Analytical solution of flux and current coefficients in a hexagonal nuclear reactor using modified flux expansion nodal method.

Nodalization, considering the spatial heterogeneities of the reactor core, is crucial for the accuracy of neutronic calculations. In this paper, Flux Expansion Nodal Method (FNEM) which is suitable for nodalization effects in the node corners is modified to solve the intranodal flux analytically. New correlations are introduced in this paper for gamma factors which are functions of buckling mode and pitch used for determining intranodal flux. Theyrevealed symmetry in intranodal flux coefficients which will reduce calculations using this method. We have found important results about the relation between flux and current coefficients with buckling mode. In two parallel node surfaces A(m) flux and current coefficients in μ= 0 (λ(m)<0and λ(m)> 0 ) are symmetric and B(m)flux and current coefficients are equal but in μ=1 this is reverse.

Keywords:

Nodalization , Flux Expansion Nodal Method