Response of theFukushima Dai-ichiNuclear Plant to theMarch 11, 2011Earthquake in Japan - 3-Flanagan-Response-of-the-Fukushima-Dai-ichi-Nuclear-plant-to-EERI-WPPComments.pdf

7/31/2019 Response of theFukushima Dai-ichiNuclear Plant to theMarch 11, 2011Earthquake in Japan - 3-Flanagan-Response

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Response of t heFuk ushim a Dai -ich iNuc lear Plant t o theMarc h 11, 2011Ear t hquake in Japan

Dr. George Flanagan

Oak Ridge National Laboratory

Presented to the EERI/NECMeeting

Apri l 12, 2012

2 Managed by UT-Battellefor the U.S. Department of Energy EERI/NEC April 12,2012

Present at ion Out l ine

Basic Reactor Physics and Boiling Water Design

Sequence of Events

Consequences and Mitigation

Conclusions and Lessons Learned


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Basic React or Phys icsand

Boi l ing -Wat er Reac t or (BWR) Design



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Af ter a React or is Shutdow n Heat is St i l lGenerated Bec ause o f t he Decay o f theRadioact ive Fiss ion product s(Fragm ents)


Boi l ing-Wat er Reac t or (BWR) Uses

Nuclear Heat t o Boi l Water t o Creat eSteam t o Produce Elec t r i c i t y

CourtesyofNEXTERAEnergy


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Nuclear Plants are Designed With ManyBarr iers t o Prevent Release of Radioact iveMater ia l Resul t ing f rom Fiss ion


Mark 1 Boi l ing-Water React or

Cont a inment Des ign Major Structures Biological Shield

Secondary Containment Build ing

Reactor Pressure Vessel

Reactor Containment (Dry Well, Duct, Suppression Chamberor Pool-torus)

Spent Fuel Pool

CourtesyofTVA


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GE BWR Mar k I Containm ent


Sequence of Events


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9.0 Ear t hquake Occ urs o f the Coast o fJapan at 2 :46 PM, March 11, 2011


Eart hquake/Tsunami Af fec t ed

Fourt een Plant s on the Easter n Coasto f Japan

CourtesyofTEPCO


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Some Uni t s o f Fuk ushima 1 (Dai -ich i )w ere in Opera t ion a t t he T ime o fEar thquake

Units 13 were operating at full power

Unit 4 was defueled (entire core stored in spent fuelpool)

Unit 56 in a refueling outage


Nuclear Plant Safety Featur es Per form

as Designed Unt i l t he Tsunami Hi t s


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Hor izonta l E-W Acc elerat ion Exc eededthe Seismic Design on Uni t s 2,3, and 5



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CourtesyofTEPCO


Tsunami Waves (47 feet ) Hi t Fukushim a 1

Plant About 1 Hour Af te r t he Ear t hquake


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Near ly a l l t he Dai ich i S i te Was

Flooded


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Only One Diesel Generat or Surv ived atDai- ichi


Eart hquake Resul ted in Loss of Of fs i te

Pow er/Tsunam i Resul t ed in Loss of Al lOns i t e AC Pow er (exc ept un i t 6)- Emergency P lan t sys tems w ork as des igned a f te r

ear thquake- D iese l generato rs w ere submerged by t sunami

(un i t 1 Bat ter ies w ere submerged)- Back up bat t er ies were deple ted af ter 810 hours


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Loss o f Bat t e ry Pow er Resu l ts in Lossof Abi l i ty t o Rem ove Decay Heat Fromt he Core


Loss of Al l AC/DC Pow er PreventedUse of Cool ing and Vent ing System s


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Possib le Sequence Leading t o CoreDama ge and Release of Hydrogen


Hydrogen Produced by Zr Clad

In te rac t i ng w i th the Steam


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Overpressure of t he Conta inm ent Resul tedin Opening Leakage Pathw ays for SomeSt eam and Hydrogen to Ent er the React or

Bui ld ingBypassing t he Vent L ines

Resulted in explosive mixture of hydrogen gas toaccumulate in the reactor buildings of Units 1 and 3

A panel was removed from Unit 2 to vent the building

A fire and explosion occurred in Unit 4 (reactor wasdefueled)

Thought to be a result of uncovering of the spent fuel

Appears this was not the case

Cause of Unit 4 explosion is now thought to be from Hydrogengenerated in unit three being carried into unit 4 through a shared ventline.


Resul t Was An Explos ion in Uni ts 1 and 3Destr oy ing Par t s of t he React or Bui ld ings


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Afterm ath Destroyed the Secondary Conta inment , SomeVent L ines - A l low ed Uncon t ro l l ed Re lease o fRadioact iv i t y to the At mosphere, to the Site , and toAreas Surrounding t he Si teResult ing in An Evacuat ion

(20 km )



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Consequences and Mi t igat ion


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Most o f t he T ime Fo l low ing theAcc iden t the Wind w as B low ing

Tow ards t he Sea, How ever, ThereWere Tim es When the Winds Blew

Towards t he Nor t hw es t

Resulted in a Plume Carrying Radiation to Drift Inland

Mandatory Evacuation Ordered for 20 km around the plant

Area between 20-30km asked to shelter in place and lateradvised to evacuate

Some areas in path of plume affected beyond 30km

Over 70,000 inhabitants affected by evacuation


Est im ated Dose Is About 10 T im es

Average Back ground (240mrem)


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With t he Succ ess ful Evacuat ion T hereWas No Sign i f icant Radiat ion Dose t ot he Genera l Publ ic Currently there are no acute radiation effects (even to workers onsite)

Estimated cancer increase is expected to be below statistical measurement threshold

Economic impacts enormous

Evacuees only allowed limited access within 30 km radius in March 2012

some limited access allowed to some areas within 20 km radius in early April2012

Loss of Productivity (manufacturing, agricultural, fishing)

Decontamination Activiti es have begun (estimates in 10 -250 billion of dollars)

Radioactive waste volumes are very large and pose a problem finding appropriate

disposal sites in a country with limited land mass


React or Cores Are Being Cooled and

Are St abi l ized

All reactors declared to be in cold shutdown inDecember 2011

Temperatures inside the reactors are below 100 C

Cooling water leaking out of reactors is collected

Treated to remove radioactive materials

Recirculated back into the reactor

Radioactive water accumulated on site immediately fol lowingaccident is being collected and treated as well

Water has been prevented from entering the ocean by use ofdikes and dams

Decontamination of areas surrounding the reactors (on site)is ongoing- surfaces have been treated to prevent dust


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Cover Has Been Inst a l led Around Uni t 1Debris Is Being Removed BeforeCovering Uni t s 3 and 4



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Socia l /Pol i t ic a l Impac t s in Japan andWorl d Wide

Resignation of Japans Prime Minister

Reorganization of Japanese Nuclear Regulatory Structure

Lack of Confidence in TEPCO and the government

Shutdown of 50+ reactors in Japan (electricity shortage predicted thissummer)

Germany, Switzerland will shutdown their existing plant and Italy has chosennot to restart their nuclear program

US NRC just issued orders to nuclear plant owners to reexamine all existingnuclear reactors regarding seismic design, AC power sources, and venting

Some delay of new reactor builds worldwide


Conclus ions and Lessons Lear ned External events may pose the greatest threat to nuclear plants

Multiple system failures can lead to significant plant damage

Loss of infrastructure (roads, bridges, water, power) prevented assistance

Planning/training i s essential to prevent injury and death (emergency planning, severeaccident plans)

Communication dur ing and following an event is crucial

Significant delays in transmission of information between onsite and centralizedlocations probably contr ibuted to the event

Instrumentation used to transmit plant status was lost

Public relations during an event is very important

Information was difficult to obtain both within Japan and clearly in other countries

Contradictions led to lack of trust by the public and media Lack of information prevented early assistance from outside sources

Documents

Response of theFukushima Dai-ichiNuclear Plant to theMarch 11, 2011Earthquake in Japan - 3-Flanagan-Response-of-the-Fukushima-Dai-ichi-Nuclear-plant-to-EERI-WPPComments.pdf