how efficient is Nuclear power as a percentage? (references please)?

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  • 1 decade ago
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    There are several dimensions to this.

    Firstly at the mining stage, uranium ore must be mined and then processed to remove the uranium. Mining is not 100% efficient, and depending on the kind of ore and the mining method, up to 50% may be left in the ground.

    Processing will typically be 85 to 95% efficient.

    Then the uranium has to be enriched to increase the percentage of fissionable U235 to U238. Natural uranium contains 0.7% U235 -traditional power reactors require about 3.5% U235. This means that 80% of the uranium goes to the U238 waste pile.

    This material can however be turned into useful fuel in a "breeder reactor", which uses the radioactivity of the reactor to turn the Uranium 238 into fissionable plutonium. Because of fears of clandestine use to make bombs, very few breeder reactors have been built. Therefore most U238 is wasted or turned into minor uses based on its density.

    In the traditional reactor, not all the U235 is fissioned, because other elements build up which stop the reaction

    Finally in a traditional power station, the heat from the reactor is used to run steam turbines to turn the heat energy into kinetic energy and then electric energy.

    At the temperatures achievable with nuclear reactors, the heat engine is about 30% efficient.

    Thus in summary

    Efficiency of mining and processing 50%

    Efficiency of uranium useage 20 %

    Efficiency of enriched fuel useage 5%

    Efficiency of heat useage 30%

    In total therefore about 50% X 20% X 5% x 30% = 0.15% of the original energy available in the uranium in the ground is turned into useful energy.

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