Calculation of the Radial and Axial Diffusion Coefficient for a Hexagonal Lattice of a High-Temperature Reactor with Block Elements

A numerical method for the calculation of the radial and axial diffusion coefficient for the hexagonal lattice of a high-temperature reactor with block elements is developed. Results for a typical lattice are given and a comparison with the formulas of Behrens and Benoist is made. A modification of Benoist's formulas for a tightly packed lattice that gives a better agreement with the numerical results is proposed.