Calculation of BWR cycles with CASMO-3-MICROBURN-B and comparison with measurements Original Research Article

The complexity of modern fuel assembly designs, together with heterogeneous core loading patterns, high enrichments and discharge burnups and unconventional reactor operation concepts, challenge the accuracy of BWR steady-state core simulators. The Siemens program system CASMO-3-MICROBURN-B is based on modern concepts and detailed physical modelling for both neutronics and two-phase thermal hydraulics and as such is suited for the analysis of current reactor cores and operation modes. A description of the main models and system qualification work mainly for reactors in the USA is presented in the first part of this report. The second part details the system validation for three German reactors with highly heterogeneous core loadings. Core reactivity for reactor power operation and cold shutdown tests are provided for 17 cycles together with comparisons of calculated and measured γ-TIP signals. Calculated data based on an older program system are given as well. The results show that within relatively tight uncertainty margins CASMO-3-MICROBURN-B is qualified for the analysis of modern heterogeneous BWR cores.