The Beznau nuclear power plant (German: Kernkraftwerk Beznau [KKB]) is a nuclear power plant of the Swiss energy utility Axpo, located in the municipality Döttingen, Canton of Aargau, Switzerland, on an artificial island in the Aare river.

On 23 December 1964 the Swiss Federal Office of Energy recognized the artificial island in Beznau as potential location for a reactor.

On the contrary Beznau 2 operated under temporary licenses until 3 December 2004, when the Swiss Federal Council removed the limitation.

The cantonal citizens systematically rejected all votes on early shutdown of existing plants and on building suspension of new ones.

At dawn on 5 March 2014, Greenpeace activists broke into Beznau, urging European governments to close down the reactors on safety grounds.

Newspaper Tages Anzeiger commented in October 2015 that two independent sources have confirmed that the reactor 1 pressure vessel contains around 1,000 cavities of half a centimetre in diameter.

[8] Similar cavities, although smaller in number, size and extension,[9] were first discovered in the Belgian Doel 3 reactor, consequently the Swiss Federal Nuclear Safety Inspectorate (ENSI) asked Beznau and Gösgen NPPs to perform adequate testing on their reactor pressure vessel.

Axpo had proved that the inclusions found in the reactor pressure vessel steel did not have a negative effect on safety.

[11][12] In 2024 Axpo is assessing the technical feasibility of operating the Beznau nuclear power plant beyond the planned 60 years, beyond 2030.

The KKB is composed of two identical pressurized water reactors units (Beznau 1 and 2) delivered by Westinghouse Electric.

This reduces the effect of the plant on the water temperature of the Aar river, and provides eleven surrounding municipalities with up to 150 GW·h of carbon-free heat per year.

They are heavily protected (bunkerised) from external hazards and, if needed, are able to cool and shut down the power plant without human intervention for 72 hours.

[24][25] The at least 1.5 m thick concrete-steel housings protect the critical systems from external agents like earthquakes or plane crashes.

The emergency core cooling (ECCS) is performed by a redundant high-pressure safety injection system with a total of three strands (one in the NANO).

Finally, in case of problems with the cooling, two containment spray systems are entrusted with the removal of excessive heat and pressure by condensation of the resulting steam.