VVER

The Water-Water Energetic Reactor (VVER), or WWER (from Russian: Водо-водяной энергетический реактор; transliterates as Vodo-Vodyanoi Energetichesky Reaktor; Water-Water Power Reactor) is a series of pressurised water reactor designs originally developed in the Soviet Union, and now Russia, by OKB Gidropress. Power output ranges from 70 to 1200 MWe, with designs of up to 1700 MWe in development. VVER power stations were, are or will be used by Armenia, Bangladesh, Belarus, Bulgaria, China, Czech Republic, Egypt, Finland, Germany, Jordan, Hungary, India, Iran, Slovakia, Ukraine, Russia and Vietnam.

The earliest VVERs were built before 1970. The VVER-440 Model V230 was the most common design, delivering 440 MW of electrical power. The V230 employs six primary coolant loops each with a horizontal steam generator. A modified version of VVER-440, Model V213, was a product of the first nuclear safety standards adopted by Soviet designers. This model includes added emergency core cooling and auxiliary feedwater systems as well as upgraded accident localization systems.

...
Wikipedia