Parameters Optimization And Experimental Research On Drop Down Of Control Rod

With the development of nuclear power enterprise in our country,the safe operation of nuclear reactor become researchers focus on the object,and the whereabouts of the control rods more relationship can reactor safety shutdown at the time of the accident,its stability is very important,if the control rod inserted into the core of the time is too long or falling CARDS appeared in the process of good situation,will lead to disastrous accident is hard to imagine.In this paper,a single control rod is taken as the research object,and the following theoretical and experimental studies are carried out on the free-falling process of the control rod.(1)The mechanical model of the control rod assembly is simplified and the basic calculation model is established.Then the force of the control rod in the falling process is analyzed in detail.Through the flow analysis,the physical quantity that needs to be calculated in the force analysis is obtained,the fluid-solid coupling calculation is completed,and the dynamic characteristics of the control rod in the falling process is finally completed.Design of the control rod drop model test,the use of the displacement of the laser displacement sensor to collect the control rod drop calculation obtained the whereabouts of velocity and acceleration,compare the results with the theoretical solution found that the theoretical calculation and experimental results of displacement,velocity and acceleration change trend,to verify the reliability of the theoretical calculation.(2)Designed a variable-parameter test for the control rod drop down,using different combinations of the central outlet hole and the bottom pressure relief hole diameter.Lateral comparison found that when the bottom pressure relief hole remains unchanged,the larger the central outlet hole diameter,the shorter the fall time,the greater the speed of the control rod reaching the central buffer section,but after the deceleration section is decelerated,the final speed of the control rod changes with the increase of the central outlet hole to a smaller extent.When the outlet diameter in the middle is unchanged,the larger the diameter of the bottom pressure relief hole,the shorter the fall time,the greater the speed and acceleration of the control rod to the bottom,the worse the deceleration effect of the deceleration section.(3)Through experimental data and theoretical data to contrast,found the reason of the local error and optimize the local loss factor adjustment,the calculation results show that the optimized results to 0-0.35 s little impact speed curve,and displacement of the error of original after 0.35 s speed and displacement of the error of the theoretical calculation results and test results of the image and trend of rod drop further,maximum relative error from11.3% to 2.3%,and change the parameters of the multiple comparison test and verify the reliability of the optimization.(4)Using high-speed camera technology and direct injection of tracer method,the flow images at the middle outlet and the upper outlet were photographed,compared with the simulation results of other scholars,it is found that the streamline law is basically the same.