Assessment of the Radiation Enclosure Models in SPACE and RELAP5 with GOTA Test 27

SPACE (Safety and Performance Analysis Code) for nuclear power plant has been developed to calculate the transient thermal-hydraulic response of PWRs that can contain multiple types of fluids. Without explaining 3-D effects such as the change of fuel rod/guide tube thermal behavior as a result of the radiation heat transfer, the 1-D code could predict an unrealistically high peak clad temperature. A useful function to simulate the wall-to-wall radiation heat transfer is implemented in the SPACE and RELAP5 codes. This paper discusses the assessment results of the radiation enclosure model of SPACE and RELAP5. The capability of handling wall-to-wall radiation problem of the SPACE and the RELAP5 codes has been evaluated using the experimental data from the GOTA test facility. At the top of the bundle, the maximum errors of SPACE and RELAP5 are less than 1.6% and 2.3%, respectively. As noted, there is a small discrepancy between the calculated results and experimental data except for the predictions near the top of the test section. The SPACE code is based on the version 2.16 distributed by KHNP. In order to perform the simulation of the GOTA test 27, it was necessary to modify the SPACE code. There was the subroutine for an input process corresponding to the radiation model, the inp_check function of the RadEncData Class, contained in a vulnerable algorithm to figure out the reciprocity rule of the view factor.