China Experimental Fast Reactor Sodium And Water Reaction Accident Signal System Reliability Evaluation Studies

The analysis of systematic reliability is a important content and base of Probabilistic Safety Assessment (PSA). By evaluating the reliability of important safety system of the reactor, It can evaluate the designing performance of the system, suportative devices, failure mode and the unavailability of the system to offer direct reference and basis for improving and optimizing devices.China Experimental Fast Reactor (CEFR) is the first sodium-cooled fast reactor of China. Its characteristic Na-Na-H20 coolant system results the risk of the accidence of Sodium-water reaction in Steam Generator. To access the probability for signal system of sodium-water reaction, it is considered that the detectors, controller, protective component, common cause failures and software reliability etc. Fault trees are build to the question of sodium-water reaction.The conclusion: With the consideration of CCF, the small leak signal system unavailability evaluation point estimation is 1.80E-4; the large leak system unavailability evaluation point estimation is 6.92E-05. The study of the software reliability method for PLC is also taken into account. After comparison, a testing method is proved suitable to CEFR, Compiled with Monte Carlo technology, the results for signal system have been proved reasonable.This paper not only acquires the quantitative assessment of reliability for the power supply systems of CEFR, but also gives some good advice for improving design, and at the same time, the results are inputted to the work of the one level PSA of CEFR. And this paper proved a way of assessment for software. That will be used for reference to computer control system in nuclear plant.