NUCLEAR
ACCIDENT
8.1

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NUCLEAR
ACCIDENTFROM INCIDENTTO ACCIDENT, A DREADEDSEQUENCE OF EVENTS

The most serious accident that can occur in a nuclear
power plant is the meltdown of the fuel and the releaseof radioactive particles into the environment. Whatcascade of events does it take to trigger a disaster like
Fukushima? Nuclear safety also means being aware ofthis chain of events and trying to prevent it.

THE CHAIN
OF EVENTS

A breakdown occurs in the coolingsystem.
If there is the slightest problem,the chain reaction within the reactor
is stopped by the fall of control rods.
Despite this, the fuel continues
to heat up and must be cooled.

The emergency coolingsystems are activated(external reservoir).

Emergencycooling systems
no longer function
because there
is no water or noelectricity.

2,000°C
The fuel pellets heat up, melt and,by mixing with structural elementsof the reactor, gradually form corium,a kind of magma at over 2,000°C
that can pierce the reactor vessel
and flow into the reactor building.

360°C
The temperature of the fuel rises.
Zircaloy cladding corrodes
and releases hydrogen.
Water vapour invades the reactor
building, and the pressure rises.

As the reactor heats up, hydrogencontinues to be released and fission
products escape into the reactor
building.
The pressure is rising. There is a riskof loss of containment.

In the event of unanticipatedleakage and damage to thebuilding, radioactive products
are dispersed into the atmosphere,
forming an invisible plume, carriedby the wind and spread on the
ground by deposition and rain.

The pressure in the building
could cause it to explode,so it is deliberately depressurised
and radioactive products are
dispersed into the atmospherein a controlled and filtered manner.

The corium can pierce thebasemat of the reactor building.
It can then reach the groundbeneath the power plant, or evenspread into the groundwater.

8.2

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NUCLEAR
ACCIDENT

THE CONSEQUENCES

 F A NUCLEARO
ACCIDENT ON
THE ENVIRONMENT
A nuclear accident would have consequences
for the entire environment, creating a risk of
exposure to radioactivity for the population.

RELEASESAND FALLOUT
Following a nuclear accident, fission products
such as caesium, iodine and strontium may bedispersed in the air.
The radioactive cloud will move with the windand radionuclides will gradually settle on the
ground, even more so if it is raining or snowing.
The weather is therefore a determining factor
in a nuclear accident, and will determine theextent of the area affected.
In the case of the Chernobyl accident, forexample, the plume affected the whole ofEurope, resulting in deposits that varied
from region to region.

Caesium-137 deposits
in Bq/m2 just after the
Chernobyl accident.

1,500,000

10,000200,000

2,000

40,0000DEPOSITS AND LONGER-TERM
CONSEQUENCES
After the plume has passed, deposits in the environment
can be significant, leading to heavy soil contamination. Some
radionuclides, such as plutonium and americium, are more likely
to contaminate the area close to the facility, while others, such as
iodine-131 and caesium-134 and -137, will be carried to greater or
lesser distances, depending on weather conditions, with rainfall
tending to wash them down to the ground.
In addition, rainfall run-off, by washing radioactive particles
downhill, can tend to concentrate radioactivity locally.
Contamination of the environment leads to external exposureof the population, which is all the more significant the larger theradioactive deposits. In some cases, the area may be closed off
and the population relocated for a certain period of time, or accessmay be restricted in highly contaminated areas (forests, etc.).
Deposits in the environment also lead to contamination offoodstuffs and consumer goods. A ban on the consumption of
locally-produced foods and checks on agricultural products prior
to their commercialisation help to protect the population andconsumers.
5 years after the accident,
decontamination work on
the Wide Area Farm roadin Fukushima Prefecture.

THE CONSEQUENCES
FOR WATERAs the plume is transported in theatmosphere, rainwater and run-off become
loaded with the radioactive elements in the
air and deposited on the ground.
The groundwater beneath the power plant
could also be at risk if the reactor core
were to melt and the reactor vessel andbasemat were to rupture. This is one of themost feared scenarios in the eventof an accident.
Drinking water wells, as well assites linked to the fishing and tourism
industries, are therefore checked
before use.

8.3

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NUCLEAR
ACCIDENT

IN THE EVENT OF
A NUCLEAR ALERT,YOU KNOW WHAT TO DO!
An alert is triggered when an event at a nuclear
facility is likely to result in radioactive releases andhave consequences for people and the environment.

QUICKLY SEEK SHELTERIN A BUILDING
Quickly but calmly make your way to a permanent building (with foundation).
If you're already in a building, isolate yourself from the outside:close the doors and windows and turn off the ventilation.

STAY
INFORMED
Listen to the public authorities' protection instructions on the radio(France Bleu, France Info, etc.), on television (France Télévisions,etc.) and on your prefecture's website.
Use a battery-powered radio and make sure you have spare batteries
on hand.

KEEP TELEPHONE CALLSTO A MINIMUM
Don't saturate communication networks.
They are needed to organise emergency services
and broadcast information.

DON'T COLLECTYOUR CHILDREN FROM SCHOOL
Stay sheltered.
At school, your children are looked after by the teachers.

ÉCOLE

You've already discussed this with the teachers.

TAKE IODINEAS SOON AS YOU ARE INSTRUCTED TO DO SO
The dose of stable iodine must be taken at the right time,and you must wait for the prefect's instructions.

PREPAREFOR A POSSIBLE EVACUATION
Pack your emergency kit, which includes your personal
documents, any medicines you may need, clothes, foodand drink.
When evacuating, follow the traffic laws and help yourfamily and friends.

Scan the QR codes
to view the safety plans
The specific safety plan
(PPMS)

8.4

The family safety plan
(PFMS)

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NUCLEAR
ACCIDENT

WHY
IODINETABLETS?
An accident at a nuclear reactor can result in a releaseof radioactive iodine. When inhaled or swallowed,
radioactive iodine binds to the thyroid gland and canincrease the risk of cancer of this organ, especially inyoung people. Iodine tablets protect the thyroid.

IODINETO PROTECT YOUR THYROIDWHY IODINE TABLETS?
The thyroid is an essential organ which regulates a number of functions (growth, developmentof the nervous system, heart rate, etc.). The thyroid naturally stores iodine.
In the event of radioactive iodine being released, this gland needs to be saturated with stableiodine tablets, so that it no longer has room to store radioactive iodine.

WARNING
Iodine tablets are not a cure-all
against the effects of radioactivity:
They do not protect against
other radioactive elements(uranium, caesium, strontium).
This is why other protective
measures are needed.

Lille

NoroetVent d'en bas

Cherbourg

SuroetNorois

WHAT SHOULD YOU DO?

Bise
Nancy

Oberwind

Trappes
Brest

Strasbourg

SuroisGalerneBise
NoroisBourgesGalerneBise

NoroisChabrier

La Rochelle

Hot, dry winds
Dry, cool winds

SuroisMild, wet winds

Clermont-FerrandWet, cool winds

The length of thesegments is proportional
to the average windfrequency in the direction
indicated

Vent
noir

Bise
Traverse

Vent
blanc

Vent
du Midi

Lyon

MistralEmbrunMontélimar

Bordeaux

Vent
blanc

Vent de bas
Tramontane

Bise

Name of the Wind

Biarritz

MistralToulouse

Cers

Montpellier

Autan

Spanishwind

Tramontane

Perpignan

Marin
Marin

Vent
du Midi Nice

LabechLevantAjaccio
Alternating wet and cool weather with hot and dry weather

Temperature reduced by altitude

Average temperature
between 16°C and 19°C

Libeccio

Hot summers, more or less heavy rain, numerous storms

Hot, dry summers, thunderstorms

Average temperature above 22°C

In France, and most neighbouring countries, the threshold forthyroid protection is set at 50 millisieverts. When expert forecasts
exceed this threshold, the Prefect issues an order to take the tablet.

Marignane

GregaleHot, dry summers, thunderstorms

TAKE IODINE AS SOON AS YOU AREINSTRUCTED TO DO SO
If a problem were to occur in a nuclear power plant, the experts
in the emergency response center would be able to estimate quite
precisely the amount of radioactivity released, the location and thetime of its dispersion in the environment. They would calculate thedose to the thyroid glands of residents exposed to the radioactive
plume.

Dijon

NantesSuroisBise

Bise

GalerneUnterwind

Average temperature
above 20°C

IT IS IMPORTANT
TO WAIT FOR THE
PREFECT'S ORDERAs the thyroid gland is constantly
producing hormones, the bodyis constantly looking for iodinein the air or in food to supply
it to the thyroid gland.

Heavy rain, cool temperatures
Average temperature around 10°C at 1000 m altitude

Map of average prevailingwinds in summer

If the iodine tablet is taken too
soon, the stable iodine will beincorporated too early and the thyroid
will no longer be saturated when thereleases occur.

IT ALL DEPENDS
ON THE WEATHER
The areas affected by the accident
depend largely on wind direction
and rainfall.
The map above shows
the prevailing winds in France
over the largest cities.

Iodine-131
at Fukushima

The number of people affected
will depend on the size of thecontaminated area and its
population density.

Radioactive iodine released during
an accident has a half-life of around 8 days,
so after 80 days there is no more in
the environment.
That's why there's no point in taking
iodine tablets if you're travelling near
Chernobyl or Fukushima, where thecontaminated areas have not contained
any radioactive iodine for a long time.

8.5

Design: ASN and IRSN Communications Departments - May 2022
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NUCLEAR
ACCIDENT

WHO IS INVOLVEDIN NUCLEAR
EMERGENCYRESPONSE?

Despite the precautions taken, a serious nuclear accident
remains a possibility in France. However, its consequences
can be limited by taking appropriate protective measures.
Citizens and public authorities have a role to play: risk
awareness is everyone's business.

THE STAKEHOLDERSPUBLIC AUTHORITIES UNDER THE AUTHORITY OF
THE PREFECT, IN LIAISON WITH THE GOVERNMENTThe Prefect triggers the Orsec Plan (Organisation of the civil
security response) and the Special Emergency Plan (PPI).
These plans provide for the organisation of all available
emergency and response resources.
In addition, local and national emergency response units
combine their efforts to limit the health effects of the accident.

ASN
The nuclear safety authority has 4 essential missions:• control the validity of the actions taken by the operator;• advise authorities on measures to protect the population;• inform the public and the media;• send and receive notifications and requests
for international assistance.

IRSN
The institute has various missions:

THE NUCLEAR OPERATOR(in France mainly Orano, the CEA or EDF)

• assess the situation on the basis of data from thefacility, model it and propose preventive action to
the public authorities;

The Internal Emergency Plan (PUI) is drawn up
and implemented by the operator, i.e. the industrial
company responsible for the nuclear facility.

• calculate possible releases, anticipate the path of theplume and estimate the doses in the area on thebasis of meteorological data;

In the event of an accident, the operator must intervene
to prevent or limit radioactive leaks while protecting
personnel working on the nuclear site.

• contribute to informing the public.

It must keep the public authorities informedof developments in the situation.

ACTIONSIMPLEMENTED
DURING THE EMERGENCY

AFTER THE EMERGENCY

The prefect decides on and organises the implementationof measures to protect the population, such as shelteringin place, distributing and taking stable iodine tablets,
evacuating the population and restricting consumptionof local foodstuffs.

In the weeks following the accident,
maps are drawn up showing the precise levelof contamination in the areas affected.

Civil protection services are preparing to help people
in areas that could be affected. Every year, around ten
exercises are organised to train the various actors
involved in a nuclear emergency.

8.6

Depending on the level of radioactivity,
action will be taken to protect the populationand introduce restrictions on the consumption
and sale of products grown and manufactured
in the affected area.

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NUCLEAR
ACCIDENT

AFTER THE ACCIDENT
The consequences of a nuclear accident continue longafter the release of radioactivity has ceased. Steps mustthen be taken to manage this post-accident phase.

SUPPORTING 
THE POPULATIONRadioactive deposits following a nuclear accident in a
power plant can have long-term health consequencesthat must be limited. But it also has major economic,
psychological and social repercussions that need tobe taken into account:• people are likely to be relocated from the area if
exposure to radioactivity in the environment is too high;• foodstuffs from contaminated areas may be banned fromconsumption and sale;

EMERGENCY
PHASE

POST-ACCIDENT
PHASE

There are radioactive
emissions in the air

The radioactivity was deposited on soil,
plants and homes

ACCIDENT

Inhalation ofradioactive
particles in
the air

Irradiation fromradioactive
releaseIngestion ofcontaminatedfood

External irradiation
by depositedradioactive
particles• industrial, agricultural and tourism sectors may beaffected by the loss of business.

EVALUATE
THE SITUATION
The nature of the accident, the extent of the releases andthe meteorological conditions at the time (wind direction
and strength, rain) will determine the extent and levels ofcontamination in the environment.
In order to specify the measures to be taken to protect the
population, the public authorities will have to roll out amajor programme of measures, in particular to:• precisely map the level of contamination in a given area;• measure the radioactivity of goods and food.

POST-ACCIDENT ZONING, THE MAIN TOOL FOR MANAGINGCONTAMINATED AREAS

WHAT ARE THE HEALTH RISKS 
AND HOW CAN YOU PROTECTYOURSELF?
The risks are related to:• internal contamination through ingestion ofcontaminated foodstuffs. This includes fruit andvegetables grown in contaminated areas, as well as meatfrom locally raised animals, and animal products (milk,eggs). To protect yourself, limit your consumptionof contaminated products or check the level ofcontamination of locally produced products (vegetablegardens, for example) before consumption;• external irradiation due to radiation emitted
by radionuclides deposited during the accident.
To protect yourself, simply avoid going to or staying
in the most contaminated areas.

The aim of post-accident zoning is to protect the
population while ensuring the economic and social
recovery of the area. It complements the general actions
and recommendations. It is decided by the Prefect, on therecommendation of ASN.
At the end of the emergency phase, IRSN carries out
measurements to map the contamination of theenvironment and foodstuffs. Based on this data, ASN
recommends that the prefect take action to protect the
population, structured by zone.
This zoning comprises a relocation zone, a zone where
consumption of fresh local produce is prohibited and azone where agricultural produce is checked before
being marketed.

PREPARING FOR
POST-ACCIDENT MANAGEMENTIN FRANCEThe Steering Committee for the Management of the
Post-Accident Phase of a Nuclear Accident (CODIRPA)
was set up by the French Nuclear Safety Authority (ASN)
in 2005, as a multi-stakeholder body to consider how tomanage the consequences of a major nuclear accident.
The post-accident website:
https://www.post-accident-nucleaire.fr/
helps you prepare.

AFTER A FEW DAYSAFTER A FEW MONTHS

In the event of an accident, a guide for residents
of a contaminated area and a question and answer
guide for health professionals can be used.

AFTER A FEW YEARS

Displacement area
No consumption zone
Pre-commercialisation inspection zone

8.7

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NUCLEAR
ACCIDENT

CLASSIFICATIONOF NUCLEAR
EVENTS
Like the Richter scale for earthquakes, the severityof nuclear events is measured on a scale called
INES (International Nuclear Event Scale).

ANALYSIS AND CATEGORISATIONOF EVENTS
There is no causal relationship between the number of non-serious events detected and reported and the probabilityof a serious accident occurring at a facility.
On the other hand, in-depth analysis of each event is a fundamental source of learning.
Detecting and then reporting events to ASN is essential to advancing nuclear safety.
This process must therefore be encouraged at both a national and international level.

MAJOR ACCIDENT

Major release of radioactive
materials with considerable effects
on health and the environment,
requiring the implementation ofprotective actions.

EXAMPLES OF LEVEL 7
Abroad:7

SERIOUS ACCIDENT

6ACCIDENT

Significant release of radioactive
materials with probable need forprotective actions.

ACCIDENT

5

leading to an off-site risk.

ACCIDENT

4

not entailing any significant risk
outside the site.

• 2011: explosion of reactors 1, 2 and 3 at the Fukushima Daiichi nuclear power plant (Japan).
• 1986: explosion of Reactor 4 at the Chernobyl nuclear power plant (Ukraine).

EXAMPLE OF LEVEL 6

Abroad:• 1957: explosion of a tank of radioactive products at the Kyshtym reprocessing plant(Russia).

EXAMPLE OF LEVEL 5

Abroad:• 1979: Partial meltdown of the reactor core at Three Mile Island (United States).

EXAMPLES OF LEVEL 4
In France:• 1980: damage to the reactor core of the A2 reactor at Saint-Laurent-des-Eaux.
• 1969: fuel meltdown in reactor A1 at the Saint-Laurent-des-Eaux power plant.

EXAMPLES OF LEVEL 3
SERIOUS INCIDENT

3

INCIDENT

Failure of all safety measures.

In France:• 1981: fire in a storage silo at La Hague.
Abroad:• 2008: abnormal release of iodine-131 at the Fleurus Institute for Radioelements in Belgium.
• 2003: release of radioactive gases from cracked fuel rods stored in the Paks nuclear power
plant (Hungary).
• 2002: discovery of a cavity in the reactor vessel closure head at the Davis Besse power
plant (United States) due to corrosion of the metal by boric acid.

EXAMPLES OF LEVEL 2
INCIDENT

2

Major failure of safety devices (afew a year in France).

1

ANOMALY(around a hundred a year in France).

DEVIATION

in relation to the normal operating
mode of a facility, with no safetyissues (around a thousand
per year in France).

08.8

In France:• 2012: non-compliance of a pipe in the spent fuel pools of reactors 2 and 3 at the Cattenom
nuclear power plant.
• 2009: blockage of a water intake by a massive influx of plant debris at the Cruas nuclear
power plant during a flood.
• 1999: a storm, combined with inadequate protection measures, leads to partial flooding at
the Blayais nuclear power plant.

EXAMPLES OF LEVEL 1

In France:• non-compliance with general operating rules during reactor restart operations;• Failure to tighten two fasteners on a reactor containment access door.

EXAMPLE OF LEVEL 0

In France:• testing of the emergency generator was forgotten.

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NUCLEAR
ACCIDENTPASTACCIDENTS
There have been several nuclear accidents aroundthe world since the 1950s. The most serious, at level 7
on the INES scale, occurred at Chernobyl in 1986
and Fukushima Daiichi in 2011. These accidents are
the subject of international experience feedback.
What are the consequences of these major accidents?
Permanently contaminated land, health consequences
and the disruption of many people's lives.

CHERNOBYL:
26 APRIL 1986

FUKUSHIMA:
12, 14, 15 MARCH 2011

A sudden and uncontrolled increase in the nuclear reaction(multiplied by 100 in a fraction of a second) led to the explosionof a reactor core and the destruction of the building. The nuclear
fuel was dispersed around the facility.

The loss of power and cooling led to core meltdowns in threereactors, releasing radioactive products into the environment.
The molten fuel remained inside the containment vessels.

RELEASES
Releases were continuous for 10 days, changing
according to the extent of the fire in the reactor
and the delivery of sand and lead by helicopter.

RELEASE DEPOSITS
The whole of Europe was contaminated to varying degrees.
Caesium-137 contamination in excess of 600,000 Bq/m2 wasdispersed over more than 13,000 km2. It has since been halved.

POPULATION EVACUATION
270,000 people were evacuated by the government.

FOOD CONTAMINATION
At first, there were no immediate restrictions on
the consumption of local foodstuffs, followed
by a ban on agricultural activities.

FUTURE OF THE FACILITIES
Construction of a sarcophagus to containthe reactor's radioactive materials, pending
a long-term solution, to be defined.

WASTE MANAGEMENT
Waste is disposed of on site: trenches
were dug in the exclusion zone.

8.9

RELEASES
About fifteen episodes of discontinuous releases over two
weeks following successive reactor explosions.

RELEASE DEPOSITS
Caesium-137 contamination in excess of 600,000 Bq/m2
was dispersed over more than 600 km2 around the plant and
up to a distance of 250 km away.

POPULATION EVACUATION
More than 150,000 people were evacuated from exclusion
zones by the government. 50,000 people decided to leave
contaminated areas of their own accord.

FOOD CONTAMINATION
Food contamination monitoring and commercialisation
restrictions.

FUTURE OF THE FACILITIESThe corium has formed a mass that must continuously becooled. Hundreds of thousands of tonnes of water will be used
and then stored on the site awaiting treatment. The reactors
will be dismantled by 2050.

WASTE MANAGEMENT
The strategy has not yet been defined:
temporary storage.

Design: ASN and IRSN Communications Departments - May 2022
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NUCLEAR
ACCIDENTCHERNOBYLAND ITS CONSEQUENCES
In 1986, the reactor at the Chernobyl
nuclear power plant in Ukraine exploded,
releasing radioactive dust and particles.

THE LOCAL CONSEQUENCESThe human toll of the Chernobyl accident is the subject of controversy(see the "Debate" section). The World Health Organisation (WHO)report, published in 2006, recorded 47 deaths in the weeks following
the accident. It also predicts thousands of cancer deaths (between
9,000 and 16,000) in the 50 years following the disaster.
Among those at risk of developing these diseases are the liquidators,
the hundreds of thousands of people who secured the site, built thesarcophagus and cleaned up the surrounding area.
Children who breathed in radioactive iodine and ate contaminatedfood may have developed thyroid cancer.
In Belarus, Russia and Ukraine, between 1991 and 2005, 6,848 thyroid
cancers were diagnosed in children who were under the age of 18 in
1986; the majority were under 14 at the time (Unscear report 2008).
These illnesses are linked to the passage of the radioactive plumeand contamination of the environment and food.
The reactor did not have robust safety systems or a containment
vessel. The reactor core melted and spread to the lower parts of thereactor building.
The 50,000 residents of Pripyat, three kilometres from the power
plant, were not evacuated until the following day.
The sarcophagus, built between April and November 1986 under
extremely difficult conditions, has deteriorated and rain can penetrate
it. It was covered by a new confinement arch, the construction ofwhich was completed in 2018.

FALLOUTIN EUROPE
The contaminated air mass travelled over a large part of Europe, with areas of significant
contamination in Norway, Sweden and the UK.
Measures were taken in various countries to limit the exposure of local residents, and inparticular the consumption of contaminated products was restricted.
The eastern part of France was affected, particularly where it rained during the plume's passage.

CAESIUM-137
DEPOSITS

Caesium-137 deposits
in Bq/m2 just after the
Chernobyl accident.

in Bq/m2 just after the Chernobyl
accident.
From 26 April 1986, the contaminated
air masses progressed towards thewest and north of Europe.
Caesium-137 was selected as
the standard for characterisingcontamination in Europe.

DEBATE

HOW MANYVICTIMS?

1,500,000

10,000200,000

2,000

40,0000

Numerous contradictory reports by agencies,
NGOs and researchers have been published on
the Chernobyl disaster. Figures of tens or even
hundreds of thousands of victims of the disaster
have been put forward, and are far greater thanthe official figures.
It remains very difficult to establish a reliable
estimate, given the scientific uncertainties andthe risks of using the figures for political ends.

There is no doubt that 47 deaths were directly
attributable to the disaster among liquidators,
firefighters and plant operators, as a result of
massive irradiation.
There have also been 7,000 cases of thyroid
cancer among the most exposed children in
Belarus, Russia and Ukraine. 15 deaths werereported among these patients.

8.10 Design: ASN and IRSN Communications Departments - May 2022
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NUCLEAR
ACCIDENT

FUKUSHIMA,

THE DAMAGEDREACTORSThe Fukushima Daiichi reactors were damagedby the earthquake and tsunami of 11 March 2011.

Steam is produced
directly in the upper
part of the reactor.
The spent fuel pool islocated in the upper
part of the building.

THE FUKUSHIMAREACTORS
They are boiling water
reactors (BWRs) in which thesteam produced by the coreturns the turbine directly.
There is no secondary system
and no steam generator.

This torus is part of
the reactor coolingsystem and thecontainment vessel.

TWO NATURAL DISASTERS IN QUICK SUCCESSION
2. Forty minutes later, a 14-metre wave drowned the emergency
generators and safety systems. The control rooms were in
darkness, and most of the sensors indicating system operation
were out of order.

1. The magnitude 9 earthquake,
whose epicentre was 180 km away,
destroyed the reactor's power supply.

CONSEQUENCES
ON THE POWER PLANT
THE CORES OF REACTORS 1, 2 AND 3 MELTED DOWN
The reactor cores formed corium which pierced the reactor vessels andcontainment walls. The volume of the corium and its exact location are notknown. The fission products contained in the corium continue to produce
heat. If the corium is not cooled, it could release radioactive products into
the air again. This is why the operator injects around 200 m3 of water perday. The water becomes loaded with fission products when it comes into
contact with the corium.
The explosion of the hydrogen released by the core meltdown blew away
the structure of the building.
The pressure in the containment vessel rose, and it was necessary todepressurise, releasing fission products and hydrogen into the atmosphere.
The corium pierced the reactor vessel and sank into the concrete.

THE PERIL OF THE REACTOR 4 POOL
There was no nuclear fuel in the core of Reactor 4, which had been unloaded.
But the spent fuel from three cores was stored in its pool, requiringcontinuous cooling.
With no cooling, the three cores heated up and the water in the pool began
to boil and evaporate. These cores could also have melted, releasing fission
products, if the fire brigade had not used exceptional means to inject water.

600,000 M3 OF CONTAMINATED WATER STORED ON THE
SITE IN MARCH 2014... AND DOUBLE THAT AMOUNT IN 2021!
The cooling water injected into the reactors leaked into the basements of thebuildings, where it mixed with groundwater seepage. The operator (Tepco)
partially treats this water and has to manage ever-increasing storage volumes.
Current storage capacity at the Fukushima site is expected to reachsaturation in the summer of 2022. To deal with this situation, Japan plans todischarge waste into the sea starting from 2023.

Read about
the situation at
Fukushima in 2021
10 years after the accident at the
Fukushima Daiichi nuclear power plant

8.11 Design: ASN and IRSN Communications Departments - May 2022
Graphic design and production: www.kazoar.fr - Pictograms: Freepik, Kazoar - Map: Iffo-RME/Google map - Illustration: EPSIM - Photos: TEPCO
Reproduction prohibited without the agreement of ASN/IRSN. For further information: contact@irsn.fr

NUCLEAR
ACCIDENT

FUKUSHIMA,
SOCIETY'SRESPONSE
In areas where annual exposure to radioactivity
exceeded 20 mSv/year, the population was
evacuated. Where it was below this threshold,in addition to government action, local residents
organised to limit the doses they received.

THE AREA WITH
AN EXPOSURE LEVEL> 20mSv/year
WAS EVACUATEDIN THE ZONE WITH
AN EXPOSURE LEVEL< 20mSv/year,
SOCIETY HAS ORGANISED

Here, the residents have been evacuated.

This dose is measured outside, one metre above theground. This is the dose a person would receive if they
stayed outdoors for a year.

The government is funding the decontamination of thisarea so that they can return. But it won't be possible forthe population to return everywhere.

The school, its
playground and thepaths used by thechildren have been
decontaminated.
Children wear
dosimeters.
In grocery shops,
food contaminationlevels are displayed.

Residents are equippedwith measuring devices
and regularly check theirsurroundings.

1m

Access toforests and theconsumption ofmushrooms andwild game areprohibited.

Local authorities and residents have taken various
steps to reduce ambient doses.

Once the area has been
decontaminated to levels
below 20 mSv/year, thegovernment invites
residents to return, but
few are willing to do so.

Some houses
remain uninhabited
and, on certain
roads, nature isreclaiming its rights.

The forests
remain highly
contaminated,
and the windcan carry theirradioactive
particles
towards
inhabited areas.

1m

1m

One kilogram of pineneedles could containup to 300,000 Bq, asignificant source ofradiation.
Residents also cut down
trees within a 20 m
radius of their houses.

In gardens, fivecentimetres of soil were
removed.
Gardeners only growplants that absorb very
little caesium. Somehave added zeolite to
fix the caesium.

To decontaminate
certain sites, public
works companies
evacuate contaminatedsoil and transport it inhuge sacks.

A factory has
been set up toprocess the cut
vegetation bycompacting it.

The houses aredecontaminated bycleaning the walls androofs.
This operation has tobe repeated because
the wind coming fromcontaminated forests
1m
can redeposit
radioactive particles.

1m

Producers fromagricultural cooperatives
check the level ofcontamination in theirproduce.

Farmers havechanged the way theygrow rice.
Now, the dose ofradioactivity present in
the harvested rice does
not exceed thestandards.

The municipalitybought several
hectares of land to
store the large bagsof contaminatedwaste and soil.

Actions taken
by local residents, cities andthe national government haveresulted in a significant reductionin the doses received comparedwith the initial measurements.

8.12 Design: ASN and IRSN Communications Departments - May 2022
Graphic design and production: www.kazoar.fr - Pictograms: Freepik, Kazoar - Illustrations: La-fabrique-créative/Bruno Bourgeois - Photo: Guillaume Bression/Fabien Recoquillé/IRSN Media Library
Reproduction prohibited without the agreement of ASN/IRSN. For further information: contact@irsn.fr

NUCLEAR
ACCIDENT

FUKUSHIMA,

THE CHALLENGES
Evacuation, decontamination, return of therelocated population, monitoring of residents'
health, measurement of foodstuffs: theseactions by the State are essential in the
post-accident situation.

EVACUEES' CHOICES

Fukushima

More than 120,000 people have been relocated because of contamination in their homes,
resulting in exposure of more than 20 mSv/year. Initially housed in 2,200 shelters, they werethen moved into temporary accommodation.
More than 40,000 people have voluntarily evacuated their land, worried about contamination.
Some cities have been decontaminated, and the population is invited to return.

Tokyo

What will they do?

CONTAMINATION IN 2011

THE FUTURE OF EVACUATEDMUNICIPALITIES

Most of the contamination was deposited downwind
within a few hours.

Marumori

Marumori

Kunimi

Kori

Kunimi

Kori
Date

Kori
Date

Date

Shinchi

Shinchi

Fukushima

Kawamata

Shinchi

Fukushima

Fukushima

30 km

30 km

LitateLitateKawamata

Lino

Minamisoma

Minamisoma

Katsurao

KatsuraoMotomiya

MiharuMotomiya

Namie

FutabaTamuraFukushima

Omuka

Omuka

Daiichi
Koriyama

Tomioka

KawauchiSukagawa

NaharaNaharaOno

Sukagawa

NaharaOno
Shidamyo

20 km

20 km

HironoTamakawa

Hirata20 km

HironoTamakawa

HirataHironoHirataIwaki
Izumizaki

30 km

Izumizaki

Ishikawa

6,000,000 to 30,000,000
3,000,000 to 6,000,000
1,000,000 to 3,000,000
600,000 to 1,000,000
300,000 to 600,000

Iwaki
30 km

Izumizaki

Ishikawa

10 km

Caesium-134 and caesium-137
deposits (Bq/m2)

30 km

Ishikawa

10 km

Number of inhabitants

20,000 to 50,000

10 km

Evacuation and return zones

Decontamination areas

 ifficult to return before a long period of time.
D
External dose > 50 millisieverts/year

200,000 to 350,000
50,000 to 100,000

Fukushima
Daiichipower plant

Tomioka

KawauchiShidamyo
Tamakawa

FutabaTamurapower plant

TomiokaOno

MiharuFukushima

Omuka

Daiichi
Koriyama

power plant

Kawauchi

Katsurao

Namie

FutabaKoriyama

20 km

Nihonmatsu

Namie
TamuraMinamisoma

20 km

Nihonmatsu

Nihonmatsu

30 km

LitateKawamata

Lino

20 km

Motomiya

The State planned this work andundertook it.

Marumori

Kunimi

Lino

Decontamination can significantly
reduce people's exposure.

Depending on the extent of thecontamination and the possibility ofdecontamination, a government plan
has provided for a differentiated future
for each municipality.

It rained and snowed: some communities were harder
hit because of the intensity of the precipitation.

Sukagawa

WINNING BACK THE LANDCompleted
Started estriction, prohibited for residential use.
R
External dose between 20 and 50 millisieverts/year reparing to return in 2015.
P
External dose < 20 millisieverts/year

DecidedNot decided
Difficult for a long time

10,000 to 20,000
0 to 10,000

HEALTHOVERVIEW
A vast programme has been set up by the Japanese authorities to monitor the health of people living in the Fukushima prefecture
and to learn lessons from this event. It is based on four 30-year epidemiological studies, the first of which covers the 2.1 million
people living in the Fukushima prefecture at the time of the accident.
Three at-risk populations are being monitored more closely: children, evacuees and pregnant women.

DEATHSPREGNANT WOMEN

360,000 THYROID CHECKS

Officially, no one has died as a resultof the radioactivity at Fukushima.
Evacuations were carried out to limit
doses and prevent cancer in the longterm. How many cancers have been
prevented as a result of the evacuations?
This is a question currently underdiscussion in the scientific community.

The main findings were drawn from asurvey of over 20,000 pregnant women:

All children who were under the ageof 18 in 2011 in the Fukushima prefecture
underwent a thyroid check-up. These
examinations will continue over the next
few years.

• no significant change in the rate of
miscarriages. After an increase in therate of premature births between 2011
and 2012, this rate fell in 2013;

The prefecture of Fukushima hasrecorded more than 1,600 deaths as aresult of the evacuations: deaths ofelderly people due to lack of care, deaths
during transport and suicides. A nuclear
disaster goes beyond the direct risk
associated with radioactivity.

• for birth defects, the rate was 2.85% forbirths between August 2010 and July
2011. These figures are comparable to
the Japanese national average
between 3% and 5%.

In 2015, more than a hundred cancers
were diagnosed. How many were causedby the Fukushima accident?

8.13 Design: ASN and IRSN Communications Departments - May 2022
Graphic design and production: www.kazoar.fr - Pictograms: Freepik, Kazoar - Maps: IRSN - Photo: The Asahi Shimbun/GettyImages
Reproduction prohibited without the agreement of ASN/IRSN. For further information: contact@irsn.fr