Research on level 1 PSA and risk-informed design for ACP100

Abstract

Advanced China Power 100 (ACP100) is a kind of multi-purpose small modular reactor (SMR) based on the present pressurized water reactor (PWR) technology. It adopts the integrated reactor technology routes, satisfies the current nuclear safety codes and guides issued by National Nuclear Safety Administration (NNSA), and also refers to the safety standards of International Atomic Energy Agency (IAEA). In the design phase, Probabilistic Safety Assessment (PSA) technology plays an important role to demonstrate the total safety level, identify the design vulnerabilities, and provide suggestions for the improvement of ACP100. After the brief summary of the level 1 PSA and its risk-informed design method, the level 1 PSA analysis was carried out for ACP100. The identification of initiating events (IEs), the event tree analysis, fault tree analysis and accident sequence quantification were performed. The main PSA results are shown in the paper, such as core damage frequency (CDF), dominating accident sequences, significant common cause failures (CCF). Finally, different design options and their impacts on risk which can be reflected by risk return were evaluated to avoid using the risk-increased design based on the quantitative risk calculation for the sake of increasing the ACP100’s safety. Consequently, the results show that the point estimated value of the total CDF of level 1 IEs PSA for operations at power of ACP100 is 1.42E-07/ry. After the design improvement proposed in this paper, the CDF (point estimate) of ACP100 can be reduced to 6.78E−08/ry. The risk were obviously reduced and the safety of the ACP100 is significant improved. This research provides a technical reference for future new nuclear reactor design.