Use of symmetry groups and component analysis for investigation and description of PWR-core physical fields

Abstract

The approach to a compact description of in-core fields (ICFs) such as neutron-flux and power distribution is described. It uses core symmetry with respect to some geometrical transformations. It is shown that any group of symmetry of reactor core, even if the symmetry is approximate, generates a separation of arguments of functions defined on the set of reactor-core points. The statistical main-component (multi-variate) analysis is then applied for the investigation of ICF distribution over a particular argument. The general formal definition of the method for the compact representation of reactor fields is given. Three groups of an approximate symmetry of the WWER-type reactor and corresponding descriptions of the in-core fields are presented. The representations of reactor-core neutron-flux and power distribution by a small number of components are obtained via theoretical treatment and numerical experiments. The applications of such representations for the reactor control and diagnostics are pointed out.