IRSN, Institut de radioprotection et de sûreté nucléaire

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The Fukushima Daiichi Accident

​​​​​​​The Fukushima Daiichi nuclear power plant accident in March 2011 was the first occurrence showing that an extreme natural event, that generated stress levels far beyond nuclear power plant design-basis values, could lead to a core meltdown accident.It also showed how the massive destruction of a site and of the surrounding infrastructures could delay and complicate all accident management operations. This  page gives access to special contents produced by IRSN following the accident.

Fukushima Daiichi, 10 years later​

Ten years have passed since the Fukushima Daiichi disaster. 

This accident, like those before it, has led IRSN to conduct extensive research and take action to enhance safety at nuclear facilities and radiological protection of people and the environment. 

We must do everything within our power to prevent accidents, even though there are no guarantees that they will not occur. In this special edition of Repères, we review the situation.

Download our newsmagazine "Fukushima Special Issue" (PDF file)

Consult our online magazine "Fukushima Special Issue"

Anticipation and resilience: considerations a decade after the Fukushima Daiichi accident

What can be learned from the accident of Fukushima Daiichi to make nuclear facilities more robust and able to withstand extreme events and to improve post-accident management? In a new report, IRSN's experts share their insights regarding this challenging and complex subject.​​

Intended for anyone interested in nuclear safety issues, and more generally in risk management, this report invites us to examine current practices in these fields, how each actor contributes to the risk management of nuclear installations, and the need to develop other approaches to better assess the risks, both in the context of normal operation of installations and in accident situations.

Better assessment to prevent nuclear accidents, better preparation to handle them if they do occur, which cannot be excluded: it is the responsibility of the experts, including IRSN, to continue the discussions, to improve knowledge, and to develop new, more systemic approaches. The purpose is to enable decision-makers to make “well-informed” decisions in view of the challenges of the protection of the people and the environment, and the safety of the installations.

Download IRSN report 2021-00176 « Anticipation and resilience: considerations a decade after the Fukushima Daiichi accident » (pdf)


Fukushima in 2016

An in-depth look at the state of the facilities of the Fukushima Daiichi nuclear power plant five years after the accident: the struggle to regain control of the plant and manage radioactive releases, the decontamination efforts, the significant health and social consequences of the accident, the progress of research to prevent nuclear accident.

Read our special coverage Fukushima Daiichi in 2016


Six questions to learn from the Fukushima disaster through Human and Organizational Factors

The accident which was triggered at Fukushima Daiichi nuclear power plant on March 11, 2011 in the wake of a massive earthquake and tsunami is the worst nuclear accident since Chernobyl. Four years later, as more witness accounts become available, IRSN feels useful to return to the human and organizational response to the accident inside the NPP itself.

Starting from the official reports and testimonies on the Fukushima accident, IRSN has published a report entitled “Human and Organizational Factors Perspective on the Fukushima Nuclear Accident”.

Download the full report PSN-SRDS / SFOHREX n°2015-01 “Human and Organizational Factors Perspective on the Fukushima Nuclear Accident” (PDF, 2,13 Mo)

Download the summary report PSN-SRDS / SFOHREX n°2015-03 “Six questions to learn from the Fukushima disaster through Human and Organizational Factors” (PDF, 0,9 Mo)

Human and organizational factors were key in determining the way the Fukushima Daiichi accident unfolded. With circumstances completely unforeseen in the manuals and procedures, actions at every level of the response structure – shift team, plant, utility, national emergency response – were determined by individual decisions and group dynamics.

By looking at each level as well as the relationships between them, this report describes the way the organizational structures and their accident management procedures contribute to or hinder the resolution of the crisis. 


Studying contaminated terrestrial Japanese foodstuffs to improve technical support during emergency response

If a nuclear accident occurred in France, IRSN would have the role of providing technical support simultaneously to public authorities, affected populations and local elected officials during and after the accident. On the basis of lessons learned from the severe accidents of Chernobyl and Fukushima, IRSN must pursue its work to be ready to perform its support role as effectively as possible. Thus, concerning foodstuff contamination, IRSN chose to analyze all measurement results published by the Japanese Ministry of Health, Labour and Welfare (MHLW).

From an immediate operations standpoint, this provided IRSN with the possibility of updating French residents in Japan and of advising DGCCRF, the French entity in charge of the monitoring of foodstuffs imported from Japan. From the standpoint of preparing its technical support mission, IRSN has used this data to test its software tools against the full complexity of a real situation. Beyond this, the data resulted in new radioecological knowledge by filling certain gaps in the understanding of fruit contamination processes.

Read the report in our Aktis newsletter #5


Using dose rate to characterize accident releases

One of IRSN's mission is to provide operational support to public authorities in the event of an incident or accident involving sources of ionizing radiation. Emergency organization, methods and tools developed by IRSN over many years for this purpose were put to the test by the accident at the Fukushima Nuclear Power Plant in Japan.

During the emergency, IRSN assessed the radiological consequences of the accident, with particular focus on the evolution of contamination in the affected regions and doses likely absorbed by the population. The consequences assessments nevertheless involve significant uncertainty, particularly those that depend on information about releases. IRSN is working to reduce uncertainty concerning these releases, and for this purpose has developed a new approach based on the principle of inverse modeling.

Read the report in Aktis newsletter #4


Core meltdown accidents: Steam explosion modeling

IRSN research relating to nuclear reactor core meltdown accidents notably focuses on identifying ways of mitigating their impact. Corium - the mixture of molten materials resulting from the accident - can interact with water in the reactor and, under certain conditions, this interaction can lead to a steam explosion.

The serious effects that such an explosion could have in terms of radioactive containment make it important to learn more about the mechanisms involved in this type of explosion and to model them for the purpose of hazard assessment calculations. Serena2, an international program led by the OECD-NEA to gather vital experimental data for understanding and modeling steam explosions, has just been completed.

Read the report in Aktis newsletter #2


Fukushima-Daiichi Accident: Information note concerning the evolution of the environmental contamination and the contamination of foodstuffs produced in Japan

From 2011 to 2013, IRSN published a newsletter for French citizens living in Japan. Prepared by experts from the Institute, this report was intended to help reduce as much as possible the exposure of French expatriates to environmental pollution persistent in parts of Japan, mainly in the districts of Fukushima, Tochigi, Ibaraki and Miyagi.

The latest version of this newsletter, published in June 2013 in French, gave IRSN’s recommendations in the light of the most recent data published in Japan on the evolution of the environmental contamination as well as that of the foodstuffs produced in Japan. It also covered two particular topics, developed respectively in appendices 1 and 2:

  • the evolution of radioactive deposits in the terrestrial environment since the year of the accident, and its impact on the zoning set up by the Japanese authorities around the Fukushima Daiichi nuclear power plant;
  • the evolution of the levels of contamination observed in the different categories of foodstuffs produced in Japan, and IRSN’s assessment of the risks for consumers.

Download the information note "Information note concerning the evolution of the environmental contamination and the contamination of foodstuffs produced in Japan (PDF file)


Fukushima, 2 years later

Analysis by IRSN of the Fukushima Daiichi accident of March 2011Two years after the accident at the Fukushima Daiichi nuclear power plant in Japan, IRSN publishes a new video looking back at the events that led to the meltdown of three reactors. It explains in particular the difficulties encountered by the operators, TEPCO and the Japanese government in the managiement of the crisis.

Video: Analysis by IRSN of the Fukushima Daiichi accident of March 2011


Report: Fukushima, one year later - Initial analyses of the accident and its consequences 

Published in March 2012, IRSN’s report "Fukushima, one year later" illustrates both the vast amount of data that are now available on the accident’s sequences, and the limited understanding achieved so far of a particularly complex accident, beyond its obvious initiating events.

Detailed understanding of how nuclear accidents unfold, of their consequences of all kinds, and of the related decision-making and response processes is a major source of short- and long-term progress in nuclear safety, radiation protection and emergency response management.

Download the report: Fukushima, one year later - Initial analyses of the accident and its consequences (pdf file)

Press briefing of February 2012: Situation in Japan one year after the Fukushima Daiichi accident

On February 28th 2012 in Paris, IRSN organized a press briefing "Fukushima, one year after" with the participation of Jacques Repussard, Director General of IRSN, Thierry Charles, Deputy Director General in charge of Nuclear Safety, Didier Champion, Director of Emergency Response, and Jean-Rene Jourdain, Assistant Director of Radiation Protection.

The syntheses of their presentation are available for download:

Assessment of the situation at the Fukushima Daiichi nuclear power plant in February 2012

Summary of the Fukushima Accident's impact on the environment in Japan, one year after the accident

Health Consequences of the Fukushima Accident: Update of the situation in February 2012


Fukushima Special Report: First lessons learned 

Fukushima Special ReportOne year after the accident, IRSN propose an English translation of a special issue of its newsmagazine, Repères, who is focused on the accident and on the first lessons drawn by IRSN regarding nuclear safety. 

The first part rev​isits the accident and its aftermath, and the mobilization of IRSN during the crisis. The second part looks at the assessments launched in 2011 to check the conformity of French nuclear facilities. It also addresses research that could better predict the fate of radionuclides released from Fukushima, as well as to improve the monitoring and radiation protection in France. 

Download our newsmagazine "Fukushima Special Report" (PDF file)


Videos: Understanding the Fukushima accident

Three videos explaining the sequence of the accident, its consequences on the terrestrial and marine and marine environments, and the protection and long-term monitoring of populations.

The development of the accident

Contamination of the environment

Health issues after the accident

Produced in February 2012, these videos are also available in high definition on IRSN channel on YouTube.


Earthquake and nuclear crisis in Japan in 2011 

During the weeks following the earthquake and tsunami that hit Japan on March 11, 2011, IRSN has published regular information notices in French regarding the status of the nuclear reactors at the Fukushima Daiichi nuclear plant, and the consequences of the radioactive releases in the environment (consult our French pages about the Fukushima accident). We provide translation in English and Japanese of some of these contents. 

Earthquake and nuclear crisis in Japan in 2011

Activity report 2011 - Fukushima focus
In 2012, IRSN also published a detailled timeline of its actions during the crisis.

Nuclear accident at Fukushima-Daiichi: Timeline of IRSN actions



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