Probabilistic Safety Analysis of a Feed water Piping Failure in a PWR due to FAC

Main feed water piping failure in the second circuit water nuclear power plant is one of the events that in case of failure in safety functions, will follow core meltdown and leaking large amounts of radioactive material outside the reactor containment. Surry Power Station experienced in 1984, stressed that flow accelerated corrosion (FAC), due to increase the rate of chemical corrosion and consequently, reduction in the thickness of the tubing and the chamber, causes a leak before failure in carbon steel pipe lines, such as the main feed water piping in a Pressurized Water Reactor. Nature of extension of FAC, the failure before of leakage, along with possible serious consequences of the failure of the pipeline in the second circuit in nuclear power plants, due to a significant increase in research of FAC identify and predict failure before it happens, in corrosion studies recent years.In this study, after the identification of the corrosion mechanism of failure of the main feed water piping in the second circuit water of nuclear power plant, core damage frequency share of it in pressurized water nuclear reactor has been gained. For this purpose, first to determine the rate of corrosion caused by the FAC, CFD simulation is used, then the reactor core damage frequency using probabilistic safety assessment (PSA), based on the mass transfer coefficient, is estimated. Also, this calculation has been done for modification model and the results were compared. The results of this research can estimate the frequency of priming event of the main feed water piping failure into the second circuit of reactor core and resultant damage considering the FAC, to be employed. The results show the importance of applying the techniques of inspection and prevention of this phenomenon.

کلیدواژه ها:

Flow Accelerated Corrosion ، probabilistic safety assessment ، core damage frequency ، Main feed water piping failure