Nuclear Power Reliable base load energy

Axpo maintains nearly 60 per cent of the installed production capacity of Switzerland’s nuclear power plants. Like hydropower plants, nuclear plants supply important base load energy that is constantly available and CO2-free. With its nuclear power plants in Switzerland and long-term contracts with EDF in France, Axpo's nuclear division covers around 20 percent of Switzerland's electricity consumption.

Our nuclear plants

Axpo's nuclear power plant portfolio includes our Beznau nuclear power plant (KKB), comprising the Beznau 1 and Beznau 2 reactors; investments in the Leibstadt (KKL) and Gösgen (KKG) partner nuclear power plants; and procurement rights to French nuclear power plants.


Wholly owned by Axpo, the KKB consists of two largely identical plants, each with a light water reactor and a capacity of 365 megawatts (MW). The two plants are designed for 8,000 full load hours or around 355 operating days per year. Together, they generate around 6,000 gigawatt hours (GWh) of electricity per year. This corresponds to about twice the electricity consumption of the city of Zurich. Beznau 1 and Beznau 2 began operations in 1969 and 1971 respectively. Beznau 1 is Switzerland's first nuclear power plant. Continuous investments in safety and ongoing modernisation ensure that both plants are kept up to date.


The KKL has an output of 1,285 MW and is located on a 24-hectare site in the town of Leibstadt, in the Aargau canton, on the river Rhine. It went into operation at the end of 1984, making it the newest and most powerful of the five nuclear power plants in Switzerland. In full operation, KKL generates around 9,600 GWh of electricity per year from its boiling water reactor. This volume is sufficient to supply two million Swiss households with electricity and corresponds to around 15% of Swiss electricity production. The Leibstadt AG nuclear power plant is managed as a partner plant. Each shareholder of a partner plant bears a proportionate share of the operating costs and receives the energy to which it is entitled. Axpo Group has a share of 52,7% and is the company's managing director.


Anyone travelling by train in Switzerland is familiar with this nuclear power station, located between Olten and Aarau. The first Swiss nuclear power plant of the 1,000 MW class went into commercial operation in November 1979. Since then, the KKG has carried out several modernisation programmes to further increase safety and today has a capacity of 1,060 MW. KKG generates around 8,000 GWh of electricity per year. Five partners hold interests in Gösgen-Däniken AG, with Swiss energy company Alpiq responsible for management of the company.

What you need to know about nuclear power

A nuclear power plant uses the energy of nuclear fission to produce electricity. Like coal-fired or gas-fired power plants, it is a thermal. However, nuclear plants do not produce air pollutants or greenhouse gases during the production of heat.

In a nuclear power plant, uranium atoms are ‘fissioned’ or split in the reactor, under controlled conditions. The energy released is used to heat water under high pressure, just like in a domestic pressure cooker. This produces hot steam. The steam drives a turbine which is connected to a generator. The generator then produces electricity, which is supplied to consumers through the power grid.

At Axpo, we have set ourselves the goal of ensuring that the nuclear facilities we manage are among the best and safest when compared internationally. We are committed to complying with the standards for the safety of nuclear facilities laid down by the International Atomic Energy Agency (IAEA) Safety Convention and ratified by Switzerland. National and international authorities regularly inspect our facilities.

In this context, periodic safety reviews are of great importance. They form the basis for measures to maintain and improve the safe operation of nuclear plants. In addition, safety is regularly analysed and assessed by the World Association of Nuclear Operators (WANO), a worldwide association of nuclear power plant operators for the mutual exchange of knowledge and experience.

The safety standards of Swiss nuclear power plants are among the highest in the world. The current practice of continuous upgrading has led to a high safety culture, which is also reflected in the low malfunction susceptibility of Swiss nuclear power plants and their high availability by international standards. During European stress tests, which recorded a very high level of safety at the Swiss plants, the Swiss Nuclear Safety Inspectorate ENSI repeatedly confirmed their safety.

In addition to their operators, the Federal Nuclear Safety Inspectorate ENSI is also responsible for the safety of Swiss nuclear facilities. All nuclear installations fall under the supervision of ENSI, including nuclear power plants, the Zwilag interim storage facility for radioactive waste, and the nuclear research facilities of the Paul Scherrer Institute in Villigen, EPF Lausanne and the University of Basel. As an independent institution under public law, ENSI regulates every step in and around nuclear energy, from project planning and operation to decommissioning and the disposal of radioactive waste. This also includes protecting personnel and the public from radiation and the nuclear facilities from sabotage and terrorism.

You can find out more about earthquake safety, radiation protection and the liability of nuclear power plants on the industry organisation website swissnuclear.

Under Swiss nuclear energy legislation, a nuclear power plant in Switzerland can remain in operation as long as it meets the legal safety requirements. There are no plans for a run-time limit on nuclear power plants.

Operation of a nuclear power plant depends on both technical conditions and regulatory and economic factors. Axpo plans to continue operating our power plants for as long as they are safe and economical.

ENSI also considers this to be unnecessary. In addition, nuclear energy plays an important role in Switzerland’s Energy Strategy 2050. As a bridge technology, it contributes to the country’s security of supply and gives us the necessary time to implement the desired transformation of Switzerland's electricity supply system to more renewable energies. 

Nuclear power plant operators are responsible for the decommissioning of facilities and the disposal of radioactive waste. Thus, the total costs for operation, post-operation, dismantling and disposal of radioactive waste are included in the electricity price, according to the polluter-pays principle. Over an operating period of 50 years, these costs amount to around one centime per kilowatt hour.

The disposal costs incurred during the operation of the power plant are paid by the operators on an ongoing basis. These costs include interim storage and transport, associated waste containers, and the preparation of radioactive waste for subsequent storage in deep geological repositories. In addition, the operators pay into two funds supervised by the Swiss government throughout the operating period. Together with the return on fund assets, these contributions cover the total costs for decommissioning and waste disposal. This ensures that the necessary funds are available to meet the costs of decommissioning and disposal when they are incurred.

Cost studies

Under the supervision of the Swiss government, expected future costs are estimated every five years in studies based on current state-of-the-art science and technology. These studies form the basis for determining contributions to the fund by the nuclear power plant operators and for them to make any necessary provisions. The studies are reviewed by the federal supervisory authority and independent experts. The aim is to ensure that the consistent application of the precautionary and the polluter-pays principles does not result in uncovered costs for the federal government or future generations.


Even during operation, a nuclear power plant generates various types of waste. The highly radioactive spent fuel elements account for only a small part of this. After removal from the reactor, they are first stored in decay basins in the nuclear power plant. After five to ten years, they are transported to the plant's own interim storage facility or the Zwilag central interim storage facility in Würenlingen. Around nine times the volume of low- and medium-level radioactive waste is generated by nuclear power plant operation than high-level radioactive waste.


Decommissioning is a complex and challenging process and, like the operation of the power plants, is monitored at every step by the supervisory authority ENSI.

The Mühleberg nuclear power plant, which belongs to the BKW Group, is the first Swiss nuclear power plant to be decommissioned as of 20 December 2019. How the Beznau nuclear power plant deals with the topic of decommissioning can be found in our Beznau nuclear power plant dossier.

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