Development Of The Uncertainty And The Sensitivity Analysis Function Module In The Nuclear Power Station PSA Software

Probabilistic Safety Assessment (PSA) is an analytical method used in the safety degree measurement which is present in the way of probability. PSA analysis, method have already been widely used in a lot of fields nowadays, such as civil engineering, chemical factory construction, especially the nuclear reactor safety analysis fields, what's more it have promoted the development of safety study about these fields in a great degree. Uncertainty analysis of PSA is used in analyzing how much the uncertainty of all part of PSA model's failure would influence uncertainty of the model's failure. Sensitivity analysis is used in analyzing how much individual part's failure of PSA model would influence the whole model. Researches and developments in uncertainty and the sensitivity analysis function module of nuclear power station PSA software has a count for much significance regarding the nuclear power station's safe operation improvement. Moreover uncertainty analysis and the sensitivity analysis have a broad research and the application future.This thesis discuss about general methods in PSA uncertainty analysis and the sensitivity analysis, as well as the methods that have been utilized nowadays in uncertainty analysis and the sensitivity analysis of PSA software. Combined with practical application consideration, we design and develop uncertainty analysis function module and the sensitivity analysis function module in nuclear power station PSA software. In uncertainty analysis function module, on the basis of traditional Monte Carlo random sampling method which has been carried out in the uncertainty analysis, we goes further more, utilizes the more advanced Latin Hypercube sampling method to carry on uncertainty analysis. The result of uncertainty analysis is that we get PSA model accumulated density picture and probability density picture of failure probability of model, so as to describe the uncertainty of the PSA model. In existed PSA software, for example Risk Spectrum PSA Professional of Sweden Relcon AB of Company used a kind of simple PSA sensitivity analysis method. In sensitivity analysis function module, we use two different methods to realizeeach parameter's sensitivity analysis, one is sampling method, and the other is Risk Spectrum the utilization sensitivity analysis method, and proposed a new kind of method combined the advantage of these two methods and may faster the courses of sensitivity analysis of the entire system.In the test processes of each function module, we adopted the method which is compared with Matlab software and Risk Spectrum, and carried out comparative analysis towards some typical trouble tree examples. On the basis of these work, we still do a thoroughly uncertainty and sensitiveness analysis on the containment spray system of Daya Bay Nuclear Power Plant. Not only did we calculate out two subsystem part's confidence degree of failure probability, but also has found out the most sensitive part in two subsystems. Therefore, the meaning of developing uncertainty analysis and sensitivity analysis module of the nuclear power station PSA software is to promote risk analysis, contribute much to improving the designer's confidence in simulation, it has very important meanings that the nuclear power station runs safe improvement.This work is supported by FDS Team, Institute of Plasma Physics, Chinese Academy of Sciences.