Environmental Engineering Reference
In-Depth Information
The biggest problem turned out to be the ability to produce signifi cant quantities of
uranium-235 to maintain a chain reaction. If metallic uranium is refi ned from
uranium ore, there is a 99.3% probability that it will consist of heavy uranium-235.
This is practically useless for producing a bomb. It even has the characteristic of
decelerating and absorbing neutrons, thus bringing any kind of chain reaction to a
halt. Only 0.7% of available uranium consists of uranium-235, which must be
enriched proportionally higher to create a chain reaction. No separation between
uranium-235 and uranium-238 can be achieved by chemical means because chemi-
cally both isotopes are totally identical. Consequently, other solutions had to be
sought. Ultimately, this separation succeeded through the use of a centrifuge because
the isotopes have different masses.
The Manhattan Project cost more than US$2 billion between 1939 and 1945. The
desired results were fi nally achieved under the direction of the physicist J. Robert
Oppenheimer: on 16 July 1945, two months after the capitulation of Germany, the
fi rst test of the atomic bomb was carried out in the US state of New Mexico. Using
the bomb on Germany was no longer up for discussion, but shortly before the end
of the Second World War the atomic bomb was dropped on the Japanese cities
Hiroshima and Nagasaki - with the well-known aftermath.
The non-military use of nuclear energy came some years later. Although physicists
like Werner Heisenberg and Enrico Fermi had been conducting tests in reactors
since 1941, it was not until December 1951 in Idaho that the research reactor EBR
1 succeeded in generating electric current using nuclear energy.
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www.iaea.org/programmes/a2/
IEA Power Reactor Information System
■
www.facts-on-nuclear-energy.info
Nuclear Power Fact File Poster
Campaign
Unlike the uncontrollable chain reaction that occurs when an atomic bomb explodes,
nuclear fi ssion in a nuclear power station should be controllable. Once a chain reac-
tion has started, the number of new neutrons resulting from the nuclear fi ssion must
be kept to a limit. Each splitting of a uranium nucleus releases two to three neutrons,
only one of which is allowed to split another nucleus. Control rods that capture the
neutrons reduce the number of neutrons released. If this number is too high, the
process gets out of control. The nuclear power station then starts to act like an atomic
bomb and an uncontrolled chain reaction occurs. Technically, and this was the
leading view at the time, nuclear fi ssion can be controlled and undesired reactions
eliminated.
The early euphoria that came with the use of nuclear energy died down when an
accident occurred with a reactor on 28 March 1979 in Harrisburg, the capital of the
US state of Pennsylvania. Large amounts of radioactivity escaped. Many animals
and plants were affected and the number of stillbirths among the nearby population
increased dramatically after the tragedy.
On 26 April 1986 another serious accident occurred with a nuclear reactor in
Chernobyl, a city in the Ukraine. What was thought to be impossible happened: the
