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Reactors |
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The nuclear reactors being offered today are essentially evolutionary developments of well-proven designs, having withstood the tests of time since the 1950s. Reactor design is commonly discussed in terms of generations and today’s models are referred to as Generation III. These offer several improvements on the previous Generation II designs, on economy of construction, safety and operating costs. There is also currently a significant amount of international R&D work going into so-called Generation IV designs, but these are unlikely to become commercialized until the 2020s, at the earliest.
Nearly 90% of existing reactors are light water reactors (LWRs) of which there are two main groups, pressurized water reactors (PWRs) and boiling water reactors (BWRs). All of the currently operating 104 US reactors, for example, are of these two types. The most significant alternative design is the pressurised heavy water reactor (PHWR) of which the CANDU design is the best known. With one exception, all of the new reactors being offered today fall into these types. Other reactor models currently in operation, such as the British gas cooled reactors and some remaining RBMK reactors in the former Soviet Union, are being gradually phased out and will not form the bases for any new designs. All of the latest models mentioned are large reactors (typically today of 1000 MWe and above) but there are some high temperature gas cooled reactors (HGRs) now being developed by China and South Africa (the PBMR) which are much smaller at only 200 MWe. These may be particularly suitable for developing countries without strong power grids, but are unlikely to be commercialized much before 2020.
The superb safety record achieved by the current generation of reactors has clearly increased confidence in them forming the basis of a renewed nuclear build program. Many initiatives were taken in the aftermath of the Three Mile Island and Chernobyl accidents to impose a strong safety culture throughout the world industry, led by the International Atomic Energy Agency (IAEA) and the World Association of Nuclear Operators (WANO).
The marketing of new major reactors has today become concentrated in a few major companies, but with some smaller players also capable of undertaking international projects. Areva, GE-Hitachi and Westinghouse-Toshiba are the three majors, and are at the centre of the proposals to build new reactors both the United States and United Kingdom. Atomstroyexport of Russia, AECL of Canada and KOPEC of Korea are also competing for major reactor contracts, having established reputations with the nuclear programs in their own countries.
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