Development of a New Mathematical Framework for Seismic Probabilistic Risk Assessment for Nuclear Power Plants – Plan and Current Status –

Abstract

After the severe accident in Fukushima Daiichi Nuclear Power Station, safety improvement and enhancement have been installed. In midterm and long term, continuous efforts to improve and enhance safety are required, and technical basis and fundamentals are needed to achieve them.Probabilistic Risk Assessment for seismic event (seismic PRA) is an effective measure to consider the countermeasures and improvement plans to secure the further safety of nuclear power plants regarding to seismic risk for the earthquake exceeding the design basis earthquake ground motion. However, the application of seismic PRA has not been utilized sufficiently so far. One of the reasons is that there is not enough agreement among stakeholders regarding to the evaluation methodology and consideration of uncertainty for decision-making.This study proposes the mathematic framework to treat the uncertainty properly related to the evaluation of core damage frequency (CDF) induced by earthquake, the methodology to evaluate the fragility utilizing expert knowledge, the probabilistic model to cope with the aleatory uncertainty as well as the development of analysing code including these considerations for the improvement of the reliability of the methodology and enhancement of utilization of the products of seismic PRA. This paper presents current status and some results from scoping calculations.

Probabilistic seismic safety assessment of a CANDU 6 nuclear power plant including ambient vibration tests: Case study

“…Following the 2011 Fukushima Daiichi nuclear accident in Japan, there is a worldwide interest in reducing uncertainties in seismic safety assessment of existing NPP. The current research emphasis is on developing robust methodology to re-evaluate the flood and seismic hazard and risk within the context of PSA (Ake et al, 2015;Mandal et al, 2016;Muta et al, 2016). Mandal et al (2016) report post Fukushima Daiichi research on seismic fragility analysis of Indian PHWR in operation since 1973.…”