Emergency core cooling system

Purpose: To improve the reliability and the safety of water feeding and core cooling, as well as the feedwater controllability both in usual operation and in emergency case in a BWR type reactor by providing the emergency core cooling function and the automatic pressure reduction function for the feedwater system to a core coolant recycling path. Constitution: Upon loss of coolant accidents in the reactor, condensates in a condensator are supplied with no interruption to a water drum to cool the reactor core by opening an emergency feedwater switching valve and a water drum injection valve and driving pumps operated in the usual operation and in the emergency case by an independent power source mechanism. A recycling control valve and minimum flow control valve are operated depending on the scale of raptures in coolant pipeways. A warming unit pressure releaser is employed for suppressing the pressure of the steam drum and for heating the condensator. The reactor core can thus be cooled by a cooler at high reliability actuated both in the usual operation and in the emergency case with no requirement for additional provision of an emergency core cooling system. (Seki, T.)