旁流对一回路非能动余热排出系统运行特性影响分析

非能动余热排出（PRHR）系统是反应堆安全运行的重要保障，但现有研究表明，一回路系统存在旁流现象，其提高了堆芯活性区流量，在增强堆芯换热的同时也增加了系统的流动阻力，使系统运行情况更加复杂，因此，需对旁流的影响进行建模分析。本文基于一维N-S方程，建立了考虑旁流的PRHR系统运行特性分析模型；在对模型进行验证的基础上，揭示了旁流存在的机理，分析了其对PRHR系统运行特性的影响规律。研究结果表明，旁流的存在降低了PRHR系统的排热能力，影响了反应堆的非能动安全性，在反应堆余热排出系统设计和安全分析过程中需考虑旁流的影响。

Effect of Bypass Flow on Operation Characteristic of Primary Side Passive Residual Heat Removal System

The passive residual heat removal (PRHR) system plays an important role in the safe operation of the reactor. However, studies have shown that the bypass flow in the primary system increases the flow rate of reactor core, which increases the flow resistance and enhances the heat transfer in the core. Therefore, operation characteristics of the system become complicated, and the effect of the bypass flow needs to be analyzed. Based on the one-dimensional N-S equation, the operational characteristic analysis model of the PRHR system considering the bypass flow was established and verified. Then the mechanism of the bypass flow was revealed, and its influence on the operating characteristics of the PRHR system was analyzed. The results show that the existence of bypass flow reduces the heat-removal capacity of the PRHR system, which affects the passive safety of the reactor. The influence of bypass flow needs to be considered in the design and safety analysis of the reactor PRHR system.