Measurement of Average Cross Section for 238U(n, 2n)237U Reaction

Accurate solution of the group diffusion equations for PWR cores requires explicit treatment of the non-homogeneous macroscopic parameters within each fuel assembly. It is argued that the response matrix approach is a convenient method to handle this problem provided all matrix elements for the non-homogeneous assemblies can be computed. This so called local problem is solved in this paper by a perturbation algorithm which leads to sensitivity coefficients for the power series expansions of the response matrix elements. A numerical study for 2 representative assemblies of the Indian Point Unit No. 2 (IP2) reactor is carried out and response matrices obtained by the perturbative method are compared with values computed by a finite difference program.