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NUCLEAR REACTORS

Nuclear energy is an energy that requires a high level of technology and a major initial investment capacity.
At present, therefore, it has essentially been developed in the industrialised countries: Western Europe, the ex-Soviet Union, North America and Japan. But it is progressing in emerging countries such as China and India, whose energy requirements are enormous.

As in 2008, 439 nuclear reactors are operational worldwide, spread throughout some thirty countries, including 15 OECD (Organisation for Economic Co-operation and Development) members. 42 reactors were under construction and 5 were in phase of dismantling. Of the 16 reactors whose construction was started in 2007 or 2008, 6 are situated in China, 4 in South Korea and 3 in Russia.

Several lines of reactor design exist, differentiated by the type of fuel employed, the fluid used to transport the heat (the thermal carrier), and the type of moderating fluid used (to slow down the neutrons).

Another type of reactor was developed earlier in France, the graphite-gas reactor (UNGG), using natural uranium, graphite as the moderator fluid (to slow down the neutrons) and carbon monoxide gas as the cooling agent. These are known as first generation reactors.

Other lines exist, using slightly different technologies:

– The boiling water reactor: the thermal transport fluid is water as in the PWR (but the water boils, because it is not under pressure other than atmospheric pressure), the fuel is enriched uranium (the BWR line, or RBMK in the ex-Soviet block);

– The rapid neutron reactor (RNR), also called a super generator: the neutrons are not slowed down and so there is no moderator fluid. The fast-moving neutrons combine with uranium 238, a non-fissile product, and are transformed into plutonium 239, a fissile product. The cooling fluid is sodium. The French Superphenix reactor uses this technology;

– The heavy water reactor (this is the type used in Canada): heavy water (deuterium oxide) is used as the moderator to slow down the neutrons. These reactors work with natural uranium;

World electricity generation from nuclear energy by country (2006) and the share of nuclear energy in total electricity generation

Continent 2006 Production
(GKWh)
World electricity generation from nuclear energy by country (2006)
North America 891 18%
Central and South America 21 2%
Europe 967 27%
CIS 232 17%
Middle East 0 0%
Africa 10 2%
Asia 540 9%
Total 2,660 15%