Application of a Time-Dependent Approach to Burnup Calculations for Pressurized Water Reactor Cores

Abstract

The feasibility and relative merits of a quasi-time-dependent approach to burnup calculations is investigated. This method, which is shown to be practically equivalent to a true time-dependent approach, uses one iterative level less than the conventional method and is less liable to nonconvergence problems. The method has been formulated using the finite difference form of the neutron diffusion equation and is implemented in a computer code named TDB. Several one- and two-dimensional pressurized water reactor cores were analyzed using both proposed and conventional methods. The calculations show that the proposed method is about twice as fast as the conventional one with a relative accuracy of less than or equal to0.5% in material power fractions and critical boron value.