射流装置启泵过程的瞬态特性

摘要

射流装置由射流泵和主泵组成,引入MRX(Marine Reactor X)压水堆一回路系统中,有助于提升反应堆的固有安全性.反应堆启泵过程中,流量急剧上升导致堆芯温度变化,影响堆芯运行安全.通过计算流体力学(Computational Fluid Dynamics,CFD)方法对引入射流装置MRX一回路10%满功率(Full Power,FP)、17.5%FP和25%FP堆芯功率下启泵进行三维瞬态模拟,分析MRX一回路中射流装置流场瞬态特性.结果表明,射流装置的加入可以改善一回路自然循环能力,提高启泵工况下冷却剂初始变化流量,减缓变化趋势,改善过渡安全性;启泵过程中一回路温度存在波动现象,且堆芯功率越大,波动幅度越大,时间越长;启泵完成后射流泵喷嘴处流速较大.验证了压水堆中引入射流装置提升反应堆固有安全性的可行性,同时为进一步优化设计方案提供方向参考.%Background:The jet device composed of jet pump and primary pump has the advantages of simple structure and high reliability, and it is suitable for the special environment, such as radioactive, flammable and explosive. It is helpful to improve the inherent safety of the reactor by introducing the jet device as primary pump for Marine Reactor X (MRX). The sudden increase of the coolant flow rate of the reactor leads to the change of the core temperature during start-up period, which affects the safety of the core operation.Purpose:This study aims to obtain the jet device transient feature during start-up period of primary pump in the MRX which introducing the jet device as primary pump.Methods:The primary loop circuit system is modeled with a 3-dimensional (3D) Computational Fluid Dynamics (CFD) code FLUENT, and transient characteristics at 10% full power (FP), 17.5% FP and 25% FP core power conditions were analyzed during the stage of primary pump startup.Results:The analysis results show that the jet device can effectively improve the natural circulation ability of the primary loop circuit system, reform the initial flow rate and slow down the trend of coolant temperature change during start-up period of primary pump, so it can improve the safety of the transition. On the other hand, there are some unfavorable factors of reactor safety during start-up period of primary pump, such as the temperature of the primary circuit fluctuates (the greater the core power, the greater the fluctuation range) and the high flow rate of jet pump.Conclusion:The design of jet device is feasible to improve the safety of MRX, but the real use also needs some adjustment.