Environmental Engineering Reference
In-Depth Information
1.1.4 Nuclear Power - Split Energy
In December 1938 Otto Hahn and Fritz Strassmann split a uranium nucleus on a
simple laboratory bench at the Kaiser-Wilhelm Institute for Chemistry in Berlin-
Dahlem, thereby laying the foundation for the future use of nuclear energy. The
laboratory bench can still be admired today at the Deutsches Museum in Munich.
In the experiment a uranium-235 nucleus was bombarded with slow neutrons. The
nucleus then split and produced two atomic parts, krypton and barium, as well as
two or three other neutrons. With a large quantity of uranium-235, these new neu-
trons can also split uranium nuclei that in turn release neutrons, thus leading to a
chain reaction. If enough uranium is available, the uncontrolled chain reaction will
create an atomic bomb. If the speed of the chain reaction can be controlled, uranium-
235 can also be used as fuel for power stations.
A so-called mass defect exists with nuclear fi ssion. The mass of all the little pieces
after the fi ssion is less than that of the original uranium nucleus. A complete fi ssion
of one kilogram of uranium-235 produces a mass loss of a single gram. This lost
mass is then completely converted into energy. An energy mass of 24 million kilo-
watt hours is thereby released. Around 3000 tons of coal would have to be burnt to
release the same amount of energy.
After Hahn's discovery the use of nuclear energy was promoted mainly by the mili-
tary. Albert Einstein, who emigrated to the USA in 1933 to escape Nazi persecution,
sent a letter to US president Roosevelt on 2 August 1939 warning him that Hitler's
Germany was making a serious effort to produce pure uranium-235 that could be
used to build an atomic bomb. When the Second World War broke out on 1
September 1939, the American government set up the Manhattan Project with the
aim of developing and building an effective atomic bomb.
Germany as an Example of Nuclear History
The Paris Treaty of 5 May 1955 allowed Germany non-military use of
nuclear energy. Expectations for the nuclear industry ran high. A separate
ministry for nuclear energy was created, and the fi rst minister was Franz Josef Strauss.
On 31 October 1957, Germany put its fi rst research reactor, called the nuclear egg, into
operation at the Technical University in Munich. In June 1961 the Kahl nuclear power
station fed electricity into the public grid for the fi rst time. In 1972 the Stade and
Wuergassen commercial nuclear power stations began to provide electricity, and with
Biblis the world's fi rst 1200 megawatt block went into operation in 1974. In 1989 the
last new power station, Neckarwestheim, was connected to the grid. Until that point the
federal government had invested over 19 billion euros in the research and development
of nuclear energy. However, public concerns about the risks of nuclear energy continued
to grow and prevented the building of new power stations. In 2000 Germany fi nally
renounced the use of nuclear power, following the example of Austria, Italy, Sweden
and Belgium. The last nuclear power station in Germany is scheduled to be disconnected
from the grid in 2023. Despite more than 50 years of nuclear energy use in Germany,
the problem of end storage for highly radioactive waste has still not completely been
resolved.
