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Chernobyl: 40 years on

On 26 April 1986, unit 4 of the Chernobyl nuclear power plant in today's Ukraine exploded. The radioactive cloud crossed all of Europe, Switzerland included. This page sets out the facts, with numbers, sources and the situation today.

40%
Caesium-137 from Chernobyl still present today

0 days since the explosion

Half-life 30.17 years. The value is calculated from today's date when the page opens.

What happened that night

During a safety test, the RBMK-1000 reactor was running at low power in an unstable state. Two design flaws, a positive void coefficient and control rods with graphite tips, met violations of the operating rules. At 01:23 local time the power surged within seconds and two explosions tore the reactor open. The graphite burned for about ten days.

  1. Unit 4 explodes. Two workers die at once.
  2. Pripyat, a town of about 49,000, is evacuated, some 36 hours after the explosion.
  3. The Forsmark nuclear plant in Sweden measures raised radiation. Only then does the Soviet Union confirm the accident.
  4. The cloud reaches central Europe. Rain brings the fallout down in Ticino as well.
  5. The 30-kilometre zone is decided. About 116,000 people are resettled in 1986.
  6. The major releases end after about ten days of fire.
  7. The first concrete-and-steel sarcophagus is completed.
  8. The plant's last reactor is shut down.
  9. The New Safe Confinement is slid over the sarcophagus.
  10. Russian troops occupy the site.
  11. A drone pierces the roof of the confinement and a fire breaks out in its cladding.
  12. The IAEA finds that the confinement has lost its main safety function, containment. Load-bearing structure and monitoring are not permanently damaged.

What was released

Mostly volatile substances were released. Two matter most for health: iodine-131 decays within weeks but concentrates in milk and in the thyroid. Caesium-137 burdens soils and forests for decades.

SubstanceHalf-­lifeRe­leased (PBq)
5.2 days6,500
8.0 days1,760
2.1 years47
30.2 years85
28.8 years10
24,100 years0.013

1 PBq (petabecquerel) is a quadrillion radioactive decays per second. Values rounded, after UNSCEAR 2008.

Tap a substance to see its atom

Xenon-133 (noble gas)

Xe
  • 54 protons
  • 79 neutrons
  • 54 electrons on 5 shells (2‑8‑18‑18‑8)

Decay: Beta decay to stable caesium-133.

In the body: Noble gas: breathed in and out again, barely retained. Mainly an external dose while the cloud is overhead.

Simplified shell model, not to scale. The nucleus is about 100,000 times smaller than the electron cloud.

Iodine-131

I
  • 53 protons
  • 78 neutrons
  • 53 electrons on 5 shells (2‑8‑18‑18‑7)

Decay: Beta decay to stable xenon-131.

In the body: Taken up by the thyroid like normal iodine, mainly through milk. That is why iodine tablets protect: they fill the thyroid with stable iodine first.

Simplified shell model, not to scale. The nucleus is about 100,000 times smaller than the electron cloud.

Caesium-134

Cs
  • 55 protons
  • 79 neutrons
  • 55 electrons on 6 shells (2‑8‑18‑18‑8‑1)

Decay: Beta decay to stable barium-134.

In the body: Behaves like potassium and spreads through the whole body, mainly the muscles. It had largely decayed after about 20 years.

Simplified shell model, not to scale. The nucleus is about 100,000 times smaller than the electron cloud.

Caesium-137

Cs
  • 55 protons
  • 82 neutrons
  • 55 electrons on 6 shells (2‑8‑18‑18‑8‑1)

Decay: Beta decay to barium-137m, which becomes stable barium-137 with a gamma flash. That gamma flash is what detectors pick up.

In the body: Behaves like potassium and spreads into the muscles. An adult excretes half of it in about three months, but in the soil it stays for decades.

Simplified shell model, not to scale. The nucleus is about 100,000 times smaller than the electron cloud.

Strontium-90

Sr
  • 38 protons
  • 52 neutrons
  • 38 electrons on 5 shells (2‑8‑18‑8‑2)

Decay: Beta decay to yttrium-90, then to stable zirconium-90.

In the body: Behaves like calcium and is built into the bones, where it stays for decades.

Simplified shell model, not to scale. The nucleus is about 100,000 times smaller than the electron cloud.

Plutonium-239

Pu
  • 94 protons
  • 145 neutrons
  • 94 electrons on 7 shells (2‑8‑18‑32‑24‑8‑2)

Decay: Alpha decay to uranium-235.

In the body: Dangerous mainly when inhaled: alpha radiation damages lungs, bone and liver from inside. Little was released, and almost all of it stayed near the reactor.

Simplified shell model, not to scale. The nucleus is about 100,000 times smaller than the electron cloud.

Where the cloud went

Wherever it rained in the days after the accident, the fallout came down. That is why the contamination is patchy and does not depend on distance alone. The charts show the area with more than 37,000 becquerel of caesium-137 per square metre, the threshold above which UNSCEAR counts an area as contaminated.

Former Soviet Union, area in km²
🇷🇺 Russia57,900🇧🇾 Belarus46,500🇺🇦 Ukraine41,900
Rest of Europe, area in km²
🇸🇪 Sweden12,000🇫🇮 Finland11,500🇦🇹 Austria8,600🇳🇴 Norway5,200🇧🇬 Bulgaria4,800🇨🇭 Switzerland1,300🇬🇷 Greece1,200🇸🇮 Slovenia300🇮🇹 Italy300🇲🇩 Moldova60

Together about 190,000 km², more than four times the area of Switzerland. In Belarus that was about a fifth of the country, in Austria about a tenth.

How the cloud spread

The maps show the sequence in rough phases: first, when the cloud reached each country, then how much caesium-137 was left on the ground. The days are rounded to phases, because the cloud moved in several waves and turned with the wind.

Europe: first arrival of the cloud
Chernobyl🇨🇭

02-05.05: France, Benelux, UK, Ireland, Balkans, Greece, Turkey

  • 26-28.04: Belarus, Baltics, Poland, Scandinavia
  • 29.04-01.05: central Europe, Switzerland, northern Italy, Romania, Bulgaria
  • 02-05.05: France, Benelux, UK, Ireland, Balkans, Greece, Turkey
Europe: area above 37,000 Bq/m² of caesium-137
Chernobyl🇨🇭

under 1,000 km²

  • over 40,000 km²
  • 5,000 to 12,000 km²
  • 1,000 to 5,000 km²
  • under 1,000 km²
  • below the threshold or no figure
Switzerland: rain and deposition, 30 April to early May 1986

Result: caesium-137 on the ground in becquerel per m²

  • 30.04.1986: the cloud reaches Switzerland. Rain in central, north-west and north-east Switzerland
  • Ticino about 40,000, locally up to 50,000
  • Graubuenden: southern valleys like Ticino, north lower
  • Eastern Switzerland about 15,000
  • Jura line about 5,000
  • Valais about 3,000
  • no cantonal figure

Values after the Federal Council 2002 and ENSI; Valais from soil profiles. Averages; some high-altitude spots had more.

Consequences for people

134

cases of acute radiation sickness, mostly firefighters and plant staff. 28 of them died in 1986.

about 530,000

registered recovery workers (liquidators) from 1986 to 1990.

about 335,000

people resettled: about 116,000 in 1986, later about 220,000 more.

over 19,000

thyroid cancer cases from 1991 to 2015 among people who were children or adolescents in 1986, in Belarus, Ukraine and four regions of Russia. About a quarter of them (range 7 to 50 percent) are attributed to radiation.

How many deaths? The estimates differ widely

A radiation-induced cancer cannot be told apart from any other cancer in the individual case. The death toll is therefore estimated with models, and the result depends on which population and which assumptions are included.

025,00050,00075,000100,000Chernobyl Forum 2005, about 600,000 most exposed4,000WHO 2006, plus 5 million in contaminated areas9,000IARC 2006, all of Europe to 20656,700–38,000TORCH 2006, worldwide30,000–60,000Greenpeace 2006, overall estimate93,000

Estimated additional cancer deaths. Bar: range, dot: central value where given.

The deaths from acute radiation sickness and the rise in thyroid cancer are established. Every figure beyond that is a model calculation.

What is still radioactive today

On farmland the caesium was diluted by ploughing and harvesting. In forests it stays in the cycle of soil, fungi and animals.

  • Wild boar in Bavaria, Austria and Ticino often still exceed the caesium limit. They eat deer truffles, underground fungi that concentrate caesium strongly. Part of this caesium comes from the nuclear weapons tests of the 1950s and 1960s.
  • Wild mushrooms and game from affected forests are still checked.
  • In Sweden and Norway reindeer meat is still tested. Sami reindeer herding is hit hardest.
  • In the UK about 9,700 sheep farms were under restrictions at the peak. The last restrictions were lifted only in 2012.
  • The exclusion zone covers about 2,600 km² on the Ukrainian side, plus a reserve of about 2,200 km² in Belarus, together almost the size of the canton of Valais.
Share of the 1986 caesium-137 still present in a chosen year
0%25%50%75%100%1986203620862136
2026: 40% still present

Only around the year 2186 will the caesium-137 have decayed to 1 percent.

Switzerland and nuclear power

The cloud reached Switzerland on 30 April 1986. Ticino was hit hardest because it rained there that day: up to 50,000 becquerel of caesium-137 per square metre were measured, the highest value in Switzerland. About 1,300 km² lay above the threshold of 37,000 becquerel.

What applied in Switzerland in 1986

  • From 3 May 1986: pregnant women, nursing mothers and small children are advised not to drink fresh milk or eat fresh vegetables. Vegetables are to be washed thoroughly, cistern water not drunk. These were recommendations, not bans.
  • Many people bought UHT milk produced before the accident. Sales of salad and vegetables collapsed for a time.
  • 25 May 1986: most recommendations are lifted; raised values remain only in southern Ticino.
  • In Ticino, sheep and goats may not be slaughtered until the end of August 1986.
  • 3 September 1986 to July 1988: fishing ban on Lake Lugano, the only ban Switzerland imposed. It did not apply to the Italian part of the lake.
  • Vegetable growers won 8.7 million francs in compensation before the Federal Supreme Court; fishermen were compensated too.
  • The additional radiation dose averaged about 0.5 millisievert, up to 5 millisievert for some individuals, mainly through contaminated food.
  • In June 1986 over 20,000 people demonstrated against nuclear power at Goesgen, the largest anti-nuclear rally in Switzerland.
  • To this day: every year 2.5 to 5 percent of wild boar shot in Ticino are seized for excess caesium (2013 to 2025).
The first 100 days: iodine-131 against caesium-137
0%50%100%0255075100DayCaesium-137Iodine-131

Iodine-131 halves every 8 days, which is why the fresh-milk advice only ran until late May. After 100 days caesium-137 is almost unchanged.

Ticino: Chernobyl caesium-137 on the ground, decay only, starting from 40,000 Bq/m²
198640,000199631,800200625,300201620,100202616,000203612,700204610,100

Calculated with the 30.17-year half-life. Migration into deeper soil layers is not included.

PlantSinceShut­down
57 years in operation1969planned 2033
55 years in operation1971planned 2032
47 years in operation1979open
42 years in operation1984open
47 years in operation1972shut down 2019

Tap a plant for details and fuel

Beznau 1 planned 2033

Location
Doettingen AG, island in the Aare
Type
Pressurised water reactor
Net output
365 MW
Operator
Axpo
Reactor supplier
Westinghouse
🇺🇸 USA
Cooling
River water from the Aare
In operation
57 years in operation, since 1969
ReactorSteam-gener-atorTurbineGene-rator

Two separate loops: the water in the reactor is under so much pressure that it does not boil. It passes its heat to a second loop in the steam generator, and that steam drives the turbine.

Fuel: uranium-235

U
  • 92 protons
  • 143 neutrons
  • 92 electrons on 7 shells

The fuel elements contain uranium oxide enriched to a few percent uranium‑235. When a uranium‑235 nucleus captures a neutron it splits, releasing heat and two to three new neutrons. This produces exactly the substances in the table above: iodine‑131, caesium‑137, strontium‑90.

Beznau 2 planned 2032

Location
Doettingen AG, island in the Aare
Type
Pressurised water reactor
Net output
365 MW
Operator
Axpo
Reactor supplier
Westinghouse
🇺🇸 USA
Cooling
River water from the Aare
In operation
55 years in operation, since 1971
ReactorSteam-gener-atorTurbineGene-rator

Two separate loops: the water in the reactor is under so much pressure that it does not boil. It passes its heat to a second loop in the steam generator, and that steam drives the turbine.

Fuel: uranium-235

U
  • 92 protons
  • 143 neutrons
  • 92 electrons on 7 shells

The fuel elements contain uranium oxide enriched to a few percent uranium‑235. When a uranium‑235 nucleus captures a neutron it splits, releasing heat and two to three new neutrons. This produces exactly the substances in the table above: iodine‑131, caesium‑137, strontium‑90.

Goesgen open

Location
Daeniken SO, on the Aare
Type
Pressurised water reactor
Net output
about 1,000 MW
Operator
Kernkraftwerk Goesgen-Daeniken AG
Reactor supplier
Kraftwerk Union / Siemens
🇩🇪 Germany
Cooling
Cooling tower
In operation
47 years in operation, since 1979
ReactorSteam-gener-atorTurbineGene-rator

Two separate loops: the water in the reactor is under so much pressure that it does not boil. It passes its heat to a second loop in the steam generator, and that steam drives the turbine.

Fuel: uranium-235

U
  • 92 protons
  • 143 neutrons
  • 92 electrons on 7 shells

The fuel elements contain uranium oxide enriched to a few percent uranium‑235. When a uranium‑235 nucleus captures a neutron it splits, releasing heat and two to three new neutrons. This produces exactly the substances in the table above: iodine‑131, caesium‑137, strontium‑90.

Leibstadt open

Location
Leibstadt AG, on the Rhine at the German border
Type
Boiling water reactor
Net output
about 1,220 MW
Operator
Kernkraftwerk Leibstadt AG
Reactor supplier
General Electric
🇺🇸 USA
Cooling
Cooling tower
In operation
42 years in operation, since 1984
ReactorTurbineGene-rator

One loop: the water boils directly in the reactor and the steam goes straight to the turbine. Turbine and pipes are therefore slightly radioactive during operation.

Fuel: uranium-235

U
  • 92 protons
  • 143 neutrons
  • 92 electrons on 7 shells

The fuel elements contain uranium oxide enriched to a few percent uranium‑235. When a uranium‑235 nucleus captures a neutron it splits, releasing heat and two to three new neutrons. This produces exactly the substances in the table above: iodine‑131, caesium‑137, strontium‑90.

Muehleberg shut down 2019

Shut down since 20.12.2019; dismantling is under way.

Location
Muehleberg BE, on the Aare, about 15 km west of Bern
Type
Boiling water reactor
Net output
373 MW
Operator
BKW
Reactor supplier
General Electric
🇺🇸 USA
Cooling
River water from the Aare
In operation
47 years in operation, since 1972
ReactorTurbineGene-rator

One loop: the water boils directly in the reactor and the steam goes straight to the turbine. Turbine and pipes are therefore slightly radioactive during operation.

Fuel: uranium-235

U
  • 92 protons
  • 143 neutrons
  • 92 electrons on 7 shells

The fuel elements contain uranium oxide enriched to a few percent uranium‑235. When a uranium‑235 nucleus captures a neutron it splits, releasing heat and two to three new neutrons. This produces exactly the substances in the table above: iodine‑131, caesium‑137, strontium‑90.

Beznau 1 is among the oldest reactors still producing power anywhere in the world.

On 21 May 2017 voters approved the Energy Act with 58.2 percent. Since then, building new nuclear plants has been banned. In June 2026 parliament decided to lift that ban, as a counter-proposal to the popular initiative "Stop the blackout", by a very narrow margin in the National Council. A referendum was launched against it. The vote will take place on 28 February 2027 at the earliest.

All voting dates

Nuclear plants in war

The war in Ukraine shows a danger nobody reckoned with in 1986. The Zaporizhzhia plant, with six reactors the largest in Europe, has been occupied by Russia since March 2022. At Chernobyl, a drone damaged the confinement in February 2025, a structure built in 2016 for about 1.5 billion euros. The European Bank for Reconstruction and Development (EBRD) is seeking about 500 million euros for the repair.

Accidents at nuclear facilities worldwide

Events at nuclear facilities are rated on the IAEA's international INES scale, from 1 to 7. Each level is roughly ten times more severe than the one below. Levels 1 to 3 are called incidents; from level 4 they are accidents. Events before 1990 were rated retrospectively.

The INES scale
1233x46x53x61x72x
  • 7 Major accident
  • 6 Serious accident
  • 5 Accident with wider consequences
  • 4 Accident with local consequences
  • 3 Serious incident
  • 2 Incident
  • 1 Anomaly

All known accidents from level 4 and the main level-3 incidents

  1. 7
    🇺🇦 Chernobyl (then Soviet Union), 1986
    Nuclear power plant

    Explosion and ten days of fire. Radioactive material across Europe, about 4,800 km² still an exclusion zone.

  2. 7
    🇯🇵 Fukushima Daiichi, 2011
    Nuclear power plant

    Earthquake and tsunami knocked out power and cooling. Meltdowns in three units, over 150,000 people evacuated.

  3. 6
    🇷🇺 Kyshtym (Mayak) (then Soviet Union), 1957
    Fuel or nuclear-waste facility

    A tank of liquid nuclear waste exploded. About 800 km² contaminated, about 10,000 people resettled, kept secret for years.

  4. 5
    🇬🇧 Windscale, 1957
    Military reactor

    Fire in the graphite core of a weapons-plutonium reactor. Iodine-131 was released and milk from the area was poured away.

  5. 5
    🇺🇸 Three Mile Island, 1979
    Nuclear power plant

    Partial meltdown in unit 2. Little was released, but tens of thousands left the area.

  6. 5
    🇨🇦 Chalk River, 1952
    Research reactor

    Operating errors at the NRX research reactor; the reactor core was destroyed.

  7. 4-5
    🇨🇭 Lucens VD, 1969
    Experimental power reactor

    Cooling failure in the experimental reactor in a rock cavern, partial meltdown. The cavern was contaminated and the Swiss reactor programme ended.

  8. 4
    🇫🇷 Saint-Laurent-des-Eaux, 1969
    Nuclear power plant

    About 47 kg of uranium melted in reactor A1 during loading.

  9. 4
    🇫🇷 Saint-Laurent-des-Eaux, 1980
    Nuclear power plant

    Partial meltdown in reactor A2.

  10. 4
    🇸🇰 Jaslovske Bohunice (then Czechoslovakia), 1977
    Nuclear power plant

    A fuel element overheated during loading; reactor A1 was shut down for good.

  11. 4
    🇺🇸 SL-1, Idaho, 1961
    Military reactor

    Power excursion in a military test reactor, three dead.

  12. 4
    🇯🇵 Tokaimura, 1999
    Fuel or nuclear-waste facility

    Uncontrolled chain reaction at a fuel plant; two workers died.

  13. 3
    🇪🇸 Vandellos, 1989
    Nuclear power plant

    Fire in the turbine hall; the unit was then shut down for good.

  14. 3
    🇭🇺 Paks, 2003
    Nuclear power plant

    Fuel elements were badly damaged during cleaning.

  15. 3
    🇬🇧 Sellafield (THORP), 2005
    Fuel or nuclear-waste facility

    About 83,000 litres of highly radioactive liquor leaked inside the reprocessing building.

Levels 1 and 2 occur every year in every country with nuclear facilities; regulators publish them, in Switzerland the ENSI. The level-3 list is a selection.

The strongest counter-argument

Supporters of nuclear power point out that, per unit of electricity, nuclear is among the safest sources once accidents and air pollution are counted together, Chernobyl and Fukushima included. These figures are correct.

Deaths per terawatt-hour of electricity (accidents and air pollution)
Coal24.6Oil18.4Biomass4.6Gas2.8Hydropower1.3Wind0.04Nuclear0.03Solar0.02

The average hides the kind of risk, though. Six points show the difference.

1Rare, but huge

Coal, oil, gasNuclearTimeTime

Coal, oil and gas do a little harm every day, mainly through the air. With nuclear, nothing happens for a long time, then a single accident hits whole regions at once.

2Lasting

Exclusion zone since 1986born 198640 todaynext generation

The Chernobyl exclusion zone has existed since 1986, about 4,800 km² on both sides of the border. Someone born in 1986 is 40 today. The area is still closed, and will stay closed for the next generation.

3Across the border

🇺🇦🇩🇪 🇦🇹🇨🇭decidednothing

Switzerland never had a Soviet power plant and still got 1,300 km² above the threshold. The risk is also borne by countries that decided nothing.

4A target in war

2022Zaporizhzhia2025Chernobyl

Zaporizhzhia has been occupied since March 2022; at Chernobyl a drone hit the confinement in February 2025. When a wind turbine or a solar plant is hit, no radiation is released.

5Just as safe, without the catastrophic risk

Wind0.04Nuclear0.03Solar0.02

By the same figures, wind and solar are as low as nuclear: 0.04 and 0.02 against 0.03 deaths per terawatt-hour.

6Switch off, or stay

CoalNuclearswitched offstays

A coal plant can be switched off, and the air clears again. An exclusion zone stays.

Schematic drawings, not to scale.

No new nuclear power plants

Nuclear power is too dangerous. An accident in one country hits all of Europe, just as the cloud from Ukraine reached Ticino in 1986. Therefore: no new nuclear power plants in Switzerland. The 2017 ban on new plants stays.

Films and documentaries

Professional productions with research, archive footage and eyewitnesses.

  • Chernobyl 2019
    🇺🇸 🇬🇧 Drama series, 5 episodes
    Director: Johan Renck
    Writer: Craig Mazin

    Emmy for Outstanding Limited Series 2019

    Dramatised retelling of the night and the clean-up. Some characters and scenes are composites or invented.

  • Chernobyl: The Lost Tapes 2022
    🇬🇧 Documentary
    Director: James Jones

    Nominated for a BAFTA TV Award

    Newly found archive footage and eyewitnesses, including the Soviet cover-up.

  • The Battle of Chernobyl 2006
    🇫🇷 Documentary
    Director: Thomas Johnson

    The liquidators' clean-up, with much previously unseen footage.

  • Chernobyl Heart 2003
    🇺🇸 Short documentary
    Director: Maryann DeLeo

    Oscar for Best Documentary Short 2004

    Children in Belarus 16 years after the accident. The link to heart defects shown in the film is scientifically disputed.

  • The Babushkas of Chernobyl 2015
    🇺🇸 Documentary
    Director: Holly Morris, Anne Bogart

    Older women who returned to the exclusion zone and live there.

Fact check: 9/10

All figures come from UNSCEAR, WHO, IARC, the IAEA and official Swiss sources. One point off: the death toll is only known as a range of model estimates.

Sources

  1. UNSCEAR 2000 Report, Annex J: Exposures and effects of the Chernobyl accident
  2. UNSCEAR 2008 Report, Annex D: Health effects due to radiation from the Chernobyl accident
  3. UNSCEAR 2018 White Paper: Evaluation of data on thyroid cancer in regions affected by the Chernobyl accident
  4. Chernobyl Forum (IAEA, WHO, UNDP) 2005: Chernobyl's Legacy: Health, Environmental and Socio-Economic Impacts
  5. WHO 2006: Health Effects of the Chernobyl Accident and Special Health Care Programmes
  6. Cardis et al. (IARC) 2006, International Journal of Cancer: Estimates of the cancer burden in Europe from radioactive fallout from the Chernobyl accident
  7. Fairlie, Sumner 2006: TORCH, The Other Report on Chernobyl
  8. Greenpeace 2006: The Chernobyl Catastrophe, Consequences on Human Health
  9. IAEA, statement of the Director General, 05.12.2025: New Safe Confinement safety assessment
  10. Kyiv Post / Dengi.ua 2026: EBRD on repair funding for the New Safe Confinement
  11. Staeger et al. 2023, Environmental Science and Technology: weapons-137Cs and the persistence of contamination in Bavarian wild boar
  12. UK Food Standards Agency 2012: removal of the last post-Chernobyl sheep restrictions
  13. Our World in Data (Ritchie 2020): What are the safest and cleanest sources of energy?
  14. Bundeskanzlei: Volksabstimmung vom 21.05.2017, Energiegesetz
  15. Axpo, Medienmitteilung Dezember 2024: Betrieb Beznau bis 2032/2033
  16. SDA / Suedostschweiz 18.06.2026: Parlament hebt AKW-Neubauverbot nach Marathondebatte auf
  17. cash.ch 30.06.2026: Breites Buendnis lanciert Referendum gegen den Bau neuer AKWs
  18. BAG: Umweltradioaktivitaet und Strahlendosen in der Schweiz, Jahresberichte
  19. BAG 2026: Tschernobyl-Unfall 1986, Auswirkungen auf die Schweiz (bag.admin.ch)
  20. ENSI 2016: Artikelserie Tschernobyl, Das Dilemma des Schutzes der Schweizer Bevoelkerung
  21. SRF: Die Chronologie, Tschernobyl und die Auswirkungen auf die Schweiz
  22. Sozialarchiv 2017: Vor 30 Jahren, Tschernobyl und Tschernobale
  23. Bundesrat 2002, Antwort auf die Anfrage Menetrey-Savary (via ENSI 2016: Die radioaktive Wolke zieht ueber die Schweiz)
  24. Natural Earth 1:50m Admin 0 Countries (Kartengrundlage Europa)
  25. Kantonsgrenzen: click_that_hood switzerland.geojson
  26. Nuklearforum Schweiz, Monatsberichte ueber den Betrieb der schweizerischen Kernkraftwerke (Nennleistungen)
  27. Filmangaben: Wikipedia-Eintraege und Verleiherseiten (HBO, Sky, Sundance Institute, Academy Awards)
  28. IAEA: INES, The International Nuclear and Radiological Event Scale, User's Manual
  29. ASN (Autorite de surete nucleaire) 2024: Les cahiers Histoire de l'ASN #1, examples of accidents classified on the INES scale
  30. Wikipedia-Eintraege und Verleiherangaben zu den genannten Filmen (Regie, Jahr, Auszeichnungen)

TS120

TS120

Fact check9/10

Pack rating 9/10 (sources UNSCEAR, IAEA, FOPH/ENSI, Federal Council). Key figures re-checked against primary sources on 07.10.2026.

As of 07.10.2026