中文摘要：

本文以严重事故分析程序MELCOR为计算工具,建立了某型船用堆的计算模型,研究了某型船用堆发生冷段双端断裂大破口失水事故的源项行为及放射性后果。分析了惰性气体Xe与挥发性气体CsI的释放、迁移和舱室分布规律,并对通风系统投入时机进行研究。结果表明：为保证堆舱临舱的剂量辐射在剂量限值内,应于事故发生后10min内投入全船通风。否则,应于全身剂量和甲状腺剂量达到剂量限值前及时采取防护措施。

英文摘要：

Based on the severe accident analysis program MELCOR as computational tool ,computational model of the marine reactor was established in the paper .Both the source behavior and radioactive consequence were researched when the double‐ended rupture large‐break LOCA happened on the cold leg of a typical ship reactor . T he release ,migration and reactor cabin distribution of the noble gas and CsI were analyzed , and the plunge criterion of ventilation system was researched .The results show that in order to assure the radiation dose of the cabin adjacent reactor cabin in the dose limits , the whole ship ventilation system should be plunged within 10 min after the accident . Otherwise ,the protective measure should be used before the whole body dose and thyroid dose reach the dose limits .