Description of the models and algorithms used in the coupled CORE SIM neutronic and thermo-hydraulic tool

Report, 2014

The development of an innovative coupled neutronic/thermo-hydraulic tool is reported hereafter. The novelty of the tool resides in its versatility, since many different systems can be investigated and different kinds of calculations can be performed. More precisely, both critical systems and subcritical systems with an external neutron source can be studied, static and dynamic cases in the frequency domain (i.e. for stationary fluctuations) can be considered. For each situation, the three dimensional distributions of static neutron fluxes, all thermo-hydraulic parameters, their respective first-order noise are estimated, as well as the effective multiplication factor of the system. The main advantages of the tool, which is entirelyMATLAB based, lie with the robustness of the implemented numerical algorithms, its high portability between different computer platforms and operative systems, and finally its ease of use since no input deck writing is required. The present version of the tool, which is based on two-group diffusion theory, is mostly suited to investigate thermal systems, both Pressurized and BoilingWater Reactors (PWR and BWR, respectively). This report describes the neutronic and thermo-hydraulic models, their coupling and numerical algorithms implemented in the tool, whereas the demonstration of the tool is reported in a companion report. The tool, for which a complete user’s manual exists, is freely available on direct request to the authors of the present report.