A Science View


9 January 2012


A Science view.

So far Fossil Fuel and Renewable generation has been considered.   The third option is the nuclear route.   Historically, this is the most modern of the power generators.

To start at the beginning, the fission of uranium was discovered in the mid 1930s.   It was of great interest only to the physics academics at the time, but consideration of the immense amounts of energy released in the process gave rise to much speculation.   Rather than peaceful uses, it was of course its military application that gave rise to the wartime and huge post-war projects in  both civil and military uses.

In the UK, the military work was pursued with the construction of the reactors at Windscale.   The peaceful uses were expanded with the formation of the Atomic Energy Authority in the mid 1950s.   The UK was the first nation in the world to open a nuclear power station, at Calder Hall in Cumbria, which was opened by the Queen on the 17th of October 1956.   I remember well the gathering of staff in the Conference Room of the ChemistryBuilding at Harwell in Oxfordshire to watch the Opening on "steam" television.

As an illustration of the amount of energy released in nuclear reactions rather than chemical ones, that is fission compared with burning; the burning of one atom of carbon (coal) releases one unit of energy, but the fission of one atom of uranium releases 60,000,000 times as much.   Hence the small amounts of fuel consumed;  it is powerful stuff!!

Certainly the uranium atom is some twenty times as heavy as carbon, so on a weight basis this reduces to 3,000,000.   And the uranium "isotope" which is used is a little less that one percent of natural uranium, reducing the ratio to 30,000, tonne for tonne.   There is however an abatement of this last reduction as a proportion of the "inactive" uranium is converted to fissionable material within the reactor.

Reactors themselves have, since the whole heating cycle is totally contained within central core, which is never exposed, a rather aseptic ambience.   As there if no combustion product, they get no untidier than an office block, and remain just as clean.

The experience of the French is worthy of note.   The Oil Crisis of 1973 sparked the decision of President Messmer to embark upon the nuclear programme France has today.   Some 83% of electricity in France is generated in nuclear power stations.   France has the Alps which give rise to a large hydro-electric generating capacity, about 12% of her electricity is produced in this way.

The French story has been dominated by the use of pressurised water reactors.   In these the reactor core is cooled by water at high pressure, which in turn produces steam which is used in steam turbines to power the electricity generators.   These power stations can operate in a more flexible fashion than our gas cooled units, enabling the high proportion of the county's electricity to be nuclear.   The huge experience which the French have in this field now results in the French companies being allotted the contracts for our new-build power stations in this country.   The EPR to be built at Hinckley point is rated at 1640 MW.   By comparison, a wind turbine on shore rated at 4 MW, would be a large machine, illustrating the very dilute nature of wind energy.

To be continued.

Richard Phillips

Topics: edie
Tags: | coal | fashion | gas | nuclear | war | water | wind energy
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