Thermal-Hydraulic Experimental Studies on Safety and Efficiency of NPP with VVER

New design of nuclear power plant with pressurized water reactor entitled “NPP-2006” is under progress in Russia. It is evolutionary type of design based on existing NPP with VVER-1000 reactors. Intensive thermal-hydraulic experimental activities support design development. They are aimed at increasing of NPP safety and efficiency. Integral test facility PSB-VVER, modeling main components of primary system of VVERs, is the main tool for experimental studies. Volumetric-power scale of the test facility is 1:300, elevations are 1:1. A core model is an assembly of 168 fuel rod imitators. About 20 experiments at the PSB-VVER have been performed to generate experimental data base for validation of best estimate thermal-hydraulic system codes for application to analyses of VVERs transients and accidents. An important direction of PSB-VVER experimental activities is connected with the development and verification of accident management procedures. 15 experiments have been conducted to support development of such procedures. For new plant design (hydroaccummulators, operating under low pressure) is under experimental studies at the PSB-VVER. The experimental program also includes the approach, based on investigations of local thermal-hydraulic parameters in the fuel rod imitators assembly at the large-scale test facility. This approach is supposed to decrease a level of design conservatism and to enhance NPP efficiency.