Emergency cooling system in a reactor

Object: To cool a core by securely operating a heat pipe when fuel is replaced or when the core is urgently cooled. Structure: A heat pipe is annularly arranged upwardly of a reactor container in a manner so as not to hamper insertion of a fuel rod. This heat pipe is connected to a heat radiating system and is sealingly filled with Li, Na, K, Nak or the like as a heating medium. In normal time, inert gases are sealed in the heat pipe to prevent vaporization of the heating medium, thus preventing heat discharge. Also, in emergency, the inert gases are extracted so that the heating medium abstracts heat from the interior of the reactor and is vaporized, condensed in the heat radiating system and recirculated within the heat pipe by means of the force of capillary action. Such vaporization, condensation and recirculation are repeated to cool the interior of the reactor. (Kamimura, M.)