EFFECTIVE DIFFUSION HOMOGENIZATION OF CROSS-SECTIONS FOR PRESSURIZED-WATER REACTOR CORE CALCULATIONS

A consistent, effective diffusion homogenization method for cross sect ions for pressurized water reactors (PWRs) is presented. It can be app lied to obtain cell-averaged as well as assembly-averaged cross sectio ns. Since no additional parameters are necessary, standard diffusion c odes can be used. It is shown that a few-group diffusion calculation o ver a fuel assembly compares favorably with a transport calculation. T his allows transport theory methods to be restricted to lattice cell c alculations. The application of the critical albedo search in fuel ass embly calculations provides for the approximate treatment of the radia l leakage and helps to decouple calculations over individual fuel asse mblies from their surroundings. Examples of calculations on unit cells , fuel assemblies, and realistic PWR core geometry are presented.