Emergency core cooling systems

Purpose: To positively supplement coolants thereby improve the reliability upon loss of coolant accidents in the ECCS of water-cooled type reactors such as BWR or PWR type reactors. Constitution: An ECCS in which a water storage tank for the system is disposed at a position higher than the reactor pressure vessel and they are connected by means of a water injection pipeway equipped with an injection valve, is adapted to open the injection valve upon loss of coolant accidents to supply the coolants gravitationally to the inside of the pressure vessel. The water storage tank is constituted as a tightly closed type pressure contained and connected by way of a pressure equalizing tube with the reactor pressure vessel to keep the same extent of pressure between them. As a result, the coolants in the water storage tank can be supplied stably and smoothly irrespective of the pressure in the reactor pressure vessel and positively cool the reactor core to surely prevent the overheat phenomenon. Further, the time required for the recovery of the reactor water level can be shortened. (Kamimura, M.)