Artificial radiation, i.e. radiation caused by human activities, adds to
the naturally occurring radiation. In the Federal Republic of Germany, it
is on average 1.50 mSv per year, about 95% of which is attributable
to medical x-rays, nuclear medicine, and radiation therapy. The remainder
is due to nuclear facilities (0.01 mSv), research activities, technical and
household applications (0.01 mSv), the Chernobyl accident (0.02 mSv), and
to fallout from nuclear weapons testing (0.01 mSv).
BSH (DHI until 1990) has carried out measurements of artificial radioactivity
in the marine environment since 1961. In the 1950s and 60s, primarily
the atmospheric nuclear weapons tests led to global contamination. Discharges
of artificial radionuclides into the North Sea from the nuclear fuel reprocessing
plants in La Hague (France) and Sellafield (Great Britain) reached a maximum
in the 70s. The reactor accident at Chernobyl in 1986 released artificial
radioactive isotopes into the atmosphere which were transported over thousands
of kilometers, contaminating large areas by radioactive rainfalls. The fallout
consisted mainly of radioactive iodine and caesium, but also included strontium,
molybdenum, barium, and the little known ruthenium. Because of its high
percentage in the total spectrum of specific Chernobyl nuclides and its
longevity, the isotope caesium-137 can be used as a radionuclide tracer.
In the Western European countries, the radiation exposure attributable to
the Chernobyl accident meanwhile has decreased to negligible levels. Their
contribution to the total radiation exposure is only 0.02 mSv per
year. However, in some areas near Chernobyl in the Ukraine, the absorbed
dose rate still is so high that those areas are considered uninhabitable.