Work at Germany’s Brunsbüttel NPP n Schleswig-Holstein to segment and package the steel reactor pressure vessel head was completed in less than two months, according to Vattenfall announced. The 70-tonne lid of the reactor pressure vessel with a diameter of more than six metres was heavier than any of its internal components and, like the internal components, it has now been dismantled and packed. The metal will now be recycled, Vattenfall noted.
The cover dome was made of 8cm-thick heat-resistant steel coated on the inside with a 6mm-thick stainless-steel plating to protect it from corrosion. The flange had a wall thickness of 42cm. The dome was cut into eight segments each weighing 2.8 tonnes. Six pieces, each weighing 7.7 tonnes, were cut from the surrounding flange.
Some of the tools used had to be specially made for this project, including the substructure to secure the individual dome segments during cutting and the wire saw used. “When you break the lid dome down into individual parts, you need a support so that the cut-out parts can be handled safely,” said Michael Maassen, who was responsible work on site. “The lid was placed on the substructure and turned seven times. So we moved the lid, not the saw.”
The dismantled parts of the cover were packed in four 20-foot IP2 containers. The cut pieces will be melted down by a contract partner as part of the release process. The steel produced can then be used for other applications.
The 771 MWe boiling water reactor at the single-unit Brunsbüttel plant was among the eight oldest German reactors taken out of service in March 2011. This followed Germany’s decision to phase out nuclear power, taken in the wake of the 2011 Fukushima accident in Japan. Germany closed eight units of its 17 nuclear immediately: EnBW’s Phillipsburg 1 and Neckarwestheim 1; E.ON’s Isar 1 and Unterweser; RWE’s Biblis A & B and Vattenfall’s Brunsbüttel and Krümmel. The remaining nine plants were gradually removed from the grid by the end of 2022 – with the exception of three plants, which remained on the grid until mid-April 2023.
Brunsbüttel had been idle since 2007 following a grid-facilitated trip. Vattenfall – which owns a 66.7% stake in the plant with PreussenElektra holding the remaining 33.3% – applied in late 2012 to decommission that plant. The power plant has been formally closed since 2019.
With the removal of the last fuel element in June 2017 and the last fuel rods in February 2018, around 99% of the radioactive inventory was removed from the plant. Of the remaining 1% of the radioactive inventory, more than 90% was in the reactor pressure vessel and its internals.
