The Full Form of VVER is Voda Voda Energo Reactor.

VVER is acronym for Voda-Vodyanoi Energetichesky Reaktor — Russian for a pressurized light water reactor which is water-cooled and water-moderated. This is Russian version of Pressurised Water Reactor (PWR).

The water-water energetic reactor (WWER), or VVER (from Russian: водо-водяной энергетический реактор; transliterates as vodo-vodyanoi energetichesky reaktor; water-water power reactor) is a series of pressurized water reactor designs originally developed in the Soviet Union, and now Russia, by OKB Gidropress. The idea of a reactor was proposed at the Kurchatov Institute by Savely Moiseevich Feinberg. VVER were originally developed before the 1970s, and have been continually updated. As a result, the name VVER is associated with a wide variety of reactor designs spanning from generation I reactors to modern generation III+ reactor designs. Power output ranges from 70 to 1300 MWe, with designs of up to 1700 MWe in development. The first prototype VVER-210 was built at the Novovoronezh Nuclear Power Plant.