Contract for removal of Mühleberg reactor vessel

19 March 2024

A consortium of German companies has been awarded a contract to dismantle and package the reactor pressure vessel, including the vessel head and insulation, at the Mühleberg nuclear power plant in Switzerland.

The signing of the contract (Image: Uniper)

The so-called UfG consortium - comprising Uniper Nuclear Services GmbH, Framatome GmbH and GNS Gesellschaft für Nuklear-Service mbH - will be responsible for the dismantling and packaging of the following components: the reactor pressure vessel (RPV) including calotte and stand frame; RPV lid; control rod drive housing; and the RPV insulation with brackets and plates.

The total amount of material to be removed under the contract - the value of which has not been disclosed - is about 270 tonnes. Work on site will start at the end of 2025.

The UfG concept includes the mechanical pre-dismantling of the RPV in the installation position into the largest possible segments. This is followed by thermal post-dismantling and packaging for storage.

Mühleberg (Image: ENSI)

The Mühleberg plant - comprising a single 373 MWe boiling water reactor - began operations in 1972 and was shut down on 20 December 2019. Dismantling operations began on 6 January 2020. However, it has only been considered permanently out of service since 15 September 2020 when its operating licence was replaced by a decommissioning order. Mühleberg is the first nuclear power plant in Switzerland to be decommissioned.

The plant is being dismantled in three decommissioning phases. The first phase lasted until all the plant's 418 fuel elements were removed. This was completed in September last year, 16 months ahead of the original scheduled date, set in 2015. The second phase ends with the lifting or clearing of controlled zones, while the third phase includes work to demonstrate that the system is no longer a source of radiological hazard.

Plant owner BKW submitted its application to the Swiss Federal Nuclear Safety Inspectorate in late June 2022 for the second decommissioning phase of Mühleberg.

During that phase, all remaining plant components that have come into contact with radioactivity will be dismantled, treated and cleaned. These include, for example, the reactor pressure vessel, parts of the containment or the fuel element storage pool that is no longer required.

In March 2023, Uniper Nuclear Services - a subsidiary of Germany's Uniper Group - was contracted by BKW to dismantle, disassemble and package the two moisture separator reheaters at Mühleberg.

By the end of 2030, Mühleberg is expected to be free of radioactive material, with conventional dismantling set to begin in 2031. BKW plans to submit an application for conventional dismantling to the authorities by 2027.

The site is expected to be available for other uses from 2034 onwards.

Researched and written by World Nuclear News