[1] In parallel with the planning of Beznau 1, the then Bernische Kraftwerke AG decided to build a second nuclear power plant in the canton of Bern.

Due to the problems noticed during the commissioning and to some ongoing tests on the emergency cooling systems performed in the United States, until 1980 it received a series of six-month license extensions, then increased to one year.

In 1992 a public referendum in the canton of Bern rejected granting an unlimited operating license to the power plant, with 51% voting against.

[3] In 2003, 68% of the population rejected the initiative named Strom ohne Atom, that proposed that the plant should be shut down by 2005 to be replaced by non-nuclear power generation.

[11][12] The operators, Axpo and BKW, announced through their subsidiary company, Resun AG, on 4 December 2008 that they had submitted to federal authorities a framework permit application to build two new nuclear reactors, one of which would be in Mühleberg.

[13] Although precise technical specifications were not defined, the reactor of choice should be of 3rd generation light water type with a net electric power between 1200 and 1600 MW.

In case of a plane crash, the building could be damaged but the reactor would remain intact due to the five 30–50 cm thick insoles and the massive drywell.

A doubly redundant low pressure core spray with a 2·100% heat removal capacity is activated in case of serious leaks in the coolant system.

In 1989, the SUSAN (Selbstständiges, unabhängiges System zur Abfuhr der Nachzerfallswärme) emergency building started operation.

Bunkerized and partially underground, its function is to ensure an emergency shutdown of the reactor even in case of extreme external agents like plane crashes or simultaneous downfall of the dams upstream the plant with resulting submergence of the structures.

Due to the 2006 moratorium on the recycling of spent fuel, the entire stock of exhausted rods was transferred to the ZZL for storage.

A substitution of the core shroud or the pressure vessel was not considered necessary by the Swiss Federal Nuclear Safety Inspectorate (ENSI) that confirmed that the power plant was able to operate safely at least until 2012, when the license expired provisionally.

After the request by an anti-nuclear group the Federal Administrative Court of Switzerland ruled in March 2012 that BKW FMB Energy should shut down the reactor by mid-2013.

[32] The Swiss NPPs - Mühleberg included - are judged to be safe in earthquakes by the ENSI and the European Nuclear Security Regulators Group (ENSREG).