Units 1 and 2 of the Oskarshamn plant

The dismantling of a reactor pressure vessel at the Oskarshamn nuclear power plant marks the completion of a project to dismantle the RPVs of four decommissioned reactors in Sweden.

Since July 2020, the UNNU Consortium - comprising Germany's NUKEM Technologies Engineering Services GmbH and Uniper Nuclear Services GmbH (UNS) - have been dismantling the reactor pressure vessels at Oskarshamn units 1 and 2 and Barsebäck units 1 and 2.

Commenting on the completion of the dismantling of the fourth RPV in December, NUKEM said: "This achievement represents the successful conclusion of an ambitious fleet dismantling project. UNS as the consortium lead, managed post-segmentation and the packaging of the cut RPV components into specialised containers, while NUKEM executed the in-situ segmentation of the RPV and the removal of asbestos insulation between the RPV and the biological shield."

NUKEM said the dismantling of an RPV - one of the largest and most radioactively contaminated components of a nuclear power plant - requires exceptional precision and strict safety compliance. The RPV was successfully cut into transportable segments and prepared for final disposal.

The process incorporated state-of-the-art technology, including a specially developed flame-cutting method and innovative tools that enabled safe handling of radioactive materials while ensuring the safety of the project team. Additional challenges, such as the removal of asbestos-containing insulation, were systematically addressed through comprehensive planning and design.

"By systematically applying lessons learned, we reduced the dismantling time by nearly half from the first to the fourth reactor, demonstrating a remarkable increase in operational efficiency," said Sergey Molodtsov, Managing Director of Operations at NUKEM. "The project also shows that even the most complex tasks can be carried out successfully, adhering to all safety and radiation protection requirements, and without any incidents."

NUKEM CEO Thomas Seipolt added: "The success of this highly technical and organisationally challenging project is a testament to the collaborative efforts of all involved stakeholders. We extend our sincere thanks to the licence holders BKAB AB, OKG AB and Uniper's Swedish ND&D programme as well as to our consortium partner UNS for their dedication throughout the project."

Uniper announced in December 2018 a "long-term and common strategy" for the demolition of the two-unit Barsebäck plant together with units 1 and 2 of the Oskarshamn plant. Under Uniper's strategy, the radiological demolition of the four reactors - during which all radioactive waste will be removed from each unit - will be carried out between 2020 and 2028. The total cost of decommissioning the Barsebäck and Oskarshamn units is estimated at SEK10.0 billion (USD918 million).

The two 600 MWe boiling water reactors (BWRs) at Barsebäck, about 30 kilometres from Malmö in southern Sweden, shut down in November 1999 and May 2005, respectively. Oskarshamn 1, a 473 MWe BWR, was shut down in June 2017, while Oskarshamn 2, a 638 MWe BWR, cease operation in 2013.