Since work began on the underground facility in the 1980s, only permission for “exploration” has been granted. But even without an official authorisation, the paper said that costs for assessing the salt dome for its suitability had been high because “the construction of the permanent storage depot was begun parallel to the investigation.”
The Federal Office for Radiation Protection did not want to confirm the existence of the document, but did admit that costs had been higher than necessary.
Some €1.5 billion has been invested in the site.
Work at Gorleben has been suspended since 2000, when the government decided to wait until 2010 to resume the controversial project.
The appearance of the documents has confirmed the doubts of nuclear energy opponents, who believed that Gorleben had been earmarked as a permanent storage depot before the safety of the salt dome had been adequately investigated.
Nuclear energy is deeply unpopular in Germany activists often stage protests at Gorleben, which is in the German state of Lower Saxony. The government has approved plans to get rid of its reactors by 2020. But high energy costs and greenhouse gas concerns have some politicians second-guessing the plans.