOYO MK-II control rods have been carried out since 1983, where 16 subassemblies with total 110 absorber pins of initial load to the fifth reload control rods have been subjected to a number of both non-destructive and destructive examinations. In the course of postirradiation examinations, a cracking of cladding tube was found in the total 15 absorber pins in five control assemblies. This paper indicates the results of postirradiation examinations and analysis of absorber pin performance using CORAL code to elucidate the cause of absorber pin cracking in JOYO MK-II control rods. No crack was found in absorber pins whose maximum burnup was lower than 39 $$times$$ 10$$^{26}$$ cap/m$$^{3}$$, whereas all the cracked pins had burnup of higher than 43 $$times$$ 10$$^{26}$$ cap/m$$^{3}$$ with the initial gap between B$$_{4}$$C pellet and cladding larger than 0.44 mm. The cracks were found at around positions corresponding to the lowest B$$_{4}$$C pellet in the stack. The ceramography analysis indicated that B$$_{4}$$C pellet exhibited extensive cracking and a part of gap between pellet and cladding closed. The cladding deformation had an ovality and the cracks tended to occur at the shorter diameter side. The cracked surface of absorber pin was of a typical grain boundary fracture. The result of He analysis for the cladding material indicated a substantial amount of He accumulation at the inner surface of cladding, but the bulk He content was not anomalously high compared with those in the neutron irradiated stainless steels. TEM observation indicated He bubbles was not clearly found in the as-irradiated cladding material. The cause of cladding failure was attributed to the ACMI where the gap closure due to relocation of B$$_{4}$$C pellet took place from early times of irradiation. The code analysis by CORAL indicated that the cladding strain due to ACMI was not fully absorbed by the irradiation creep and that the plastic strain became large enough to ...

38 (Records 1-20 displayed on this page)