Multi-Cycle Neutronics Verification in the Kraken Framework

Verifying a nodal neutronics solution against a Monte Carlo reference solution over multiple fuel cycles is a difficult task. This article describes the extension of the neutronics solvers Serpent and Ants as well as the reactor simulator Cetus in the Kraken framework for multi-cycle simulations with automated fuel shuffling. In order to verify the Ants reduced order solution with the Serpent high fidelity solution in manageable time, a new cycle replay capability is implemented. The cycle replay capability models the fuel-cycle depletion based on thermal hydraulic fields and reactor stored during an earlier fuel-cycle simulation. The capabilities are demonstrated in the context of control the LDR lite benchmark, which describes a boron free light water small modular reactor. The new Serpent related capabilities should prove useful for any users working with multi-cycle simulations or fuel shuffling.