The WWER-1000 is a four-loop pressurized water-cooled reactor that incorporates active and passive safety systems, and partly adapts to Western standards the substantial design and operating experience accumulated in the Russian Federation in the last 50 years. It is currently operating in the Russian Federation and under construction in China, India and Iran. The WWER-1200 is a scaled-up version of the WWER-1000. Like its predeces­sor, it is a four-loop design with horizontal steam generators, which have a track record of providing the longest operating life. The WWER-1200 also includes active and passive safety systems, a double containment and severe accident mitigation systems, such as a core catcher. Both the WWER-1000 and WWER-1200 cores use the characteristic hexagonal fuel assemblies (as opposed to the traditional square ones used by all other water-cooled reactor designs) and would allow for the possibility of using MOX fuel. It is currently under construction in the Russian Federation and planned for construction in Bulgaria. Since there are some WWER-1000 and WWER — 1200 units currently in operation or under construction, this design has a proven construction schedule, as well as some operating experience.

The following designs, also ordered alphabetically, are also evolutionary concepts but their current stage of development indicates that they would

only be available for deployment in the middle-term. The detailed technical data for all these designs can be found in ARIS (IAEA, 2010).