Interface Current Method for PHWR Cluster Geometry

Abstract

A method based on combination of interface current formalism (large scale) and P method (small scale) has been developed for solving the integral transport equation for cylindered pressurized heavy water reactor (PHWR) fuel lattices. In this method, the whole lattice cell is divided into number of annular regions. Of these, first few regions called rings, each of which contains fuel pins of a particular ring of a fuel cluster within it, are further subdivided into homogeneous zones. The interaction between zones within a ring and their contribution to outgoing currents are calculated by P method and the angular flux at each region interface, is expanded separately In the incoming and outgoing directions in terms of spherical harmonics. In addition to this, the usual flat flux approximation is assumefodr each of the homogeneous zones/regions. Thus, each region is connected to the neighbouring regions by interface currents. Based on this method, we have developed a mul tigroup code CLUB for analysing the lattice properties of the PHWR lattice cells. In this code, most of the computer time is spent in the precalculation of various probabilities. We have used certain efficient schemes to calculate these, which will also be discussed in the paper.