混合能谱超临界水冷堆快谱区流动稳定性研究

在混合能谱超临界水冷堆中,冷却剂通过堆芯过程中跨拟临界点引起的密度等参数的剧烈变化易导致系统产生密度波振荡而不稳定,因此混合能谱超临界水冷堆的稳定性对系统的安全性至关重要。本文利用频域法研究快谱区的流动稳定性,给出在不同状态下的稳定性边界,同时对冷却剂入口流量、进出口压差和通道划分等对稳定性的影响进行了分析。结果表明：大的入口流量有利于系统的稳定;高的进出口压差对系统稳定性有利;轴向功率均匀分布较非均匀分布系统的稳定性差,可提供保守结果;热通道的功率密度越大,对系统的稳定越不利。研究结果对超临界水冷堆设计和优化有一定指导价值。     

Loss of flow accident and its mitigation measures for nuclear systems with SCWR-M

Based on a revised version of RELAP5, which can be used for super-critical pressure calculation, a model of mixed spectrum SCWR (SCWR-M) system is established. To analyze the transient behavior of SCWR-M and develop mitigation measures during loss of flow accident (LOFA), some important parameters, e.g. reactor coolant pump (RCP) coast-down time, Reactor Pressure Vessel (RPV) upper water volume and safety injection flow, etc., are chosen for the parametric analysis. The results achieved so far indicate that the SCWR-M system design is feasible and promising. Three important mitigation measures for LOFA of SCWR-M are derived from the results: RCP coast-down time of more than 15 s, RPV upper water volume of more than 27 m³, and safety injection of more than 5% of the system design flow.     

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。