Substep methods for burnup calculations with Bateman solutions

► Bateman solution based depletion requires constant microscopic reaction rates. ► Traditionally constant approximation is used for each depletion step. ► Here depletion steps are divided to substeps which are solved sequentially. ► This allows piecewise constant, rather than constant, approximation for each step. ► Discretization errors are almost completely removed with only minor slowdown.