Nonlinear dynamic model of Molten-Salt Reactor Experiment - Validation and operational analysis

Several molten-salt reactor (MSR) concepts are currently being developed by private vendors and national organizations. Molten-Salt Reactor Experiment (MSRE) is the only MSR that operated for several years, for which the performance was well documented in the literature. Experimental data from MSRE serve as the standard for developing models and tools for MSR analysis. MSRE underwent several design changes from conception to construction to operation. Model validation requires the use of parameters consistent with those that existed during the various measurements. The paper therefore presents a brief discussion of the parameters that evolved over time, and details of sources for all the parameters used in the modeling. This report is part of a series of papers on modeling MSR dynamics. The goal here is to validate the modeling approach by comparing simulation results with experimental data. For this purpose, two nonlinear dynamic models are developed. The first model uses a one-region one-dimensional representation of the core. The second reproduces the nine-region core model developed by Oak Ridge National Laboratory for MSRE studies. The dynamics are analyzed by simulating transients during normal power operation. The frequency response of the models is also evaluated. Both models show excellent agreement with experimental data for both U-235 and U-233 fuels. Some apparent discrepancies in experimental data are reported and their consequences discussed. The one-region model is modified to simulate reactivity excursions resulting from operational anomalies, and the results are presented. This modeling approach can be applied to other MSR systems provided valid system parameters.