Swiss power company BKW has shut down its Muhleberg nuclear power plant for scheduled refuelling and annual upgrades.

The work, which is expected to take four weeks, will include repeat tests and inspections in and on the reactor pressure vessel, and six of the 57 control rod drives will be replaced.

A reactor recirculation pump motor is also being replaced and a main cooling water pump motor is being revised.

Muhleberg was built in 1972 and is one of four nuclear plants in Switzerland.