Development of a RBMK-1500 Reactor Model Based on a Coupled Version of The Thermal - Hydraulic Code ATHLET and the 3D Neutronics Code QUABOX/CUBBOX

The codes ATHLET and QUABOX/CUBBOX were developed by German company GRS for light water reactors. For RBMK-1500 NPP a model for the simulation of transients was developed, using a coupled version of the thermal - hydraulic system code ATHLET and the 3D core model QUABOX/CUBBOX. The coupled code system was applied to the analysis of an ATWS event with 'loss of feedwater'. There are local differences, which are influencing the transient behaviour and can be taken into account only by the 3D core model. The LAC system can only compensate the strong reactivity feedback by the fuel temperature rise for a short time. The results of 3D -kinetics and point kinetics models were compared. (author)