The assessment of the radioactive releases from the confinement structure of AP1000 by probabilistic safety analysis

Abstract

The fundamental safety function of the power reactor is to control reactivity, to removal heat from the reactor, and confinement of radioactive material. The safety analysis is used to ensure that each parameter is fulfilled on the design and is done by deterministic and probabilistic method. The evaluation of the third fundamental safety function can be analyzed by the probability of radioactive material releases, which are caused by the failure of radioactive waste management system and fuel handling accident. The failure frequency analysis for combination of those systems have not been done. The purpose of this research is to determine the safety level of the AP1000 by assessing of the radioactive releases frequency from the cofinement structure using probabilistic safety analysis. The analysis is carried out by determination of intermediate events that cause the radioactive release from a subsystem or component. Furthermore, the basic event is determined by deductive analysis that is the fault tree analysis. The AP1000 is used as the object of research. The probability data of component failure or human error that used in the analysis are collected from IAEA, Westinghouse, NRC and other published documents. The results show that there are five the intermediate events which caused the radioactive release from a subsystem or component. These intermediate events are liquid waste management system, gas waste management system, release of radioactivity to the environment via liquid pathways, fuel handling accident and spent fuel cask drop accident. Based on the assessment, It was concluded that the frequency of radioactive release from confinement structure is 1.54E-04 per year, which is still within the IAEA safety criteria because if core damage frequency (CDF) is considered, then the large release frequency is lower than 1.00E-06. Furthermore, the design of AP1000 has the high safety level.The fundamental safety function of the power reactor is to control reactivity, to removal heat from the reactor, and confinement of radioactive material. The safety analysis is used to ensure that each parameter is fulfilled on the design and is done by deterministic and probabilistic method. The evaluation of the third fundamental safety function can be analyzed by the probability of radioactive material releases, which are caused by the failure of radioactive waste management system and fuel handling accident. The failure frequency analysis for combination of those systems have not been done. The purpose of this research is to determine the safety level of the AP1000 by assessing of the radioactive releases frequency from the cofinement structure using probabilistic safety analysis. The analysis is carried out by determination of intermediate events that cause the radioactive release from a subsystem or component. Furthermore, the basic event is determined by deductive analysis that is the fault tree an...