Probabilistic Safety Assessment on Water Intake Blockage of Nuclear Power Plant

Abstract

The marine organism outbreak can lead to water intake blockage, system degradation, equipment failure, and even worse, trip or lose of heat-sink event. According to a survey conducted by the American Electric Power Research Institute (EPRI) in 2009, among the 77 plants surveyed, more than 55% of plants suffered unplanned shutdown or unplanned power reduction events caused by water intake blockage. In recent years, several water intakes blockage events caused by marine organism were reported by domestic nuclear power plants. which leaded to power reduction or shutdown event and heat sink SSCs (systems, structures, and components) degrade or failure. These events greatly threaten operation management, equipment maintenance and emergency response of nuclear power plants. Hence, it is necessary to carry out detailed risk assessment on the water intake blockage event caused by marine organism outbreak. Aiming at a large-sized pressurized water reactor (PWR) nuclear power plant, this paper builds a realistic model to analyze the risk caused by marine organism using PSA (probabilistic safety assessment) method, and obtains quantitative results of the unit. This paper also identifies the problems and deficiencies in plant’s response to the water intake blockage events, and provides us with risk insight to improve the safety level of nuclear power plants combining the analysis results.