直流蒸汽发生器传热管破裂事故分析

通过对直流蒸汽发生器传热管破裂（SGTR）事故的分析，可看出RELAP5瞬态分析程序能较好地模拟一体化反应堆在SGTR事故后的事件响应序列及主要热工水力现象，例如环路的不对称效应、主回路的自然循环等。一体化反应堆在发生SGTR事故后，可通过一系列安全与保护系统的动作得到有效缓解，并最终能应用非能动余热排出系统（PRHRS）的自然循环导出堆芯余热，使反应堆处于安全状态。同时，受事故影响蒸汽发生器压力在PRHRS投入运行后会快速升高，最终与一回路压力相平衡，此后，破口处的泄漏也会终止。此外，本文还研究了破口处临界流量及其积分流量结果不确定性的影响因素，其中主要考虑了采用不同的临界流模型和破口建模方式等两个方面。

Once-Through Steam Generator Tube Rupture Accident Analysis

The RELAP5/MOD3.4 predicts well the sequence of events and the major phenomena during the steam generator tube rupture(SGTR) accident transient,such as the asymmetric loop behavior,the reactor coolant system(RCS) cooldown and heat transfer by natural circulation,and so on.These results show that a single steam generator tube rupture is effectively and automatically mitigated in the integral type reactor,and the reactor is then cooled down and depressurized by the passive residual heat removal system(PRHRS).Also,the loss of RCS fluid slows down following the activation of PRHRS and the subsequent increase in the steam generator pressures,and is finally terminated once the RCS and steam generator pressures equalize.Finally,a sensitivity study is performed for understanding the effects of the break models and choking models in the RELAP5.