SOFTENING OF THERMAL SHOCK DURING START-UP OF EMERGENCY COOLING SYSTEMS FOR THE CORE OF VVER-1000 REACTORS

摘要

The requirement that the temperature of the boron solution in water containers of the emergency core-cooling system (ECCS) and in reserve tanks holding the boron solution be maintained at no less than 55℃ to provide brittle strength to the housing of the VVER-1000 reactor in an emergency where heat-transfer medium is lost and water is subsequently delivered from the ECCS is discussed. The ineffectiveness of the existing design for heating of the water containers in the ECCS is demonstrated experimentally. Deficiencies in the heating systems for the reserve tanks of boron solution, which are employed in the design of the V-428 reactor plant, are indicated. Methods are proposed for heating of the water containers and tanks with the organization of natural circulation in the containers (tanks).