Investigation of heat transfer and hydraulic resistance during the flow of water with supercritical parameters in application to reactor facilities

Together with evolutionary development of light-water vessel reactor facilities with subcritical pressure, an innovative path for the development of VVER with the coolant pressure increase above a critical value has been under study since the 1960s. Of greatest interest is the possibility of increasing the efficiency of a power- generating unit in a nuclear power plantfrom 30-35% at subcritical pressure to 44-45%, reached by the same time at heat and power plants operating at steam pressure ~24 MPa and temperature 560°C and higher. However, the problems which must be solved in this approach delayed the development of reactor facilities with supercritical pressure. One problem is developing reliable methods for calculating the temperature of fuel-element cladding and the hydraulic resistance with water flow at supercritical pressure in the core. This problem is also important because according to current assessments the materials in the core will work at the limit of their possibilities. Possible approaches to a solution of this problem are examined.