Development of a Computer Tool for In-Depth Analysis and Post Processing of the RELAP5 Thermal Hydraulic Code. International Agreement Report

摘要

A computer tool has been developed to assist RELAP5 users in the interpretaiton and qualification of pressure and level transients. For that purpose some balance equations have been rigorously derived from the original mass and energy equations. Those balances include the pressure, level and non-equilibrium mass equations. The balances are used to check the consistency of the solution and to interpret the pressure and level evolution in terms of physically meaningful variables. Verification of the equations is implemented in the tool with the aid of an AWK script and the general purpose simulation language BABIECA. The AWK script automatically generates the BABIECA input file necessary to check the RELAP5 transient. The execution of BABIECA with the corresponding input file implies the spawning of the RELAP5 transient. RELAP5 information is transferred to BABIECA through PVM, so that the balance equations can be verified. The tool has been applied to some application examples, which have revealed some misconceptions in RELAP5, such as the overspecification of boundary conditions and the flow mixing problems. Some guidelines for the development of future codes, with full control of the discretization errors, are pointed out.