Study On The Characteristics Of Liquid Suspension Passive Structure And Buffer Segment Optimization

As the core part of nuclear primary circuit,reactor core is the source of power conversion in nuclear power plant.Passive technology refers to the technology that moves spontaneously without relying on power source.It has high automaticity,reliability and simplicity,so as to ensure that the device can complete the shutdown operation in time and autonomously under the transient accident condition.The passive components need to meet the following requirements:the upper working position can be suspended,the falling position is fast,stable,and the buffering effect is good.In view of the working mechanism of the liquid suspended passive shutdown module,the main research contents and research results obtained in this paper are as follows For the working mechanism of the liquid suspension passive stop assembly,the main research contents of the paper and the research results obtained are:(1)In this paper,through the research on the structure and working principle of liquid suspension passive components,the narrow gap flow test and the drop of the spindle structure in the water-filled pipe tube were designed and numerically simulated.And verify the model test.Finally,the standard turbulence model,standard wall function model and finite volume method for numerical dispersion were selected,besides,the dynamic grid technology and SIX-DOF model was adopted.This paper carried out the steady-state numerical simulation when the liquid suspension passive component was at the upper working position,and the transient numerical simulation when it falling from the upper working position.(2)Based on the fluid flow characteristics in the suspension of active component analysis,regardless of the contribution to resistance is small and complex neutron absorption bundle,design the scale of 1:1 test piece,respectively the physical test and numerical simulation on the move shut down component test pieces to work on in a steady condition,and the move shut down component test a loss of flow falls the transient motion of the process were studied.(3)For the move shut down component test pieces in constant flow field research work on position,get the internal flow field in detail information,the mobile body stress and the flow distribution of the flow channel,and analyzes the key factors that affect mobile body suspension condition,get in on a moving body to keep the critical flow state of suspension.(4)In this paper,the falling time of the moving body under a given slot-flow curve,the changing rules of the falling displacement,velocity,acceleration,force and total pressure drop of the system are obtained.The whole falling process can be divided into accelerated falling segment,buffer segment and upper hydraulic self-tightening vanishing segment.(5)In view of the fact that the buffer throttling effect of the lower buffer throttling is not ideal in the process of losing the flow of the test piece of the liquid suspension passive shutdown module,an optimization and improvement scheme is proposed to lengthen the length of the lower buffer throttling and change the size of the buffer throttling,and the effect of the buffer throttling is verified.