Reactor physics and dynamics (READY): ARES - a new BWR simulator

Coupling the three-dimensional Analytic Function Expansion Nodal (AFEN) nodal model [1, 2] developed within the READY project in 2000-2001 with a four-equation based stationary-state thermalhydraulics module [3] and a new cross section model [4], a basis has been created for a sophisticated BWR simulator code. Motivation for distilling the efforts into a new simulator, named ARES (AFEN Reactor Simulator), can be summarized in three main points: · Stationary-state analyses required by the safety authorities must be independent from the calculations made by the power utilities. Using a different simulator for some calculations is an effective method for obtaining independent results. · In order to keep up with the development in the core analysis field, a "test bench" is required for testing and evaluating new ideas and models. In addition, accuracy of the commercial codes and the models incorporated in them can be evaluated by benchmarking them against the new simulator. · Writing a new program from scratch is potentially a good way to transfer experience from the first generation of Finnish nuclear engineers. It also gives the opportunity to re-evaluate some of the ideas used in the older codes written in times of significantly smaller computer capacity.