ENSI
150 employees of the Swiss Federal Nuclear Safety Inspectorate ENSI work every day in various fields for the nuclear safety of the Swiss population.
News
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Oversight authority and operators of Swiss nuclear facilities continue to develop safety culture
The Country-Specific Safety Culture Forum Switzerland took place in Bern on 19 and 20 November 2024. Representatives from various institutions discussed Switzerland’s national culture and analysed its influence on the safety and oversight culture of nuclear facilities. The aim is to continuously improve safety and security. The results will be summarised in a report and…
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The CNS confirms: Switzerland complies with international requirements
The eighth and ninth review conference of the Convention on Nuclear Safety praised Switzerland for the federal partial funding of ENSI’s research programme. The long-term retention of competence for nuclear safety in Switzerland was also highlighted as a challenge. In summary, Switzerland performed well in an international comparison.
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Seventh Review Meeting of the Joint Convention: Switzerland Honours its Commitments
From 27 June to 8 July 2022, ENSI participated in the Seventh Review Meeting of the Joint Convention at the IAEA headquarters in Vienna. ENSI Director Marc Kenzelmann led the Swiss delegation, with Switzerland receiving top marks for its handling of spent fuel and radioactive waste.
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The Swiss Federal Council appoints Martin Zimmermann as a new member to the ENSI Board
From 01 April 2017, the ENSI Board will once again comprise seven members. The Federal Council appointed Martin A. Zimmermann as the successor to Karine Rausis. The 65-year old has more than 30 years experience in the nuclear reactor research field.
Background articles
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Ten years on from Fukushima, the ENSI Board still holds that safety has priority over political or economic interests
Where there are conflicts of interest between politics, safety and profitability, safety must always take priority. This is one of the most important lessons learnt from the Fukushima nuclear accident.
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‘Switzerland is regarded as very reliable in nuclear matters’ – a commentary by former Federal Councillor Doris Leuthard
At the time of the fateful accident in Fukushima, Doris Leuthard was head of the Federal Department of the Environment, Transport, Energy and Communications (DETEC). To commemorate the tenth anniversary of the nuclear disaster, the former Federal Councillor explains why it was essential to provide political support for nuclear safety after the accident.
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Ten Years on from Fukushima (5/6): Switzerland’s International Position
After the accident at Fukushima, there was an increasing demand for international safety standards and their international monitoring. Switzerland, and in particular ENSI, was committed to mandatory backfitting on a global basis. Even if such safety principles are still not legally binding, the reactor accident acted as a booster for a new safety awareness amongst…
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Ten Years on from Fukushima (4/6): The Consequences for Swiss Nuclear Power Plants and the Oversight Activities
After the events in Fukushima Daiichi, ENSI ordered immediate actions and additional safety tests for the Swiss nuclear power plants. Moreover, from the accident analysis and the EU stress test, ENSI derived a need for action to improve nuclear safety in Switzerland: the “Fukushima Action Plan”.
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Ten Years on from Fukushima (3/6): the EU Stress Test
The tests at the time confirmed that, in international comparison, Swiss nuclear power plants have a high safety level. Despite these learnings, it is important to remain attentive at all times, to keep the proofs of safety up to date, to live a strong safety culture and to systematically analyse events.
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What Oskar Grözinger learned from his international reviews
Oskar Grözinger has spent most of his working life in nuclear regulation. During the EU stress test, the physicist was deputy chairman of the “Topic 1 – External Influences” division.
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How Nils Cordua companioned the EU stress test at ENSI
Nils Cordua was the project leader at ENSI during the EU stress test in Switzerland. He has been working at ENSI since 2010 and is now a specialist in systems engineering.
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How Jukka Laaksonen initiated the EU stress tests
Jukka Laaksonen was Chairman of the Western European Nuclear Regulators Association (WENRA) and Director General of the finnish nuclear safety authority Säteilyturvakeskuksen (STUK) when the events in Fukushima took place. He has held nuclear safety expert positions within the International Atomic Energy Agency (IAEA), the Organization for Economic Co-operation and Development (OECD) and the European…
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Ten Years on from Fukushima (2/6): The radiological effects of the accident
After the nuclear accident in Fukushima Daiichi, extrapolations revealed that about one-eighth of the amount of radioactivity that escaped at Chernobyl was released into the surrounding area. The maximum estimated radiation dose for the population was 7.5 millisievert. However, various studies revealed that mental problems in the aftermath of the accident had a greater impact…
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Ten Years on from Fukushima (1/6): The lead-up to the 2011 Disaster
After Chernobyl, the Fukushima accident of 11 March 2011 is history’s most serious reactor accident. An expert team from ENSI carried out an in-depth analysis of the circumstances leading up to the disaster. As a result, ENSI was able to derive important conclusions both for its own regulatory role and for the safety of Swiss…
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Series of articles on barriers 6/6: The containment holds radioactive substances in the reactor building
The reactor pressure vessel is enclosed by the containment as the third barrier. This consists of a steel primary containment and a concrete secondary containment.
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Series of articles on barriers 5/6: The water circuit (primary circuit part 2 of 2)
With its pipelines, shut-off valves and other components, the cooling circuit, together with the reactor pressure vessel, is the second barrier for trapping radioactive substances.
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Series of articles on barriers 4/6: The reactor pressure vessel (primary circuit part 1 of 2)
The reactor pressure vessel, together with the water’s cooling circuit, is the second barrier for trapping radioactive substances.
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Series of articles on barriers 3/6: The fuel rod cladding tubes (fuel assemblies part 2 of 2)
The fuel pellets are filled into metal tubes. Together with the nuclear fuel matrix, the cladding tubes are the first barrier for trapping radioactive substances in nuclear power plants.
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Series of articles on barriers 2/6: The nuclear fuel matrix (fuel assemblies part 1 of 2)
The nuclear fuel is pressed into pellets and compacted using the sintering process before use in nuclear power plants. This process transforms the nuclear fuel into a ceramic material, which is able to retain the fission products that arise during operation in the nuclear fuel matrix.
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Series of articles on barriers 1/6: Barriers protect people and the environment from radioactive substances
The barrier concept aims to trap sources of radiation in nuclear facilities across several levels. Similar to the layers of an onion, independent barriers ensure that the risk from sources of radiation are minimised for people and the environment.
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Prevention of sabotage and theft: an overview
«The protection of nuclear installations and nuclear materials against sabotage, violent actions or theft has to be based on an in-depth defence system which involves structural, technical, organisational, personnel and administrative measures. In my section we examine the measures in effect at nuclear installations on the basis of national and international requirements. To determine the…
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Unannounced inspections
«I’m a site inspector for ENSI, responsible for the Beznau NPP. Every week I pay a control visit to the nuclear power plant without prior announcement. I’m interested in everything, including ladders that have fallen over and that you can trip over. Thanks to their training and experience, inspectors know what to look for. We…
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A focus on upgrading
«Nuclear power plants are periodically upgraded with modern technology, such as here in Beznau. Together with my section I check, in a multi-stage approval procedure, whether electrical and process control upgrades fulfil the legal requirements and can be implemented without reservation. Only then do we issue approval for operation. We do not allow ourselves to…
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Strict requirements for deep geological repositories
«I, together with other experts, oversee Nagra’s search for sites for deep geological repositories for radioactive waste. When making its proposals for sites Nagra has to adhere to the legal framework and our technical safety requirements. In order to ascertain whether these can be implemented and whether the proposals are in line with the state…