The Assessment of the Radioactive Releases from the Confinement Structure of AP1000 by Probabilistic Safety Analysis (D T Sony Tjahyani1,a) , J H Purba1,b), Deswandri1,c) 1)

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.
Keywords: fundamental safety function, radioactive material release, confinement structure, probabilistic, AP1000