Results of two-dimensional hexagonal dynamic benchmark problems solved using diffusion kinetic code

A two-dimensional nodal kinetics code was developed to solve for the time-dependent neutron diffusion equation in the hexagonal geometry. Direct space time method was used for solving the time-dependent multi-group diffusion equation. The space part was solved using higher order nodal expansion method, wherein one-dimensional neutron flux in each node and energy group was approximated using higher order polynomial, while the first-order time derivative was approximated by finite difference implicit scheme. The code was used to solve two problems based on (1) VVER-440 and (2) HWR. (author)