混合能谱超临界水冷堆反应性引入事故安全分析

本文研究了混合能谱超临界水冷堆(SCWR-M)在发生控制棒失控提升事故和弹棒事故这两类反应性引入事故后的反应堆系统响应。首先利用修改的可用于超临界条件下的系统程序RELAP5对混合能谱超临界水冷堆进行系统建模，并计算分析在功率运行工况下事故过程中功率、流量及包壳温度等重要参数的变化趋势，最后对反应性参数如控制棒价值、控制棒抽出速率和负反馈系数进行了参数效应分析。结果表明，在设计工况下混合能谱超临界水冷堆系统可有效地将衰变热导出堆芯，保证了燃料棒的完整性。另外，反应性参数对控制棒失控提升事故的安全性影响不大，但对弹棒事故的包壳峰值温度影响很大，过于保守的反应性参数估计会使安全裕量大为减小。

Safety Analysis of Reactivity Initiated Accidents in SCWR-M

The reactor system response of the mixed neutron energy spectrum of supercritical water cooled reactor (SCWR-M) under two types of reactivity initiated accidents (inadvertent control rod withdrawal and rod ejection) was studied. Firstly, applying the modified system code RELAP5 which is available for supercritical conditions, a model of SCWR-M system was established. Then, in the process of the accident under operation conditions, some important parameters, such as power, flow rate and cladding temperature were calculated and analyzed. Finally, analysis of parameters, such as worth and withdrawal speed of the control rod and negative feedback coefficient of the core was carried out. The results show that under the design condition, SCWR-M can effectively remove the decay heat from the core to ensure the integrity of the fuel rods. In addition, reactivity parameters have little influence on the safety under the control rod withdrawal accident. But they have strong effect on the peak cladding temperature under the control rod ejection accident. The safety margin will be greatly reduced when too conservative parameters are taken into the safety analysis.