XCOBRA-T: a computer code for analyzing the transient thermal-hydraulic response of BWR cores

Safety analyses for boiling water reactors (BWRs) are performed to assure that the operating limits observed during normal plant operation provide an adequate level of protection for the fuel during anticipated operational occurrences. For this purpose, Advanced Nuclear Fuels Corp. applies an appropriate methodology to determine the minimum critical power ratio operating limits of BWR cores. This methodology includes the XCOBRA-T code, developed for thermal-hydraulic analyses of BWR cores during normal and transient operation. The XCOBRA-T code represents an improved version of COBRA-IIIC. Major advantages of XCOBRA-T include modeling of separated BWR channels, the capability of using an inlet pressure boundary condition, an improved solution of the energy equation, and the use of a detailed fuel model. The analytical models and improved capabilities of XCOBRA-T are reported elsewhere. The XCOBRA-T code has also been successfully compared with selected analytical and computational results. The purpose of this paper is to provide representative XCOBRA-T benchmarking critical heat flux (CHF) results for steady-state and transient conditions