End Flux Peaking Study for ACR-700-Type Reactor

Abstract

The main objective here is to determine the axial profile of the flux along a fuel channel as a function of the fuel bundle burnup taking into account the effect of water interfaces at the end of fuel bundles (end flux peaking). In order to perform these calculations, we have to establish a 3D representation of an ACR reactor channel (each channel contains a set of two to 12 bundles). All these calculations are performed using the transport cell code DRAGON. The DRAGON calculation procedure we selected is the following: we first perform a 2D calculation to generate homogenized cross sections for annular 2D fuel cells by using a direct or SPH homogenization procedure. No energy condensation is performed. In the second step, we proceed to the 3D calculations for the fuel channel. For our 3D fuel model, we first study the tracking effect to minimize the errors on volumes and surfaces, and then we carry out the calculation of neutron flux. The flux along the z-axis is condensed to 2-energy groups. The effect of fuel burnup on end flux peaking is finally studied.