Consideration of decontamination model for severe accident consequence assessment

Silva, K.*; Okamoto, Koji*; Ishiwatari, Yuki*; Takahara, Shogo; Promping, J.*

Journal of Nuclear Science and Technology, 52(11), p.1402 - 1416, 2015/11

https://doi.org/10.1080/00223131.2015.1005033

Cost per severe accident as an index for severe accident consequence assessment and its applications

Silva, K.*; Ishiwatari, Yuki*; Takahara, Shogo

Reliability Engineering & System Safety, 123, p.110 - 122, 2014/03

AA2012-0781.pdf:0.77MB

https://doi.org/10.1016/j.ress.2013.11.004

The experiences of the Fukushima Accident and also the Chernobyl Accident point out the needs to integrate the assessments of health effects, economic, social and environmental impacts of severe accidents in nuclear power plants, in order to perform a comprehensive consequence assessment. The authors introduced the cost per severe accident as an index for that purpose. The index is calculated based on the systematic accident consequence assessment method which consists of level 2 and 3 probabilistic risk assessments. In the present study, the index was used to evaluate the consequences of severe accidents of a virtual boiling water reactor. The breakdown of the cost per severe accident was provided, and the decontamination cost accounted for the greatest proportion. As applications of the index, it was used to optimize the management levels of protective actions for the public, and to evaluate the consequence-reduction effects of accident management.

The International Atomic Energy Agency Nuclear Energy Management School 2012

Ohgama, Kazuya; Ando, Yoko; Yamaguchi, Mika; Ikuta, Yuko; Shinohara, Nobuo; Murakami, Hiroyuki; Yamashita, Kiyonobu; Uesaka, Mitsuru*; Demachi, Kazuyuki*; Komiyama, Ryoichi*; et al.

JAEA-Review 2013-004, 76 Pages, 2013/05

JAEA-Review-2013-004.pdf:13.53MB

JAEA together with the Japan Nuclear Human Resource Development Network (JN-HRD Net), the University of Tokyo (UT) and the Japan Atomic Industrial Forum (JAIF) cohosted the IAEA-Nuclear Energy Management School in Tokai Village, aiming that Japan will be the center of nuclear HRD in the Asian region. In the school, not only lectures by IAEA experts, but also lectures by Japanese experts and technical visits were included for foreign participants. The school contributed to the internationalization of Japanese young professionals, development of nuclear human resource of other countries, and enhancement of cooperation between IAEA and Japan. Additionally, collaborative relationship within JN-HRD Net was strengthened by the school. In this report, findings obtained during the preparatory work and the school period are reported for future international nuclear HRD activities in Japan.

Modification of severe accident consequence analysis calculation method of nuclear power plant and consideration of effect of discount rate

Silva, K.*; Ishiwatari, Yuki*; Takahara, Shogo

Proceedings of 2nd International Symposium on Technology for Sustainability (ISTS 2012) (USB Flash Drive), p.31 - 34, 2012/11

The authors introduced the external cost regarding severe accident as an index for severe accident consequence analysis of nuclear power plants in the previous work. In this research, we modify the calculation methods of two components of the external cost regarding severe accident; decontamination cost and health effect cost, in order to obtain more reality-based results. The decontamination cost calculation method is renewed based on data obtained from decontamination demonstration project of JAEA and land use data of Ibaraki Prefecture. Willingness to pay is used to estimate the health effect cost instead of human capital method. To investigate the effect of discount rate on severe accident consequence, sensitivity analysis was performed using discount rates from 0%, 1%, 3%, 5%. Changes of the fractions of the costs comprising the external cost regarding severe accident are very small even in the case of discount rate of 5%.

Measurements of neutron capture cross section of Np for fast neutrons

Harada, Hideo; Nakamura, Shoji; Hatsukawa, Yuichi; Toh, Yosuke; Kimura, Atsushi; Ishiwatari, Yuki*; Yasumi, Atsushi*; Mabuchi, Yukio*; Nakagawa, Tsutomu*; Okamura, Kazuo*; et al.

Journal of Nuclear Science and Technology, 46(5), p.460 - 468, 2009/05

https://doi.org/10.3327/jnst.46.460

The neutron capture cross section of Np has been measured for fast neutrons supplied at the center of the core in the Yayoi reactor. The activation method was used for the measurement, in which the amount of the product Np was determined by -ray spectroscopy using a Ge detector. The representative neutron energy and the corresponding capture cross section of Np in the experiment were analytically deduced as 0.80 0.04 b at 0.214 0.009 MeV from the measured reaction rate by combining the energy dependence of the cross section in the nuclear data library ENDF/VII.0. The deduced cross section of Np at the representative neutron energy agrees with the evaluated data of ENDF/B-VII.0, but shows 15% larger value than that of JENDL-3.3 and 13% larger value than that of JENDL/AC-2008.

Current status of research and development of supercritical water cooled fast reactor (super fast reactor) in Japan

Nakatsuka, Toru; Oka, Yoshiaki*; Ishiwatari, Yuki*; Okumura, Keisuke; Nagasaki, Shinya*; Tezuka, Kenichi*; Mori, Hideo*; Ezato, Koichiro; Akasaka, Naoaki; Nakazono, Yoshihisa*; et al.

no journal, , 

Pressure-vessel-type supercritical water cooled reactors (SCWRs) have been developed at the University of Tokyo (UT) since 1989 and are studied in Japan, Europe and other countries. UT's concepts of the reactor are termed "Super LWR" for thermal neutron spectrum and "Super Fast Reactor (FR)" for fast spectrum respectively. With the scope of developing an economical fast reactor system, a Japanese research project of the "Super FR" had been conducted since December 2005 to March 2010. UT, Kyushu University, Japan Atomic Energy Agency and Tokyo Electric Power Company have participated in the project. It consisted of three subjects: (1) development of the Super FR concept, (2) thermal-hydraulic experiments and (3) materials developments. All items have successfully finished. The present paper will summarize the results of the project.

Consideration of decontamination cost calculation model for severe accident consequence assessment indexed by cost per severe accident

Silva, K.*; Okamoto, Koji*; Ishiwatari, Yuki*; Takahara, Shogo; Promping, J.*

no journal, , 

Measurement of fast-neutron capture cross-section of I

Nakamura, Shoji; Toh, Yosuke; Hatsukawa, Yuichi; Kimura, Atsushi; Harada, Hideo; Yasumi, Atsushi*; Nakagawa, Tsutomu*; Mabuchi, Yukio*; Saito, Isao*; Ishiwatari, Yuki*

no journal, , 

The fast-neutron capture cross section of I was measured at the YAYOI reactor by the activation method. The amount of I was obtained by measuring -rays emitted from I. The neutron flux was monitored by a piece of gold foil. The fast-neutron capture cross section was derived from the information of the production amount of I and the neutron flux. This work found that the evaluated data might be overestimated by about 10% and more.

Introduction of external cost regarding severe accident as an index of nuclear power plant risk and its relationship with sourceterm

Silva, K.*; Ishiwatari, Yuki*; Takahara, Shogo

no journal, , 

In this research, the authors introduce the "external cost regarding severe accident" as an index to evaluate the effect of severe accident in a nuclear power plant. This can contribute to an improvement in nuclear power plant risk evaluation which needs not only probability evaluations but also effect evaluations. To calculate the external cost regarding severe accident, typical sequences of severe accidents are picked up first. Containment failure frequency (CFF) and sourceterms of each sequence are taken from the results of level 2 PSA. The sourceterm of each sequence is input into the level 3 PSA code OSCAAR which was developed by Japan Atomic Energy Agency (JAEA). Using these outputs, the external cost regarding severe accident is calculated. The results were compared with the amount of sourceterms of each severe accident which can be one of the indexes to evaluate the effects of severe accident.

Structure analysis of resin-filler compounds by small-angle neutron scattering

Yamaguchi, Daisuke; Koizumi, Satoshi; Ojima, Hitoshi*; Isoyama, Ryo*; Ishiwatari, Yoshiyuki*; Kodama, Hiroto*; Takeda, Hisanori*; Fukita, Hitoshi*; Takashima, Yoshiyuki*

no journal, , 

Resin-filler composites were investigated by small-angle neutron scattering (SANS). Two types of fillers, talc and TiO, were employed and compounded with polypropylene in this study. The dispersion state of the fillers was examined by SANS measurements. In addition, the size distribution of the fillers was separately measured through the laser right scattering and SEM. The calculated scattering function including the polydispersity of fillers whose size distribution reflects the results of laser right scattering and SEM consistently reproduced the experimental SANS scattering profiles.