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One year on from the shutdown at Mühleberg, the decommissioning of the nuclear power plant is progressing according to plan, despite the coronavirus pandemic. The turbines, for example, have already gone from the turbine hall. In reality, however, work has only just begun.

A year ago, the site was in the spotlight: on 20 December 2019, the Mühleberg Nuclear Power Plant was definitively shut down by BKW. The event – a first for Switzerland – was covered live on TV. It was a heart-wrenching day for employees, even though they had seen it coming.

At a stroke, their main job switched from generating electricity to dismantling their place of work. Decommissioning will take more than a decade, and will largely be carried out by the same team that operated the plant.

One year one from the start of work, the interim report from Stefan Klute, overall project manager for decommissioning, is positive. “From my bird’s eye viewpoint, at any rate, we’re on track.” (Bird’s eye viewpoint refers to the view that an overall project manager gets.)

Decommissioning project manager speaks to BKW Talk (german)

There are always minor challenges at the detailed project level, however. Many of these challenges are due to the coronavirus, which began to sweep across the world just a few months after the power plant was shut down.

“Nuclear power is an international business,” says Klute. Mühleberg was one of a total of four sites in Switzerland, and there are many more in neighbouring countries. Suppliers and partners, as well as know-how, are often brought in from other countries. Travel to Switzerland from certain countries was restricted in the spring of 2020, and the restrictions have recently been re-imposed. “In May, we had nine experts from the USA on site. They had previously provided training to some of our personnel,” explains Klute.

“At that time, the virus was more widespread in Europe than in the USA. This meant that organising the flights presented a challenge,” Klute adds. This is just one example of the additional problems caused by coronavirus.

Radioactivity and the virus

Stefan Klute, Head of Decommissioning and Waste Disposal

Wearing masks is, of course, mandatory inside the plant. According to Klute, the level of compliance with the mask mandate is high. This is because people working at a nuclear power plant are trained in the use of personal safety measures. “Just like radioactivity, the virus is invisible,” says Klute. In this area too, however, question marks suddenly began to arise in the spring of 2020: the whole world was buying protective masks. Some of the models being purchased were those used in nuclear power plants. However, Mühleberg was able to find timely solutions to cushion the impact of the resulting supply shortages. Despite these obstacles, decommissioning of the plant is on track. This can be most clearly seen in the turbine hall. The turbines and generators used to produce electricity have already been disassembled. “We have removed 2,500 tonnes of material from this area,” says Klute. The massive turbine missile shields, which protect the surrounding area against flying turbine fragments (known as missiles) in the event of failure of the turbine, account for around half of this weight on their own.

The once full turbine hall is now quite empty. There is a good reason for this: the empty turbine hall provides enough space for cleaning radioactively contaminated materials before they are transported off-site.

Milestones from the first year of decommissioning

Everything is meticulously examined

Before: the turbine hall with all of the turbines and generators in place.

The turbines have been transported to a specialist company in Sweden to be melted down. Before the melting process, radioactive waste is separated out from re-usable steel. This steel is just one example of the way in which materials arising from decommissioning are being recycled. Stefan Klute expects that around 80% of components will be able to be recycled. The majority of the plant has never come into contact with radioactivity: over 98% of the total mass of material does not have to be managed as radioactive waste. Nevertheless, everything is meticulously examined for traces of radioactivity, with checks also being carried out by the Swiss Federal Nuclear Safety Inspectorate (ENSI).

Today: the turbine hall looks like a storage facility. There is no trace of the turbines.

The turbine missile shields themselves are also being recycled. They are crushed and turned first into cement and then concrete, which can be used in the construction sector, in what is known as a “recovered material cycle”.

A year has passed since the big day at Mühleberg. Stefan Klute refers to 2020 as the “initial/preparatory phase”, while 2021 is the “ramp-up/optimisation phase”. Starting in 2022, the fuel elements will gradually be transported from the plant’s fuel storage pool to the central interim storage facility operated by Würenlingen AG, until all the fuel has been removed from the site by the end of 2024. When that milestone is achieved, over 98% of the plant’s radioactivity will have been removed. Nuclear decommissioning will take place between 2025 and 2030. By 2034, the site of the former Mühleberg Nuclear Power Plant should finally be ready to be used for other (as yet unknown) purposes.

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In Kooperation mit

Beitrag aus im Rahmen einer Zusammenarbeit der BKW mit Ringier / Article de dans le cadre d’une collaboration de BKW avec Ringier.