Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Silva, K.*; Okamoto, Koji*; Ishiwatari, Yuki*; Takahara, Shogo; Promping, J.*
Proceedings of 12th Probabilistic Safety Assessment and Management Conference (PSAM-12) (USB Flash Drive), 12 Pages, 2014/06
no abstracts in English
Fukano, Yoshitaka; Naruto, Kenichi*; Kurisaka, Kenichi; Nishimura, Masahiro
Proceedings of 12th Probabilistic Safety Assessment and Management Conference (PSAM-12) (USB Flash Drive), 12 Pages, 2014/06
Experimental studies, deterministic and probabilistic and risk assessments (PRAs) on local fault (LF) propagation in sodium cooled fast reactors (SFRs) have been performed in many countries because LFs have been historically considered as one of the possible causes of severe accidents. Adventitious fuel pin failures were considered to be the most dominant initiators of LFs in these PRAs because of high frequency of occurrence during reactor operation and possibility of subsequent pin-to-pin failure propagation. Therefore event tree analysis (ETA) on fuel element failure propagation initiated from adventitious fuel pin failure (FEFPA) in Monju was performed in this study based on state-of-the-art knowledge on experimental and analytical studies on FEFPA and reflecting latest operation procedure at emergency in Monju. Probability of adventitious fuel pin failures in SFRs which is the initiating event of this ETA was also updated in this study. It was clarified that FEFPA in Monju was negligible and could be included in core damage fraction of the anticipated transient without scram and protected loss of heat sink in the viewpoint of both probability and consequence.
Yamano, Hidemasa; Nishino, Hiroyuki; Kurisaka, Kenichi; Sakai, Takaaki; Yamamoto, Takahiro*; Ishizuka, Yoshihiro*; Geshi, Nobuo*; Furukawa, Ryuta*; Nanayama, Futoshi*; Takata, Takashi*
Proceedings of 12th Probabilistic Safety Assessment and Management Conference (PSAM-12) (USB Flash Drive), 11 Pages, 2014/06
This paper describes mainly preliminary risk assessment against snow in addition to the project overview. The snow hazard indexes are the annual maximum snow depth and the annual maximum daily snowfall depth. Snow hazard curves for the two indexes were developed using 50 year weather data at the typical sodium-cooled fast reactor site in Japan. In this paper, the snow risk assessment showed less than 10
/reactor-year of core damage frequency. The dominant snow hazard category was the combination of 1-2m/day of snowfall velocity and 0.75-1.0 day of snowfall duration. Sensitivity analyses indicated important human actions, which were the improvement of snow removal velocity and the awareness of snow removal necessity.
Nishida, Akemi; Takada, Tsuyoshi*; Itoi, Tatsuya*; Furuya, Osamu*; Muramatsu, Ken*
Proceedings of 12th Probabilistic Safety Assessment and Management Conference (PSAM-12) (USB Flash Drive), 12 Pages, 2014/06
This study focused on uncertainty-assessment frameworks and utilization of expertise develops methodology for quantification of uncertainty associated with final results from SPRA in the framework of risk management of Nuclear Power Plant (NPP) facilities. This research aimed to contribute to the development of probabilistic models for uncertainty quantification- and software (1); to the aggregation of expert opinions on structure/equipment fragility estimation and development of implementation guidance on epistemic uncertainty (2); and to the study of applicability of newly proposed SPRA models to plant models (3). In particular, we focused on the second goal. There were two different groups of experts used: those in the field of civil engineering, and those in the fields of mechanical engineering. With these groups, we conducted a pilot study on the use of expert-opinion elicitation for identification and quantification of parameters of fragility assessment.
