Heavy water moderated pressure tube type reactor

Purpose: To minimize the damaging probability of the reactor core due to overheat to zero by emergency cooling systems constituted with passive equipments. Constitution: In a heavy water moderator pressure tube type reactor, fuel assemblies are contained in a pressure tube and pressure tubes are in contact with heavy water by way of the calandria tube. After-heat generated in the reactor core is propagated through the radiation conduction from fuel rods to pressure tubes, from pressure tubes to calandria tubes and then through convection to heavy water. In a case where heavy water cooling system is actuated, heavy water boils into steams and flows into an injector. Since cooling water is sucked by the injector and sent into a calandria tank, water level in the tank can be maintained to remove after-heat with water in the tank. In this way, since the emergency cooling circuit is constituted only with passive elements, possibility for the occurrence of severe reactor core damages can be reduced extremely. (Kamimura, M.)