Research On Loss Of Residual Heat Removal Based On Integral Effect Experiment

The residual heat removal system(RHRS)is one of the special safety facilities for advanced nuclear power plants,the nuclear safety accident caused by its failure under cold-shutdown conditions will cause a series of very serious consequences,and even cause the risk of core-melt.At present,there is a lack of international research on the thermal and hydraulic phenomena of the system during the RHRS loss accident in the cold shutdown reactor operation of nuclear power units.In addition,due to the relatively few experimental studies related to the accident conditions and the large cost required,it is necessary to verify the accuracy and applicability of the system program for the accident simulation.In view of the above research status,this thesis is based on the RHRS failure accident experiment under the cold shutdown state 3/4-LoopOperation condition carried out by the German overall effect experimental device PKL-III,and the simulation calculation research is performed on the accident using the RELAP5 program.The calculation results are compared with the experimental results and with the calculation results of the ATHLET program,which verifies the applicability and accuracy of the program under the accident conditions.It can be used for subsequent simulation safety analysis and application of the program.Provide theoretical guidance to the study of the wider reactor-type RHRS loss accident;analyze the key thermal hydraulic phenomena in the accident process,such as the impact of the primary steam condensing and reflux of the steam generator on the waste heat removal process of the reactor core,etc.A series of important action sequence parameters such as the moment when the core was exposed,the moment when the emergency core was injected,and the amount of water injected were quantitatively analyzed,and the mitigation capabilities of the two emergency core injection measures after the loss of RHRS were evaluated.This work can provide necessary references for the safety improvement of related systems and equipment of pressurized water reactor nuclear power plants,the formulation of emergency measures for operators under emergency conditions,and the improvement of the predictive ability of numerical simulation calculation procedures.