Research on Mitigation Measures for Severe Accident Source Terms of Small Modular Reactor

Small modular reactor (ACP100), as a key scientific and technological project of third-generation nuclear power technology of China National Nuclear Corporation, must achieve the purpose of eliminating large-scale radioactive substances release. In order to meet this requirement, it is necessary to study the source term release and mitigation of small modular reactor in severe accident. In this paper, ISAA code is used to model the small modular reactor, and the typical severe accident sequence is selected to simulate the accident and calculate the source term. Containment spray and double containment model are set up respectively. The feasibility and effectiveness of the two measures on the source term mitigation are illustrated by comparing the source term results. The calculation results show that containment spray and double containment can significantly alleviate the release of radionuclides under severe accident conditions, and can play a role in reducing radioactivity. Meanwhile, for double containment, the leak rate from the inner containment to the annular space has a great impact on the mitigation of the source terms. To reduce the release of the source term to the environment, it should be reduced as far as possible.