The Safty Analyses About Boron Dilution Event In Maintenance Cold Shutdown State Of Qinshan Second Power Plant

In the international practice, the technique of PSA has been widely applied into many fields of nuclear power plant, including design, operation, and maintenance and so on. It is very important to advance the development of nuclear power plant.Boron dilution is a kind of influential accident in nuclear power plant, and the"dilution"is analyzed as a kind of original case or one part of"reactor coolant system transient"original cases in the probability safety assessment(PSA)of many nuclear power plant. By analyzing the risk of dilution, to find out the weakness points on system design and normal maintenance, so that we can find the pertinence measure to reduce or avoid the risk of dilution. And from this, we can find out the key and important points of PSA, so that can collect beneficial experience for the future.The dilution under maintenance cold shut down is defined as a kind of original case in this thesis, I analyzed and described the response of reactor system and people after the original case , on this basic, I constructed the event tree and all of fault trees. Due to Qinshan phaseâ…¡have a short running history, the representation of facility reliability data can not satisfied by the require of PSA analysis. Therefore, the process manners of reliability data are used the common data as per-test data, use the historic data of the plant as model data, and processed by Bayesian method to gaining the final test data . Moreover, the collection of the reliability data considers the common-cause factor and human factor of the facility. After finished the works above all, this thesis make the ration and qualitative analysis to the fault tree and event tree by RS software. By the analysis , we can testify the design of Qinshan phaseâ…¡which aim at dilution case under maintenance cold shut down is safety, the disposal way and the measure of interrelated accident regulations is effective, we also can improve the safe level of reactor by pertinence advance management and technology.By research this object makes us find out the basic way and emphasis case in PSA analysis, and it is a good foundation to do the next work of Qinshan phaseâ…¡in the future.