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Sodium fast reactor needs long time decay heat removal compared with Light water reactor. This reports trial evaluation of dynamic PRA application on Sodium cooled fast reactor in terms of decay heat. Thanks to this application, dominant risk factor could be cleared out.

Oral presentation

Development of failure mitigation technologies for improving resilience of nuclear structures, 7; Effectiveness evaluation technology of the measures for improving resilience at ultra-high temperatures

Onoda, Yuichi; Nishino, Hiroyuki; Kurisaka, Kenichi; Yamano, Hidemasa; Demachi, Kazuyuki*

no journal, ,

In order to evaluate the effectiveness of the measures for improving resilience at ultra-high temperatures, a concept of evaluation focusing on core damage frequency was proposed. Assuming loss of heat removal systems event after reactor shutdown which may result in core damage in sodium-cooled fast reactors, the measures for improving resilience which enable to recover the safety functions at ultra-high temperatures are identified: one is to retain the primary coolant using failure mitigation technology, and the other is to add a heat removal system that can be used under ultra-high temperature conditions. The core damage frequencies were calculated preliminarily and their reduction effect was estimated by comparing them before and after the introduction of the measures for improving resilience.

Oral presentation

Development of dynamic PRA using multi-fidelity models

Zheng, X.; Tamaki, Hitoshi; Sugiyama, Tomoyuki; Maruyama, Yu

no journal, ,

no abstracts in English

Oral presentation

Development of failure mitigation technologies for improving resilience of nuclear structures, 20; Effectiveness evaluation methodology of the measures for improving resilience against excessive earthquake

Kurisaka, Kenichi; Nishino, Hiroyuki; Yamano, Hidemasa

no journal, ,

This study aims to evaluate the effectiveness of the measures for improving resilience against excessive earthquake. Loss of heat removal systems (LORHS) after reactor shutdown is focused on. Implementation of those measures could prevent the seismic-induced LOHRS itself or core damage due to ultra-high temperature condition resulting from LOHRS. Based on this, we developed the methodology that the effectiveness is evaluated by the reduction of core damage frequency. As an example, its applicability to sodium-cooled fast reactors was examined.

Oral presentation

Development of failure mitigation technologies for improving resilience of nuclear structures, 16; Effectiveness evaluation methodology of the measures for improving resilience at ultra-high temperatures

Onoda, Yuichi; Kurisaka, Kenichi; Yamano, Hidemasa

no journal, ,

We invented an effectiveness evaluation method of the measures for improving resilience by quantifying the event tree focusing on the accident sequence that leads to an ultra-high temperature state due to loss of heat removal systems in a sodium-cooled fast reactor and by evaluating the reduction rate of core damage frequency before and after the introduction of measures for improving resilience. If the conditional success probability of measures for improving resilience is tentatively set to 0.81, the reduction rate of core damage frequency for all accident sequences leading to loss of heat removal systems becomes 19%. By taking measures to improve resilience, the core damage frequency can be reduced to the order of 1.010 $^{-8}$ (1/reactor year).

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Design and evaluation methodology for seismic base isolation of nuclear components by probabilistic approach

Modeling of human error for a seismic PSA

Effect of human error on frequency of dominant core damage sequences intiated by loss of offsite power at a BWR

Summary report of seismic PSA of BWR model plant

Insights from the seismic PSA of the BWR model plant at JAERI

Consideration of the effect of human error in a seismic PSA

Development of methodology for probabilistic safety assessment of seismic events

Development of seismic PSA methodology at JAERI

Application of dynamic PRA to the design optimization of sodium-cooled fast reactors

Development of failure mitigation technologies for improving resilience of nuclear structures, 7; Effectiveness evaluation technology of the measures for improving resilience at ultra-high temperatures

Development of dynamic PRA using multi-fidelity models

Development of failure mitigation technologies for improving resilience of nuclear structures, 20; Effectiveness evaluation methodology of the measures for improving resilience against excessive earthquake

Development of failure mitigation technologies for improving resilience of nuclear structures, 16; Effectiveness evaluation methodology of the measures for improving resilience at ultra-high temperatures