中文摘要：

事故是压水堆固有属性之一，在众多导致核事故的初因事件中，大破口事故现象复杂，后果特别严重。基于此，本文以小型动力堆为研究对象，针对最重要的设计基准事故——大破口事故，计算了50、150、320满功率燃耗天冷端安注、双端安注条件下安全壳内放射性源项，并将部分计算结果与安全分析报告计算结果进行了对比。结果表明：假设合理、结果正确，对于保障反应堆运行安全、及时采取合理应急措施，意义重大。

英文摘要：

Accident is one of the basic properties of PWR. Among these accidents, the large break loss of coolant accident is one of the accidents with complicated phenomena and severe consequences which may result in nuclear accident. The paper focused on a small power reactor, analyzing and calculating the source term in-containment separately in 50, 150, 320 days full power operation, with cold leg or cold and hot legs emergency core cooling system （ECCS） injection, with or without emergency ventilation conditions. Some of the results were compared with those of safety analysis report. The results show that the assumptions are reasonable, the results are logical. It is important for safety operation and nuclear emergency of nuclear reactor.