A dynamic homogenization model for pebble bed reactors

We have used a macro-stochastic model to provide a new homogenization paradigm for pebble bed core calculations. Our method results in an iterative core homogenization for which each homogenized region accounts for interactions between different pebble types and the neighboring regions. Hence, at convergence pebble depletion and power computation are done using the fine-group transport fluxes. We discuss the validation of the method and give a new and accurate estimation of the critical height for the HTR-10 international benchmark. Finally, we introduce a general formulation for the search for the equilibrium core with a multi-pass fuel management where the pebble recycling strategy is defined by a limit of the actual pebble burnup in the core, as opposed to a fixed number of passes through the core. We also extend this formulation to account for a radial loading distribution.