Analysis of post-LOCA long-term core safety characteristics for the Small Modular Reactor ACP100

The China Small Modular Reactor ACP100 is an integral pressurized water reactor with a passive core cooling system. Analyses have been carried out to evaluate the ability to remove decay heat and to prevent boric acid precipitation during the long term cooling phase post-LOCA. The long-term core cooling characteristics have been analyzed on a postulated DEDVI accident. The results show that the key parameters affecting the core cooling ability are the containment pressure and the steam discharge resistance. Simplified calculations have been performed on the boron concentration variation before the automatic depressurization system (RDP) actuation as well as after the RDP actuation. The results indicate that the climbing speed of the core boron concentration and the maximum value that can be reached depend on the core exit quality. The improved passive core cooling system can prevent the core from boron precipitation and returning to criticality post-LOCA. (C) 2020 Elsevier Ltd. All rights reserved.