Accident analysis of NPP with WWER reactor by means of DYMO and DYNAMIKA codes

The DYMO-VVER code development procedure and the DYNAMIKA-GKAEh code modification are described. Thesecodes are used in INR-Rzhezh to compute transition processes during primary and secondary loop accidents, e.g., at failure of the main circulation pumps, turbogenerators etc. The power plant mathematic model includes thermodynamic and hydrodynatic descriptions of all processes taking place in theconsidered plant components. The major components are: the reactor, presented by models of heat release, heat transfer, coolant flow in the core and mixing chambers; the coolant pipeline; the main circulation pumps; the volume compensator; the steam generators; the main steam collector; the steam lines; the reactor control members; the primary loop pressure, feed water flow rate and secondary loop pressure regulators; steam turbine. As an example, the calculation results for a transition processes after the failure at 75% reactor power level of two out of 6 operated main circulation pumps are given. Calculation data are compared with experimental ones obtained during tests at the 1st unitpower start-up of NPP V-1. Sufficiently high accuracy of computerized simulation is noted