Swiss electricity companies, Axpo and BKW Energy, are submitting plans to replace the country's oldest nuclear plants with two new facilities.
The firms confirmed on Thursday they would be filing an initial application with the Federal Energy Office for licences to replace two reactors at Beznau in canton Aargau and Mühleberg in canton Bern.
Axpo and BKW, which supply about four million people with energy and produce about half the electricity consumed in Switzerland, said they felt "obliged" to offer a solution to a foreseeable power shortfall when old plants reach the end of their life spans.
The firms have already set up a joint company to develop their plans. The new plants would be operational from 2020.
Opponents of nuclear power, who form an alliance called "Stopp Atom", have threatened to fight the plans with a referendum.
The centre-left Socialist Party criticised the company's announcement on Thursday, saying nuclear technology was obsolete, expensive and dangerous. The Green Party announced its "decisive resistance" to the measure, and vowed to take the issue to a referendum if necessary.
Switzerland has five nuclear power stations which account for around 39 per cent of the country's electricity production.
The district of Döttigen, which is home to the Beznau plants, has backed plans for a new station but called for a lower cooling tower. It also hopes to profit from payments from the new facility. It already collects SFr1.2 million ($990,000) annually from Beznau I and II.
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