The determination of dipole extrapolation lengths for use in heterogeneous AGR core calculations

Abstract

A method has been developed for the calculation of the channel wall dipole extrapolation lengths required in heterogeneous calculations of neutron flux in an Advanced Gas-Cooled Reactor. Considerable improvement over previous methods has been achieved by treating the geometry of the fuel cluster explicitly and by using a P1 angular flux distribution at the channel wall. The calculation is done in one energy group using a collision probability method.

The results are compared with other methods and with some measurements of cross-cluster flux tilts made at Berkeley Nuclear Laboratories.