Reduction of initial steam parameters to extend the term of operation of units with VVER-440

Lowering the pressure of main steam of 44 to 22 Bar permits to reduce the pressure in the primary circuit from 125 to 65 Bar without compromising the nuclear safety. This leads to significant reduction of tension strength in the metal all the elements of the primary circuit and eases nonstationary regimes. The pressure drop in the I and II circuits allows the average temperature in the primary circuit to be reduced by 50^oC. This, in turn, will allow additional reactivity of nuclear fuel (temperature coefficient of reactivity). In other words, work with lower average temperature of the coolant in the primary circuit will lead to prolongation of the fuel cycle and deeper fuel burnup. In this way it is possible to improve the integral efficiency of the unit and to limit the deterioration of the technical- economic indicators