Repères - N°48 / March 2021 - The IRSN magazine - 4
JAPAN 2011
The accident at Fukushima Daiichi
What happened?
On Friday, March 11, 2011, at 2:46 p.m. local time, a 9.0 magnitude earthquake
struck 130 kilometers off the coast of Honshu Island in Japan. This knocked out off-site
power at the Fukushima Daiichi nuclear power plant. The reactors shut down, and
the emergency generators started up.
Less than an hour later, a tsunami wave with a run-up height of 14 meters flooded
over the seawall protecting the plant and submerged the emergency generators.
The water intakes needed for reactor cooling were damaged.
Japanese
nuclear
facilities
Tomari
© Hervé Bouilly/Médiathèque IRSN
PACIFIC
OCEAN
KashiwazakiOnagawa
Kariwa
Shika
Ohi
Fukushima I
Mihama
Fukushima II
Tokaï
Takahama
Tokyo
Shimane
Hamaoka
Genkai
Monju
Tsugura
Ikata
Fugen
0
200 km
Sendai
4
3
2
1
100 m
0
March 11, 2011
Core melt. The earthquake caused the
automatic shutdown of units 1, 2 and 3, as
well as the loss of off-site power. The plant's
emergency diesel generators took over.
Forty minutes later, the tsunami wave
triggered by the earthquake reached the
coast. The site was hit by seven waves, the
highest measuring fourteen meters high.
It damaged the seawater intakes and shut
down the emergency diesel generators
supplying power to units 1 through 4. The
unit 2 and 3 emergency backup systems
continued to function for a few days,
thereby delaying core melt in these reactors. The core damage in units 1, 2 and 3
led to radioactive releases into the environment. The decision was made to vent
the reactor containments in order to reduce
pressure.
Page 4 - Repères No. 48 - March 2021
March 12, 2011
Unit 1. An explosion occurred at 3:36 p.m.
in the upper part of the reactor building,
an hour after containment venting began.
Given the loss of cooling systems, the plant
manager decided to inject seawater into
the reactor coolant system as a last resort.
March 14, 2011
Unit 3. The upper section of the reactor
building also exploded, even though it had
been vented 24 hours earlier. Seawater was
injected to cool down the reactor core.
Unit 4. An explosion occurred inside the
reactor building, probably caused by an
inflow of combustible gas via the pipes
shared with unit 3.
Unit 2. The operators failed to vent the
containment. On March 15, in the morning, the high pressure level caused a break,
resulting in significant radionuclide
releases. Seawater was injected to cool the
reactor core. n
Repères - N°48 / March 2021 - The IRSN magazine
Table of Contents for the Digital Edition of Repères - N°48 / March 2021 - The IRSN magazine
Cover
Contents
Editorial
JAPAN 2011 - The accident at Fukushima Daiichi: What happened?
JAPAN 2021 - Ten years later: What is the state of affairs?
SAFETY - Extreme risks: Enhanced protection nuclear facilities
Station blackout diesel generator: Assessments made during design
Severe accidents: Ultimate heat sink performance
Tricastin nuclear power plant: Dike reinforcements follow assessment
Research: Innovative materials
EMERGENCY - Emergency management and recovery: Defining new zoning
HEALTH - Population protection: What progress has been made in ten years?
ENVIRONMENT - Environmental contamination: Models are progressing
IRSN - 2011-2021: IRSN’s actions
Repères - N°48 / March 2021 - The IRSN magazine - Cover
Repères - N°48 / March 2021 - The IRSN magazine - Contents
Repères - N°48 / March 2021 - The IRSN magazine - Editorial
Repères - N°48 / March 2021 - The IRSN magazine - JAPAN 2011 - The accident at Fukushima Daiichi: What happened?
Repères - N°48 / March 2021 - The IRSN magazine - 5
Repères - N°48 / March 2021 - The IRSN magazine - JAPAN 2021 - Ten years later: What is the state of affairs?
Repères - N°48 / March 2021 - The IRSN magazine - 7
Repères - N°48 / March 2021 - The IRSN magazine - SAFETY - Extreme risks: Enhanced protection nuclear facilities
Repères - N°48 / March 2021 - The IRSN magazine - 9
Repères - N°48 / March 2021 - The IRSN magazine - Station blackout diesel generator: Assessments made during design
Repères - N°48 / March 2021 - The IRSN magazine - Tricastin nuclear power plant: Dike reinforcements follow assessment
Repères - N°48 / March 2021 - The IRSN magazine - 12
Repères - N°48 / March 2021 - The IRSN magazine - Research: Innovative materials
Repères - N°48 / March 2021 - The IRSN magazine - EMERGENCY - Emergency management and recovery: Defining new zoning
Repères - N°48 / March 2021 - The IRSN magazine - 15
Repères - N°48 / March 2021 - The IRSN magazine - 16
Repères - N°48 / March 2021 - The IRSN magazine - 17
Repères - N°48 / March 2021 - The IRSN magazine - HEALTH - Population protection: What progress has been made in ten years?
Repères - N°48 / March 2021 - The IRSN magazine - 19
Repères - N°48 / March 2021 - The IRSN magazine - ENVIRONMENT - Environmental contamination: Models are progressing
Repères - N°48 / March 2021 - The IRSN magazine - 21
Repères - N°48 / March 2021 - The IRSN magazine - IRSN - 2011-2021: IRSN’s actions
Repères - N°48 / March 2021 - The IRSN magazine - 23
Repères - N°48 / March 2021 - The IRSN magazine - 24
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