Verification And Validation Of System Analysis Code FASYS For Sodium-cooled Fast Reactor

As the advanced reactor type of the Generation-IV nuclear reactor,sodium-cooled fast reactor(SFR)has been paid more and more attention in the world due to its outstanding advantages in nuclear fuel proliferation and inherent safety.The system analysis code for the transient response of fast reactor core and system is one of the most important analysis tools in the safety and accident analysis of fast reactor.However,the research on the system analysis code based on SFR in China is still very limited,lacking the system analysis code of SFR with independent intellectual property rights.So,China Institute of Atomic Energy(CIAE)has developed the system analysis code FASYS(Fast-Reactor Analysis System)for SFR.How to ensure the correctness,accuracy and reliability of FASYS code design,modeling and development,and ensure that the code can be effectively used for core and system transient simulation and related safety analysis has become a key issue.Under this background,the V&V strategy is adopted in this paper.Based on the investigation of the V&V of the system analysis program for SFR at home and abroad as well as relevant regulations and guidelines,the implementation scheme of FASYS code V&V is proposed in combination with the scope of development and application of FASYS code.Firstly,the code requirements and development are verified and validated.On the basis of tracing the requirements,the program V&V test plan is established,and the phenomenon identification and ranking table(PIRT)is established by using the nine steps method.Based on the established PIRT,the standard case library and experimental database for verification are collected,and the verification matrix is established.Secondly,verifying and validating the function and performance of the program.Through manual walk through of the program,unit test of the basic module,and integration test and function test of the program function design case,validate that the key functions of the program can be used normally and meet the requirements of functional design specification.Finally,the applicability of the program is verified and validated.The correctness and accuracy of the program model are verified by the separation effect tests in the verification matrix and that the program can be used for the core and system transient accident analysis of SFR is validated by the integrated effect test in the verification matrix.The results show that the model of FASYS code is correct and accurate,and it is preliminarily validated that the FASYS code can be used for transient accident analysis of core and system of SFR.The purpose of this paper is to explore the verification and validation method of the system analysis program for SFR.The results will provide some reference for the verification and validation of similar programs in the future.