Development of a Containment Code KUPOL-M for a Substantiation of the VVERs Accident Localization System Functions

Computer code KUPOL-M is made for analysis of thermodynamic parameters of medium within full pressure containment for NPPs with VVER under LOCA conditions. The analysis takes into account the effects of non-stationary heat-mass transfer of gas-drop mixture in containment compartments with natural convection, volume and surface steam condensation in the presence of non-condensable, heat-mass exchange of compartment atmosphere with water in sumps. The model for hydrogen deflagration is capable of evaluating gas temperature and pressure in specified containment compartments. The operation of the main safety systems is simulated in KUPOL-M code including spray system, hydrogen catalytic recombiners, emergency core cooling pumps, valves and fan system. Vast program of the code testing and verification is performed at each stage of development. Verification matrix of KUPOL-M code comprises separate effects experiments (e.g. volumetric or surface steam condensation) as well as integral tests, reproducing at some extent conditions of design basis and severe accidents of LOCA type. Main results of the code verification are presented. (authors)