Comparative Analysis of FAST-2 and MATRA-S Code Using Validation Problem

FAST code is developed to calculate quickly the MDNBR calculation for this purpose. Recently, the FAST code, named as FAST-2, is entirely improved as adopting an expanded multichannel ability, iterative linear solver to improve the calculation speed and robustness of linear system of equations, and transient term considering unsteady condition. In this study, validation of FAST-2 is performed with comparing the experiment results which are used to validate MATRA-S code. These validation problem set are basically consisted of the single phase and two phase condition where test geometry is constricted as a bundle geometry. Fast running DNBR calculation code to implement core monitoring and protection system, FAST-2 code, is developed with enhancing the functionality and accuracy compared with original FAST code. It is a result of pay-off for improving robustness caused by removing the iteration and 2 or 3 times of calculation speed. Acutally, the calculation time of FAST-2 is consumed with 1/5 and 1/10 of MATRA-S calculation time on CNEN 4x4 and WH 14x14 problem and 1/2 or 1/5 in two-phase flow condition.