Year-end brings trio of reactor retirements

BKW announced in late 2013 that Mühleberg will be permanently shut down in 2019 instead of the earlier planned 2022 because of "uncertainty surrounding political and regulatory trends". The utility announced in March 2016 that the plant would be disconnected from the grid on 20 December 2019. The single 372 MWe boiling water reactor (BWR) began operating in 1972. It has since generated some 130 terawatt-hours (TWh) of electricity, providing about 5% of the country's electricity demand. It will be the first Swiss nuclear power plant to be decommissioned.

During the annual outage in summer 2018, the core of the Mühleberg reactor was loaded with fuel assemblies for the last 15-month operational cycle. The fuel quantities were calculated to allow the plant to reduce operations from mid-November. The shutdown of the plant has been carried out in steps, with the first of the two turbines disconnected from the grid early this morning and the second disconnected shortly after midday. The last control rod was inserted into the core, deactivating the reactor, at 12.30pm.

BKW said work on dismantling the Mühleberg plant will begin on 6 January. Decommissioning of the plant is expected to take about 15 years, concluding in 2034. According to a cost study from 2016, the costs of decommissioning and disposal total CHF3 billion (USD3 billion), 80% of which are already covered. The remaining 20% will be incurred by 2126 and will be covered by further fund contributions and plant yields.

Swedish shutdown

Meanwhile, Sweden's Vattenfall has announced that Ringhals 2 will be retired at 9.00am on 30 December, ending 44 years of operation and 215 TWh of generation.

Unit 2 of the Ringhals plant, with unit 3 in the background (Image: Vattenfall)

The company said the final shutdown of the 807 MWe pressurised water reactor (PWR) began in September, when it went into a phase called 'coast down'. "This means that the reactor output falls as the energy in the fuel decreases," Vattenfall said. "In November, the output fell to below 50% and one of the turbines was taken out of operation. On 30 December, the other turbine will also be shut down and electricity generation will cease."

Vattenfall announced in October 2015 that Ringhals 2 would be decommissioned in 2019, with Ringhals 1 (an 878 MWe BWR that started up in 1976) following in 2020. The company said the decision to close the reactors five years earlier than originally planned was taken for commercial reasons as it "would not be possible to continue operation of either of the two reactors, for both economic and practical reasons".

Two newer and larger PWR units at the Ringhals site, Ringhals 3 and 4, are expected to remain in operation until 2041 and 2043 under current plans.

German unit retires

EnBW said it plans to permanently shut down unit 2 at the Philippsburg plant "at the latest at the end of the year, as provided for by the Atomic Energy Act".

Helmfried Meinel (right), ministerial director of the Baden-Württemberg Ministry of the Environment, presents the decommissioning and dismantling permit to EnBW's Jörg Michels (left) in front of Philippsburg unit 2 (Image: EnBW)

The utility yesterday received a permit from the state of Baden-Württemberg's Ministry of Environment for the decommissioning and dismantling of the 1392 MWe PWR, which began commercial operation in April 1985.

"We are pleased to have received approval for the dismantling of KKP2 in good time before the plant is finally shut down," said Jörg Michels, head of EnBW's nuclear power division. "That was precisely the aim of our early application in 2016."

The dismantling of Philippsburg 2 will begin with the dismantling of the primary coolant lines in the second half of 2020. EnBW expects the dismantling of the entire unit to take around 10 to 15 years.

Philippsburg 1 - an 890 MWe BWR - was among the eight oldest German reactors taken out of service at the order of Chancellor Angela Merkel days after a tsunami hit Japan's Fukushima Daiichi nuclear power plant in March 2011.