Electricity generation at Gösgen nuclear power station: increased efficiency thanks to improved technology

As part of the 2013 annual overhaul, Gösgen nuclear power station (KKG) is updating its turbine generator group. This will result in greater energy efficiency and an additional output of around 30 megawatts.

The annual overhaul of the KKG, which started on 4 May 2013, is focused on energy efficiency. During the course of the overhaul the turbo generator group will be comprehensively refurbished. The state-of-the-art technology will increase the plant's efficiency yield. The enhanced efficiency will increase the plant's capacity by around 30 megawatts (MW). Over the year the KKG will generate some 240 million kilowatt hours (kWh) of electricity: equivalent to the annual production of a medium-sized run-of-river power station. By way of comparison, the neighbouring Gösgen hydroelectric power station generates an average of approximately 300 million kWh a year.

Improved technology While the turbines' outer housing will be retained, the rotors and internal housings will be replaced. The turbine blades and the flow pattern between the turbine and condenser will also be structurally optimised. In total, 24 condenser modules with around 90,000 pipes will be replaced. The new single-shaft turbo group consists of a high-pressure turbine and three low-pressure turbines, a generator, agitator and auxiliary agitator. It is 55 meters long and rotates at 3,000 rpm. The turbine components and the new generator were manufactured by Siemens.

36 new fuel elements During the overhaul the KKG will replace 36 of the 177 fuel elements. The overhaul also includes numerous tests and maintenance work on the structural, mechanical, electrical and control systems and components. In all, the 2013 overhaul covers more than 3,000 separate maintenance tasks. With more than 1,000 experts from around 170 companies in Switzerland and abroad involved alongside the KKG's own staff, the logistical and organisational challenges are correspondingly enormous.

CHF 1 billion for modernisation between 2010 and 2017 Swiss nuclear power stations are continually upgraded by their operators. The KKG projects an investment sum of around CHF 1 billion for the modernisation of the power station between 2010 and 2017. Of this, 40 percent will be earmarked for additional investments in safety, 20 percent for higher energy efficiency and 40 percent for long-term maintenance and new investments.

The following parties hold a stake in Gösgen-Däniken AG nuclear power station: Alpiq (40 percent), Axpo (25 percent), CKW (12.5 percent), ewb Bern (7.5 percent) and the City of Zurich (15 percent). The pressurised water reactor has an electrical capacity of 1,035 Megawatt and was put into service in 1979.