Asse II mine

The Asse II mine (Schacht Asse II) is a former salt mine used as a deep geological repository for radioactive waste in the Asse Mountains of Wolfenbüttel, Lower Saxony, Germany.

The Asse II mine was developed between 1906 and 1908 to a depth of 765 metres (2,510 ft). Initially extracting potash, the mine also produced rock salt from 1916 to 1964. Potash production ceased in 1925. Between 1965 and 1995, the state-owned Helmholtz Zentrum München used the mine on behalf of the Federal Ministry of Research to test the handling and storage of radioactive waste in a repository. Between 1967 and 1978 low-level and intermediate-level radioactive waste were emplaced in 13 chambers in the Asse II mine. Two chambers are located in the middle part and ten in the southern flank of the mine at depths from 725 to 750 metres (2,379 to 2,461 ft) below surface. Between 1972 and 1977, exclusively medium-level radioactive waste was emplaced in a chamber on the 511 metres (1,677 ft) level. Research was stopped in 1995; between 1995 and 2004 cavities were filled with salt. After media reports in 2008 about brine contaminated with radioactive caesium-137, plutonium and strontium, politicians accused the operator, Helmholtz Zentrum München – German Research Center for Environmental Health, of not having informed the inspecting authorities. On 8 September 2008, the responsible ministers of Lower Saxony and the German government replaced the operator with Bundesamt für Strahlenschutz (BFS) - the Federal Office for Radiation Protection. In April 2017, operator responsibility for Asse II was transferred from BFS to the Supervisory Board of the Bundes-Gesellschaft für Endlagerung mbH (BGE), under the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety.

Asse II contains intermediate radioactive waste (LILW-LL, Long lived) and low level waste (LILW-SL, Short lived), defined as waste without significant heat generation. After public speculation about the presence of radioactive high level waste in the mine the old documentation was once again reviewed in August 2008:

125,787 drums of low level radioactive waste stored from 1967 to 1978 in various chambers at the 750-metre (2,460 ft) level. The containers are mostly drums with volumes from 100 to 400 litres (26 to 106 US gal) or concrete vessels. The declared total activity at the time of storage was 1.8·1015 Bq. Around 50% of the containers came from the former Forschungszentrum Karlsruhe nuclear reprocessing plant, 20% from nuclear power plants and 10% from the former Jülich Research Centre. The containers typically included mixed and laboratory waste, rubble, scrap, filter residues and combustion residues. Liquids such as evaporator concentrates, sludges, oils, resins and solvents had to be bound as solids. According to some former employees barrels of liquid waste were accepted in the early days of storage. 1,293 containers with medium-level radioactive waste stored from 1972 to 1977 in Chamber 8a at the 511-metre (1,677 ft) level. Only 200-litre (53 US gal) roll drums were permitted with waste fixed in concrete or bitumen. The declared total activity at the time of storage was 2.8·1015 Bq. About 97% of the packages (over 90% of the total activity inventory of Asse II) originated from the Karlsruhe reprocessing plant. Some of the Karlsruhe drums contained waste from the reprocessing plant itself, and thus fissile material. Storage limits per drum were 200 grams (7.1 oz) U-235, 15 grams (0.53 oz) U-233 and 15 grams (0.53 oz) Pu-239. These limits were not exceeded. Maximum values per drum were 24 grams (0.85 oz) U-235, 5.7 grams (0.20 oz) Pu-239 and less than 1 gram (0.035 oz) U-233 on the 511-metre (1,677 ft) level. However the type of the waste was determined by the measurable amou

Mine data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).