Floods and heavy rainfall events do not pose a threat to the LoK. The renowned flood expert Professor Jürgen Jensen from the University of Siegen has presented calculations to support this assessment in an expert report.
The law stipulates that the LoK must be out of reach of the peak of a flood that recurs statistically every 100 years. This is easily possible at the Würgassen site: A flood of this kind would raise the level of the Weser to 99.5 metres – the bottom of the former Würgassen nuclear power plant is 100.75 metres, i.e. significantly higher. However, structures such as dams, chemical plants or the LoK have to fulfil another requirement: Technical means must be in place to prevent the flooding that would result from high water levels that recur every 10,000 years. In Würgassen, this would mean a level of 100.9 metres – 15 centimetres above the top of the ground. This would not represent a fundamental problem for the sealed containers as the water would not reach the nuclear waste. Nevertheless, BGZ has decided to backfill the construction site to such an extent that no water would be able to enter the LoK even in the event of a 10,000-year flood.
After the floods triggered by heavy rain in Rhineland-Palatinate and North Rhine-Westphalia in the summer of 2021, BGZ asked Professor Jensen to expand his expert report by considering the potential impact of heavy rain at the LoK. Professor Jensen concluded that such events are already included by the conservative calculations in his study.