Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
4925841 | Nuclear Engineering and Design | 2016 | 10 Pages |
Abstract
This paper describes snow probabilistic risk assessment (PRA) methodology development through external hazard and event sequence evaluations mainly in terms of decay heat removal (DHR) function of a sodium-cooled fast reactor (SFR). Using recent 50-year weather data at a typical Japanese SFR site, snow hazard categories were set for the combination of daily snowfall depth (snowfall speed) and snowfall duration which can be calculated by dividing the snow depth by the snowfall speed. For each snow hazard category, the event sequence was evaluated by event trees which consist of several headings representing the loss of DHR. Snow removal action and manual operation of the air cooler dampers were introduced into the event trees as accident managements. Access route failure probability model was also developed for the quantification of the event tree. In this paper, the snow PRA showed less than 10â6/reactor-year of core damage frequency. The dominant snow hazard category was the combination of 1-2Â m/day of snowfall speed and 0.5-0.75Â day of snowfall duration. Importance and sensitivity analyses indicated a high risk contribution of the securing of the access routes.
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Authors
Hidemasa Yamano, Hiroyuki Nishino, Kenichi Kurisaka,