The safety of Switzerland’s nuclear power plants is defined by law

People who talk about safety are often referring to a personal feeling. Anyone who does not feel that they are in danger is “safe”. The accident at Fukushima has robbed many people of this safety. Couldn’t the events that took place in Japan also happen at any time in Switzerland?

Safety is ENSI’s core mission. This core mission is mainly technical in nature, but ultimately it involves something that is very much alive: safety is brought about by the actions of human beings. The safety of nuclear plants is based on a large number of technical measures. But it is also based on several other factors: employees in nuclear power plants must be well trained, they must consciously shoulder their responsibilities, and they must always be attentive to safety as they go about their work. Last but by no means least, safety is also achieved through a vital interplay of forces between the operators on the one hand, and ENSI together with the Federal Nuclear Safety Commission (NSC) on the other.

How safe is safe enough? Different people answer this question in different ways. Some years ago, therefore, we conducted a comprehensive democratic process in Switzerland to determine what “safe” means to us in the context of nuclear energy. This matter is clearly regulated in the legislation on nuclear energy.

ENSI carries out monitoring to ensure compliance with these regulations. As a Federal authority, it implements the legal requirements which are issued to it by the Federal Council and the Parliament. The accident at Fukushima did not change the legal requirements – even though it did change many people’s sensitivities about safety. Consequently, the accident does not result in ENSI gearing its work to new safety standards, nor does it cause the Federal Department of Environment, Transport, Energy and Communications (DETEC) to revoke a nuclear power plant’s licence.

On the other hand, this does not mean that Fukushima has no impact on supervisory activities. In contrast to the situation in many other countries, legislation in Switzerland requires continuous improvement of safety in nuclear power plants. Whenever new findings become known that help to achieve a further increase in safety, the plant operators are obliged to implement appropriate back-fitting measures – although these may often be very costly. The principle that “Safety is not a state but a process” is therefore enshrined in Swiss law – and one of the results of this is that our older nuclear power plants are now 100 times safer as regards frequency of core damage than they were on the dates when they started to operate.

If the operator of a nuclear power plant is unable to comply with the statutory safety requirements, the power plant in question must be shut down in accordance with the Ordinance on the Taking Out of Service of Nuclear Power Plants (Ausserbetriebnahmeverordnung). Once the operator meets the statutory requirements, the power plant can resume operation. This clear regulation ensures the necessary legal certainty. If operators of nuclear power plants comply with the statutory requirements, they have the right to operate their plants. Only if this legal certainty is guaranteed will the owners of the nuclear power plants be prepared to make the investments in safety improvements that are always necessary.

The supervisory authority carries out monitoring to ensure that the operators meet their obligation to improve the safety of their plants on a continuous basis. According to the Nuclear Energy Act, they must back-fit their plants “to the extent necessary according to experience and the state of the art in back-fitting technology, and beyond that level insofar as this contributes towards a further reduction of hazards and is appropriate.” For this purpose, the operators must keep track of developments in science and technology, and must follow operating experience gained in comparable plants.

Over the last twelve months, ENSI has devoted intensive attention to the accident at Fukushima, and this will continue to be the case in the future. The progression of the accident was evaluated in detail, and measures to continue improving safety at Swiss nuclear power plants were ordered on several occasions. Moreover, ENSI has carried out a self-critical analysis of its own supervisory activities based on the knowledge gained from Japan.

Floods, earthquakes, extreme weather events, aircraft crashes and power outages, as well as the failure of important components, are all scenarios that are examined in depth when assessing the safety of nuclear power plants. In particular, the hazard due to natural events is being re-examined at present, and the scope of this review even includes natural hazards that are expected no more than once in every 10,000 years. The PEGASOS Refinement Project was launched in 2007 with lead management by swissnuclear. This project is determining the hazard assumptions for earthquakes in Switzerland in greater detail than ever before. The consolidated results should be available by the end of 2012. In addition, ENSI is engaged in dialogue with experts and official bodies in order to arrive at a more accurate determination of the flooding hazard. And as part of the action plan that ENSI initiated following the accident at Fukushima, another detailed review of extreme weather conditions is being conducted.

Nevertheless: couldn’t the events that took place in Japan also happen at any time in Switzerland? No-one can rule out a severe accident in a nuclear power plant with absolute certainty – in the same way, for example, as it is impossible to exclude the possibility of a disastrous earthquake in Switzerland. However, the Swiss nuclear power plants maintain extremely high safety standards. The Nuclear Energy Act also obliges them to continue improving their safety. These measures position Switzerland as one of the leading nations in terms of the safety of nuclear power plants.

The nuclear power plants meet the safety requirements that we have stipulated in a democratic process. As Chair of the ENSI Board, I am therefore justified in stating that Switzerland’s nuclear power plants are safe. However, ENSI and the ENSI Board will not content themselves with this statement, but will continue to work on further improvements to safety in the future as well.


Dr Anne Eckhardt
Chair of the ENSI Board