Development and verification of multicycle depletion perturbation theory

Recently, Williams has developed a coupled neutron/nuclide depletion perturbation theory (DPT) applicable to multidimensional and multigroup reactor analysis problems. This theoretical framework has been verified using the newly developed DEPTH module within the context of the VENTURE modular code system. The accuracy and usefulness of this alternate calculational method for burnup analyses has been demonstrated for a variety of final-time response functionals. However, these examples were restricted to single-cycle depletion analyses due to the theoretical assumption that the nuclide density field was continuous in time. Clearly, in multicycle problems, the nuclide concentrations must vary discontinuously with time to model refueling and shuffling operations or discrete control rod movements. Thus, the purpose of this work is to generalize the original DPT framework to include nuclide discontinuities and to verify that this generalization can be employed in realistic multicycle applications