Again no enhanced radioactive exposure
All samples taken in the vicinity of the Asse mine are harmless – No limits have been exceeded despite of more strict methods of calculation
In the past year, too, no enhanced radioactive exposures were measured in the vicinity of the Asse repository in the administrative district of Wolfenbüttel. As the Federal Office for Radiation Protection (BfS) has informed, four institutions examined nearly 600 samples independently. The examinations did not show any exposure of soil, air, water and agricultural produce and of needles and foliage. The measurements carried out in 2010 have not shown any significant changes. The various measurements are currently quality-assured, summarised and then published in an annual report. Furthermore, measurements are directly available at all times.
According to statements by the BfS, the Asse GmbH examined altogether 360 samples in 2009, the Lower Saxony Water Management, Coastal Defence and Nature Conservation Agency (NLWKN) examined 44 samples and the Agricultural Examination and Research Agency (LUFA) North-West examined 194 samples. Furthermore the BfS itself examined drinking water samples at the municipality of Kissenbrück on a monthly basis. All measured results were harmless and in the range of the natural environmental radioactivity, a BfS spokesman said. All samples proved to be altogether clear with respect to possible radionuclides from the Asse repository. The measured results show that levels in the vicinity of the Asse can be compared with those from other areas of Germany.
The samples had been taken within a radius of one, five and twenty kilometres around the Asse. Among others, the cities of Braunschweig, Königslutter, Schöningen, Osterwieck and Salzgitter are located within a radius of 20 kilometres, the cities of Wolfenbüttel and Schöppenstedt are located within a radius of five kilometres.
The samples were examined for so-called gamma radiation, additionally for the activity of Strontium-90, water samples also for tritium. Only natural radionuclides could be detected which always occur in the environment as well as artificial radionuclides that had been released as a result of the Chernobyl accident or of the above-ground nuclear weapons’ tests of the 1960s. A contribution of discharges from the Asse, on the other hand, could not be measured.
It was further stated that it did not come as a surprise that no enhanced radioactivity contamination could be found in agricultural produce from the vicinity of the Asse. Currently there are no discharges of radioactive substances with waste water. Those radioactive substances that are discharged into the environment in a controlled way with the exhaust air of the facility are very far below the licensed limit.
To be able to calculate and control the possible radiation exposure to the population, the radioactivity discharged with the exhaust air of nuclear facilities is permanently monitored. From these measured values the potential radiation exposure to the population can be calculated with the help of mathematical models. Among others, such models simulate how the radioactive substances can get into the air and deposit in the environment. When calculating the dose levels unfavourable model assumptions were chosen and critical parameters were selected deliberately. Thus it is ensured that the calculated radiation exposure is on no account underestimated. The calculated values are therefore always clearly higher than the actually occurring radiation exposures.
Since the beginning of 2009 the Asse mine has been treated as a repository for radioactive waste according to nuclear law. Thus the BfS has become the operator of the Asse. As a result of this, also the calculation method was adapted to the procedure to be applied to nuclear facilities. Compared with earlier calculations, more unfavourable assumptions were again taken as a basis. Compared with values reported earlier, this results in calculated potential radiation exposures that are about three times as high as the values that had been calculated and reported until 2008. However, also the newly calculated values are far below the permissible limits.
The determined upper level of the effective dose in the vicinity of the Asse II mine amounted to 0.016 millisievert (mSv) in 2009 for adults, to 0.022 mSv for infants of one to two years and to 0.026 mSv for babies. That is 5.3 per cent, 7.3 per cent and 8.7 per cent of the limit according to the provisions of the Radiation Protection Ordinance. The determined dose levels were published in the annual report of the federal government to the Bundestag on environmental radioactivity and radiation exposure.