Research On Seismic Induced Fire Probabilistic Safety Analysis For NPPs

In March 11th,2011,a big earthquake happened in Japan near the Fukushima Nuclear Power Plant,this brought about a series of severe accidents in the Fukushima Nuclear Power Plant.This accident was a wake-up call for all the nuclear power industries around the world.It had made a major shift of nuclear safety concepts in the United States,France,Germany and other countries in order to take great attentions on the consequence of severe accidents in nuclear power plant,especially to reconsider emergency preparedness and the effect of external disasters caused by severe accident.In this paper,based on Seismic PSA and Fire PSA,the critical elements for seismic induced fire PSA are identified.The analysis frame and flowchart for seismic induced fire PSA is given first,and corresponding tasks are analyzed.It begins with the first element in the Chapter 3,the structures,systems and components lists for seismic induced fire PSA are provided;According to the seismic induced fire PSA mechanism study,the important ignition sources are identified after qualitative analysis.Then,based on this analysis procedure,we develop the fault tree and event tree models.The influence factors and calculation process for ignition probability are given by consideration of civil architecture and chemical industry experience.We give the explicit quantitative screening criteria and use this criteria to define the ignition source what we need to analysis.Finally,we develop the detailed fire scenario analysis and fire propagation analysis and obtain the consequence and critical minim cut sets by the fault trees and event trees model quantification.By using sensitive analysis,we obtain the quantification results and risk insights which are significant to the CDF(core damage frequency).Based on the analysis in this paper,seismic fire risk of the plant is relatively high and the contribution of the PGA(peak ground acceleration)interval between 0.1g and 0.25g is the most significant.Seismic induced fire PSA is a part of seismic PSA,many institutes are developing seismic induced fire PSA research,mostly focused on qualitative screening method about ignition source for seismic induced fire PSA.In the publicly published literature,we scarcely saw the quantitative consequence for seismic induced fire PSA.This work is aimed to develop a useful quantitative assessment method to receive seismic induced fire CDF and risk insigths,which is applicable to the engineering practice.