FinalPresentation.pptx

The Fukushima Daiichi Incident
NUC271: Fundamentals of Reactor Safety
Presentation by Joshua Gerry

The need for Energy
At the end of the US Occupation, the Japanese
culture underwent a transformation; massive
migration from rural farming areas into city centers
promising jobs in technology and trade. Japan was
used by the US as a showcase for the powers of
democracy and capitalism. A period of
unprecedented growth began, but this growth
required more energy than ever. The problem is
that Japan had to import 80% of that energy, most
of which was crude oil from neighbors such as the
USSR or China Reference: Kingston

The Solution:
• US President Eisenhower’s “Atom’s
for Peace” speech in 1953 was
exactly what Japan needed to start
fixing that problem. Despite some
public protest, The Atoms for Peace
exhibit went on display at
Hiroshima in 1956.
The ideal political circumstances also existed: A single political party existed that
was being indirectly directed by The US. This allowed Japan to pour enormous
resources into their fledgling program and receive support directly through the
Atomic Energy Act of 1954. Japan’s own Atomic Energy Basic Act came in 1955 and
then joining the International Atomic Energy Association in 1956
References: Zwigenberg & Kingston

Japanese Research Reactors
The newly founded Japan Atomic Energy Research Institute (JAERI) constructed
Japan’s first reactor, the Japan Research Reactor 1 (JRR-1) went critical for the first
time in 1957. It was a simple Boiling Water Reactor (BWR) based on US design. The
relatively small (50kw) reactor was built to help the Japanese understand reactor
dynamics and train personnel for operation of larger reactors.
It was followed successfully by JRR-2, for large scale material testing
JRR-3, dubbed the JAERI Power Demonstration Reactor, was built using all
domestic suppliers such as Hitachi, Fuji, Toshiba, and Mitsubishi in 1963. It is still in
use today
References: Yamashita (2015)

The first commercial reactor was Tokai-1,
a 160-MWe carbon dioxide cooled
reactor. The initial draw to the gas cooled
reactor came from the ability to more
easily attain high temperatures and
operate with natural uranium, which
made electricity production more cost
effective. The plant lived a long successful
life free from major incident.
The Japanese decided to move forward
with Light Water Reactors, building 30
Boiling Water Reactors and 24 Pressurized
Water reactors since then.
Tokai-1
References: Shropshire

Light Water Reactors(LWR), with a focus on Boiling Water Reactor (BWR)
A BWR can be simplified to 5 major steps:
1. The nuclear fuel inside the core creates heat from fission
2. A steam-water mix is produced when water is moved up
through the core
3. The mix leaves the top of the core and enters separation
phases
4. The dry steam is sent to the main turbine, which spins a
turbine generator and produces electricity
5. The exhausted steam returns to water in the condenser,
where it is pumped back to the reactor to start the process
over again.
The benefit of this design is that it is simpler and more
efficient than that of a PWR. The downside is that BWR use a
void coefficient, which is more susceptible to transients than a
PWR is.
The NRC defines a LWR as one using ordinary water as a
moderated coolant, and lists both the PWR and Boiling Water
Reactor (BWR) as examples
References: NRC BWR

The Pressurized Water Reactors (PWR)
The principal difference between the PWR and the BWR are
two separate loops. The water that passes through the core is
kept under a high pressure to keep it liquid and is used to heat
a secondary loop that generates steam. The benefits of this
design
1. A negative-coefficient of reactivity
2. Ability to contain fission products in coolant totally inside a
containment building
The PWR is the backbone of the US Navy’s Nuclear Power
Program.
References: NRC NUREG-1350

GE Design Evolution
GE BWR reactors account for almost 1 in 5 commercial
reactors used around the world. All 6 units at Fukushima were
of a GE BWR design.
Starting with the implementation of BWR-3 as used in Unit 1,
Jet pumps internal to the reactor vessel provided major
improvement to recirculation, allowing the external
recirculation loops to be minimized. Power output was
439MW
BWR-4, used in units 2-5, increased power density by 20%. Of
note, unit 3 was partially refueled with Mixed-Oxide (MOX)
Fuel. Power output was 760MW each
BWR-5, used in unit 6, further improved internal recirculation
and increased power output to 1060MW.
The design benefit of the GE BWR design is the bottom-entry,
bottom-mount control rods that allow for refueling without
removing control rods.
References: Oak Ridge, 1989

Emergency Cooling BWR-3 vs BWR-4

GE Design Evolution
Units 1 – 5 at Fukushima utilized GE’s Mark I containment.
Major components include the drywell, which surrounds the
reactor vessel and recirculation loops, and a suppression
chamber, which stores a large body of water. There are vents
that connect the drywell and suppression pool.
Mark I
Mark II
Units 6 utilized GE’s Mark II containment, which improved
upon the Mk I by using a concrete for the suppression
chamber instead of the just metal.
References: Oak Ridge, 1989

Fukushima Daiichi Site Layout
The plant was built on a bluff that was originally 35 meters
above sea level. When viewed from the ocean, the left group
contained units 4, 3, 2, and 1 from left to right. The right group
was made of units 5, and 6.
The bluff was lowered 10 meters, so the base of the reactors
could sit on solid bedrock to assist with mitigating seismic
activity. This was determined acceptable because of the
construction of a sea wall that would provide protection for a
maximum design basis tsunami.
References: Acton

Fukushima Daiichi: Contested Design
During plant construction, two design features came under
suspicion: the location of the emergency diesel generators and
the relative height and protection of the sea water pumps.
Yukiteru Naka, who was involved with the design of Units 1, 2,
and 6 at Fukushima asked why the backup emergency diesel
generators and DC batteries were located in the turbine
building’s basement. He had not been thinking of a worst case
scenario tsunami, it was simpler than that, what if a pipe in the
plant burst and flooded the basement? Still, the plant was built
according to the original GE specification.
References: Acton, Yoshida
At the time of initial licensing, the design basis tsunami was
estimated to have a maximum heigh of 3.1 meters above sea
level. This allowed them to build the seawater pumps at 4m
and the main plant buildings at 10m above sea level.
In 2002, during a voluntary self-evaluation, TEPCO revised the
design basis tsunami height to 5.7 meters. No action was taken.

Tōhoku Earthquake
At 14:46 JST on 11 March 2011, a magnitude 9
earthquake originated 45 miles east of Oshika
prefecture. This is the most powerful
earthquake recorded in Japan, and fourth most
in the world. It moved the main island of Japan
8 feet. If the Energy from this earthquake could
have been harnessed, it would have been able
to power Los Angeles for a year.
References: NOAA

Tōhoku tsunami
Areas along the coast of Japan were affected
between 10-50 minutes from the earthquake
origin, with some locations seeing wave heights
as high as 14m. The reason for the extreme
difference in reported wave heights has to do
with coast topography. Some areas allow for
initial waves to be reflected and cause
constructive interference, turning a 6 meter
wave 10km offshore of the Fukushima plant
into a 13m wave by the time it reaches land.
For comparison, the Fukushima Daiini plant is
12km south and only saw waves of 9m tall.
References: Acton

Initiating events
All three operating reactors at Fukushima Dai-
Ichi shut down upon detection of seismic
activity, as programmed. All six external power
supplies were lost due to earthquake damage,
so the emergency diesel generators (EDGs)
started.
At 15:37 JST all AC power is lost due to flooded
EDG from >10m waves
At 15:46 DC power is lost at Units 1 & 2. This
results in a loss of Instrumentation and Control
equipment for Control Room Operators.
References: National Research Council

Preliminary timeline
Units 1, 2, and 3 were operating at rated
power, so even after all three units were
scrammed, they were still generating between
22-30 MW of thermal energy due to decay
heat.
This graph represents how long plant operators
were able to maintain some sort of core
cooling before ultimately experiencing some
form of core damage.
References: National Academies, INPO,
ANS

Accident timeline
ANS
The control room operators were managing pressure and
temperature after shutdown as normal using the isolation
condensers. When both AC and DC power were lost, the
condenser shut down due to failsafe logic. This was not
originally understood, and delayed action for hours. The
control room operators lost the ability to cycle the motor
operated valves, and thus lost the immediate ability to
remove heat from the core. All other failsafe systems such as
Reactor Core Isolation Cooling (RCIC) or the High Pressure
Coolant Injection (HPIC) were unavailable. Rising radiation
levels in the turbine building signaled core damage had
begun at 22:00 JST. The RPV would need to be depressurized
to get makeup water in and restore core cooling.
Unit 1

Accident timeline
Both isolation condensers were on service in Unit 2
and failed “as is” when power was lost. This
allowed the system to remain on service, and
casualty response went mostly as expected for this
unit. The worsening conditions of Units 1 & 3
paired with the limited resources available in the
wake of the tsunami was the ultimate downfall of
Unit 2. Preparations were completed to inject
water using firetrucks but there weren’t initially
trucks available. Pressure rose in the containment
more slowly but exceeded design pressure, and
investigators believe the leaking containment saved
Unit 2 from a hydrogen explosion.
ANS
Unit 2

Accident timeline
DC power was not lost immediately, and operators
were able to monitor plant conditions as well as use
core isolation cooling (20 hours) and the high-
pressure coolant injection system (HPCI). 24VDC
power was lost and the gage that monitored the
source for the HPCI water read depleted. A plan was
devised where they would shut down HPCI,
depressurize the pressure vessel and use the fire
protection system to inject water. They could not vent
pressure because the DC batteries were depleted
and could not restart the HPCI. Cooling was lost for
six hours and the reactor damage began.
ANS
Unit 3

Portable equipment
Using Unit 1 as an example, after all normally
installed methods of cooling failed, the site
switched to using firetrucks and 17.5 hours after
the blackout, there was continuous water injection
using the trucks. The onsite water was quickly
depleted, and the decision was made to switch to
seawater. Low and High-Power voltage supply
trucks arrived from Tohoku electric and Japanese
Self-Defense forces and were connected to Units 1
& 2. At 1530 on 12 March, AC power was restored
to Unit 1. Both the temporary sea water and power
grids were rendered inoperable by a Hydrogen
explosions moments after they were completed.
ANS

Hydrogen explosion
Hydrogen is generated in a reactor when zirconium
in the fuel cladding reacts with steam at elevated
temperature and is exothermic. This reaction can
become self-sustaining at high enough
temperatures. It is estimated Unit 1’s core
temperature was as high as 2800°C. The hydrogen
explosions destroyed temporary water-line and
power cables, as well as prompted evacuations that
stopped recovery efforts.
ANS

Accident timeline
The substantial destruction in Unit 4 suggests that
hydrogen reached the reactor building by flowing
back through the ventilation system for the standby
gas treatment system. This endangered the 1331
spent and 204 fresh fuel assemblies loaded in the
storage pools of unit 4. Was Units 1-3 had seawater
cooling successfully applied to them, TEPCO was
able to turn their attention to the spent fuel pools.
There was enough water in the containment to
keep the fuel covered and a combination of
helicopter drops and water cannon trucks started
applying fresh and seawater by 17 March.
References: IAEA
Unit 4

Upon the loss of all AC, notifications were
immediately due to NISA and TEPCO under the
Nuclear Emergency Act. Concurrently local
response should be established at the prefecture
level. Due to rolling local blackout, TEPCO had to
send people physically to the surrounding areas to
initiate communications. NISA was informed by
15:42 JST but due to internal conflict between
METI, NISA, and TEPCO, the Prime Minister was not
informed until 17:42 JST.
References: IAEA, WNA
Communication woes

Leadership failure
Japan has a strong reliance on the Top-Down approach,
because of the respect for Senior/Junior relationships
culturally. This created a reliance on the government for
guidance and governing action in a dynamic situation
that required timely and precise response. In this time
of crisis, the Japanese government chose to abandon its
established process for managing a nuclear crisis. At the
core of this issue was the Prime Minister (PM) of Japan,
who had built his career on distrust of the ties between
industry and bureaucracy. Instead of relying on the
system built to handle the situation, he turned to a
group of close advisors who were overwhelmed with
the amount and complexity of the information being
relayed.
References: National Academies

Local leadership
The PM declared a Nuclear Emergency at 19:03 and
established the Nuclear Emergency Response HQ in
his office. Instead of waiting, Fukushima Governor
Yuhei Sato ordered an evacuation of residents
within 2km at 20:50. The local infrastructure was
still in disarray, so most of this notification was
delivered locally by loudspeaker, radio, and door-
to-door visits. Admirable although premature as
NISA was in the process of advising the PM that in
order to vent the affected units, a 3km radius was
needed. This created confusion and disarray.
References: ANS

Indecision
The evacuation order would be updated three
more times; slowly expanding and changing
directions for staying indoors. Part of this was due
to limited data input to the government’s SPEEDI
system, used to help predict where radioactive fall
out will be deposited. Another major factor was that
23 of the 24 external monitoring stations used to
track contamination spread were destroyed. The
government did get creative and start employing
aircraft and other mobile sensing stations starting on
12 March.
References: Investigation Committee on the
Accident, The Sasakawa Peace Foundation

Evacuation
The government pooled its resources and utilized a
combination of buses originating in nearby towns
such as Okuma, ambulances, and even helicopter
squadrons belonging to the Ground Self-Defense
Force to successfully move 97% of the estimated
76,000 affected residents within the first 72 hours
of the event. Six area hospitals were established to
treat and decontaminate residents while a seventh
was designated for advanced radiological injuries.
References: Investigation Committee on the
Accident, The Sasakawa Peace Foundation

Radioactive release
Overall, it is estimated that Fukushima released
roughly 520 Petabecquerels (PBq) of volatile
elements, including but not limited to Tellurium-
129m and 132, Iodine-131 and 133, and Cesium-
124, 136, and 137. Tellurium-129m can be used to
track the dispersion of fission products from a
reactor accident due to its trace natural abundance
in the earth’s crust and its highly reactive nature.
The total area affected using this form of dispersion
monitoring is around 640 square kilometers around
the Fukushima plant, as far north as Namie and as
far south as Iwaki.
References: Bushberg, EISSA, Oshidori,
Steinhauser, Yamashita (2013)

Population effects
Based on a sample size of almost 10,000 evacuees, the total
exposure to non-radiation workers was found to be 23
milliSieverts (mSv). 99.3% of people affected externally by the
release of radiation received less than 10 mSv, which converts
roughly to 1 REM, which is less than the annual limit for
radiation workers in the United States. When averaged out
over the 300,000 residents of the Fukushima prefecture, the
dose drops to <1 mSv. The risk of external radiation dose from
the accident was low, the real risk comes from internal
radiation due to contamination of watersheds and food stuffs.
In the process of evacuation, the Japanese government was
able to distribute 1.5 million iodine pills to Fukushima
Prefecture to help prevent evacuees from up taking
radioactive iodine that was released in the accident

Population effects
While following Tellurium is useful for tracking dispersion, the
radionuclides of concern are Iodine-131 and Cesium-137.
Radioiodine, when ingested can cause wreak havoc on the
endocrine system, which is responsible for regulating your body’s
cell signaling through hormone release. It is also likely to result in
thyroid cancer.
Cesium-137’s risks come from its long half-life of about 30 years and
its ability to be absorbed by most vegetative food stuffs like spinach
and wasabi. Shipments of milk and spinach from Fukushima,
Ibarakia, and Tochigi prefectures were restricted within the first
month of the incident.

Radiation Workers
The exposure limit was temporarily raised to 250
mSv to roughly 20,000 emergency workers. The
NRC limit is 50 mSv per year for healthy adults.
There has only been 1 confirmed death attributed
to radiation exposure.

Source Term 50.67
The NRC follows the guidance of 10CFR50.67, which states
that an individual located at any point on the boundary of the
exclusion area for any 2-hour period following fission product
release or an individual located at any point on the boundary
of the low population zone who is exposed to the radioactive
cloud resulting from a fission product release will receiving
greater than 0.25 Sv Total Effective Dose Equivalent (TEDE).
Control room workers should not receive greater than 0.05 Sv
REM TEDE.
Civilians at the worst received 23 mSv of exposure, so TEPCO
was successful in meeting the first two conditions. They were
not successful in meeting the third condition in regard to
control room operators. There were three operators who
received greater than 350 mSv total, with at least 200 mSv of
that being internally. Two of the operators did ingest
potassium iodide at the time of the event.
USNRC

Japan’s Energy Future
Before Fukushima, 30% of Japan’s energy was generated by Nuclear
power, with a plan to go to 40%. Currently only 42 of the 54 reactors
are operable, with only nine reactors currently generating electricity.
The anti-nuclear sentiment is still strong, but waning. Japan is
currently generating about 12% of its energy through Nuclear power,
with a goal of 20% by 2030. Renewed partnerships with France’s
ASTRID program have given renewed enthusiasm to the future of
nuclear power in Japan.
References: IAEA, WNA

NRC Response
In April 2011, NRC experts examined information from
the accident to determine whether any actions were
needed to ensure the safety of U.S. nuclear power plants
The result was three new orders in March 2012, requiring
U.S. reactors to:
1. Obtain and protect additional emergency equipment,
such as pumps and generators, to support all reactors
at a given site simultaneously following a natural
disaster
2. Install enhanced equipment for monitoring water
levels in each plant's spent fuel pool.
3. Improve/install emergency venting systems that can
relieve pressure in the event of a serious accident

References
Acton, J. M., & Hibbs, M. (2012, March 6). Why Fukushima Was Preventable. Carnegie Endowment for International Peace.
https://carnegieendowment.org/2012/03/06/why-fukushima-was-preventable-pub-47361
American Nuclear Society. (2012). Fukushima Daiichi: ANS Committee Report. https://www.ans.org/file/3413/Fukushima_report.pdf
Bushberg, J. T. (2022, January 24). Radiation Exposure and Contamination. Merck Manuals Professional Edition. Retrieved February 7,
2022, from https://www.merckmanuals.com/professional/injuries-poisoning/radiation-exposure-and-contamination/radiation-
exposure-and-contamination Dedman, B. (2011, March 13). General Electric-designed reactors in Fukushima have 23 sisters in U.S.
MSNBC. Retrieved February 8, 2022, from
https://web.archive.org/web/20120320141531/http://openchannel.msnbc.msn.com/_news/2011/03/13/6256121-general-electric-
designed-reactors-in-fukushima-have-23-sisters-in-us
EİSSA, M. (2021). Study of Tellurium-129m (129mTe) Ground Deposition Following Fukushima Nuclear Disaster: Descriptive Analysis of
UNSCEAR Database Using Statistical Process Techniques. Mugla Journal of Science and
Technology. https://doi.org/10.22531/muglajsci.955946
IAEA. (2015, August). The Fukushima Daiichi Accident Technical Volume 3. Emergency Preparedness and Response. Vienna, Austria.
https://www-pub.iaea.org/mtcd/publications/pdf/pub1710-reportbythedg-web.pdf
Institute of Nuclear Power Operations. (2011). Special Report on the Nuclear Accident at the Fukushima Daiichi Nuclear Power
Station (INPO 11-005). https://www.nrc.gov/docs/ML1134/ML11347A454.pdf
Investigation Committee on the Accident at the Fukushima Nuclear Power Stations of Tokyo Electric Power Company. (2012,
July). Fukushima Nuclear Accident Independent Investigation Commission Report. https://www.cas.go.jp/jp/seisaku/icanps/eng/final-
report.html

References Janos, A. (2021, March 5). Fukushima Timeline: How an Earthquake Triggered Japan’s 2011 Nuclear Disaster. HISTORY. Retrieved
January 24, 2022, from https://www.history.com/news/fukushima-nuclear-disaster-japan-earthquake-timeline
Kinefuchi, E. (2015). Nuclear Power for Good: Articulations in Japan’s Nuclear Power Hegemony. Communication, Culture & Critique,
8(3), 448–465. https://doi.org/10.1111/cccr.12092
Kingston, J. (2012). Contemporary Japan: History, Politics, and Social Change since the 1980s (2nd ed.). Wiley-Blackwell.
https://ebookcentral.proquest.com/lib/excelsior-ebooks/detail.action?docID=932016&query=9781118315071#
Koppenborg, F. (2020). Nuclear restart politics: How the 'nuclear village' lost policy implementation power. Social Science Japan Journal,
24(1), 115-135. https://doi.org/10.1093/ssjj/jyaa046
Maize, K. (2018, December 3). A Short History of Nuclear Power in Japan. POWER Magazine. Retrieved February 8, 2022, from
https://www.powermag.com/blog/a-short-history-of-nuclear-power-in-japan/
National Academies of Sciences, Engineering, and Medicine, Studies, D. E. L., Board, N. R. S., Plants, C. L. L. F. N. A. I. S. S. U. S. N., &
National Academies Of Sciences, E. M. (2016). Lessons Learned from the Fukushima Nuclear Accident for Improving Safety and
Security of U.S. Nuclear Plants. Amsterdam University Press.
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(NCEI). Retrieved February 10, 2022, from https://www.ncei.noaa.gov/news/day-2011-japan-earthquake-and-tsunami
Oak Ridge National Laboratory. (1989, June). Physical Characteristics of GE BWR Fuel Assemblies. https://doi.org/10.2172/5898210

References Oshidori, M. (2016, February 27). Exposure status of workers after the fukushima daiichi ... Retrieved February 6, 2022, from
https://www.chernobylcongress.org/fileadmin/user_upload/T30F5/F6_oshidori_final_web.pdf
Shropshire, D. E. (2004, April). Lessons Learned From Gen I Carbon Dioxide Cooled Reactors. Idaho National Engineering And Environmental
Laboratory. https://inldigitallibrary.inl.gov/sites/sti/sti/2761750.pdf
Steinhauser, G., Brandl, A., & Johnson, T. E. (2014). Comparison of the Chernobyl and Fukushima nuclear accidents: A review of the environmental
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The Sasakawa Peace Foundation. (2012, September). The Fukushima Nuclear Accident and Crisis Management. https://www.spf.org/en/global-
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Yoshida, R. (2011, July 14). GE plan followed with inflexibility. The Japan Times. https://www.japantimes.co.jp/news/2011/07/14/national/ge-plan-
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Zwigenberg, R. (2012). The Coming of a Second Sun”: The 1956 Atoms for Peace Exhibit in Hiroshima and Japan’s Embrace of Nuclear Power. The
Asia-Pacific Journal, 10(6). https://apjjf.org/-Ran-Zwigenberg/3685/article.pdf

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