Verification of a three-dimensional multi-energy group kinetic analysis model by using BWR critical operation data

A time-dependent diffusion model of a three-dimensional, multi-energy group kinetic analysis program STAND has been verified by using neutron detector responses in the subcritical condition. The responses were obtained from a BWR start-up examination. STAND is based on a polynomial nodal expansion m ethod and an improved quasi-static model. It can simulate transients and re activity accidents of boiling water reactors in critical and subcritical co nditions, and works efficiently on a vector computer. This paper describes the core neutronic model including treatment of extern al neutron sources and verification results tracing about a 10-min control rod operation during the BWR start-up examination. Calculated transient det ector responses had good agreement with experimental ones. The CPU time nec essary to calculate is of behavior for a full core (460 radial meshes x 30 axial meshes) with three energy groups was about 13 s on the HITACHI S-3800 vector computer when the shape function time step was set to 0.1-0.2 s.