The Federal Department of the Environment, Transport, Energy and Communications (UVEK) approved the licences earlier this month for the single-unit Mühleberg nuclear power plant and for the Zwilag plasma oven, which is used for the smelting of low-level radioactive waste.

Mühleberg's operators BKW FMB Energy (BKW) said they welcomed the move because it finally puts all five nuclear power plants in Switzerland on par with each other.

In 2006, UVEK rejected a request to waive the time limit on the operating licence for Mühleberg. But at the time UVEK said BKW would be allowed to file another application using the same licensing procedure that had been followed by for the Beznau plant, which is operated by Nordostschweizerische Kraftwerke AG (NOK).

The Swiss government granted an unlimited operating licence for unit two of the Beznau plant in 2004. Beznau-1, the country's oldest nuclear power unit, and the newer Gösgen and Leibstadt units have had unlimited licences from the beginning.

Only Mühleberg had still been limited to a 10-year licence, which was due to expire in 2012.

The Zwilag facility is owned by the four Swiss nuclear utilities. It began operations as a central interim dry cask storage facility for high-level waste in 2001.  Apart from the plasma oven Zwilag also has facilities for the storage of low- and intermediate-level radioactive waste.

Switzerland's five nuclear reactor units generate 40 percent of its electricity. The units are: Beznau-1, Beznau-2, Gösgen, Leibstadt and Mühleberg.