Verification/Validation of ESATAN Fluid Capability Against RETRAN

The Fluid Heat Transport Systems (FHTS) extension to the ESATAN thermal analyser was released to industry in 1989. A significant as effort has been directed towards obtaining, far as possible, an error free code which gives results in reasonable agreement with reference data.

The first steps to ensure confidence in FHTS have been taken by system testing during software acceptance and by means of a comparison with RETRAN, a US code unique in possessing a US safety evaluation report for reactor licensing applications. RETRAN output data was taken as the a priori reference data to verify FHTS.

Two sets of test cases have been defined, one concerning single-phase problems (basically the Columbus water loop), the second set containing models with two-phase conditions (a simple idealised loop and boundary conditions). The paper highlights the difficulties encountered during the comparison work, presents the major results and discusses the main issues involved in FHTS verification/validation.