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Journal Articles

Development of level-1 PSA method applicable to Japan Sodium-cooled Fast Reactor

Kurisaka, Kenichi; Sakai, Takaaki; Yamano, Hidemasa; Fujita, Satoshi*; Minagawa, Keisuke*; Yamaguchi, Akira*; Takata, Takashi*

Nuclear Engineering and Design, 269, p.268 - 280, 2014/04

 Times Cited Count:3 Percentile:61.51(Nuclear Science & Technology)

This paper describes a study to develop the level-1 probabilistic safety assessment (PSA) method that is applicable to the Japan Sodium-cooled Fast Reactor (JSFR). This study aims to provide a new evaluation method of (1) passive safety architectures related to internal events and (2) an advanced seismic isolation system related to a seismic event as a representative external event in Japan. Regarding the internal events evaluation, a quantitative analysis on the frequency of the core damage caused by reactor shutdown failure was conducted. A failure in passive reactor shutdown was taken into account in the event tree model. The failure rate of sodium-cooled fast reactor (SFR) specific components was evaluated based on the operating experience in existing SFRs by applying the Hierarchical Bayesian Method, which can consider a plant-to-plant variability. By conducting an uncertainty analysis, it was found that the assumption about the correlation of the probability parameters between the main and backup reactor shutdown systems is sensitive to the mean value of the frequency of the core damage caused by reactor shutdown failure. As for the seismic event evaluation, seismic response analysis and sensitivity analysis of a seismic isolation system were carried out. As a result, it was confirmed that nonlinear properties of rubber bearings have influence on response of the building and inner equipment.

Journal Articles

Analytical study on seismic response of isolated structure considering nonlinear properties of rubber bearing

Minagawa, Keisuke*; Fujita, Satoshi*; Yamaguchi, Akira*; Takata, Takashi*; Kurisaka, Kenichi

Nippon Kikai Gakkai Rombunshu, C, 79(804), p.2684 - 2693, 2013/08

Journal Articles

Seismic response analysis of isolation system considering coupling effect between horizontal and vertical deformation of rubber bearings

Minagawa, Keisuke*; Fujita, Satoshi*; Yamaguchi, Akira*; Takata, Takashi*; Kurisaka, Kenichi

Transactions of 22nd International Conference on Structural Mechanics in Reactor Technology (SMiRT-22) (CD-ROM), 9 Pages, 2013/08

Application of seismic isolation system using rubber bearings into nuclear power plants has been expected. Generally, rubber bearings have nonlinear characteristics in case of large deformation. In addition, the horizontal nonlinear characteristics depend on vertical load. Therefore it is important to consider these nonlinearity and coupling effect. Authors have already reported results of seismic response analysis of an isolated reactor building considering the nonlinearity of rubber bearings. In this paper, seismic response analysis considering the coupling effect of horizontal and vertical deformation of rubber bearings is investigated by numerical simulations. The summaries of the simulations are as follows. The vertical motion affected the start displacement of hardening, so that the coupling effect decreased isolation performance of horizontal direction. However the isolation system is still effective to reduce seismic force even if the nonlinearity and the coupling effect were considered.

Journal Articles

Development of level-1 PSA method for sodium-cooled fast reactor

Kurisaka, Kenichi; Sakai, Takaaki; Yamano, Hidemasa; Nishino, Hiroyuki; Fujita, Satoshi*; Minagawa, Keisuke*; Yamaguchi, Akira*; Takata, Takashi*

Proceedings of Probabilistic Safety Assessment and Management Topical Conference; In light of the Fukushima Dai-ichi Accident (PSAM 2013) (USB Flash Drive), 10 Pages, 2013/04

This study includes a level-1 PSA related to internal events and a seismic event as a representative external event for Japan sodium-cooled fast reactors with passive safety features and a seismic isolation system. For the internal events, it is necessary to evaluate the passive safety features, of which reliability depends on uncertainties of related physical phenomena. In order to consider the reliability of the passive natural circulation, accident sequences leading to core damage result from natural circulation failure were developed, and the annual frequency of the accident sequences was evaluated for the PSA method study. In respects of seismic event, we developed response analysis method considering the coupling effect of horizontal and vertical shaking on the horizontal seismic isolation characteristics, and developed a fragility evaluation model including the effect of seismic non-linearly for the seismic isolation system.

Journal Articles

Seismic response of isolated nuclear power plant considering nonlinear restoring force characteristics of rubber bearings

Fujita, Satoshi*; Minagawa, Keisuke*; Yamaguchi, Akira*; Takata, Takashi*; Kurisaka, Kenichi

Proceedings of 15th World Conference on Earthquake Engineering (WCEE-15) (USB Flash Drive), 9 Pages, 2012/09

Journal Articles

Development of level-1 PSA method applicable to Japan sodium-cooled fast reactor, 1; Research plan and internal event evaluation related to reactor shutdown failure

Kurisaka, Kenichi; Sakai, Takaaki; Yamano, Hidemasa; Fujita, Satoshi*; Minagawa, Keisuke*; Yamaguchi, Akira*; Takata, Takashi*

Transactions of 21st International Conference on Structural Mechanics in Reactor Technology (SMiRT-21) (CD-ROM), 8 Pages, 2011/11

This paper describes a study to develop the level-1 probabilistic safety assessment (PSA) method that is applicable to the Japan Sodium-cooled Fast Reactor (JSFR). This study has been started since August 2010 and aims to provide a new evaluation method of (1) passive safety architectures related to internal events and (2) an advanced seismic isolation system related to a seismic event as a representative external event in Japan. However, after the nuclear accident at Fukushima Dai-ichi Nuclear Power Plant on March 11 2011, the research-period was shortened from four to two years by political reason, and only a limited scope of the research subject will be performed in the two years. Regarding the internal events evaluation, a quantitative analysis on the frequency of the core damage caused by reactor shutdown failure was conducted. A failure in passive reactor shutdown was taken into account in the event tree model. The failure rate of sodium-cooled fast reactor (SFR) specific components was evaluated based on the operating experience in existing SFRs by applying the Hierarchical Bayesian Method, which can consider a plant-to-plant variability. By conducting an uncertainty analysis, it was found that the assumption about the correlation of the probability parameters between the main and backup reactor shutdown systems is sensitive to the mean value of the frequency of the core damage caused by reactor shutdown failure.

Journal Articles

Development of level-1 PSA method applicable to Japan sodium-cooled fast reactor, 2; Seismic response analysis considering characteristics of the advanced seismic isolation system

Minagawa, Keisuke*; Fujita, Satoshi*; Yamaguchi, Akira*; Takata, Takashi*; Kurisaka, Kenichi

Transactions of 21st International Conference on Structural Mechanics in Reactor Technology (SMiRT-21) (CD-ROM), 8 Pages, 2011/11

We carried out fundamental seismic response analysis that considers both horizontal and vertical nonlinearity of rubber bearing. In this study, the horizontal nonlinearity was considered independently from vertical response in order to construct accurate nonlinear analytical model of rubber bearing. That is to say, the coupling effect was not considered. Both horizontal and vertical nonlinear characteristics of rubber bearing were explained by multi-linear model. Analytical model of building for horizontal direction consists of 3 mass points that is the isolation layer, lower and upper layer of the building. It for vertical direction consists of 4 mass points, that is ground layer, the isolation layer, lower and upper layer of the building. At first, nonlinear seismic response analysis was executed in order to confirm nonlinear characteristics of analytical model of rubber bearing. Influence of nonlinearity of rubber bearing upon response of building was also investigated by the analysis. After that, sensitivity analysis was executed. Parameters of rubber bearing, oil damper and building were fluctuated, and influence of variation of these parameters upon response of building was investigated.

Journal Articles

Study on seismic response of isolated nuclear power plant based on probabilistic assessment, 1; Modeling considering nonlinearity of rubber bearings

Fujita, Satoshi*; Minagawa, Keisuke*; Yamaguchi, Akira*; Takata, Takashi*; Kurisaka, Kenichi

Dynamics and Design Conference 2011 (D&D 2011) Koen Rombunshu (CD-ROM), 7 Pages, 2011/09

The response to the input more than assumption is requested in the seismic response analysis used for the Probabilistic Safety Assessment. Rubber bearings used as the isolation system cause nonlinearity in the restoring force when the input more than assumption is received. However, the seismic response analysis method for considering nonlinear of the rubber bearing has not been established. Therefore, this study aims at the development of the seismic response analysis method of an isolated nuclear power plant based on the probabilistic safety assessment. In this paper, isolated building model that the nonlinearity of the rubber bearing is considered is made, the seismic response analysis is done, and the influence that it gives respond was verified. As a result, in horizontal direction, it was confirmed that the increasing tendency of the response acceleration was remarkable because of the increase of the earthquake size. In vertical direction, it was confirmed that the increasing tendency of the response displacement was remarkable.

Journal Articles

Study on seismic response of isolated nuclear power plant based on probabilistic assessment, 2; Sensitivity analysis on parameter of isolated nuclear power plant model

Minagawa, Keisuke*; Fujita, Satoshi*; Yamaguchi, Akira*; Takata, Takashi*; Kurisaka, Kenichi

Dynamics and Design Conference 2011 (D&D 2011) Koen Rombunshu (CD-ROM), 10 Pages, 2011/09

It is necessary to consider the change in the response by the difference of the physical properties value and the material characterizations of an isolation layer and a building in Probabilistic Safety Assessment. Then, in this paper, the sensitivity analysis of the parameter of the isolated building model that the nonlinearity of rubber bearing is considered used for the seismic response analysis done by the first report is done. The response when an arbitrary parameter is set to the upper limit or the lower limit by the logarithm standard deviation is compared with the response when all parameters are set to the median, and the error ratio is examined as sensitivity. As a result, in the earthquake size in which the nonlinearity is caused, the difference of the parameter of the building, the isolation layer such as the displacement that hardening begins and the load that softening begins of the rubber bearing shows high sensitivity, and it has a bad influence for the building response. Therefore, it was confirmed that the parameter that showed high sensitivity had to examine the difference in detail.

JAEA Reports

Re-Evaluation of a Method for Monitoring Airborne$$^{14}$$C Discharge and its Contribution to Development of an Advanced Method

Koarashi, Jun; Isaka, Keisuke*; Yokota, Tomokazu*; Kozawa, Tomoyasu*; Mikami, Satoshi; Kiyomitsu, Akiyama,; Kobayashi, Hirohide

JNC-TN8410 2005-005, 55 Pages, 2005/05

JNC-TN8410-2005-005.pdf:2.0MB

Some investigations were made for re-evaluating collection and measurement techniques in an airborne $$^{14}$$C discharge monitoring at the Tokai reprocessing plant (TRP), which include (1)collection efficiency of CO$$_{2}$$ in a carbon sampler using monoethanolamine as CO$$_{2}$$ absorbent;(2)affect of incorporating tritiated water into the carbon sampler on quantitative estimation of $$^{14}$$C activity in airborne effluent; (3)affect of leakage in air sampling on evaluating airborne $$^{14}$$C discharge; and (4)determination of chemical forms of $$^{14}$$C in airborne release from the TRP. The results presented not only the validity of the TRP's monitoring method, but also the technical aspects required for establishing a more reliable and effective monitoring method.

JAEA Reports

Re-Evaluation of a Method for Monitoring Airborne$$^{3}$$H Discharge and its Contribution to Development of an Advanced Method

Koarashi, Jun; Yokota, Tomokazu*; Kozawa, Tomoyasu*; Isaka, Keisuke*; Mikami, Satoshi; Kiyomitsu, Akiyama,; Kobayashi, Hirohide

JNC-TN8410 2005-004, 73 Pages, 2005/05

JNC-TN8410-2005-004.pdf:2.48MB

Some investigations were made for re-evaluating collection and measurement techniques in an airborn $$^{3}$$H discharge monitoring at the Tokai reprocessing plant (TRP), which include (1)collection efficiency of water in a tritium sampler; (2)quench correction in $$^{3}$$H activity measurement by liquid scintillation counting; (3)affect of leakage in air sampling on evaluating airborne $$^{3}$$H discharge; and (4)determination of chemical forms of $$^{3}$$H in airborne release from the TRP. The results presented not only the validity of the TRP's monitoring method, but also the technical aspects required for establishing a more reliable and effective monitoring method.

JAEA Reports

Methods and Their Performances for Collecting Tritium, Carbon-14 and Radioiodine in Airborne Effluent from Tokai Reprocessing Plant

Koarashi, Jun; Kozawa, Tomoyasu*; Yokota, Tomokazu*; Isaka, Keisuke*; Kiyomitsu, Akiyama,; Asano, Tomohiro

JNC-TN8410 2004-003, 49 Pages, 2004/07

JNC-TN8410-2004-003.pdf:1.45MB

Radioactive airborne effluent discharged from Tokai reprocessing plant (TRP) contains tritium, carbon-14 and radioiodine. These radionuclides are collected with appropriate methods, respectively, in stacks to monitor their concentrations and discharged amounts. This report describes (1) the methods for collecting these radionuclides in TRP; (2) evaluations of the concentrations and discharged amounts; and (3) investigations on estimating performances of the collecting methods. The investigations showed that the collecting methods used in TRP have collecting efficiencies of more than 90% for tritium and radioiodine, and almost 100% for carbon-14. Considerations concerning collection of radionuclides in airborne effluent, made in this study, provided some technical aspects required for establishing more reliable monitoring systems.

Journal Articles

Observation of X-ray spectra from nitrogen clusters irradiated with high-intensity ultrashort laser pulses

Sagisaka, Akito; *; Kondo, Kiminori*; Suzuki, Hajime*; Nagashima, Keisuke; Nagashima, Akira; Kawachi, Tetsuya; Kato, Yoshiaki; Takuma, Hiroshi

Applied Physics B, 70(4), p.549 - 554, 2000/04

 Times Cited Count:7 Percentile:58.26(Optics)

no abstracts in English

Journal Articles

Collisional effects on population inversion in optical-field-ionized plasmas

Sagisaka, Akito*; Nagashima, Keisuke; Yamagiwa, Mitsuru; Matoba, Toru; *

Journal of the Physical Society of Japan, 68(4), p.1221 - 1227, 1999/04

 Times Cited Count:2 Percentile:70.9(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Relaxation of electron energy distributions and population inversion in optical-field-ionized plasmas

Sagisaka, Akito*; Nagashima, Keisuke; Yamagiwa, Mitsuru; Matoba, Toru; *

Inst. Phys. Conf. Ser., (159), p.289 - 292, 1999/00

no abstracts in English

Journal Articles

X-ray laser gain distribution in OFI plasmas

Kado, Masataka; Nagashima, Keisuke; Sagisaka, Akito*; Hasegawa, Noboru; ; Kato, Yoshiaki

Inst. Phys. Conf. Ser., (159), p.293 - 296, 1999/00

no abstracts in English

Journal Articles

Collisional relaxation of an electron velocity distribution function in ultra-fast laser irradiation

Yamagiwa, Mitsuru; Koga, J. K.; Sagisaka, Akito*; Nagashima, Keisuke

Plasma Physics and Controlled Fusion, 41(2), p.265 - 270, 1999/00

 Times Cited Count:2 Percentile:89.88(Physics, Fluids & Plasmas)

no abstracts in English

JAEA Reports

Generation of ultra-short pulse hard X-rays with ultra-short pulse intense laser

Ueshima, Yutaka*; Kishimoto, Yasuaki; Sasaki, Akira; Moribayashi, Kengo*; Nagashima, Keisuke; Kado, Masataka; Sagisaka, Akito*; Tajima, Toshiki*

JAERI-Research 98-048, 46 Pages, 1998/08

JAERI-Research-98-048.pdf:1.88MB

no abstracts in English

Oral presentation

Temporal variation in performance of iodine-129 collecting media for a long-term and large-volume sampling

Miyauchi, Toru; Koarashi, Jun; Mikami, Satoshi; Kozawa, Tomoyasu*; Yokota, Tomokazu*; Isaka, Keisuke*; Akiyama, Kiyomitsu

no journal, , 

no abstracts in English

Oral presentation

Airborne radioiodine monitoring technique without interference of Krypton-85 in nuclear fuel reprocessing operation

Mikami, Satoshi; Miyauchi, Toru; Koarashi, Jun; Kozawa, Tomoyasu*; Yokota, Tomokazu*; Isaka, Keisuke*; Akiyama, Kiyomitsu

no journal, , 

no abstracts in English

28 (Records 1-20 displayed on this page)