ENSI’s tasks

150 employees of the Swiss Federal Nuclear Safety Inspectorate ENSI work every day in various fields for the nuclear safety of the Swiss population.

Surveying installations


ENSI staff survey and monitor nuclear installations on the basis of international requirements, laws and regulations. On this basis ENSI formulates guidelines that are continually developed and technically updated in accordance with the state of the art.

Safety evaluation reports

ENSI experts prepare safety reports when operators of nuclear installations make applications that go beyond the existing operating licence.

Permits and approvals

ENSI specialists review applications for modifications to the installation and grant the corresponding permits if the assessment proves to be positive.

Monitoring operations


ENSI inspectors check the reports submitted by operators, conduct regular regulatory discussions and control nuclear installations through local inspections, which includes their organisation and operation.


ENSI staff supervise and monitor the audits that nuclear power plants carry out for several weeks each year in summer.

Monitoring radiation

ENSI’s specialists for radiological protection monitor compliance with the requirements for radiological protection and dose limits – for the protection of the personnel at the installations, the population and the environment.

Remote monitoring and forecasts

ENSI staff monitor radioactivity in the surrounding areas of nuclear power plants with their own monitoring network. Furthermore, in the case of incidents the emergency organisation has access to readings from the installations. The measurements are made for purposes of remote monitoring and in order to make forecasts in the event of abnormal occurrences.

Processing incidents

ENSI experts systematically assess incidents in Swiss and foreign nuclear installations with regard to their significance for nuclear safety and enforce improvements where necessary.

Safety assessment

ENSI collates all data collected during the course of a year to form a comprehensive safety assessment. From this it derives any measures that need to be taken and plans for future oversight activities.

Waste management

ENSI staff monitor the entire waste management process – from decommissioning through interim storage – to deep geological repositories. This also includes the monitoring of operational activities such as the conditioning or transport of radioactive waste.

Furthermore, ENSI’s waste management experts prepare safety evaluation reports on waste management issues, especially on site proposals for deep geological repositories and on the Nagra waste management programme (National Cooperative for the Disposal of Radioactive Waste). As in other cases the central issues are: Safety has top priority.

Emergency preparedness

ENSI’s emergency organisation makes a rapid, professional and independent assessment of the situation when incidents occur at nuclear installations. It supports the responsible emergency protection organisation in taking decisions.

In the case of an NPP accident, for instance, ENSI’s experts advise the National Emergency Operations Centre (NEOC) and calculate the possible spread of radioactive substances. They assess the appropriateness of the measures taken by nuclear power plants in relation to the protection of people and the environment.

The alerting of ENSI’s emergency organisation is guaranteed 24 hours a day.

Further tasks

International bodies

ENSI staff represent Switzerland on international bodies such as the Convention on Nuclear Safety of the International Atomic Energy Agency, IAEA, where it advocates the strengthening of supervision worldwide or the Joint Convention on the Safety of Spent Fuel Management and on the Safety of Radioactive Waste Management. They regularly report to the IAEA regarding the safety of Swiss nuclear installations.


ENSI follows international developments in safety research in the field of nuclear energy. It cultivates contacts with research institutions at home and abroad and evaluates research trends.

Technical forums

Technical forums are where answers are provided to technical and scientific questions from the population concerning the safety of nuclear power plants and waste management. The questions and answers are available online.


Dual-control principle

According to the Nuclear Energy Act operators are responsible for the safety of nuclear installations. On the basis of this Act and thus on behalf of the Swiss population ENSI is responsible for supervising nuclear installations and ensuring their safety. The safety authority ensures that the operators of nuclear power plants comply with their legal obligations. The proven dual-control principle therefore also applies in the area of nuclear energy: besides operators ENSI is the second institution concerned with safety.

Legal basis

The legal basis for ENSI’s regulatory activities is primarily to be found in the Nuclear Energy Act and the Federal Law on radiological protection. The ENSI Act governs the organisation of ENSI.


ENSI funds itself through fees, supervisory levies and compensation from the Confederation for services of public interest. According to federal law, ENSI’s accounts are included in the consolidated accounts of the Confederation.