.relap5/mod3 And Thas-pc4, Program Coupling Method

With the technique developing of nuclear reactor design and safety analysis, code coupling has been highlighted to enhance the plant safety as well as the plant economy by resolving the actual safety problems and by removing the over-estimated conservatism. In this paper, a new system analysis code has been developed by combining the excellent features of the RELAP5/MOD3 and THAS-PC4 codes. This approach to link the existing code is very reasonable and economical to take the advantage of the existing capabilities of the verified codes, yielding a new code with an extended scope of applications. The basic principal of code coupling is that the inherent features of each code are to be maintained so all features available from both codes can by fully utilized.This report presents the RELAP5/MOD3 and THAS-PC4 code coupling works as well as the new coupling code application to a loss-of-flow accident analysis.The major works of code coupling includes: 1). Developing a preprocessor program and a postprocessor program for both the RELAP5/MOD3 and THAS-PC4, which are very helpful to manage the data input and the result analysis. 2). Establishing two approaches to coupling the system analysis code RELAP5/MOD3 and the subchannel code THAS-PC4. One approach couples the two codes in such a way that the boundary condition of THAS-PC4 is transferred from RELAP5/MOD3 output data, the other approach exchanges data between both codes each other in each time step. The second approach has a more promising application scope. 3). Developing the coupling codes by both approaches.Loss-of-flow accident of Qinshan Nuclear Power Plant is analyzed with the new developed coupling code. Comparation the core DNBR results calculated by the subchannel code with by single channel hot pipe model shows that the advantage of the coupling code.The coupling code is verified successfully to be a promising tool for safety analysis of PWR thermal-hydraulic transients. The code coupling experiences are helpful to further development of coupling system code with 3-D kinetics codes.