The presentation summarizes the Fukushima nuclear accident, including an overview of the events, reports from ENSI (the Swiss Federal Nuclear Safety Inspectorate), and lessons learned. On March 11, 2011, a large earthquake caused tsunamis that flooded the Fukushima Daiichi nuclear power plant, resulting in station blackouts and core meltdowns. ENSI analyzed human and organizational factors that contributed to the origin and management of the accident. Key lessons include strengthening protections against natural hazards, ensuring backup power sources, and improving emergency response organizations, safety culture, and crisis communication.

1. Eidgenössisches Nuklearsicherheitsinspektorat ENSI
How to improve safety in
regulated industries
The nuclear accident in
Fukushima
Presentation for October 16th 2012
Content
1. The accident - General Overview
2. ENSI – Reports
3. Human and organisational factors
• Origin and development of the accident
• Management of the accident
• Consequences of the accident
4. Management of the accident
• Lessons learned from a Technical perspective
• Lessons learned from a Human Factors perspective
5. Conclusion
6. Final words
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2. Earthquake on March 11th, 2011
Power Production
The earthquake on March
11th, 2011 at 14:46 caused
the shutdown of several
conventional and nuclear
power stations.
Nuclear sites:
- Fukushima Daiichi (1 - 6)
(unit 4 - 6 in outage)
- Fukushima Daini (1 - 4)
- Onagawa (1 - 3)
- Tokai 2 (unit 1 in
decommissioning phase)
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Earthquake on March 11th, 2011
Industrial sites
Refinery in Ichihara Oiltank in Minami Soma
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3. Earthquake on March 11th, 2011
Infrastructure
Access difficulties – Heavily damaged roads
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Earthquake on March 11th, 2011
Consequences for Nuclear Power Stations
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4. Tsunami on March 11th, 2011
Transport infrastructure
Airport of Sendai
Port of Kamaishi
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Tsunami on March 11th, 2011
Flood wave at Fukushima site
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5. Tsunami on March 11th, 2011
Hydrogen Explosions
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ENSI reports about Fukushima accident
Event Human and Lessons learned
Radiology
Sequences organisational factors and checkpoints
These reports are available on ENSI website: www.ensi.ch – Dossiers
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6. ENSI Action Plan Fukushima
Action Plan ENSI – Focus in 2012
1. Earthquake
2. Flooding
3. Extreme weather conditions
4. Long term station blackout (SBO)
5. Lost of the ultimate heat sink
6. Containment-pressure relief and hydrogen
management
7. Emergency management in Switzerland
8. Safety culture
9. Experience feedback
10. International oversight and cooperation
11. External storage facility (Reitnau, Switzerland)
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Human and organisational factors
ENSI - Analysis
1. Origin and development of the accident
Why did a Station Blackout (SBO) occur on 11 March 2011
after the earthquake and the tsunami?
2. Management of the accident
Why did damage occur to the fuel assemblies and why did
all the safety barriers fail, with the subsequent release of
massive amounts of radioactivity into the environment?
3. Consequences of the accident
Why were the plant staff and the public exposed and why
was the environment contaminated?
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7. Origin and development of the accident
Why did a Station Blackout (SBO) occur on 11 March 2011 after the earthquake and the tsunami?
Two kinds of explanations from a Human Factors perspective within a whole set of hypotheses laid out in the ENSI - Analysis
Aspects related to Aspects
strategy and practice Insufficient Overall difficulty to related to
independence of the consider possible an
of government regulatory body event which has a low safety culture
supervision probability to occur
Structural Oveerall
deficiencies in the unfavorable
overall supervision Inappropriate corporate culture
system measures to Complacency and
excessive trust
protect the plant
Deficiencies in the
against a tsunami
supervision of Conflict between
emergency measures safety and cost
andin the underlying efficiency
legislative and regulatory
framework
Deficiencies regarding
Insufficient
the development of a
supervision culture of learning in
the organisation
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EU-Stresstest Medienkonferenz, 10. Januar 2012 – R. Sardella (ENSI) 13
Nuclear supervision and energy policy in Japan
Origin and development of the accident
Background information
The structure of the Japanese nuclear sector is (was) very complex - a large number of different players!
Risk of lack of independence and transparency in the supervision of nuclear safety!
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8. Management of the accident
Why did damage occur to the fuel assemblies and why did all the safety barriers fail, with the
subsequent release of massive amounts of radioactivity into the environment?
Three kinds of explanations from a Human Factors perspective within a whole set of hypotheses laid out in the ENSI - Analysis
Inappropriate
measures to manage
Organisational the plant during an
accident with a Human aspects
aspects
cumulative loss of
safety functions
Documentation
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EU-Stresstest Medienkonferenz, 10. Januar 2012 – R. Sardella (ENSI) 15
Management of the accident
Organisational aspects
• Delayed decisions Complex crisis
• Deficiencies in information and Organisation
• protective measures of the general public
Lack of clarity in the roles
Communications disrupted
Unsuitability of some crisis
centers
Failures in communication
between the two crisis centers in
the government building
Difficult to know or even to appreciate
the situation on-site
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9. Management of the accident
Human aspects
Difficult to have an exact appreciation of the plant state due to loss of most of the information
Difficulties to implement severe accident management measures
• Environment conditions: aftershocks, plant damages, loss of electricity,
radiological situation at the plant and in the MCR
• Number of people available at the site
• Difficult to implement actions
• Lack of protective measures for intervention teams
Difficulties to find how to restart safety functions with the tools and means available in a rapidly
worsening stuation
• Operating crews are dependant on the tools and instruments available (or not available at the site)
• Lack of training
Difficulties to communicate during interventions (between local and MCR / Crisis Center)
Individual and collective stress
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EU-Stresstest Medienkonferenz, 10. Januar 2012 – R. Sardella (ENSI) 17
Management of the accident
Documentation
• …the risk of simultaneous
destruction of all
Procedures and infrastructure.
Emergency plan
insufficiently • …the lack of accessibility to
certain equipment / systems.
took into
account …
• …the inability to connect the
installation with the mobile
emergency power supply.
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10. Consequences of the accident
Why were the plant staff and the public exposed and why was the environment contaminated?
Delays in the management of the event
• Cooling by injecting seawater
• Release of steam
• Control hydrogen
Delays in the disclosure of information about radioactivity levels on-site and off-site
Delays to protect the public
Tendency to communicate information which did not specify the risks
This demonstrates that it is still necessary to improve:
Proactive information and communication on accidents and incidents; natural or industrial
Communication in crisis situations must satisfy the need of the population for clear and
understandable information
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EU-Stresstest Medienkonferenz, 10. Januar 2012 – R. Sardella (ENSI) 19
Earthquake information
Japan Meteorological Agency (JMA)
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11. Management of the accident
Lessons learned from Fukushima from a Technical perspective
Need to strengthen the protection of facilities
against natural hazards
Examples:
• diverse power sources (off-site supply, external emergency power
system, etc.) ensured by different cable routes
• diverse water supply (wells, reservoirs, etc.)
• better flood protection of the emergency diesels and associated cooling
systems
could have minimised the consequences of the tsunami
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Comparison of building structures
Lessons learned from Fukushima in a Technical perspective
Background information
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12. Safety features
Lessons learned from Fukushima in a Technical perspective
Background information
«Defense in Depth»
«Active Safety Systems»
«Separation»
«Redundancy» «Diversity»
«Passive Safety Systems»
Common Cause Failures (CCF):
Failure of two or more structures, systems and
components due to a single specific event or cause.
Common Mode Failure (CMF):
Failure of two or more structures, systems and components
in the same manner or mode due to a single event or cause.
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Operational experience feedback
Lessons learned from Fukushima in a Technical perspective
Background information
Blayais, 27.12.1999
Flood over the sea walls
after combination of tide
and high winds
Forsmark, 25.07.2007
Short circuit in the
switchyard resulted in a
severe disruption of the
auxiliary and emergency
power supply
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13. Management of the accident
Lessons learned from Fukushima from a Human Factors perspective
People which operate a plant need a lot of information,
tools, instrumentation, protective measures,
management support, documents, organisational and
training measures… to be able to perform their tasks
successfully.
The human performance is a result of all these factors
during normal and accidental situations. All these
factors have to be considered as “Factors of success”
or “Failure factors”.
During an accident, if these supports are not available
or not completely usable / adequate for the situation,
then the workers (individually and collectively) are
“deprived”, whatever their commitment and
motivation.
From a human factors perspective, everything must be
done so that the teams are best supported in managing
situations that require emergency actions to protect the
safety goals or to recover the safety functions.
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Management of the accident
Lessons learned from Fukushima from a Human Factors perspective
We do not mean here that the human factor is the “weakest
link”. On the contrary, in many situations, operators and
organisations are able to find “ultimate solutions”.
But…beyond these exploits… we have to ensure that teams "always“
have information resources, control means, procedures, knowledge, ...
to handle all possible events.
Otherwise, we need to give to the teams, the means which help them to
ensure their role as “producers of reliability”.
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14. HF perspective
Lessons learned from Fukushima event
We need to continue:
To adopt appropriate measures to protect the nuclear
plants against the consequences of a severe accident
exceeding standards taken into account during design
(even if the probabilities of such events are very low)
To have on- site and at the crisis centers, organisations
with the knowledge to fully play their role efficiently
This also includes cultural, organisational and individual
capabilities to manage unexpected/unanticipated
situations!
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F. Meynen, Section Head ENSI - MEOS
EU-Stresstest Medienkonferenz, 10. Januar 2012 – R. Sardella (ENSI) 27
HF perspective
Lessons learned from Fukushima event
We need to continue:
To take into account new knowledge & skills in regulatory
requirements and safety guidelines
To have on-site and in each crisis center means adapted to
allow teams to assess efficiently the state of the plant and
to continuously update this assessment
To develop and continuously optimize the conditions in
which the human actions are performed by personnel
during emergency situations
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15. Conclusion
• Taking into account extreme hazards • Independency
• Appropriate technical and human • Protection of the population
resources to cope with the event and the environment
• Develop a good safety culture • Communication
• Preparation for the
management of crisis situations
Autorities
measures
Utilities On site
measures measures
• Preparing staff training
Exemplarity and Commitment
• Appropriate materials and documents
of all actors involved in safety
• Exemplarity, responsibility and proactivity
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Final words
Safety is not a state –
Safety is a process
Authority
Environment
Unit
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16. Information Sources
• METI (Ministry of Economy, Trade & Industry)
• NISA (Nuclear and Industrial Safety Agency)
• TEPCO (Tokyo Electric Power Company)
• JAIF (Japan Atomic Industrial Forum)
• JMA (Japan Meteorological Agency)
• IAEA (International Atomic Energy Agency)
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Thank you
very much
for your attention!
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