Buckling Correction for Experimental Power Distribution within Fuel Assemblies in a Finite System

摘要

For design calculations to determine the local power distribution in a fuel assembly of a power reactor, the neutron flux is usually assumed to be symmetrical at the outer boundary of the assembly. In actuality, experimental data on power distributions are obtained in a finite system where this symmetry does not apply, so that the calculated values cannot be directly compared with observed data. In a zero power critical experiment in particular, the measure-ment must be performed in a fairly small core assembly so economize the amount of fuel materials to be used for simulation. This introduces the necessity of special considerations in the comparison between design and observed data.The authors propose a method incorporating direct corrections to the experimentally deter-mined power distributions based on the geometrical buckling of the system. In this method the experimental power P0(r) is divided by the neutron flux Q(r) which is determined in the critical state with geometrical buckling in a bare (one neutron energy group) reactor, neglect-ing the reflector region of the experimental system. A sample application of the method to an actual light water lattice has confirmed the validity of the method.