Increased inflow of saline solution in front of chamber 8
According to most recent measurements, the volume of the radioactively contaminated saline solution being collected in front of emplacement chamber 8 on the 750-m-level of the Asse mine has increased from four to eight litres per day compared to the volume measured half a year ago. This must be considered in relation to the current, daily inflow of uncontaminated saline solution amounting to approximately 12,000 litres. The radiological analyses carried out on a regular basis show that the activity concentration of caesium-137 has increased from 2.4 to about 4.3 kilobecquerel per litre in the same period of time. Classification of this value: Permitted is the handling of a radioactivity concentration which is about 180 times higher. Those solutions that need to be pumped out of the collecting point are intermediately stored underground in containers.
No need results from the detected increase for a modification of the protection concept or, respectively, the plans for the first step of fact finding, as the BfS - as a precaution - had already based its calculations on considerably higher contaminations in order to be able to respond to unfavourable developments, too. The same applies to precautionary and emergency measures for the protection of staff and population, which were presented by the BfS in March 2010. Regarding the retrieval of the radioactive waste the BfS is currently carrying out a finding of facts to be able to state the necessary safety requirements for the procedure. The findings in front of chamber 8 are taken into account.
What is new about this is that probably for the first time, uncontaminated solutions from the overburden flow through an emplacement chamber where radioactive waste is stored. On their way they take up radionuclides. In chamber 8, 11,278 waste packages containing low-level radioactive waste are stored.
The solution has been observed since 1991. Whether the volume of contaminated solution will continue to increase, cannot be prognosticated. The increased inflow of saline solution through emplacement chamber 8 is probably associated with the backfilling of the adjacent chamber 9 (where no waste is stored) by the former operator HMGU which had been responsible until 2008. In front of chamber 9 different volumes and chemical compositions of the influent saline solutions were already observed in autumn of 2009. The increase of the inflow of 4 litres per day in front of chamber 8 recently detected does not indicate a possible overall increase in the inflow of saline solutions into the Asse.