Development and assessment of the COBRA/RELAP5 code

The COBRA/RELAP5 code has been developed to combine the realistic three-dimensional reactor vessel model of COBRA-TF with RELAP5/MOD3.2, thus to produce an advanced system analysis code with a multidimensional thermal-hydraulic module. This paper provides the integration scheme of the two codes. The results of developmental assessments are also provided, which include single channel tests, manometric flow oscillation problem, THTF Test 105, and LOFT L2-3 large break loss-of-coolant experiment. From the single channel tests, the integration scheme was proven to be valid. Other simulation results showed good agreement with the experimental data. The computational speed was also satisfactory. Therefore, the assessment confirmed that the COBRA/RELAP5 code can be a promising tool for analysis of complicated, multidimensional, two-phase flow system transients. (author)