Four giant steam generators from a German nuclear plant has been successfully removed. Unterweser nuclear power plant’s steam generators, each measuring 65.6 feet (20 meters) in height and weighing about 300 tons, were lifted entirely out of the facility.
“The expansion of the four steam generators at the Unterweser nuclear power plant (KKU), which has been running since mid-May 2025, has been completed,” said PreussenElektra, which operated Unterweser nuclear power plant, in a statement.
“Today, the fourth steam generator was lifted out of the reactor building and made available for transport to the plant site.”
Dismantling underway
Located on the lower reaches of the River Weser in the rural district of Wesermarsch in Lower Saxony, the Unterweser nuclear power plant was first commissioned in 1978. It was claimed to be a world champion in terms of annual power generation in 1980, 1981, and 1993.
However, when Germany decided to phase out nuclear energy, Unterweser, along with seven other nuclear power plants was shut down in March 2011.
The permit to decommission and dismantle the power plant was granted on February 5, 2018, and decommissioning started two weeks later, according to PreussenElektra.
Highest safety standards
The recent removal of steam generators at the Unterweser nuclear power plant was carried out in accordance with the highest safety standards.
“This was absolute precision work and a masterpiece of engineering. The intensive preparation has paid off,” said Attila Damon, project manager.
“Our experienced partners Framatome and Mammoet have done a good job of this task.”
Unterweser held the world record in power generation. No other single-unit power plant in the world had ever generated a total of 305 billion kW/h of electricity until March 2011.
Reports revealed that the steam generators will be shipped to Cyclife in Sweden in July. These will be dismantled on-site, and then melted down in a smelter.
PreussenElektra is also decommissioning the Brokdorf, Grafenrheinfeld, Grohnde, Isar 2 and Stade PWR nuclear power plants. In 2021, PreussenElektra awarded the contract for the dismantling and disposal of a total of 16 steam generators from the Unterweser, Grafenrheinfeld, Grohnde, and Brokdorf plants to Cyclife, a subsidiary of EDF specializing in nuclear power plant decommissioning and waste management, reported World Nuclear News.
Innovative Mammoet DHS-500 system was used to lift generators
The steam generators at the Unterweser plant were lifted using the innovative Mammoet DHS-500 system.
Mammoet designed, engineered, and built its own DHS-500 steam generator handling system, to decommission steam generators safely and efficiently. The system previously removed steam generators at Neckarwestheim Nuclear Power Station.
In combination with the existing overhead crane and a hydraulic skidding system, a more time-consuming transport alternative could be avoided. Mammoet provided extensive documentation to use this pioneering system and comply with the strict safety standards of the nuclear industry. With approved planning documents Mammoet could carry out a load and function test to prove the safe and efficient performance of the DHS-500.