Drift Effects in CANDU Reactors

Abstract

The diffusion equation is an approximation to the transport equation whichrelies on the validity of Fick's law. Since this law is not explicitely integrated in the transport equation it can only be derived approximatively using homogenization theories. However, such omogenization theories state that when the cell is not symmetric Fick's law breaks down due to the presence of an additional term to the neutron current, called the drift term. In fact, this term can be interpreted as a transport correction to Fick's law which tends to increase the neutron current in a direction opposite to that specified by the flux gradient. In this paper, we investigate how the presence of asymmetric liquid zone controllers will modify the flux distribution inside a CANDU core.