Fukushima-Daiichi accident and nuclear safetyenhancement: IRSN's contribution
IRSN FACT SHEETSMarch 2021

www.irsn.fr

The situation in Japan
Post-Fukushimameasurements in figures
Phase 1
Short-term modifications
and reinforcements ofmobile resources,
implementation of the FARN
(nuclear rapid responseforce): phase completed.
Phase 2
• Emergency dieselgenerators(56 completed out of 56
planned)• Emergency water sources(7 completed out of 56
planned, others planned forend-2021)• Reinforced local crisis
centers (1 currently inservice in Flamanville, theother 17 will be entered into
service between 2022 and2026)
Phase 3Full-scale long-term
improvements as part of thefourth ten-yearly inspectionsof the 900 and 1,300 MWe
reactors, currently in placeat Tricastin 1 and Bugey 2.

March 11, 2011
▪ A magnitude 9.0 earthquake triggered the emergency shutdown of three reactors at the Fukushima-Daiichi power
plant and led to the loss of external power supplies. The plant was then powered by emergency generators. The tidal
wave following the earthquake destroyed the power plant’s cooling water pumping station and led, in particular, to theloss of the emergency generators, depriving the facility of all power supply.
▪ The successive loss of the cooling systems of the first three reactors resulted in core meltdown between March 11and 14, and several hydrogen explosions damaged the reactor buildings. Massive releases of radioactive products
into the atmosphere and marine environment occurred, requiring evacuation of the population within a radius of 20 km
from the site.
Ten years after the accident▪ In industrial terms, Tokyo Electric Power Company (Tepco), the plant's operator, stabilized the situation of the facilities
but is still managing the consequences of the accident. Decommissioning operations will last between 30 and40 years. The nuclear fuel must be removed from storage pools and damaged reactors beforehand. In the short term,
Tepco must manage 1.2 million m3 of contaminated water, which increases by 54,000 m3 per year and will exceed thesite’s storage capacity in 2022.
▪ In environmental terms, the management of 20 million m3 of waste linked to the rehabilitation of areas contaminatedby radioactivity is another challenge. Stored in various locations in the prefecture, it will be transported to a centralized
warehouse, the ISF, sized for 30 years of operation.
▪ In terms of health, the population of Fukushima Prefecture continue to be monitored by medical services. Theirexposure was limited; the first studies carried out do not show any increase in thyroid cancer in children present in
the prefecture during the nuclear accident in 2011.
▪ In terms of land management, regarding the population's return to areas where the evacuation order has been lifted,
the situation is very disparate depending on the municipality concerned, ranging from 0% to 75% but with an averageof 22% for the “special decontamination area”.

Lessons learned in France for nuclear power plants
The Fukushima-Daiichi accident demonstrated that a nuclear power plant could be exposed to external loads (earthquake,tsunami, etc.) at a level higher than that taken into account in its design. This observation led the French public authorities
to request complementary safety assessments of the nuclear facilities.
IRSN, a public expert in nuclear safety and radiation protection, analyzed the results of these safety assessments, in France,
and their European equivalent, called ‘stress tests’. Drawing upon this analysis, the Institute recommended that the ASN
equip nuclear facilities with a “hard core” of material, human, and organizational resources aimed at, for EDF plants,
preventing core meltdowns in the event of an “extreme” natural event and limiting the consequences should a meltdown
still occur.

IRSN’s contribution to enhancing nuclear facility safety
Facility safety is first and foremost based on the compliance of its equipment with its safety standard. As part of theten-year nuclear safety assessment of the facilities and the consideration of the feedback from the accident of March
11, 2011, IRSN continues performing numerous assessments on this subject.

Contact
Emmanuelle Mur
Tel. +33(0)1 58 35 96 71
Registered office31, av. de la Division Leclerc
92260 Fontenay-aux-Roses

As part of these safety assessments, IRSN recommended the implementation of additional safety resources
constituting a “hard core” (see diagram below), operational in the event of an extreme external loads. The Instituteassessed the levels of natural events to be taken into account, as well as the resources of the hard core. For EDF plants,in particular, it ensured the completeness of the resources implemented to avoid core meltdowns and to limit its
consequences in the environment, should one occur. In particular, IRSN relies on its calculation tools and the lessons
learned from its research programs. These resources will be gradually deployed on the nuclear fleet. In addition to these
fixed resources, there are mobile resources on site as well as those of the Nuclear Rapid Response Force (FARN), which
is tasked with taking over the “hard core” within 24 hours in the event of an accident.

IRSN is a French Stateowned industrial andcommercial establishment(EPIC) the missions, status,and operation of which are
determined by Articles L59245 to L592-49 and R592-39
to R592-61 of the French
Environment Code. IRSN isunder the joint supervision ofthe French Minister for theEnvironment, the French theMinister of Defense, and theFrench Ministers of Energy,
Research, and Health.
As a public expert, IRSN
advances scientificknowledge to manage all
nuclear and radiation risks.
Through its research,methods, and interactions
with all stakeholders, IRSN
assesses these risks andtheir consequences
independently. It thus
contributes to theirprevention, detection, andthe limitation of their
possible effects, in order toprotect the population andthe environment.

Find out more• On IRSN research
programs:
https://en.irsn.fr/research•
On the situations covered in“Fukushima, ten years on”:
www.irsn.fr/Avis-2021-1• On the French-Japanese
research project SHINRAI:
https://en.irsn.fr/news/irsnpublishes-study-socialconsequences-311-nuclearaccident-fukushimaprefecture• On the initiativeof dialog with the populationof the Fukushima prefecture:

With regard to the other civil nuclear facilities, IRSN examined the means proposed by the operators, in particular thedefinition of the hard core and the new crisis centers, and carried out assessments on the organization of the national
task force (FINA).

The three main
objectives of
the “hard core”• Prevent an accident
with core meltdown• Limit emissions incase of core meltdown• Allow the operator tomanage the crisis.

Interactions with society
For several years, the International Commission on Radiological Protection (ICRP) engaged in dialog with the Fukushima
prefecture's population, while IRSN carried out various actions with local stakeholders, notably under European projects
devoted to the management of post-accident situations, such as SHAMISEN, TERRITORIES, or the French-Japanese
SHINRAI project. Analysis of the results demonstrates the importance of the involvement of the various segments ofsociety (citizens, elected representatives, associations and professionals, etc.) in decisions impacting their daily lives(environmental and individual radiation monitoring, health monitoring, socio-economic aspects, etc.) and theimplementation of dialog mechanisms between the various stakeholders.
The lessons learned highlight the complexity of situations and the need to empower citizens to make their choices, forexample by encouraging radiation measurement initiatives or by developing the sharing of assessments. With this inmind, IRSN developed the OpenRadiation project, allowing access to and the sharing of the citizen measurements ofradiation in the environment or the OPAL mapping tool aimed at raising local stakeholders’ awareness of post-accident
management.

IRSN’s contribution to research on nuclear safety and radiation protection
Following the Fukushima-Daiichi accident, the public authorities launched a call for projects in 2012 on “Research on nuclear
safety and radiation protection” (RSNR) financed by the French National Research Agency (ANR). Several research projects
have been undertaken by IRSN in this context.
Nuclear safety research: the Institute has notably managed research projects relating to the risks of dewatering of spent
fuel pools (DENOPI project), the improvement of the governance of organizations and networks of nuclear safety
stakeholders (AGORAS project), the knowledge of the risk of hydrogen explosions and its management (MITHYGENEproject), and the limitation of releases to the environment in the event of a serious accident (MIRE project).
Radiation protection research: France has conducted particularly active research in this field, benefiting from significant
public support as part of the RSNR call for projects. The programs concerned focused mainly on chronic exposure toand contamination with radionuclides, such as caesium 137 or iodine 129. This is the case for programs, such as
AMORAD (which aims to optimize the models for predicting the dispersion of radionuclides in the environment andassessing their impact), DEMETERRE (study of phytoremediation techniques for soils contaminated withradioelements), or PRIODAC (repeated prophylaxis with stable iodine in an accidental situation).
Economic studies: IRSN conducts studies aimed at assessing the economic consequences of a nuclear accident.
Created in 2012 by the Institute, the purpose of ARPAGON software is to provide public authorities, at the end of theemergency phase, with options for the management of contaminated areas, including costing. In particular, the costsof accidents and their prevention can be considered.
Sociological studies: the French-Japanese research project SHINRAI studied the decision-making methods of theauthorities in a post-accident context and their impact on the population, with a particular focus on the methods ofinvolving citizens in these decisions. The project allowed a number of assumptions, on which the post-accident policy
defined by the institutions was based, to be compared with the actual experience of the Fukushima-Daiichi accident andto learn from it.