Former iron ore mine at Salzgitter-Bleckenstedt, closed in 1976, now being converted by the BGE into Germany's first fully licensed underground repository for low- and intermediate-level radioactive waste, with the Schacht Konrad 1 headframe visible from
The Schachtanlage Konrad is a former iron ore mine in the district of Bleckenstedt in the city of Salzgitter, Niedersachsen, named after Konrad Ende, the former chairman of the supervisory board of the Salzgitter AG. Iron ore in the area was first encountered in 1933 during a search for oil at depths of over 800 metres; exploration was interrupted by the Second World War and resumed in the 1950s. Schacht Konrad 1 was sunk from the late 1950s and reached its final depth of 1,232 metres at the start of 1960; Schacht Konrad 2, approximately 1.8 kilometres to the south-east on the Salzgitter steelworks site, followed.
Ore extraction from both shafts began in early 1964, even before an underground connection was in place. In total, 6.7 million tonnes of iron ore were extracted from 1964 to 1976, when mining was discontinued for economic reasons as cheaper imported ore undermined domestic production. Following a proposal from the mine's own Betriebsrat, the Physikalisch-Technische Bundesanstalt (PTB) assessed the site from 1976 to 1982 for suitability as a repository; the geology — in particular thick clay layers above the iron-ore seams that prevent water ingress — was found favourable.
The PTB initiated the formal Planfeststellungsverfahren on 31 August 1982. After a 75-day public hearing in 1992–1993, the Planfeststellungsbeschluss was issued on 22 May 2002, permitting the emplacement of a maximum 303,000 cubic metres of low- and intermediate-level radioactive waste with negligible heat generation. All legal challenges were finally dismissed by the Bundesverwaltungsgericht on 26 March 2007.
Conversion of the mine to a repository began in 2007, carried out by the BGE (Bundesgesellschaft für Endlagerung mbH). Total conversion costs are estimated at approximately 2.9 billion euros. The BGE currently projects completion and the start of waste emplacement in the early 2030s.
The iron ore deposit beneath the Bleckenstedt area was first encountered in 1933 during exploratory drilling for petroleum at depths exceeding 800 metres below the surface. The ore was identified as an oolithic Brauneisenerz (brown iron ore). Exploration was interrupted by the Second World War and could not be completed until the 1950s, by which time demand for iron ore was high and the global supply was still constrained enough to make the deep deposit commercially attractive.
Schacht Konrad 1 was sunk from the late 1950s and reached its final depth of 1,232 metres at the start of 1960. Schacht Konrad 2, located approximately 1.8 kilometres to the south-east on the land of the Salzgitter steelworks (now the Salzgitter AG), was sunk subsequently. Ore extraction from both shafts began in early 1964, before the underground connection between them was fully in place. Between 1964 and 1976, a total of 6.7 million tonnes of iron ore were extracted and supplied to the Salzgitter steelworks. In 1975 and 1976, however, the progressive expansion of global ore trade — enabled by ever-larger bulk carrier vessels — allowed cheaper foreign ores from Australia and Brazil to undercut domestic German production; the Konrad mine was discontinued in 1976 for economic reasons.
Rather than proceeding to immediate closure and flooding, the Betriebsrat of the Salzgitter Eisenerzbergbau AG took the initiative of lobbying federal and regional politicians to consider the mine's geological properties as a basis for nuclear waste disposal. The mine's geology was particularly favourable: thick impermeable Tonschichten (clay layers) above the iron-ore seams in the Dogger B horizon, combined with an unusually low water inflow of only about 16,300 litres per day, provided the multi-barrier system required for long-term isolation from the biosphere. The Gesellschaft für Strahlenforschung (GSF) — the same body then operating the Schachtanlage Asse II — carried out the initial geoscientific investigations from 1976 to 1982. The results were positive and the PTB (Physikalisch-Technische Bundesanstalt) submitted a formal application to the then competent authority, the Niedersächsisches Sozialministerium, on 31 August 1982 to initiate a Planfeststellungsverfahren under § 9b Atomgesetz.
The planning documents, completed by 1989, were submitted to the Niedersächsisches Umweltministerium and made available for public inspection for two months, during which approximately 290,000 objections were recorded. The public hearing (Erörterungstermin) ran from September 1992 to March 1993 over 75 days — the longest such procedure in the history of the Federal Republic at the time. After further examination of approximately 400 technical and 100 legal questions raised during the hearing, the Planfeststellungsbeschluss was issued by the Niedersächsisches Umweltministerium on 22 May 2002, authorising the emplacement of up to 303,000 cubic metres of radioactive waste with negligible heat generation, with a maximum radioactivity of 5 × 10¹⁸ becquerels of beta and gamma emitters and 1.5 × 10¹⁷ becquerels of alpha emitters. Approximately 90 per cent of the volume of all radioactive waste arising in Germany falls within this category, though it represents only about 1 per cent of total radioactivity.
Eight legal challenges were filed by municipalities, districts, churches, and private individuals. In March 2006, the Oberverwaltungsgericht Lüneburg dismissed all challenges without leave to appeal. A Nichtzulassungsbeschwerde was rejected by the Bundesverwaltungsgericht on 26 March 2007, finally confirming the Planfeststellungsbeschluss. On 31 August 1982, construction was formally authorised and actual conversion work began in summer 2007 under the former operator, the Bundesamt für Strahlenschutz (BfS). Since 2017 the BGE has been the operator. Important required underground cavities have been completed; all new buildings on the Schacht Konrad 1 site and the Betriebshof buildings on the Schacht Konrad 2 site have been finished. Remaining structures including the Führungsgerüstwechsel at Konrad 1, additional surface buildings at Konrad 2, and the full equipping of the shaft Konrad 2 remain to be completed. Estimated total conversion costs are approximately 2.9 billion euros, compared to an earlier estimate of 900 million euros in the 1990s. The BGE projects completion and the start of waste emplacement in the early 2030s. Once the emplacement period of approximately 30 years is complete, all underground cavities will be backfilled and the two shafts sealed in a manner designed to maintain safety for an isolation period calculated at 300,000 years. The Schacht Konrad 1 headframe is described as clearly visible from both the A 39 motorway and the Industriestraße Nord. Visitors may participate in underground inspection tours of the future repository, offered by the BGE.