Beznau nuclear power plant:
climate-friendly electricity

Our plant

The Beznau nuclear power plant (KKB) consists of two identical light water reactors with a rated electrical output of 365 megawatts (MW) each. Together, they generate around 6000 gigawatt hours (6000 GWh) of electricity per year. This corresponds to around twice the electricity consumption of the city of Zurich. In addition, the Beznau nuclear power plant supplies hot water to the regional district heating network in the lower Aare River valley.

The commercial commissioning of KKB 1 took place in December 1969 after a construction period of 48 months. KKB 1 is thus the first of its kind in Switzerland. KKB 2 followed in April 1972, again after a construction period of around four years. As is standard practice in Switzerland, both units have an unlimited run-time licence.

Take a closer look at Beznau nuclear power plant


The Beznau nuclear power plant has been supplying reliable, climate-friendly electricity for 50 years. Beznau 1 is Switzerland's first nuclear power plant. Despite more than 50 years of operation, the KKB is one of the safest nuclear power plants in the world. Thanks to extensive upgrading, maintenance and modernisation investments amounting to over CHF 2.5 billion, the plant meets all regulatory and statutory safety requirements.

Reactor pressure vessel safety case

The long-term operation of a nuclear power plant requires comprehensive ageing management. In a detailed safety report, Axpo recently demonstrated  that the Beznau 1 reactor pressure vessel continues to meet all requirements for safe operation. The Swiss Federal Nuclear Safety Inspectorate (ENSI) issued the restart permit for Unit 1 at the beginning of March 2018 after a three-year verification period. This enabled the successful completion of an extensive testing and analysis process along a roadmap defined as expedient by the supervisory authority and its international experts.

With ENSI's confirmation of the safety case, KKB can provide verifiable evidence that the safety of the Unit 1 reactor pressure vessel is guaranteed in accordance with the state-of-the-art in science and technology as well as national and international regulations. The proof also confirms earlier assessments and investigations and corroborates a sufficient safety margin for the safe operation of the plant for more than 60 years.

The KKB has set international standards with probably the most comprehensive investigations on the subject of RPVs. Internationally recognised experts were consulted and cooperated with specialised companies and organisations.

Media conference 6 March 2018

On 6 March 2018, Axpo hosted a media conference in Brugg on the subject of "Safety case for Unit 1 of the Beznau nuclear power plant". The presentation material of the event can be downloaded here.

Important projects

The Beznau nuclear power plant has been continuously upgraded since it was commissioned. More than CHF 2.5 billion has been invested in retrofitting and renewal. All safety precautions therefore comply with the latest standards and all regulatory safety requirements have been met. The KKB also passed the EU stress test in 2012 with top marks.

In 2015, a new redundant, bunkered, earthquake-protected emergency power supply and a new plant information system were put into operation at the KKB during two long revisions of Unit 1 and Unit 2. In addition, the  two reactor pressure vessel heads were replaced as a precaution. All three projects were long-term projects under the supervision of the Swiss Federal Nuclear Safety Inspectorate ENSI.

The various renewal and replacement investments were made with a view to the long-term operation of the nuclear power plant. They improve the availability of the plant and further increase its already high safety level. 

The projects in detail

In 1993/1999 the steam generators in both units of the Beznau nuclear power plant were replaced. The preventive measure reduces the risk of an unplanned production loss.

In 1993, the NANO emergency system was implemented at the Beznau nuclear power plant. The system keeps the plant in a stable and safe state even if the control room or the originally existing safety systems fail. 

2015: Based on international experience, Axpo preventively replaced the reactor pressure vessel heads at the Beznau nuclear power plant in 2015. The investment decision, which Axpo had already made in 2008, was taken from a purely entrepreneurial point of view. The already high reliability of the plant was further increased by the new components.

You can see how the replacement was carried out here:

In 2015, an autarkic, bunkered, earthquake- and flood-proof emergency power supply was installed at the Beznau nuclear power plant. The four diesel engines have an output of 3750 kilowatts (kW) each, which corresponds to 400 percent of the power required in the event of a malfunction. 

In 2015, a new plant information system was installed: State-of-the-art hardware and software solutions process thousands of signals per power plant unit to ensure seamless monitoring and recording of operating data.


Nuclear energy and the environment are only two opposites at first glance. Sustainable production is top priority at Axpo, and, therefore, we attach great importance to the careful use of resources and the environment. Electricity from nuclear energy is climate-friendly - and the Beznau nuclear power plant is the first nuclear power plant with an environmental declaration.

Climate power plant

Nuclear energy generates far less CO2 than fossil energy over its entire service cycle. Countries with a high proportion of nuclear power, such as Switzerland, Sweden or France, meet their climate targets. 

Axpo electricity is climate-friendly. Axpo protects the climate and the environment by producing electricity that is nearly CO2-free - thanks to hydropower, nuclear energy and new energies such as wind or solar power. Since commissioning to the end of 2018, Axpo was able to save a total of around 300 million tonnes of CO2 emissions compared to lignite-fired power plant generation thanks to the Beznau nuclear power plant.

A country's electricity mix determines its emissions. The table below shows how Switzerland compares with neighbouring countries in terms of greenhouse gas intensity.

Environmental declaration

The Beznau nuclear power plant is the first power plant in Switzerland for which an Environmental Product Declaration (EPD®) in accordance with ISO 14025 was drawn up. The core of the environmental declaration is a life cycle assessment that enables the quantification and assessment of emissions to the environment and the use of resources along the entire electricity production process chain. Other environmental information collected included biological diversity in the vicinity of the nuclear power plant, radiation exposure of personnel and electromagnetic fields. 

Water temperatures

Unlike the newer Swiss power plants in Gösgen and Leibstadt, the Beznau nuclear power plant does not have a cooling tower. The KKB takes water from the Aare River for cooling purposes. This water is heated through the operation of the plant and returned to the river. In full load operation, the Beznau nuclear power plant heats the Aare River by 0.7 to 1 degree - depending on water conditions. Axpo is bound by strict regulations regarding the discharge of cooling water, which are observed at all times. If the water temperature of the Aare River rises significantly during a heat wave, the power plant has to reduce its output.

Decommissioning, dismantling and disposal

Axpo plans to continue operating the two units of the Beznau nuclear power plant as long as this is safe and economically possible. The continued operation of the plant depends both on technical as well as regulatory and political framework conditions, and the market environment.

Axpo intends to prepare for the future decommissioning process in advance and with foresight. A corresponding project was launched in the summer of 2016.

After the definitive conclusion of power operation, the Beznau nuclear power plant will enter into what is known as post-operation. Nuclear decommissioning will start once the fuel elements have been removed from the facility. The plant will be dismantled step by step until all radioactive material has been removed from the units. Subsequently, the Federal Nuclear Safety Inspectorate ENSI will confirm that the plant is no longer a radiological source. The power plant site can then be used for other purposes. The process of decommissioning and dismantling will take around 15 years and will cost around six billion Swiss francs.

How BKW will decommission the Mühleberg nuclear power plant as of 20 December 2019 can be seen here.

People at KKB

The Beznau nuclear power plant employs around 450 Axpo employees and 100 third-party companies. The plants are monitored by a team of specialists in three-shift operation. All settings, values or changes for all important plant components are displayed and recorded in the control room. Deviations from target values are immediately reported acoustically and visually so that the specialists can take the necessary precautions. 

The Beznau nuclear power plant celebrated its 50th anniversary in 2019. Three generations that have operated and still operate the power plant talk about their experiences and memories at Beznau: From the euphoric beginnings in the 60's through all the upheavals up until today. These are testimonies on 50 years of nuclear history in Switzerland. The employees of the youngest generation, who have spent the least amount of time at the Beznau nuclear power plant, are proud to work at one of the oldest nuclear power plants in the world. They know that their work in its present form will come to an end. 

"Wir von der Insel"

Axpo took the fiftieth year of KKB's operation as an opportunity to pay tribute to the achievements of the men and women who built the plant, connected it to the grid and operated it with a high sense of responsibility.

The Beznau anniversary book "Wir von der Insel" tells the story of former and current employees: The first generation that was inspired by pioneer spirit and great ideas; the second that got caught in the storms, and the third that knows they will dismantle their own workplace. The book makes the Beznau spirit, the strong dedication and the daily work of the employees perceptible. At the same time, it documents an important piece of Swiss industrial and technological history.

The book "Wir von der Insel" - Beznau nuclear power plant 50-year anniversary - has been available in bookshops since the beginning of October 2019 and can be ordered at a price of CHF 49 plus shipping costs.

ISBN 978-3-033-07414-9

A range of jobs

Over 500 people work at the nuclear power plant. You can see here which positions are currently open at KKB.

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