Level 1 Probabilistic Safety Analysis (PSA) of TNPP Units 3 and 4

Tianwan Nuclear Power Plant (TNPP) Units 3&4 (the second phase) are a landmark project for Chinese and Russian governments to jointly promote China-Russia nuclear energy cooperation.All the reactor units adopt the Russian VVER-1000 improved nuclear power units which are now operated by project owner, Jiangsu Nuclear Power Corporation (JNPC). The depth and quality of PSA development, at the stage of Units 3&4 commercial operation,should be sufficient to obtain the risk-informed insights, enough to support the Risk-Informed application of PSA, and also reflect the actual design and its operation experience of TNPP. This paper presents the brief introduction of PSA of Unit 3&4 of TNPP (power operation mode). The important parts of this presentation are as follows:probabilistic safety indices, study scope, technical elements and the analysis of Core Damage Frequency (CDF) quantitative results. Through quantitative calculation, the point estimation value of the total CDF of TNPP under the power condition is obtained. And the frequency of occurrence of each event sequence and the CDF contribution of each initiating event (IE) etc., are analyzed. Based on the developed PSA models, four PSA application tools have been developed and applied in the risk monitoring activities of nuclear power plant. This PSA model is used to take the lead in carrying out the Online maintenance in China.