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Summary Case Study Fukushima
- Instelling
- Universiteit Leiden (UL)
This document contains a summary of all lectures, readings, and workgroups.
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Case Study Fukushima – Exam MaterialJapan’s Fukushima Nuclear Disaster: A Overwies – Kushida (2016)
2011 March 11
The earthquake itself already caused major damage at the Fukushima Daiichi nuclear plant. External
power lines were destroyed making the nuclear plant dependent on its on-site backup power
sources.
After the earthquake the tsunami hit with a wave exceeding a seawall designed to stop tsunamis. The
tsunami destroyed much of the cooling systems, consisting of pumps responsible for pumping
sweater into the reactor building to cool the fuel rods. It also damaged all the on-site backup power
sources (diesel generators, batteries, and circuit boards). There was no way to cool the reactors.
Only Fukushima Daiichi reactors one, two and three were operating (excluding four). Those are
boiling water reactors (BWR), meaning that the heat from the nuclear reaction of the fuel rods boils
water, creating steam that rotates turbines to generate electricity.
The initial scrams (emergency shutdowns) when the earthquake hit was successful. However, the
fuel rods retained considerable heat, requiring large amount of water for cooling. Restoring the
cooling was the most important task, but almost impossible with all the damage.
The water levels of reactor one and two could also not be monitored. As soon as the core of the fuel
rods would evaporate the water, it would become exposed to the air, meaning they would overheat
and become damaged, resulting in a meltdown.
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The earthquake made telecommunications around the network difficult. Lots of public transport was
closed and roads were severely damaged.
The Japanese legal framework made it that the power operator was in charge of the situation, but
because of the transportation issues at the time, it took TEPCO’s president and chairman over 17
hours to get to headquarters. The office of the Prime Minister was not aware of this issue, which lead
to mistrust on the part of the PM Kan Neto.
He made the choice to get personally involved. However, the communication in the PM’s office itself
suffered from problems. They had one phone line, no computer, fax, or information about the
nuclear plant.
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They started making efforts to inject water into the reactor by manually opening valves, as the
electricity was out. The PM also send battery trucks from the Japanese military to provide electricity
for cooling the systems. However, it took some time before the trucks arrived (locked traffic grid) and
worked (different voltages and incompatible connectors).
Another problem arised: a radiation leak in reactor one. The water level was lower than they
originally thought. They took the step to reduce the pressure within the containment vessel by
venting. This would however release radioactive material into the atmosphere.
,The venting had to be done manually as the electricity was out, but the radiation levels were already
too high, forcing the teams to fall back. The fuel core of reactor one had melted and a half hour later
a hydrogen explosion followed.
Even though reactor three was cooled with both sea- and foam water, it was not enough, as it also
exploded. This explosion made efforts to cool down reactor two more difficult, as it damaged the
manual cooling systems. It later also exploded.
Executive Summary of the Official Report – The Fukushima Accident Independent
Investigation Commission (2012)
The accident was declared a level 7 “sever accident” by the International Nuclear Event Scale (INES).
The disaster is seen as a manmade disaster as the root causes of the accident were the
organizational and regulatory systems that supported faulty reasoning for decisions and actions. The
accident is seen as something foreseeable, but all the actors involved failed to develop the most
basic safety requirements (evacuation plans, probability reports, containing collateral damage). A lot
of measures could have prevented the accident from happening, but TEPCO did not take these
measures, and NISA (Nuclear and Industrial Safety Agency) and NSC (Nuclear Safety Commission)
went along.
TEPCO assigned the accident cause to the tsunami. However, it cant be ruled out that the accident
was already caused because of the earthquake alone. They do this to avoid responsibility by putting
blame on the unexpected (the tsunami) and not the expected (the earthquake). Also equipment cant
be examined (radiation) to rule out causes.
There were lots of problems with communicating the evacuation to local residents. The government
and regulators were not committed to protect the public health and safety. The situation continued
to deteriorate because the crisis management system, the regulators and other responsible agencies
did not function correctly. The boundaries that should define the roles and responsibilities of the
parties involved were unclear and problematic.
The accident was not preventable because of the combined earthquake and tsunami; the severity
however could have been lessened wit more preparation. There were no appropriate anti-seismic
reinforcements and a lack of tsunami countermeasures.
,
, Lecture 1
Disaster = a serious disruption of the functioning community or society at any scale due to hazardous
events interacting with the conditions of exposure, vulnerability, and capacity, leading to one or
more of the following: human, material, economic, and environmental losses and impacts.
Disaster risk = hazard X exposure X vulnerability
Earthquake = describes both sudden slip on a fault and the resulting ground shaking and radiates
seismic energy cause by the slip, or by volcanic or magmatic activity, or other sudden stress changes
in the earth.
Different types of plate boundaries
Divergent
Convergent
Transformation
Earthquake is the result of sudden movement along faults within the earth. The movement releases
stored-up “elastic strain” energy in the form of seismic waves, which propagate through the earth
and cause the ground surface to shake. Such movement on the faults is generally a response to long-
term deformation and the build-up of stress.
Japanese thought that the catfish god caused earthquakes.
Disaster was first meant bad star. When the stars were badly aligned something bad would happen.
The pacific plate moves northwest and goes into three different plates (convergent) causing a lot of
earthquakes. Japan is in the connection of four different plates (Pacific Plate, Philippine Sea Plate,
Eurasia Plate, Okhotsk Plate). Japan is located on the so called ‘Ring of Fire’, which is the edged of
the Pacific Plate. Next to Japan is a convergent margin, where the Pacific Plate goes under
(subduction) the Eurasian Plate
Different kind of seismic waves:
1. P-Waves travel along the direction of propagation as a series of compressions
and rarefactions (body waves)
2. S-waves travel orthogonally of both the direction of propagation and the
earth’s surface. S-waves are more destructive because of their lower
energy decay (body waves)
3. Love waves travel orthogonally with the direction of propagation but parallel
with the surface of the earth (surface waves)
4. Rayleigh waves propagate near the earth’s surface as ripples and cause a rotation
(surface waves)
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