Long-Term Operation of VVER Power Plants

Abstract

The VVER reactors are light-water-moderated and water-cooled i.e. pressurized water reactors (PWRs). The name comes from Russian “うそおそ-うそおяせそこ эせかちえかてけчかつさけこ ちかаさてそち” which transliterates as Vodo-Vodyanoi Energetichesky Reaktor (Water-Water Energetic Reactor WWER but the Russian type acronym VVER is more often used). The VVERs were developed in the 1960s. There are 52 Russian designed VVER-type pressurized water nuclear power plants operating in the world today under of 437 nuclear power plants (for the latest operational statistics VVER plants see IAEA PRIS database www.iaea.org). The cumulative time of safe operation of VVER reactors currently exceeds 1200 reactoryears. The first three VVERs were built in Russia and in Eastern-Germany in 1964-1970 and they were operated up to 1990. The first standard series of VVER have a nominal electrical capacity of 440 MW and the second standard series have the capacity of 1000 MW. There are two basic types of VVER-440 reactors, which are based on different safety philosophies. The VVER-440/230 type is a Generation I design while the VVER-440/213 is representing already the Generation II reactor design with reduced pressure containment. Outside Russia all VVER-440/230 type plants of the standard design are already shut down. There are two specific VVER-440 designs in operation the Loviisa NPP with reduced pressure western type containment and the Armenian Medzamor NPP. In the VVER 1000 MW series, there is a gradual design development through the five oldest plants (small series) while the rest of the operating plants represent the standardised VVER-1000/320 model. The VVER-1000 units commissioned recently and those currently being under construction are improved versions of the VVER-1000/320; for example the Tianwan (China) plant with AES-91 type units and the Kudankulam (India) plant with AES-92 type units. New VVER models e.g. the AES-2006 design is being considered for future bids. The older types of VVER-1000 are of Generation II while the new evolutionary models of large VVER already exhibit Generation III features. The design operational lifetime of the VVER plants is generally 30 years. Exceptions are only the newly designed and operating VVER-1000 units with 50 or 60 years of designed operational lifetime. A great majority of VVER plants are aged nearing the end of the design-lifetime. Except Russia the VVER operating countries are dependent on nuclear power production for example the Nuclear Power Plant Paks in Hungary provided 40 % of domestic production in 2010. The nuclear power capacities in these countries ensure the necessary diversity of power generation and contribute to the security of supply. Therefore, the VVER owners in Central and Eastern Europe intend to keep their plants in operation via implementing plant lifetime management (PLiM) programmes with the intention of