Analysis Of The Flow Field Characteristics Of Conversion Of Operating State Of A Small Pressurized Water Reactor Primary Loop System With Jet Device

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 small pressurized water reactor.The sudden change of the coolant flow rate of the reactor leads to the change of the core temperature during conversion of operating state,which affects the safety of the core operation.Therefore,it is significance to analysis of the transient flow field characteristics of the conversion of operating state of small pressurized water reactor primary loop system with jet device.In this paper,by using CFD(Computational Fluid Dynamics),the jet device is introduced into the MRX(Marine Reactor X)by referring to the arrangement of the jet device in the boiling water reactor.Using FLUENT to do simulation analysis of conversion of operating state,theresults shows:(1)Rated power under steady state condition,The CFD simulation value of the auxiliary model and the primary loop system model has a good coincidence with the MRX design value on inlet and outlet of steam generator and core,flow rate and operation pressure of the primary loop,the maximum error of 1.28%.Using CFD method to simulate the flow field of the primary loop system is feasible.(2)The jet pump plays a bypass effect since the forced circulation to the natural circulation,which prevent the continuous decline in primary loop of coolant flow;After the particular moment,the coolant flow rate of the primary loop increases slowly as the temperature difference between the core and the steam generator increases.But core power is larger,so the primary loop system has appear a coolant boiling point before establishing a stable natural circulation;In 100%FP(Full Power)condition,the coolant boiling point appears in 28 s after forced circulation to natural circulation when it appears in 43 s in 90%FP condition.(3)In the process of natural circulation to forced circulation,the addition of jet device can improve the natural circulation ability,improve the initial coolant flow in the process of transformation,slow change trend,improve transient security;During the conversion process,there is a fluctuation in the temperature of the primary circuit,and the greater the core power,the greater the amplitude,the longer the time.(4)Under different power,the velocity field and pressure field distribution of jet pump under forced circulation are similar.The maximum velocity of the jet pump is 169m/s,and the main pump pressure is mainly lost in the jet pump.The CFD method is feasible to analysis the flow field characteristics of the primary loop system.And the jet device has the potential to improve the inherent safety of small pressurized water reactors,it is of great importance for the development of small pressurized water reactors.However,the current jet device needs to be further optimized.