Development of time-dependent reaction rates to optimise predictor-corrector algorithm in ALEPH burn-up code

This work presents a unique and innovative feature of the ALEPH Monte-Carlo burn-up code which optimises the depletion algorithm by using time-dependent matrix coefficients. Linear polynomials interpolate the evolution of the matrix coefficients along a few consecutive time steps. Then, trend curves are constructed and used to extrapolate the effective reaction rates in the following intervals, thus reducing the total required computational time spent in the neutronic calculations. This technique has been implemented in the version 2 of the ALEPH Monte-Carlo burn-up code and validated against the REBUS experimental benchmark. The results revealed a considerable computational time saving without any drawbacks in the accuracy.