The nuclear power station Unterweser is a nuclear power plant in Kleinensiel (Municipality of Stadland), close to Nordenham.
When it first started up, it was the largest nuclear reactor in the world. It has 193 fuel assemblies. In 2004, the measured radioactivity released into the air amounted to 3.8 TBq/a for all radionuclides, and 14 TBq/a in the water.
Unterweser was one of the seven reactors shut down on 17 March 2011 (although actual shutdown was several days later) pending the results of a three-month moratorium on nuclear power. On 30 May 2011, the German government announced that Unterweser would not be returning to operation following the moratorium and would be decommissioned.