The most eagle-eyed residents of Zurich and Canton Aargau may have noticed more helicopters flying around recently, or perhaps some military trucks driving through the city and the countryside. Both of these unusual occurrences are part of an ongoing emergency nuclear exercise, designed to practice the response to an accident at the nearby Leibstadt Nuclear Power Plant. The exercise will take place from September 27 to 29. 

The exercise is to assess how accidents could be effectively managed

According to the Swiss government, the exercise is designed to simulate how authorities from the local council (Gemeinde) and nearby Swiss cantons would deal with an accident at the nuclear plant. It will also be used to prepare the emergency services so that they can effectively protect the population if there is an accident in the future. 

While the risk of an accident at the Leibstadt Nuclear Power Plant is generally low, authorities want to understand how they could best proceed in a crisis situation, in order to minimise the risk to the health of humans, flora and fauna. A key part of the exercise will involve protecting civilians. Taking place on September 29, measurement teams will practice measuring radioactivity levels across several cantons, in real weather conditions.  

Since the Leibstadt plant is located on the Rhine, a river which forms most of the border between Switzerland and Germany, the German authorities are also expected to play a role in the exercise, since any accident could affect German territory too. Such exercises at the Leibstadt plant take place once every two years. 

Emergency exercise practices for the worst-case scenario

Exercise manager Thomas Breu, from Federal Office for Civil Protection, told Swiss broadcaster SRF that the event the authorities are practising for is “the failure of the external power supply of the Leibstadt Nuclear Power Plant." In this case, a backup diesel power system would kick in, but for the sake of this particular exercise, authorities will assume that this backup power supply will fail. 

This then means that a new emergency power supply must be created so that the core of the reactor can be effectively cooled, preventing a potential nuclear meltdown which can occur when the reactor core overheats.

"In the event of a failed emergency power supply, those responsible can, first of all, count on help from the Beznau nuclear power plant, after which there are other options. For example, material from the emergency camp," Breu explained. The emergency camp is located in Reitnau in Aargau. From there, emergency supplies for the power station such as generators and pumps could be flown by helicopter to Leibstadt in order to secure an emergency power supply.