The document analyzes the Fukushima disaster, highlighting the interplay of natural catastrophes and human errors in risk assessment and management. It discusses the chronological events, the structural and design failures of nuclear plants, and the ongoing challenges in decommissioning and public trust. Additionally, it emphasizes that the disaster was largely preventable, driven by complacency and inadequate regulatory practices in the nuclear industry.

1. Fukushima in Retrospect
(Lessons in Risk Assessment)
Brian Landberg
2013-Jul-17

2. Myths: Stories of Gods, Technology,
and Consequences
Prometheus : A central Greek myth ... human technology & associated risks.
Knowledge stolen  Progress for humans, but also hubris (angering the gods) and other
subsequent troubles: Endless torture (search for the truth?), and Pandora’s box (uncertainty)

3. Comparative myth (Greek vs. Indian)
Prometheus (name=foreknowledge)
Fire (useful, but dangerous) as
acquired knowledge , separate from
nature [= invention]
Mātariśvan: (name=grown from mother)
Fire (benevolent), gifted to the people with
auspices of the gods, part of nature
[= discovery]

4. Nuclear Power and Prometheus
• New force of nature (discovery & invention)
• 1940s Powerful weapon  1950s useful energy source
• Longstanding controversy:
– Dangers, uncertainties & serious accidents.
– Advantages for gov’t & industry
– Long term pros & cons continuously debated

5. Is nuclear power actually safe?
YES NO
Atoms for peace* … “swords into plowshares”.
Not like a bomb: U235 ~5% (vs.~90% for bombs)
Difficult to assure Pu non-proliferation
(byproduct of U238 + n reactions)
Cannot explode like an A-bomb (runaway chain
reaction); Delayed-neutron critical design; H2O
as moderator/coolant = failsafe feedback
Hydrogen/steam explosions, meltdowns can
occur (due to LOCA); Chernobyl type reactors
do (did) enable prompt-supercritical reaction.
Fundamentally similar to other power generation
(make steam, turn turbines); Proven/reliable.
Complex to control reactor; Decommission
difficult (radioactively contam. structures).
Multiple levels of design/engineering safety and
redundancy (“defense in depth” philosophy);
Earthquake proof construction (built on
bedrock), proved at Kobe, Niigata earthquakes.
• Vulnerable to nat. disasters (common
cause to knock out all defense levels.)
• Human error & human mgt./systems
(including biased fault-line data)
• Design blind spots (e.g. spent fuel pools)
439 plants around the world operating safely for
decades/millions of plant-hours.
Serious Accidents have occurred, with very
messy consequences.
Environmentally friendly (CO2, pollution); Much
less waste than conventional oil, coal.
Only if accidents are fully prevented; Hi-level
waste is a problem (reprocess or storage)
* “My country wants to be constructive, not destructive. It wants agreement, not wars, among nations. It wants itself to live in freedom,
and in the confidence that the people of every other nation enjoy equally the right of choosing their own way of life.“ -D.Eisenhower, 1953

6. Fukushima Status
(and scope of damage)
• Fukushima 1, 2 : total 6+4 = 10 reactors
– Meltdowns(3), Fuel recovery(4), decommissioning (10?)
 10-year clean-up plan proposed (aggressive?)
• Fallout contamination area and evacuation
– ~60,000 people remain evacuated in 2013 (orig.# 160k in 2011)
– 1000 sq.km., 15~30million m^3 of soil
• Water contamination (ongoing)
– Ground water contamination by contact with melted nuclear fuel/soil:
– Water filtration systems remove Sr, Cs, etc. but not 3H Tritium (minor fission product, forms HTO
water), so water must be stored in tanks rather than returned to ocean…
• Denied permission to restart (ongoing)
– Most of Japan’s 50 commercial nuclear power plants are off-line now [20~30% of all electric capacity]
– About 10 reactors are applying for permission to restart, after safety measures added, data shown
– Covered by increased imports of LNG/LPG and oil (energy costs up 20%, CO2 up 15%)
– Early decommission costs also to consider
• Japan’s regulatory authority reorganized/empowered
– Tougher stance to regain public trust. Reopen fault-line surveys at all plant sites, etc.
– Recommended to close plants at Hamaoka & Tsuruga due to seismic fault line risks
• Huge financial costs to consider (details later in the presentation).

7. Preventable Man-Made Disaster?
Natural Catastrophe?
“It was a profoundly man-made disaster — that could and should have been foreseen and prevented,”
Its effects could have been mitigated by a more effective human response.”
- Dr. Kiyoshi Kurokawa, M.D. (Chair, Nuclear Accident Indep. Investig. Comm./Prof. Tokyo Univ. )
Most powerful quake in Japan’s history (350x energy vs. Kobe)
9m~40m tsunami height, affected up to 10km inland
~18,500 lives lost to Tsunami & Earthquake
~1M bldgs. Destroyed/damaged
13~14m tsunami hit Fukushima Daichi
Sea wall only 5.7m, all station power knocked out
including control room

8. Defense in Depth (DiD)*
* DiD: originally military strategy to minimize enemy attack by prolonging/diffusing effects.
Multi-layered design protection philosophy
(perhaps not good enough…)
1. U02 Oxide Fuel Pellet (Non-volatile, ~2800degC melt temp)
2. Fuel cladding (Zircalloy, ~1800degC melt temp)… H2 gas,
embrittlement, swelling, at high temp
3. Pressure Vessel (Ni-SUS)…Spent fuel is external to PV
4. Containment vessel/steel floor (thick concrete &
steel)…Containment of molten fuel could fail if structural integrity of CV is
compromised by H2 explosion, earthquake, etc.
5. Secondary containment building (std. building materials)
6. Environmental buffer: Land/Forest; Water (sea, river)…
May contaminate adjacent sea/river ground water
7. Location in remote, unpopulated region
(e.g. 30km radius)… No longer in common practice!

9. Preventable Man-Made Disaster
or Natural Catastrophe?
• What is a black swan event?
• Example a): Lehmann Shock
• Example b): Collision/sinking of USS Titanic
• Example c): M9.0 earthquake + Tsunami
1. Judged “Highly improbable” from past experience, risk estimations.
-Conditional assumptions, extrapolations taken as absolute facts
-Hints / early warnings easily ignored or covered up
2. Wipes out multiple levels of “safety” or “redundancy” at once
-Design basis can be exceeded…then what?
Obvious facts about Fukushima:
• M9.0 has occurred before (e.g. 2004 Sumatra M9.1)
• Very large tsunami has occurred (e.g. Hokkaido 1993, 32m)
• LWR nuclear plants are on the shoreline, by design

10. Rasmussen Study (1975, MIT/AEC)
Historic study to integrate
risk severity (public
attention) with occurrence
frequency (industry focus)
Biased: used to try to
convince gov’t, public of
safety of nuclear power.
Millitaristic approach: only
considering # of deaths as
measurable impact.
* Risk of lethal dose of Chlorine release during domestic transport by train in USA..
(Cl used as example of toxic chemical release in populated areas).
*
Source: http://www.osti.gov/energycitations/product.biblio.jsp?query_id=6&page=0&osti_id=7134131
First use of probabilistic method for safety risk assessment (contrib. to FMEA method)

11. …Collateral Risks Underestimated
Practically zero deaths due to Fukushima accident, however
HUGE DAMAGES to people, gov’t, and industry!
– Evacuations (indefinite) & resettlement
– Personal/medical damages and claims
– Contamination of land (Cs-137, 134) & water (Cs-137, Tritium)
– Fukushima-1 cleanup/fuel recovery
– Decommissioning of other nuclear plants
– Added fossil plants/fuels Oil, LPG
– Lost tourism (radiation concerns)
– Limited mfg.supply (power peaks, costs)
– Kyoto Protocol decommit (CO2 targets)
– Deaths from heatstroke due to excessive
energy conservation (ironically)…
http://whenthecrisishitthefan.com/2012/02/

12. Costs and Recovery ($USD equiv.)
(paid by TEPCO & gov’t eventually by citizens…)
What How Long HowMuch $
On-site clean-up & decommission 10~30yr 250B
Affected lands decontamination 5yrs 10B
Evacuation living costs (housing, etc.) 5yrs 9B
Reparations to evacuees (lost assets, jobs) 3yrs 8B
Purchase contaminated land (20km zone) 5yrs 50B
Medical claims & monitoring (evacuees) 30yrs 1B
Decomm. other reactors (fault line risk, etc.) 5yrs 10B
Upgrade other reactors 5yrs 11B
Rebuild towns/communities over time 10yrs 269B
Added fossil fuel plants & fossil fuels (+100T BTU/yr) 20yrs 460B
Ramp-up solar/renewables infra & incentives 20yrs 100B
Roughly ~$1.2T USD (= avg. 60B/year, or $500/person/year)
…to be paid for by increased taxes and higher energy prices.

13. Fukushima- what went well
Despite widespread anger, mistrust, and
confusion in Japan, at least… (arguably)
• Evacuations – rapid and orderly
• Heroic response on site during disaster to help
limit damage

14. What Failed ? (Quite a lot!)

15. Technical Blind Spots
• Protective sea wall too low (5.7m vs. 13m): risk assess insufficient
• Backup generators, battery sys., & control/breakers at
ground/basement level
• No independent backup battery/generator power to control
room: electric power required to control key functions and
monitor reactor status via lights/gages
• Spent fuel pools vulnerable to loss of coolant & exposure/melt
• H2 production from overheated Zr cladding
• Vents unable to open due to failure of compressed air supply to
open the valve, also without filters (despite backfit
recommendations)
• Safety relief valves sealed shut under high pressure (unable to
open in emergency)

16. Case Study#1: Isolation Condenser
(Backup cooling water system for emergencies)
• Unable to confirm operation or not
– No power to central control room; all metrologies lost
– Radiation prevented access Containment Vessel (CV) to check
– External steam from Iso-con exhaust seen (misjudgment)
• Never tested Iso-con in 40yrs of operation
– Unable to notice signs that Isocon not operating
• Water level dropped, Steam visible was not vigorous
• No one had ever seen Iso-con in operation
• No emergency ops training

17. Case Study#2: SR Valves
(failed at Reactor#2)
• 8 valves, to reduce pressure in Reactor pressure vessel (PV) at time
of LOCA accident (steam build-up due to cooling system failure,
causing excess pressure )  release steam from PV to within
Containment vessel (CV).
• Operated remotely from main control room
– Requires electric power to operate & view status via indicator lights.
• Insufficient pressure differential between CV and PV can prevent
valve opening. (Normally PV is much higher pressure vs. CV).
– CV reached ~7 Atm or 0.75MPa, vs. typcial 1 Atm. [PV is ~7.5MPa]

18. Systemic/Political Failure
• FMEA worst case was only single-event LOCA
– Beyond design-basis, station power outage, etc. not incl.
– Bigger risks assumed designed-out, or too low probability
• Regulatory Independence/Competency Lacking
– Regulatory agency not having “teeth” for enforcement
– Operators voluntarily apply regulations
– Regulatory agency taking data from operators on faith (without validation)
– NISA Lacking sufficient org. independence (from MEXT gov’t branch that
serves to promote the industry and technical expertise to assure
quality/safety?
• Geological site data uncertainty:
– Historical tsunami risks underestimated and fault line evidence
conveniently interpreted as low-risk by utilities.

19. Case Study: Geological Site Surveys
NRA has concerns/investigations about possible active fault lines
at or near some reactors:
• Hamaoka (Shizuoka)
– Requested by PM in 2011 to decommission, due to location in earthquake
susceptible zone, near 2 tectonic plate boundaries (Utility accepted)
• Tsuruga (Fukui)
– NRA recommended to decommission (Utility disagrees)
• Ooi (Fukui)
• Shika (Ishikawa)
Nuclear fuel cycle program also at risk due to fault concerns:
• Monju Fast Breeder reactor (Fukui)
• Rokkasho reprocess facility (Aomori)
Estimations of max Tsunami and protective wall heights are
also in contention.

20. Case Study: JCO Criticality Accident
• JCO – Japan Nuclear Fuel Conversion Company (Sumitomo Metals), working as
subcon for Donen- Nuclear Fuel Development Corporation
• 1999 Serious nuclear accident (unrelated to TEPCO/Fukushima)
• Workers were mixing a batch of Uranium for Joyo experimental breeder reactor
(U-235 with 18% enriched solution)
• Accidental criticality, resulted in workers deaths by irradiation
• Serious failures in training , ignorance of SOPs, and lack of safety precautions.
• Outside of the commercial reactor industry, hence not subject to regular safety
audits, etc.
• It resulted in ending of Japan’s U-235 reprocessing activities.

21. Response/Communication Failure
• Gov’t’s Off-Site Control Center (OFC) unusable
• No available emergency pumps and systems
for high pressure injection to PV
• No training to actually deal with serious
accidents of this level.
• SPEEDI system results with-held by gov’t
– Initial evacuation based on flawed data

22. Case Study: Off-Site Control Center (OFC)
• Gov’t’s emergency center, just 5km from Fukushima Daichi
• 20 such locations in Japan, established after JCO criticality accident in 1999
• After only a few days of accident, the site was evacuated (moved to
prefectural gov’t bldg.)
– Inadequate radiation protection (no air filters for ventilation system)
– Failed Audio/Video communications equipment (only satellite link was
operational)
– Backup generator with limited fuel, not waterproofed
• Siting of OFCs indicates poor accident scenario planning.
– 5km proximity is too close for case of H2 explosion, etc.
– Siting on shoreline, on landfill or potentially unstable grounds
– Another OFC (Onagawa, Miyagi) was destroyed by Tsunami

23. Case Study: SPEEDI
• SPEEDI (System for Prediction of Environment Emergency Dose
Information) for monitoring & predictive mapping of fallout.
• SPEEDI was developed by Japnese gov’t explicitly for use in
nuclear emergencies.
• Information was not publicly released to citizens for until Apr-25.
• Also the data was partially compromised due to lost power to
some monitoring stations after the earthquake. (Some data
interpolated).
• The gov’t said it wanted to avoid releasing imperfect modeled
data, due to potential misinterpretation of the data/maps, etc.
Initial gov’t evacuation (Mar-14~15) was based simply on a
simple circular radius, but the SPEEDI data indicated clearly that
certain directions were more contaminated than others. It was
recommended to expand/modify the evacuation zones.
• The failure to release critical info resulted in significant loss of
trust/confidence in government information and reporting.
• Many local governments and citizens felt that if they had the
data, they could have made better decisions to choose
sites/directions to evacuate. Hence they felt that the gov’t
exposed them needlessly to radiation risks. (Some evacuation
centers outside of 30km but still with significant fallout.)

24. Other Blind Spots
• Radiation safety limits on foods and understanding of
“internal exposure” (vs. external ionizing radiation
damage)

25. Japan’s Safety Myth – Paradise Lost?
• Context of Japan’s great industrial prowess (technology & also
quality), including nuclear. As nuclear industry leader, perhaps
Japan strove to make rules, rather than follow them.
• Japan’s dependence on foreign oil/gas also underscores nuclear
power as a national security priority. Hence a long-term, strong
gov’t agenda to support nuclear energy policy .
• 1995 Kobe earthquake served to demonstrate robustness of
Japanese plants. (2 nearby power plants, were undamaged).
• Criticism of safety (site fault line analyses, disaster response plans,
etc.) were often brushed aside. Nuclear operators became
defensive against ‘no-nukes’ critics, sometimes perceived as
ignorant or irrational. As in US, Chernobyl type accident was
considered unconceivable in Japan.
• Nuclear operators allegedly utilized $ incentives also mafia
connections to secure local gov’t approval for new plants. It
was/is not a healthy economic environment. This also fosters
conflicts of interest, and makes criticism difficult.
• The nuclear industry promoted itself as absolutely safe… and
came to believe its own marketing promotion, to the point where
tough questions (e.g. tsunami risks) were assumed irrelevant.
• Regulatory authority (gov’t) was believed to be too close to the
interests of the nuclear industry. (known as “regulatory capture”) .
It did not promote checks & balances.
• Nuclear industry failed to invest in recommended backfits (from
IAEA, WANO, NRC); Falsified docs related to Equipment
Inspections, and avoided investment in disaster response systems
(since it might encourage fears among the public.)
“It’s a fact that there was an unreasonable overconfidence in the technology of Japan’s
nuclear power generation.” -Banri Kaeda (Chief Minister, METI, 2011)
"If culture explains behavior, then no one has to
take responsibility," he said. "People have
autonomy to choose. At issue are the choices they
make, not the cultural context in which they make
them.“ –Gerald Curtis, Columbia Univ. prof.

26. What is Changing? (Japan)
Energy policy and nuclear fuel cycle policy re-assessment, but also,
Tougher regulations, new design requirements, better oversight.
Nuclear Regulatory Org/Systems
– More independent, tougher function, enforcement
– Better communication/reporting to local/nat. gov’ts
Emergency Response
– Emergency/Disaster response systems/resources
– Radioactivity filtration systems & power/comms for disasters
– More robust radiation monitoring and gov’t communications
Earthquake/Tsunami Proofing
– Re-assess on-site seismic fault lines
 Forced decommissioning of some plants
– Higher walls against tsunami
– Auxiliary gen./battery located higher-up,
water-tight bldgs.
Reactor Design Changes : see next page 

27. New Regulations (Japan)
Reactor Engineering Design Changes
– Filters on external emergency CV vents
– Manual operation option for key valves
– Auxiliary pumps and water source for spent fuel pools
– Additional injection pumps into Containment vessel
– Secondary control room & backup power, away from reactor bldg.

28. What is Changing? (World)
1. Beyond design-basis accident scenarios:
– Plant design reviews by 3rd party org. (WANO)
• Higher safety standards by pop density, multi-plant sites, etc.
– Inspection of emergency response systems
– Bunker style backup safety systems , Trained “SWAT” response team (France)
– Backup batteries for 72hrs (rather than 8hrs)
– Others (USA)
2. Robust fuel storage solutions
– Spent fuel storage (after 5yrs in pool) in self-contained dry casks (USA/France)
3. Organizational Changes
– NRC chief Jaczko resigns (USA) – partly over push for stronger US regulations
after Fukushima disaster
– IAEA shakeup after criticism of slow/ineffective response (UN)
• Failed to mediate btw’n gov’t reports from JP (downplay) and US (over-react)
• IAEA Radiological Event Scale also confusing/ineffective

29. What Have We Learned?
• Central problem of conflict of interests must be acknowledged
and the bias compensated
– Experts are mostly insiders/supporters…
– Regulators’ jobs tied to industry success (“regulatory capture”)
• Civilian-run utilities must open up to gov’t/international help
in a disaster situation
• “Defense in depth” and “design basis” philosophy can fail by
black-swan induced common cause failures
– Long technical experience/judgment does not justify low-risk
• Emerg. response systems are necessary - “black swan” events.
• Low ocurrence, high severity risks must be in planning
– Risk assessment estimates - large uncertainty; Black swans happen
– Robust metrologies are critical to know status and make decisions

30. What Must We Do
(Quality/Reliability professionals)
• Frequently re-assess systemic/org. biases
– Keep balance between Lean (reduce data) & Conservative (demand more data)
– Rotate people to keep fresh viewpoints
– Checks and balances to compensate org. biases, avoid “regulatory capture”.
• Diligently avoid reality distortion
– Reject fitting/interpreting data to the requirement
– Plan ahead to avoid ignoring key info due to short timeline (rushed).
– 3rd party oversight : Prevent censoring of dissenting/competing views
(intentional/unintentional)
• Ensure planning & systems for black swan events
– ‘Estimated as low chance of occurrence, hence do nothing’…is not acceptable.
– No data or few data points = high uncertainty
– Probabilistic Risk and FMEA have difficulty to estimate Frequency for rare or
unknown events Supplementary tools required.
• Release data quickly during excursions (even with known uncertainties)
– Don’t wait for perfect decisions

31. Ref: Evolution of Dealing with Risk
Past Present Future
Tools Common sense Statistical/ Logical
(SPC, FMEA)
Predictive by design; Real-
time sensors; X-checking
Bias Subjective Objective Known bias compensation
Approach Engineering
experience
Conservative
(max data)
Lifetime value (DFR, Taguchi
loss function, Lean, etc.)

32. Ref: Further Reading/Watching
Overall Summaries
• http://world-nuclear.org/info/Safety-and-Security/Safety-of-Plants/Fukushima-Accident-2011/#.Udpomm2yzAA
• http://www.iaea.org/newscenter/focus/fukushima/japan-report2/japanreport120911.pdf (IAEA summary)
• http://www.bbc.co.uk/news/world-asia-18718486 (BBC summary)
• http://www.dipity.com/edyong209/Fukushima-disaster/ (timeline)
• http://www.ifs.tohoku.ac.jp/maru/kougi/thermal-science/data/2013.04.30/2013.pdf (Tohoku Univ. technical analysis)
• http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_111130_04-e.pdf (TEPCO core meltdown technical analysis)
• http://spectrum.ieee.org/energy/nuclear/24-hours-at-fukushima (first 24hrs in detail)
• http://www.youtube.com/watch?v=ixjlSsUlNBw (Meltdown – NHK documentary, English subtitles/narration)
Impacts/Results/Ongoing Issues
• http://thebreakthrough.org/archive/new_data_japanese_fuel_imports (CO2)
• http://e360.yale.edu/feature/as_fukushima_cleanup_begins_long-term_impacts_are_weighed/2482/ (land contamination)
• http://www.world-nuclear-news.org/RS_Japan_readies_for_restarts_1906131.html (restarts)
• http://www3.nhk.or.jp/nhkworld/english/news/20130706_27.html (Tritium levels in local ocean)
Global Reactions/Analyses
• http://www.nature.com/news/france-imagines-the-unimaginable-1.9780 (France, on failure of “defense in depth”)
• http://www.engineeringnews.co.za/article/lessons-from-japans-nuclear-crisis-2011-11-04 (technical lessons)
• http://www.nytimes.com/2011/06/02/world/asia/02japan.html?_r=2&ref=world& (NYT analysis)
• http://www.youtube.com/watch?v=AG1QmEQ84aY (Gregory Jaczko video interview)
• http://ajw.asahi.com/tag/PROMETHEUS%20TRAP?page=4 (Asahi Newspaper, “Prometheus Trap” series)
Lessons for Risk Assessment Methodology
• http://thebulletin.org/beyond-our-imagination-fukushima-and-problem-assessing-risk
• https://qir.kyushu-u.ac.jp/dspace/bitstream/2324/20493/1/p001.pdf

33. Ref: LWR Nuclear Plant Safety Design
• Design Considerations
– Negative Feedback mechanism vs. chain reaction criticality (sustainability)
• Delayed supercriticality (chain reaction dependent on delayed neutrons rather than prompt)
• H2O coolant is also moderator of reaction (i.e. loss of coolant physically stops nuclear reaction)
• Temp increase leads to voiding  reduces/stops reaction
– Control Rods (pull out/up to operate, drop down to stop reaction)
– Boric Acid (absorb neutrons to stop reaction, reduce heat)
– Scram / Trip (emergency shutdown)
• Physical Levels of Containment (DiD)
– Fuel pellet, Cladding, PV, CV, Building, ( plus surrounding environs ~2km)
http://en.wikipedia.org/wiki/Nuclear_safety

34. Ref: Nuclear Power Plants in Japan
• ~30% Japan’s electricity until 2011 (~50% for Tokyo)
• 50 nuclear reactors (PWR, BWR) at 15 locations. Biggest
sites are:
– Fukushima (10), Kashiwazaki (7)
• Decommissioned
– Hamaoka (3 of 5); Fugen (1, FBR);
Tokai (1 of 2, GCR)
• Others
– Fast Breeder (FBR)
• Monju (Fukui)
– Fuel process related
• Rokkasho (Aomori),
• Tokai (Ibaraki)