06.08.2012

Mühleberg nuclear power plant

Scheduled annual revision begins

BKW AG has shut down Mühleberg nuclear power plant (KKM) on August 5, 2012, as scheduled, for refuelling and annual revision work. The work is due to take roughly four weeks. BKW is carrying out a range of important renewal and maintenance work with a view to long-term operation of the plant.

During the operating period from the end of September 2011 to early August 2012, KKM fed a gross volume of 2,935 million kWh of CO2-neutral electricity into the BKW grid over a period of 7,594 operating hours. This very satisfactory result is due to preventive maintenance and an on-going modernisation programme, backed up by optimised fuel application. KKM has once again made a significant contribution to maintaining security of supply in north-west Switzerland.

Main focus of revision work
The main focus of the 2012 revision work will be on extensive repeat tests and inspections in and on the reactor pressure vessel using qualified testing systems. Six of the 57 control rod drives are being replaced. A reactor recirculation pump motor is also being replaced and a main cooling water pump motor is being revised. Replacement of the drive systems for the two feedwater pumps and the relevant measuring points will make the plant compliant with the state of the art in this area. Repeat testing of the electrical systems (instrumentation, reactor protection, control equipment of the SUSAN emergency system), replacement of some of the emergency power batteries in the SUSAN system, and tests on alternative emergency power supply systems form part of a maintenance and inspection cycle, and provide an additional assurance of plant safety. Annual inspection and maintenance work is also being performed on many other parts of the facility.

This year, 32 of the total 240 fuel elements are being replaced. Preventive recurrent revision and inspection work is also being carried out on the safety systems, the turbine and generator groups, the electrical protection and control systems and the transformers. During the work, the 330 BKW employees are being supported by some 650 external specialists from the region, from elsewhere in Switzerland and from abroad.

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