tank reactor[′taŋk rē¦ak·tər]
a nuclear reactor whose core is encased in a sturdy vessel (tank). In most cases, the coolant in a tank reactor also acts as the moderator (ordinary or heavy water, or organic liquids). In some reactors different substances are used as coolants and moderators. For example, the EDF tank reactors (France) use carbon dioxide and graphite.
A tank reactor generally consists of a cylindrical vessel with a cover, which contains a removable structure (cage) with the reactor core. The coolant enters the core, which consists of fuel assembly elements, from below. The reactor core contains movable control rods, whose drive mechanisms have hermetically sealed outlets in the top or bottom of the reactor tank. The hot coolant is discharged through outlets in the upper portion of the tank.
Owing to their relative simplicity, compactness, and high-energy flux from the core, tank reactors are extensively used in nonmilitary nuclear power engineering. There are also tank reactors based on fast and thermal neutrons, the latter being the most widespread. A tank reactor with a 1,375-MW output is in operation at the Novovoronezh Atomic Power Plant in the USSR. In this reactor, ordinary water under a pressure of 12.5 meganew-tons per m2 (125 kilograms-force per cm2) serves both as the coolant and moderator. The water in the core is heated in the range of 269°−300°C and flows to the steam generators. Forced circulation of the water is used. In the USA the following tank reactors are in operation at atomic power plants: pressurized-water reactors (Shippingport, Yankee) and boiling-water reactors (Dresden, Oyster Creek). Tank reactors with graphite moderators and gas coolants are widely used in Great Britain (Calder Hall, Hinkley Point).
V. P. VASILEVSKII