<script>on mouseUpput the short name of this card into xTempput char 2 to 6 of xTemp & ".mov" into Movie--put Movieif Movie is not empty then-- put "Animations:" & Movie into pMovieplayMovie Movie,"Animations:"end ifend mouseUp</script>
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<text><span class="style10">nergy (4 of 6) 1. Coal, Oil and Nuclear</span><span class="style7"></span><span class="style10">Types of nuclear reactor</span><span class="style7">The first commercial nuclear power station, opened in 1956 at Calder Hall in Cumbria, England, was a </span><span class="style19">magnox reactor</span><span class="style7">. Magnox reactors are so called because their fuel - natural (unenriched) uranium - is clad in an alloy of magnesium and aluminum called magnox. They are cooled by carbon dioxide gas. In the 1970s a new generation of much bigger gas-cooled reactors was developed in Britain - the </span><span class="style19">advanced gas-cooled reactors</span><span class="style7"> or AGRs. Meanwhile, the Canadians have developed reactors that use 'heavy water' (deuterium oxide). Because heavy water (unlike ordinary water) absorbs few neutrons itself, reactors using it as moderator and coolant can operate with unenriched (and thus cheaper) fuel. The economy in fuel costs is offset, however, by the additional expenditure involved in producing heavy water.Today, the most widespread nuclear power plants are </span><span class="style19">light-water reactors</span><span class="style7">. The coolant and moderator - ordinary ('light') water - is readily available and cheap, but the uranium fuel has to be highly enriched. In the case of </span><span class="style19">boiling-water reactors</span><span class="style7"> (BWRs), the water is allowed to boil to make steam, which is less efficient at cooling and moderating the reactor, and so must be prevented from building up in the reactor core. In </span><span class="style19">pressurized-water reactors</span><span class="style7"> or PWRs, the water must remain at even higher pressure than is required in a BWR, so that it can reach useful temperatures without boiling.The world's reserves of uranium will not last for ever, but one sort of reactor could make them go a lot further - the </span><span class="style19">fast breeder reactor</span><span class="style7"> or FBR. The drawback of fast reactors is that they require the reprocessing of spent nuclear fuel both to extract plutonium (its main fuel) in the first place and to recover it from the uranium blanket. Reprocessing is a highly complex and expensive operation - as well as being unpopular with environmentalists. Nevertheless - and in spite of funds for FBR programs generally being cut back - prototypes exist, including one at Dounreay in northern Scotland, a large one on the River Rhone in France and one in India.</span></text>
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<text><span class="style10">he advanced gas-cooled reactor (AGR).</span><span class="style7"> In an AGR, the heat exchangers are located within the pressure vessel itself. The carbon-dioxide coolant is pressurized and heated up to 600 C (1112 F) or more as it is pumped through the core, which is made up of fuel rods filled with enriched uranium dioxide.</span></text>
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<text>ΓÇó ELECTRICITY IN ACTIONΓÇó ATOMS AND SUBATOMIC PARTICLESΓÇó THREATS TO THE ENVIRONMENTΓÇó ENERGY 2ΓÇó OIL AND GASΓÇó MINING, MINERALS AND METALS</text>
