|Fig. 1: Gosgen nuclear power plant. (Source: Wikimedia Commons)|
In Switzerland, nuclear power accounts for about 40% of total electricity generated. [1,2] Just in 2013, 24.8 TWh of electricity was produced by the 5 nuclear reactors operating inside 4 nuclear power plants in Switzerland. The 5 reactors are: Beznau 1 (1969), Beznau 2 (1972), Gosgen (1979; Fig. 1), Muhleberg (1972) and Leibstadt (1984). [1,2] The first 3 reactors are pressurized water reactors while the other 2 are boiling water reactors. Another reactor, Lucens (1968), was decommissioned since 1969 after a partial core meltdown.
Switzerland, being at the intersection of the Apulian and Eurasian tectonic plates, is prone to seismologic events such as earthquakes. The Pegasos (Probabilistic Seismic Hazard Analysis for Swiss Nuclear Power Plant Sites) study initiated in 1999 showed that the risks of earthquake to nuclear power plants in Switzerland were more serious than expected.  At the same time, the costs involved in putting together safety measures for nuclear plants were also getting higher. For example, more than 1 billion Swiss francs was spent on supplementary diesel generators in the Beznau 1 plant, which would help to reduce the temperature of the fuel rods if an earthquake occurred. 
In 2011, the Fukushima Daiichi nuclear disaster occurred in Japan.  The cause of the disaster was the Tohoku earthquake, which triggered a tsunami that hit the Fukushima power plant. Huge amounts of radioactive waste were released into the atmosphere, causing the worst nuclear incident since the Chernobyl accident in 1986.  After the Fukushima nuclear accident, many countries around the world took steps to review their nuclear power plans and safety protocols. Switzerland, in particular, decided to phase out nuclear power.  Plans to build new reactors were abandoned. Moreover, the 5 existing nuclear reactors would not be renewed when their operational lifetime ends. For instance, the 2 nuclear power reactors in Beznau nuclear power plant will be decommissioned by 2029 and 2031 respectively, after their operational lifetime of 60 years has ended. In the meantime, Switzerland has to develop new and cheaper renewable sources of energy to replace nuclear power, including hydropower, wind and solar energy. 
© Zhi Wei Seh. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
 I. Foulkes, "Swiss Search For Strategy on Nuclear," BBC News, 23 Mar 11.
 J. Kanter, "Switzerland Decides on Nuclear Phase-Out," New York Times, 25 May 11.
 K. J. Coppersmith, R. R. Youngs and C. Sprecher, "Methodology and Main Results of Seismic Source Characterization For the PEGASOS Project, Switzerland," Swiss J. Geosci. 102, 91 (2009).
 M. L. Wald, "Japan Orders Evacuation Near 2nd Nuclear Plant," New York Times, 11 Mar 11.