IAEA
Original English

MISSION REPORTTHE GREAT EAST JAPAN EARTHQUAKEEXPERT MISSION

IAEA INTERNATIONAL FACT FINDING
EXPERT MISSION OF THE
FUKUSHIMA DAI-ICHI NPP ACCIDENTFOLLOWING THE GREAT EAST JAPAN
EARTHQUAKE AND TSUNAMI
Tokyo, Fukushima Dai-ichi NPP, Fukushima Dai-ni NPP and
Tokai Dai-ni NPP, Japan
24 May – 2 June 2011

IAEA MISSION REPORTDIVISION OF NUCLEAR INSTALLATION SAFETY
DEPARTMENT OF NUCLEAR SAFETY AND SECURITY

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Original English

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REPORT
THE GREAT EAST JAPAN EARTHQUAKEEXPERT MISSION

IAEA INTERNATIONAL FACT FINDING
EXPERT MISSION OF THE
FUKUSHIMA DAI-ICHI NPP ACCIDENTFOLLOWING THE GREAT EAST
JAPAN EARTHQUAKE AND TSUNAMIREPORT TO
THE IAEA MEMBER STATESTokyo, Fukushima Dai-ichi NPP, Fukushima Dai-ni NPP and
Tokai Dai-ni NPP, Japan
24 May – 2 June 2011

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REPORT
THE GREAT EAST JAPAN EARTHQUAKEEXPERT MISSION

IAEA INTERNATIONAL FACT FINDING
EXPERT MISSION OF THE
FUKUSHIMA DAI-ICHI NPP ACCIDENTFOLLOWING THE GREAT EAST
JAPAN EARTHQUAKE AND TSUNAMI
Mission date:

24 May – 2 June 2011

Location:

Tokyo, Fukushima Dai-ichi, Fukushima Dai-ni and Tokai Dai-ni, Japan

Facility:

Fukushima and Tokai nuclear power plants

Organized by:International Atomic Energy Agency (IAEA)

IAEA Review Team:WEIGHTMAN, Michael
JAMET, Philippe
LYONS, James E.
SAMADDAR, Sujit
CHAI, Guohan
CHANDE, S. K.
GODOY, Antonio
GORYACHEV, A.
GUERPINAR, Aybars
LENTIJO, Juan Carlos
LUX, Ivan
SUMARGO, Dedik E.

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HSE, UK, Team Leader
ASN, France, Deputy Team Leader
IAEA, NSNI, Director
IAEA, NSNI, Head, ISCC
People‘s Republic of China
AERB, India
Argentina
NIIAR, Russian Federation
TurkeyCSN, Spain
HAEA, Hungary
BAPETEN, Indonesia

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SUNG, Key Yong
UHLE, Jennifer

KINS, Republic of Korea
USNRC, USA

BRADLEY, Edward E.
WEBB, Gregory PaulPAVLICEK, Petr
NAMMARI, Nadia

IAEA, NEFW, RRS
IAEA, MTPI
IAEA, MTPI
IAEA, NSNI

Issue Date: 16 June 2011

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REPORT
THE GREAT EAST JAPAN EARTHQUAKEEXPERT MISSION

IAEA INTERNATIONAL FACT FINDING
EXPERT MISSION OF THE
FUKUSHIMA DAI-ICHI NPP ACCIDENTFOLLOWING THE GREAT EAST
JAPAN EARTHQUAKE AND TSUNAMICONTENTSSUMMARY ............................................................................................................................. 11
1. INTRODUCTION ............................................................................................................ 19
1.1. BACKGROUND ...................................................................................................... 19
1.2. OBJECTIVE OF THE MISSION ............................................................................ 27
1.3. SCOPE OF THE MISSION ..................................................................................... 27
1.4. CONDUCT OF THE MISSION .............................................................................. 27
2. SEQUENCE LEADING TO THE FUKUSHIMA DAI-ICHI NPP ACCIDENT ........... 29
2.1
FUKUSHIMA DAI-ICHI NUCLEAR POWER STATION ................................... 29
2.2
FUKUSHIMA DAI-NI NUCLEAR POWER STATION ....................................... 37
2.3
TOKAI DAI-NI NUCLEAR POWER STATION ................................................... 38
3. MAIN FINDINGS, CONCLUSIONS AND LESSONS.................................................. 39
3.1
PREAMBLE............................................................................................................. 39
3.2
CONTEXT ............................................................................................................... 39
3.3
IAEA FUNDAMENTAL SAFETY PRINCIPLES: GENERAL............................. 42
3.3.1 Fundamental Safety Principle 3: Leadership and Management for Safety .......... 43
3.3.2 Fundamental Safety Principle 8: Prevention of Accidents................................... 44
3.3.3 Fundamental Safety Principle 9: Emergency Preparedness and Response .......... 50
3.4
IAEA SAFETY REQUIREMENTS AND GUIDES ............................................... 54
3.5
IAEA SAFETY SERVICES .................................................................................... 54
3.4.1 Road Map to Restoration...................................................................................... 55
3.4.2 External Hazards .................................................................................................. 55
3.4.3 Off-site Emergency Response .............................................................................. 56
3.4.4 Organization of Large Scale Radiation Protection for Severe Accident Conditions56
3.4.5 Follow-up IRRS Mission ..................................................................................... 56
4. ACKNOWLEDGEMENTS ............................................................................................. 59
APPENDICES .......................................................................................................................... 61
A1 - EXTERNAL HAZARDS ................................................................................................. 85
A2 - SAFETY ASSESSMENT AND MANAGEMENT ........................................................ 92
A3 - MONITORING, EMERGENCY PREPAREDNESS AND RESPONSE ..................... 117

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ANNEXES ............................................................................................................................. 143
ANNEX I - MISSION PROGRAMME ................................................................................. 145
ANNEX II - LIST OF PARTICIPANTS ............................................................................... 149

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ACRONYMS
AC
BAF
BWR
DC
EDG
EPR
EPREV
FAO
HPCI
IAEA
IC
ICRP
IEC
IRRS
ISSC
LPCI
MAAP
MUWC
NISA
NPP
NSC
OECC
PSA
RCIC
RHR
RPV
SAMG
SFP
SRV
SSC
TAF
TEPCO

Alternate Current
Bottom of Active Fuel
Boiling Water Reactor
Direct Current
Emergency Diesel Generator
Emergency Preparedness and Response
Emergency Preparedness Review
Food and Agriculture Organization
High Pressure Coolant Injection
International Atomic Energy Agency
Isolation Condenser
International Commission on Radiation Protection
Incident and Emergency Centre
Integrated Regulatory Review Service
International Seismic Safety Centre
Low Pressure Coolant Injection
Modular Accident Analysis Programme
Makeup Water Condensate
Nuclear Industrial Safety Agency
Nuclear Power Plant
Nuclear Safety Commission
On-site Emergency Control Centre
Probabilistic Safety Assessment
Reactor Core Isolation Cooling
Residual Heat Removal
Reactor Pressure Vessel
Severe Accident Management Guidelines
Spent Fuel Pool
Safety Relief Valve
Structures, Systems and Components
Top of Active FuelTokyo Electric Power Company

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SUMMARY
The Great East Japan Earthquake on 11 March 2011, a magnitude 9 earthquake, generated aseries of large tsunami waves that struck the east coast of Japan, the highest being 38.9 m at
Aneyoshi, Miyako.
The earthquake and tsunami waves caused widespread devastation across a large part ofJapan, with 15 391 lives lost. In addition to this, 8 171 people remain missing, with many
more being displaced from their homes as towns and villages were destroyed or swept away.
Many aspects of Japan‘s infrastructure have been impaired by this devastation and loss.
As well as other enterprises, several nuclear power facilities were affected by the severe
ground motions and large multiple tsunami waves: Tokai Dai-ni, Higashi Dori, Onagawa, andTEPCO`s Fukushima Dai-ichi and Dai-ni. The operational units at these facilities weresuccessfully shutdown by the automatic systems installed as part of the design of the nuclear
power plants to detect earthquakes. However, the large tsunami waves affected all thesefacilities to varying degrees, with the most serious consequences occurring at Fukushima Daiichi.
Although all off-site power was lost when the earthquake occurred, the automatic systems at
Fukushima Dai-ichi successfully inserted all the control rods into its three operational reactors
upon detection of the earthquake, and all available emergency diesel generator power systems
were in operation, as designed. The first of a series of large tsunami waves reached the
Fukushima Dai-ichi site about 46 minutes after the earthquake.
These tsunami waves overwhelmed the defences of the Fukushima Dai-ichi facility, whichwere only designed to withstand tsunami waves of a maximum of 5.7 m high. The larger
waves that impacted this facility on that day were estimated to be over 14 m high. The
tsunami waves reached areas deep within the units, causing the loss of all power sources
except for one emergency diesel generator (6B), with no other significant power source
available on or off the site, and little hope of outside assistance.
The station blackout at Fukushima Dai-ichi and the impact of the tsunami caused the loss of
all instrumentation and control systems at reactors 1–4, with emergency diesel 6B providing
emergency power to be shared between Units 5 and 6.

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The tsunami and associated large debris caused widespread destruction of many buildings,
doors, roads, tanks and other site infrastructure at Fukushima Dai-ichi, including loss of heatsinks. The operators were faced with a catastrophic, unprecedented emergency scenario withno power, reactor control or instrumentation, and in addition, severely affected
communications systems both within and external to the site. They had to work in darkness
with almost no instrumentation and control systems to secure the safety of six reactors, six
nuclear fuel pools, a common fuel pool and dry cask storage facilities.
With no means to confirm the parameters of the plant or cool the reactor units, the threereactor units at Fukushima Dai-ichi that were operational up to the time of the earthquake
quickly heated up due to the usual reactor decay heating. Despite the brave and sometimes
novel attempts of the operational staff to restore control and cool the reactors and spent fuel,there was severe damage to the fuel and a series of explosions occurred. These explosions
caused further destruction at the site, making the scene faced by the operators even moredemanding and dangerous. Moreover, radiological contamination spread into theenvironment. These events are provisionally determined to be of the highest rating on theInternational Nuclear Event Scale.
To date no confirmed long term health effects to any person have been reported as a result ofradiation exposure from the nuclear accident.
By agreement with the Government of Japan, the International Atomic Energy Agency
conducted a preliminary mission to find facts and identify initial lessons to be learned fromthe accident at Fukushima Dai-ichi and share this information across the world nuclear
community. To this end, a team of experts undertook this Fact Finding Mission from 24 May
to 2 June 2011. The results of the Mission will be reported to the IAEA Ministerial
Conference on Nuclear Safety at IAEA headquarters in Vienna on 20 24 June 2011.
During the IAEA Mission, the team of nuclear experts received excellent cooperation from allparties, receiving information from many relevant Japanese ministries, nuclear regulators andoperators. The Mission also visited three affected nuclear power plants (NPP) — Tokai Daini, Fukushima Dai-ni and Dai-ichi — to gain an appreciation of the status of the plants andthe scale of the damage. The facility visits allowed the experts to talk to the operator staff aswell as to view the on-going restoration and remediation work.
The Mission gathered evidence and undertook a preliminary assessment and has developed

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preliminary conclusions as well as lessons to be learned. These preliminary conclusions andlessons have been shared and discussed with Japanese experts and officials. They fall broadly
under the three specialist areas of external hazards, severe accident management andemergency preparedness. They are of relevance to the Japanese nuclear community, the IAEA
and the worldwide nuclear community to learn lessons to improve nuclear safety.
The IAEA Mission urges the international nuclear community to consider the following 15
conclusions and 16 lessons in order to take advantage of the unique opportunity created by the
Fukushima accident to seek to learn and improve worldwide nuclear safety.

Conclusion 1: The IAEA Fundamental Safety Principles provide a robust basis inrelation to the circumstances of the Fukushima accident and cover all the areas oflessons learned from the accident.
Conclusion 2: Given the extreme circumstances of this accident the local management of
the accident has been conducted in the best way possible and following Fundamental
Principle 3.
Conclusion 3: There were insufficient defence-in-depth provisions for tsunami hazards.
In particular:although tsunami hazards were considered both in the site evaluation and thedesign of the Fukushima Dai-ichi NPP as described during the meetings and the
expected tsunami height was increased to 5.7 m (without changing the licensing
documents) after 2002, the tsunami hazard was underestimated;

thus, considering that in reality a ‘dry site’ was not provided for these operating
NPPs, the additional protective measures taken as result of the evaluation
conducted after 2002 were not sufficient to cope with the high tsunami run up
values and all associated hazardous phenomena (hydrodynamic forces anddynamic impact of large debris with high energy);moreover, those additional protective measures were not reviewed and approvedby the regulatory authority;because failures of structures, systems and components (SSCs) when subjected tofloods are generally not incremental, the plants were not able to withstand the
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consequences of tsunami heights greater than those estimated leading to cliff edge
effects; andsevere accident management provisions were not adequate to cope with multiple
plant failures.

Conclusion 4: For the Tokai Dai-ni and Fukushima Dai-ni NPPs, in the short term, thesafety of the plant should be evaluated and secured for the present state of the plant andsite (caused by the earthquake and tsunami) and the changed hazard environment. In
particular, if an external event Probabilistic Safety Assessment (PSA) model is alreadyavailable, this would be an effective tool in performing the assessment.
Short term immediate measures at Fukushima Dai-ichi NPP need to be planned andimplemented for the present state of the plant before a stable safe state of all the units isreached. Until that time the high priority measures against external hazards need to be
identified using simple methods in order to have a timely plan. As preventive measures
will be important but limited, both on-site and off-site mitigation measures need to be
included in the plan. Once a stable safe state is achieved a long term plan needs to beprepared that may include physical improvements to SSCs as well as on-site and off-site
emergency measures.
Conclusion 5: An updating of regulatory requirements and guidelines should be
performed reflecting the experience and data obtained during the Great East Japan
Earthquake and Tsunami, fulfilling the requirements and using also the criteria andmethods recommended by the relevant IAEA Safety Standards for comprehensively
coping with earthquakes and tsunamis and external flooding and, in general, allcorrelated external events. The national regulatory documents need to include databaserequirements compatible with those required by IAEA Safety Standards. The methods
for hazard estimation and the protection of the plant need to be compatible withadvances in research and development in related fields.
Conclusion 6: Japan has a well organized emergency preparedness and response system
as demonstrated by the handling of the Fukushima accident. Nevertheless, complicatedstructures and organizations can result in delays in urgent decision making.
Conclusion 7: Dedicated and devoted officials and workers, and a well organized andflexible system made it possible to reach an effective response even in unexpected
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situations and prevented a larger impact of the accident on the health of the generalpublic and facility workers.
Conclusion 8: A suitable follow up programme on public exposures and healthmonitoring would be beneficial.
Conclusion 9: There appears to have been effective control of radiation exposures on theaffected sites despite the severe disruption by the events.
Conclusion 10: The IAEA Safety Requirements and Guides should be reviewed toensure that the particular requirements in design and severe accident management for
multi-plant sites are adequately covered.
Conclusion 11: There is a need to consider the periodic alignment of national regulations
and guidance to internationally established standards and guidance for inclusion inparticular of new lessons learned from global experiences of the impact of external
hazards.
Conclusion 12: The Safety Review Services available with the IAEA’s International
Seismic Safety Centre (ISSC) would be useful in assisting Japan’s development in thefollowing areas:External event hazard assessment;

Walkdowns for plants that will start up following a shutdown; andPre-earthquake preparedness.

Conclusion 13: A follow-up mission including Emergency Preparedness Review(EPREV) should look in detail at lessons to be learned from the emergency response on
and off the site.
Conclusion 14: A follow-up mission should be conducted to seek lessons from theeffective approach used to provide large scale radiation protection in response to the
Fukushima accident.
Conclusion 15: A follow-up mission to the 2007 Integrated Regulatory Review Service(IRRS) should be conducted in light of the lessons to be learned from the Fukushima
accident and the above conclusions to assist in any further development of the Japanese
nuclear regulatory system.

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Lesson 1: There is a need to ensure that in considering external natural hazards:


the siting and design of nuclear plants should include sufficient protection against
infrequent and complex combinations of external events and these should beconsidered in the plant safety analysis – specifically those that can cause site
flooding and which may have longer term impacts;

plant layout should be based on maintaining a ‘dry site concept’, wherepracticable, as a defence-in-depth measure against site flooding as well as
physical separation and diversity of critical safety systems;common cause failure should be particularly considered for multiple unit sites
and multiple sites, and for independent unit recovery options, utilizing all on-siteresources should be provided;

any changes in external hazards or understanding of them should be periodicallyreviewed for their impact on the current plant configuration; andan active tsunami warning system should be established with the provision for
immediate operator action.

Lesson 2: For severe situations, such as total loss of off-site power or loss of all heat sinks
or the engineering safety systems, simple alternative sources for these functions
including any necessary equipment (such as mobile power, compressed air and watersupplies) should be provided for severe accident management.
Lesson 3: Such provisions as are identified in Lesson 2 should be located at a safe place
and the plant operators should be trained to use them. This may involve centralized
stores and means to rapidly transfer them to the affected site(s).
Lesson 4: Nuclear sites should have adequate on-site seismically robust, suitably
shielded, ventilated and well equipped buildings to house the Emergency Response
Centres, with similar capabilities to those provided at Fukushima Dai-ni and Dai-ichi,
which are also secure against other external hazards such as flooding. They will requiresufficient provisions and must be sized to maintain the welfare and radiologicalprotection of workers needed to manage the accident.

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Lesson 5: Emergency Response Centres should have available as far as practicableessential safety related parameters based on hardened instrumentation and lines such as
coolant levels, containment status, pressure, etc., and have sufficient securecommunication lines to control rooms and other places on-site and off-site.
Lesson 6: Severe Accident Management Guidelines and associated procedures shouldtake account of the potential unavailability of instruments, lighting, power andabnormal conditions including plant state and high radiation fields.
Lesson 7: External events have a potential of affecting several plants and several units at
the plants at the same time. This requires a sufficiently large resource in terms of
trained experienced people, equipment, supplies and external support. An adequate poolof experienced personnel who can deal with each type of unit and can be called upon to
support the affected sites should be ensured.
Lesson 8: The risk and implications of hydrogen explosions should be revisited andnecessary mitigating systems should be implemented.
Lesson 9: Particularly in relation to preventing loss of safety functionality, therobustness of defence-in-depth against common cause failure should be based onproviding adequate diversity (as well as redundancy and physical separation) for
essential safety functions.
Lesson 10: Greater consideration should be given to providing hardened systems,
communications and sources of monitoring equipment for providing essential
information for on-site and off-site responses, especially for severe accidents.
Lesson 11: The use of IAEA Safety Requirements (such as GS-R-2) and related guides
on threat categorization, event classification and countermeasures, as well as
Operational Intervention Levels, could make the off-site emergency preparedness andresponse even more effective in particular circumstances.
Lesson 12: The use of long term sheltering is not an effective approach and has beenabandoned and concepts of ‘deliberate evacuation’ and ‘evacuation-prepared area’ wereintroduced for effective long term countermeasures using guidelines of the ICRP and
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Lessons 13: The international nuclear community should take advantage of the data andinformation generated from the Fukushima accident to improve and refine the existing
methods and models to determine the source term involved in a nuclear accident andrefine emergency planning arrangements.
Lesson 14: Large scale radiation protection for workers on sites under severe accident
conditions can be effective if appropriately organized and with well led and suitabletrained staff.
Lesson 15: Exercises and drills for on-site workers and external responders in order toestablish effective on-site radiological protection in severe accident conditions would
benefit from taking account of the experiences at Fukushima.
Lesson 16: Nuclear regulatory systems should ensure that regulatory independence andclarity of roles are preserved in all circumstances in line with IAEA Safety Standards.

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1.

INTRODUCTION

1.1.

BACKGROUND

The ―2011 Off the Pacific Coast of Tohoku Earthquake‖ occurred at 05:46 UTC (14:46 JST)on 11 March 2011. The magnitude (Mw) of the earthquake was 9.0. Extreme vibratory groundmotion and tsunami were generated from this large earthquake. These caused massive
devastation with 15 391 lives lost and 8 171 people still missing.

Because of the widespread disaster caused by this large earthquake, it is called the Great East
Japan Earthquake. The hazard of severe vibratory ground motion and tsunami hit five nuclear
power plant (NPP) sites in the North Eastern coast of Japan — Higashi Dori, Onagawa,
Fukushima Dai-ichi (1F), Fukushima Dai-ni (2F) and Tokai Dai-ni. A sequence of events
initiated by the earthquake led to the severe accident at the Fukushima Dai-ichi NPP site.

The epicentre of the earthquake was located at 38.1N and 142.9E (130 km ESE off Ojika
Peninsula), at a focal depth of 24 km on the subduction zone between the North American
plate and the Pacific plate. The earthquake is estimated to have originated from the rupture ofa subduction zone area having a length of more than 400 km and width of about 200 km. The
main shock was preceded by a strong motion foreshock and followed by a number ofaftershocks over a long period. Table 1.1 contains information on the foreshock and some of
the aftershocks (magnitude greater than or equal to 7.0) that occurred shortly after the main
shock. Large tsunamis were created by the earthquake. Tsunamis were observed to be morethan 8.5 m at Miyako, 8.0 m at Ofunato and 9.3 m at Soma. The maximum tsunami heightwas 38.9 m in Aneyoshi, Miyako.

The location of the five power plants site vis-à-vis the epicentre of earthquake is shown in
Fig. 1.1. All sites have NPPs of the boiling water reactor (BWR) type. There is one BWR-5
reactor of 110 MW(e) in Higashi Dori. The Onagawa site has one BWR-4 reactor of 524
MW(e) capacity and two BWR-5 of 825 MW(e) capacity. Fukushima Dai-ichi has the largest
number of reactors among the five sites. Six reactors are located on this site: Unit 1 (BWR3)
460 MW(e), Units 2, 3, 4 and 5 (4-BWR4) 784 MW(e), and Unit 6 (BWR5) 1100 MW(e).
There are four units of BWR5 reactors each having 1100 MW(e) capacity at the Fukushima

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Dai-ni site. Tokai Dai-ni has one operating BWR-5 unit of 1100 MW(e) capacity. Pictorial
views of Fukushima Dai-ichi NPP, Fukushima Dai-ni NPP and Tokai Dai-ni NPP are given in
Figs 1.2, 1.3 and 1.4 respectively.

At the time of the earthquake, all the reactors were in operation except the one unit ofHigashi Dori and Units 4, 5 and 6 of Fukushima Dai-ichi NPP. The earthquake caused
automatic shutdown of all the operating units. Large tsunamis caused by this earthquake hit
all the five sites within an hour of the main shock and caused damage at several sites. The
status of the NPP reactors is summarized in Table 1.2.

The worst affected sites were Fukushima Dai-ichi and Fukushima Dai-ni. Fukushima Dai-ni
lost some safety related equipment but off-site and on-site power remained available albeit
somewhat degraded. On the other hand, Fukushima Dai-ichi lost much of its safety related
equipment from the tsunami and all off-site and on-site power except for one diesel serving
Unit 6. This led to a loss of cooling for the reactors of Units 1, 2 and 3 and the spent fuelpools (SFP) of Unit 4. In addition, cooling for other safety related equipment was unavailable
or inaccessible. All these resulted in accident conditions at four units of Fukushima Dai-ichi
NPP.

The International Seismic Safety Centre (ISSC) of the International Atomic Energy Agency(IAEA) received information about the earthquake on 11 March 2011 through its ―External
Event Notification System‖ within about half an hour. The ISSC promptly conveyed theinformation to the IAEA Incident and Emergency Centre (IEC).

The Japanese authorities subsequently informed the IAEA about the event. The IAEA has
been in constant contact with the Government of Japan and disseminating information toMember States on a regular basis since that time. The IAEA Director General,
Yukiya Amano, called for a robust follow-up action. The IAEA has been collaborating with
the Government of Japan in sharing information about the status of the damage at the nuclear
power plants and its effect on the surrounding areas. As immediate assistance, the IAEA sent
seven expert teams to Japan, including a joint IAEA/FAO team on food monitoring tocoordinate information sharing on radiation and environmental monitoring, on boiling water

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reactors and on marine environment monitoring.

Since late March 2011, the Government of Japan and the IAEA were engaged in consultations
over sending a fact finding expert mission to explore the impact of the earthquake andtsunami on several of Japan‘s NPPs, including Fukushima-Dai-ichi. The Government of Japanand the IAEA agreed to send to Japan a mission comprising international experts together
with IAEA staff in order to provide a preliminary assessment of the accident at Fukushima
Dai-ichi and recommend areas that need further exploration. The Mission was one of theinitial activities of the IAEA and would be followed by other missions as well as relevantinternational cooperative activities including further information exchange. These future
activities may include facilities not covered by the scope of the present Mission and would
comprise technical studies, discussions with the participation of relevant Member Stateinstitutions, and the organization of international, regional and national workshops andtraining courses. Covering the areas of external hazards and structural response, safetyassessment and management of severe accidents, and monitoring, emergency preparedness
and response, the IAEA could support the development and incorporation of the lessons
learned from different issues identified by this and subsequent relevant missions.

The findings of the Mission are being shared with the international community to assist in
identifying the lessons learned and their incorporation into the global nuclear safety structure.
In this connection, the Director General informed IAEA Member States that an IAEA
Ministerial Conference on Nuclear Safety will be held from 20 to 24 June 2011, in Vienna.
The more specific objectives of the Conference are the following:

To provide a preliminary assessment of the Fukushima Dai-ichi NPP accident;To assess national and international emergency preparedness and response levels inlight of the Fukushima Dai-ichi NPP accident, with a view to strengthening them;

To discuss safety implications and identify those areas of safety which may bereviewed with the aim of strengthening them through launching a process to that
effect;

To identify lessons learned and possible future actions.

The findings of the Mission will be reported to the Ministerial Conference.

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TABLE 1.1. FORESHOCK, MAIN SHOCK, AFTERSHOCKS AND ASSOCIATED
EVENTS OF THE 2011 OFF THE PACIFIC COAST OF TOHOKU EARTHQUAKE
Location
Shock

Date

Magnitude
Epicentre

depth

Foreshock9 Mar. 11:45 (JST)N38d20m, E143d17m

8 km

M7.3

Main shock

11 Mar. 14:46 (JST)N38d06m, E142d52m

24 km

M9.0

11 Mar. 15:08 (JST)N39d50m, E142d47m

32 km

M7.4

11 Mar. 15:15 (JST)N36d06m, E141d16m

43 km

M7.7

11 Mar. 15:25 (JST)N37d50m, E144d54m

34 km

M7.5

7 Apr. 23:32 (JST)N38d12m, E141d55m

66 km

M7.1

11 Apr. 17:16 (JST)N36d57m, E140d40m

6 km

M7.0

Aftershocks

AssociatedeventsTABLE 1.2. STATUS OF NPPS AFFECTED BY THE 2011 OFF THE PACIFIC COAST
OF TOHOKU EARTHQUAKE
Type
NPP

Unit

StatusCapacity

CV** type

Safetysystem(MW(e))

Beforeearthquake

After
earthquake

After
tsunami1

Mark I R

BWR-5

1,100

OutageCold Shutdown

Cold Shutdown

1

Mark I

BWR-4

524

OperatingAutomatic Scram

Cold Shutdown

2

Mark I

BWR-5

825

Automatic Scram

Cold Shutdown

3

Mark I

BWR-5

825

OperatingAutomatic Scram

Cold Shutdown

1

Mark I

BWR-3

460

OperatingAutomatic Scram

Loss of Cooling

2Mark I

BWR-4

784

OperatingAutomatic Scram

Loss of Cooling

Fukushima

3Mark I

BWR-4

784

OperatingAutomatic Scram

Loss of Cooling

Dai-ichi4Mark I

BWR-4

784

OutageCold Shutdown

Loss of SFP*
cooling

5Mark I

BWR-4

784

OutageCold Shutdown

Cold Shutdown

6

Mark II

BWR-5

1,100

OutageCold Shutdown

Cold Shutdown

1

Mark II

BWR-5

1,100

OperatingAutomatic Scram

Cold Shutdown

Fukushima

2Mark II R

BWR-5

1,100

OperatingAutomatic Scram

Cold Shutdown

Dai-ni3Mark II R

BWR-5

1,100

OperatingAutomatic Scram

Cold Shutdown

4

Mark II R

BWR-5

1,100

OperatingAutomatic Scram

Cold Shutdown-Mark II

BWR-5

1,100

OperatingAutomatic Scram

Cold Shutdown

HigashiDori

Onagawa

Tokai Daini*: Spent Fuel Pool**: Containment Vessel

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FIG. 1.1. NPP sites affected by the “2011 Off the Pacific Coast of Tohoku Earthquake”.

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a) Pictorial view

Unit 6
Unit 5
BWR Mark I (Unit 1~5)
Unit 1
Unit 2
Unit 3
Unit 4
BWR Mark II (Unit 6)b) Layout
FIG. 1.2. Fukushima Dai-ichi NPP.

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Unit 4
Unit 3
Unit 2
Unit 1a) Pictorial view

Unit 4
BWR Mark II (Unit 1)

Unit 3

Unit 2
Unit 1

BWR Mark II R (Unit 2~4)b) Layout
FIG. 1.3. Fukushima Dai-ni NPP.

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a) Pictorial view

Unit 1

BWR Mark II (Unit 1)b) Layout
FIG. 1.4. Tokai Dai-ni NPP.

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1.2.

OBJECTIVE OF THE MISSION

The Mission conducted a fact finding activity for a preliminary assessment of the accident (inparticular at the Fukushima Dai-ichi NPP (1F)). The Mission also collected information on
the Fukushima Dai-ni (2F) and Tokai Dai-ni (T2) NPP sites located in Fukushima Prefecture
and in Ibaraki Prefecture respectively to make a preliminary assessment of the generic safetyissues associated with the natural events and the identification of issues that need further
exploration or assessment based on IAEA Safety Standards.
The Mission received information on the progress reached to date on the Japanese assessmentof the accident and discussed specific technical issues to develop an informed assessment of
the accident for sharing with the international nuclear community.

1.3.

SCOPE OF THE MISSION

The scope of the Mission, while focusing on overall nuclear safety issues, covered the following
specific areas:a.

External events of natural origin;b.

Plant safety assessment and defence-in-depth;c.

Plant response after an earthquake and tsunami;d.

Severe accident;e.

Spent fuel management under severe facility degradation;f.

Emergency preparedness and response; andg.

Radiological consequences.

The Government of Japan provided the Mission Team with all relevant information it had readily
available at the time of the Mission.

1.4.

CONDUCT OF THE MISSION

The Mission was conducted through discussions with the counterparts and observations madeduring the visit to the sites.
The official language of the Mission was English and Mission documents were prepared and

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finalized in English. The documents summarize the studies and inspections performed and theresults obtained, and recommend future actions.
The Mission consisted of meetings at offices in Tokyo and a two-day visit to the Fukushima
Dai-ichi, Fukushima Dai-ni and Tokai Dai-ni sites.
Courtesy visits were paid to various Ministers.
The meetings over the first two days in Tokyo addressed the general safety issues listed under
Section 1.3. Presentations by the Japanese counterparts during these meetings included therequirements, regulations and procedures pertaining to the issues addressed in this report.
The visits to the sites included question and answer sessions in which the Japanesecounterparts provided detailed answers to the questions of the Mission Team.
The Mission Team was divided into the three following groups:
1. External Hazards Group — comprising experts on the assessment of external
hazards of natural origin and plant response. They interacted with the Japanese experts on
assessment of hazards of natural origin and their incorporation in design, and on the responseof the plants, including structures, systems and components, against the hazards.
2. Safety Assessment and Management Group — comprising experts in the area ofsafety assessment, of severe accident and management, and defence-in-depth analysis. The
team held discussions with the Japanese experts on the response of plant systems after the
events, severe accident management, defence-in-depth and fuel pool cooling after severe plantdegradation.
3. Monitoring, Emergency Preparedness and Response Group — comprisingexperts in the areas of emergency preparedness and response (EPR), and of radiologicalconsequences. They addressed the plant specific protective actions taken and reviewed thedetails of the governmental infrastructure and communication along with the radiologicalconsequences of the accident.
The experts attended multiple presentations to address cross-cutting issues. The meetings ofthe groups were held in parallel following the site visits in order to gain as much informationas possible from the Japanese experts prior to the finalization of the Mission Report, including
the development of conclusions and lessons learned. Press contacts with the Mission leader
were arranged, as appropriate. The Mission was conducted by a team of international experts
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and IAEA staff. The list is given on page iii and iv of this report.

2.

SEQUENCE LEADING TO THE FUKUSHIMA DAI-ICHI NPPACCIDENT

2.1

FUKUSHIMA DAI-ICHI NUCLEAR POWER STATIONThe Fukushima Dai-ichi site NPP has six BWR reactor units. Unit 1 is a BWR-3 reactor witha Mark I containment, Units 2–5 are BWR-4 reactors with Mark I containments, and Unit 6 isa BWR-5 reactor with a Mark II containment. At the time of the earthquake, Units 1–3 wereoperating and Units 4–6 were in refuelling/maintenance outages. In response to theearthquake, Units 1–3 automatically scrammed (shutdown). All six off-site power lines werelost as a result of the earthquake and all 12 of the available plant‘s emergency diesel
generators (EDG) started. The site has 13 EDGs but one had been taken out of service formaintenance. About 46 minutes after the earthquake, the first tsunami wave hit the site. It
was followed by several additional tsunami waves leading to the inundation of the site. The
resulting ground acceleration at Units 1, 4 and 6 did not exceed the standard seismic groundmotion, whereas at Units 2, 3 and 5, the resulting ground acceleration did exceed the standard
seismic ground motion. The tsunami exceeded the design basis at all units. The standard
seismic ground motion was established for each unit for the purpose of a seismic back checkbased on the Seismic Design Review Guideline revised in 2006.
The extent of flooding was extensive, completely surrounding all of the reactor buildings at
the Fukushima Dai-ichi site. The tsunami caused the loss of all nine available EDGs cooledby sea water and the loss of all but one of the three EDGs cooled by air. The air-cooled EDG
at Unit 6 was the remaining source of AC power at the six-unit site. Workers were
temporarily evacuated from the site as a result of several after-shocks and accompanying
tsunami alerts. On the entire site, no means of communication between the On-site
Emergency Control Centre (OECC) and on-site personnel executing recovery actions wasavailable. Only one wired telephone was available between the OECC and each control room.
The seawater pumps and motors located at the intake were totally destroyed so the ultimate
heat sink was lost.

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Core Damage Progression of Units 1–3
With the loss of all AC power, all safety and non-safety systems driven by AC power became
unavailable. At Units 1 and 2, the 125 V DC batteries were flooded, so no instrumentation andcontrol was available, thereby hampering the ability of the operators to manage the plantconditions. No lighting was available in the main control rooms in either unit. At Unit 3, DC
power and, in turn, main control room lighting and instrumentation and control systems, wereavailable for 30 hours but were lost once the batteries drained, as the battery charger was
flooded and AC power was not available. During the initial response, work was conducted in
extremely poor conditions, with uncovered manholes and cracks and depressions in the
ground. Work at night was conducted in the dark. There were many obstacles blocking accessto the road such as debris from the tsunami and rubble that was produced by the explosions
that occurred in Units 1, 3 and 4. All work was conducted with respirators and protective
clothing and mostly in high radiation fields. All three units experienced severe core damage
but during the Mission no further detail was provided. The system response described below
is preliminary and lacks a number of details in many areas. It is likely that the description will
be changed once TEPCO can obtain more information and analyse it.
Some systems were available to cool the cores in Units 1–3 after the earthquake. In Unit 1, theIsolation Condenser (IC) is designed to operate through gravity driven natural circulation of
coolant from the reactor pressure vessel (RPV) through a heat exchanger immersed into alarge tank of water in the reactor building at an elevation above the core. The Unit 1 IC wasdesigned to have a decay heat removal capacity of about 8 hours. A valve must be
manipulated to bring the IC into service. It was started at 14:52 on 11 March after theearthquake. Although unconfirmed it appears to have operated for about 11 minutes and wasthen manually shutdown at 15:03 because the RPV temperature was dropping rapidly. Thisaction is consistent with the plant operating procedures which direct the operator to control
the IC so that the RPV temperature reduction rate does not exceed 55°C per hour. After thetsunami, at about 18:18, the IC was started by manually opening the DC powered valve as it islocated outside of containment. At about 18:25 the valve was closed. It was then reopened at
21:30. Steam generation was confirmed in the IC pool after the valve was opened at 18:18 and21:30, so it appears that heat was being removed from the core to the IC pool during these
periods. The IC was the only system available to cool the core during this period and it
eventually failed. TEPCO is further investigating the failure of the IC and operator actions
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related to its operation during this period.
As designed, the Reactor Core Isolation Cooling (RCIC) systems in Units 2 and 3 utilize apump which is driven by a turbine that takes steam from the RPV. The turbine exhaust steam
is discharged to the suppression pool. The RCIC systems are limited to operation when thesteam pressure in the RPV is above a certain pressure rating. In order to start the RCIC
systems, valves must be realigned. Some are operated with AC power and some are operated
with DC power. After the earthquake at Fukushima Dai-ichi, the RCIC systems in Units 2 and3 were manually started and then tripped on a high RPV water level automatically before thetsunami. After the tsunami, the RCIC systems were started at 15:39 and 16:03 in Units 2 and3, respectively. Conditions indicate that the RCIC system of Unit 2 operated as designed forabout three days until 14 March at 13:25, although the actual status could not be confirmed in
the control room. The RCIC system in Unit 3 stopped after about 19.5 hours, on 12 March at
11:36, and after an approximately 1 hour delay the turbine-driven high pressure coolant
injection (HPCI) system started automatically on a low RPV water level signal and remained
operable for about 14 hours. Their failures will be investigated by TEPCO once stableconditions are achieved.
Once the IC in Unit 1, the RCIC system in Unit 2, and the RCIC and HPCI systems in Unit 3
were unavailable, an alternative cooling process had to be established. In Unit 1, the alternate
process involved injecting feed from a low discharge pressure fire engine pump through thefire protection and makeup water condensate (MUWC) lines connected to the core spray line.
On 11 March at approximately 20:00, the reactor pressure was 6.9 MPa. Once the pressure
reading could be taken again on 12 March at 2:45 (the lack of DC power for instrumentation
required the use of car batteries so only intermittent readings were available), the pressure was
0.8 MPa. The cause of the depressurization will be investigated once conditions are stable. As
a result, the fire engine pump could begin to inject freshwater into the core, and it was
initiated at 5:46 on 12 March. Over the next nine hours, approximately 80 tonnes of water was
supplied to the core until the water supply ran out. As steam was bled from the RPV to thecontainment through an unconfirmed pathway, the containment pressure increased and it
became necessary to align the valves in order to vent the containment and reduce pressure.
Venting requires instrument air as well as AC power. High radiation levels in the reactor
building impeded the work. Beginning on the morning of 12 March, the operators attempted
to open the valves manually. In the afternoon, an engine driven air compressor (typically used
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for construction work) and an engine-generator to provide AC power to a solenoid valve wereused. At approximately 14:30 on 12 March, the operators confirmed a decrease in the dry wellpressure, providing some indication that venting had been successful. Approximately an hourlater, the first hydrogen explosion occurred at the site in the Unit 1 reactor building at 15:36
on 12 March. About 3.5 hours after the explosion a means to inject sea water (borated
intermittently to ensure subcriticality of the core) was established. This was discontinued on
25 March, once a source of fresh water was secured. Injection using fresh water is now
provided through a pump taking suction from a filtered water tank and injecting into thefeedwater line. Fresh water is obtained via a piping system that connects the site to a dam
located approximately 10 km away. Measures have been taken to inert the containment withnitrogen.
The alternative cooling process used in Units 2 and 3 involved feeding water to the RPV
using a fire engine pump injecting sea water, which was borated intermittently, and bleeding
the steam to the suppression pool through the safety relief valves (SRVs). This ―feed andbleed‖ process essentially moves heat from the core to the containment and therefore thesuppression pool temperature increases as does the pressure of the wet well. Since theultimate heat sink was lost, venting from the containment was used to reduce pressure, as
discussed below.
After RCIC failed in Unit 2, approximately six hours elapsed until an alternative injection
source could be established using a fire engine pump injecting sea water. The RPV pressure
was reduced using the SRVs to allow injection, due to the low discharge pressure of the fireengine pump. Several attempts were made to open the SRVs, which require both DC power
and adequate nitrogen pressure in the valves‘ accumulators to assist in the manipulation of thevalve. The operators tried to open several valves using a car battery as the DC power source
but the nitrogen pressure in the valves‘ accumulators was insufficient to either open the valvesor keep them open. A valve was eventually opened and the RPV pressure was reduced. A
nitrogen cylinder was used to maintain a vent path through the SRVs. About 9197 tonnes ofsea water was injected between 14 March and 26 March through the fire protection and
MUWC lines connected to the low pressure coolant injection (LPCI) lines. LPCI is one modeof the residual heat removal (RHR) system. At one point, the injection was temporarily
discontinued when the truck ran out of fuel. After 26 March, a fresh water source wasestablished similar to that of Unit 1.
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Alignment of the valves to vent the Unit 2 containment was carried out on 13 March by
opening an air operated valve using an air cylinder and another valve with AC power suppliedby an engine generator. After the Unit 3 explosion, discussed below, the valve was rendered
inoperable. The operators then attempted to open another air operated valve to establish thevent path. An engine driven air compressor and AC power supplied by an engine generator
were used and the valve appeared to open slightly. However, the successful venting of theUnit 2 containment could not be verified.
After the HPCI failed in Unit 3 on 13 March, approximately seven hours elapsed until analternative injection source could be established. The RPV pressure was reduced throughsteam discharge through one of the SRVs into the suppression pool. The accumulator of the
SRV contained adequate nitrogen pressure so the SRV could be opened with car batteries.
Once pressure was reduced, injection of water was established using a fire engine pumpinjecting through the fire protection and MUWC lines connected to the LPCI (one mode of
the RHR system) lines. Boron was added intermittently. The suction of the pump waschanged to a pit filled with sea water at one point temporarily interrupting injection for a shorttime, on the order of minutes. A further interruption occurred for two hours. Once restarted, atotal of 4495 tonnes of sea water was injected from 13 March until 25 March, at which time afresh water source was established similar to that of Unit 1.
Alignment of valves to vent the Unit 3 containment was begun on 13 March at approximately
8:41 using air cylinders and an engine generator. Several attempts were made to open thevalves and at 9:20 successful venting was confirmed by the decrease in dry well pressure;
however, due to the leakage of air, an engine driven air compressor was finally used toprovide the required air pressure. At 11:01 on 14 March, a hydrogen explosion occurred in the
Unit 3 reactor building resulting in substantial damage. At approximately 6:00 on 15 March,an explosion occurred in the Unit 4 reactor building. Since the spent fuel in the Unit 4 spent
fuel pool appears to have been covered with water precluding the generation of hydrogen, thesource of flammable gas is unclear. A potential source is hydrogen in the Unit 4 reactor
building backflowing from the Unit 3 standby gas system lines through the vent lines ofUnit 4. Units 3 and 4 share a common header that vents to the exhaust stack. This is notconfirmed. Plans have been made to inert the Unit 3 containment with nitrogen in the future.
MAAP Calculations of the Unit 1-3 Core Degradation Sequence

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TEPCO has performed a simulation of the accident using the Modular Accident Analysis
Programme (MAAP) code. The information below is only an estimate of the core behaviour.
Based on the calculation, assuming an estimated injection rate, the top of active fuel (TAF)
was reached in Unit 1 about three hours after the plant trip. The core was completely
uncovered two hours later. Core damage is calculated to have begun four hours after the trip
and a majority of the fuel in the central region of the core was melted at 5.3 hours after thetrip. At 14.3 hours after the trip, the core was completely damaged with a central molten pooland at 15 hours after the trip, all fuel had slumped to the bottom of the vessel. Although thecalculation shows that the RPV is severely damaged, measured data show much cooler
temperatures. Due to the uncertainty in the instrumentation at Dai-ichi, the state of the vessel
is unknown.
The calculation of the accident progression of Unit 2 is based on an assumed seawater
injection rate such that the reactor water level was maintained at about the midpoint of theactive fuel as measured by the instrumentation available during the event. The calculationshows that when the RCIC system was available, the water level was maintained well above
the TAF. Once RCIC was lost and the system was depressurized the water level dropped tothe bottom of active fuel (BAF) about 76 hours after the trip. Seawater injection was initiatedand according to the instrumentation, the water level remained at the midpoint of the active
fuel region, leading to a rapid increase in core temperature, reaching the melting point. A
molten pool existed in the central region of the core with melted fuel surrounding it at 87
hours after the trip. The molten pool was shown to grow larger by 96 hours and then begin tocool at 120 hours. At one week after the trip, there was a small molten pool surrounded bymelted fuel. Due to the uncertainties in instrumentation which gave information about the
selection of seawater injection rate, another calculation was performed using a reduced rate.
This model shows that the fuel has slumped and in turn the RPV is extremely damaged at 109
hours after the trip. Although the calculation shows that the RPV is severely damaged,
measured data show much cooler temperatures. Due to the uncertainty in the instrumentation
at Dai-ichi, the state of the vessel is unknown.
The calculation of the accident progression at Unit 3 is based on an assumed seawater
injection rate such that the reactor water level was maintained at about 3 m below the TAF, asmeasured by the instrumentation available during the event. The calculation shows that the

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core was covered until the RCIC and HPCI systems failed. Once seawater injection was
initiated and the water level stayed at around 3 m below the TAF, the temperature of the core
increased quickly, reaching the melting point. The extent of fuel melting is less than that ofUnit 1. This is presumed to be because the time between failure of the RCIC and start of the
HPCI system was smaller than the time of no injection in Unit 1. At 64 hours after the trip, amolten pool smaller than Unit 1 was surrounded by melted fuel, and a week after the scramthe molten pool had cooled somewhat. No slumping of the fuel to the bottom of the RPV waspredicted. Due to uncertainties in instrumentation which gave information about the selectionof the seawater injection rate used in the calculation, another calculation was performed using
a reduced injection rate. This case predicts that slumping of the fuel occurs at 62 hours after
the scram. Although the calculation of this scenario shows that the RPV is severely damaged,
measured data show much cooler temperatures. Due to the uncertainty in the instrumentation
at Dai-ichi, the state of the vessel is unknown.
Response of Units 5 – 6 and Site Spent Fuel Storage
Units 5 and 6 are located a distance from Units 1–4, and are at a higher elevation than Units
1–4. They suffered less damage than Units 1–4, although the damage was still severe. As aresult of the earthquake all off-site power was lost. As in Units 1–4, the seawater ultimate heatsink was lost as a result of the tsunami, and in Unit 5, all EDGs were lost due to flooding. One
air cooled EDG was available at Unit 6 because the air intake louvers were located above thetsunami inundation height. Units 5 and 6 had been shutdown since January 2011 and August
2010, respectively, and the fuel had been reloaded into the core recently, awaiting startup.
Though decay heat was much lower than the operating plants, cooling the fuel in the cores
was necessary and action was taken to restore the seawater cooling system.
On 12 March, measures were successful to provide AC power to important components ofUnit 5 using the Unit 6 EDG. On 13 March, the MUWC system was used to inject coolant
into the core, and steam was discharged through the SRVs to the suppression pool. Due to thelow decay heat of the fuel, venting of the containment was not necessary. On 19 March, analternate cooling path to cool the RHR system was established. The RHR pump was poweredfrom the Unit 6 EDG. A temporary pump provided sea water to the RHR heat exchangers
using an engine-generator to provide AC power. On 20 March, the core was cooled to cold
shutdown levels. Plans are underway to provide more heat removal capacity.

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There are seven spent fuel pools (SFPs) at the Fukushima Dai-ichi site. One at each unit and acommon SFP located behind Unit 4, which contains older fuel removed from the Units‘ SFPs.
SFPs have a large inventory of water above the TAF, approximately 7–8 m, although at
Fukushima some of the water inventory could have been lost as the result of the sloshing fromthe earthquake. Although dependent on the heat load of the fuel stored in the pool, the large
inventory of water typically allows many days before the pool would boil to a level below the
TAF. Therefore, immediate action to cool the SFPs was not necessary. Because of the lack of
instrumentation and high radiation levels, the water levels in the SFPs of Units 1–4 could not
be determined in the first several days of the accident. However, the explosions at the site
destroyed the reactor building roofs of Units 1, 3 and 4, providing access to the SFPs. Several
options were considered to provide coolant to the SFPs periodically. Both fresh and sea water
were used. Two techniques involved the use of a water cannon and dropping a water supply
from a helicopter. These techniques were used on the Unit 3 SFP beginning 17 March, andthen on the Unit 4 SFP beginning 20 March. The success of these techniques could not be
verified. Another technique which involved utilizing existing fuel pool cooling system lines
and temporary pumps was used on the Unit 2 SFP beginning 20 March and on the Unit 3 SFP
beginning 23 May. Beginning 22, 27 and 31 March, coolant was provided to the Unit 4, 3 and1 SFPs, respectively, using a concrete pumping truck with a hose secured to a boom lifted tothe appropriate height. To determine the status of the SFPs, images were taken of the Unit 3
and 4 SFPs remotely. The images verified the presence of a water level and showed that thefuel appeared to be intact. An extensive amount of debris generated by the explosion in Unit 3
had fallen into the Unit 3 SFP, so that the structural integrity of the racks could not be
confirmed. There was some debris in the Unit 4 SFP, likely due to the explosion at Unit 4, but
the status of the racks and the fuel is reported to be near normal on the basis of present
information. At this stage, the concrete pumping truck and boom technique is being applied to
the Unit 1 and 4 SFPs. Inventory is being provided to the Unit 2 and 3 SFPs via the fuel poolcooling system lines. Both techniques connect to a header that is fed by a pump taking suction
from a large water tank. Fresh water is pumped to the tank from the nearby dam.
Forced cooling was used at the site to cool the Unit 5 and 6 SFPs, using the AC power fromthe Unit 6 EDG. Forced cooling was established in the common SFP once AC power wasprovided to the site in late March. Because of its low heat load, no action was necessary
earlier in the event.

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A dry cask storage building is located adjacent to the Unit 5 turbine building. The building
was damaged by the tsunami but the casks appear to be intact. Radioactivity monitoring has
been used to determine the status of the fuel. Because no radioactivity release has been
detected, the dry casks appear to be unaffected.

2.2

FUKUSHIMA DAI-NI NUCLEAR POWER STATIONThe Fukushima Dai-ni site has four BWR-5 reactors with Mark II containments. At the timeof the earthquake, all four units at Fukushima Dai-ni were operating. In response to theearthquake, all four units automatically scrammed (shutdown). One off-site power source
remained operable, while the other three off-site power sources were either lost or inscheduled maintenance. About 37 minutes after the earthquake, the first tsunami wave hit thesite followed by several additional tsunami waves, leading to the inundation of the site.
Workers were temporarily evacuated from the site as a result of several aftershocks andaccompanying tsunami alerts, which hindered recovery actions. The maximum acceleration of
the earthquake was less than the standard seismic ground motion for each unit. However, thetsunami was much greater (inundation height of approximately 6.5–7 m) than the reference
tsunami level of 5.2 m. The reactor buildings and the turbine buildings are at an elevation of
12 m, and although the run-up wave of the tsunami that reached this elevation caused partial
flooding of these buildings, the extent of flooding was less than at Fukushima Dai-ichi.
The tsunami waves flooded the heat exchanger building, the seawater pumps and electric
power centres, which caused the loss of core cooling functions and pressure suppressionfunctions in three of the four units. The run-up wave that reached the reactor building of Unit
1 flooded its EDGs. Unit 3 was the least affected and was able to reach cold shutdown the day
after the earthquake.
Because the extent of damage caused by the tsunami was not as great as at Fukushima Daiichi, the plant superintendent had more options for dealing with the effects of the tsunami.
The plant operators were able to continue to provide water to the reactor cores with the RCIC
and MUWC system, and to manually depressurize the reactors. The plant superintendent
called for mobile power trucks and mobilized the workers on site to lay more than 9 km of
temporary power cables in 16 hours. In addition, replacement motors were procured for someof the flooded pumps. This allowed the normal RHR systems to be returned to service three

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days following the tsunami, and the units were brought to cold shutdown either on the same
day or the day after RHR had been restored.

2.3

TOKAI DAI-NI NUCLEAR POWER STATIONThe Tokai Dai-ni site has a single BWR-5 reactor with a Mark II containment. At the time ofthe earthquake, Tokai Dai-ni was operating. In response to the earthquake, the reactor
automatically scrammed (shutdown). All three off-site power sources were lost and all three
emergency diesel generators started automatically. About 30 minutes after the earthquake atsunami flooded the lower level of the site. The maximum acceleration of the earthquake wasless than the design basis of the site. However, the tsunami was 5.4 m (above Hitachi Point)whereas the design value (at the construction time) is 6.61 m (above Hitachi Point).
The tsunami flooded one bay containing some of the seawater pumps which caused the loss of
one of the emergency diesel generators and one source of core cooling when the seawatercooling function was lost. The other bay containing seawater pumps had previously been
upgraded to be watertight and the bay that was flooded was in the process of being upgraded.

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3.

MAIN FINDINGS, CONCLUSIONS AND LESSONS

3.1

PREAMBLE

These main findings are presented against the global context of the IAEA Safety Standards(Fundamental Safety Principles, Requirements and Guides) and Safety Services, and the workof the three groups covering: external hazards; safety assessment and management; andmonitoring, emergency preparedness and response. The Fact Finding Expert Mission visited
three of the sites affected; Tokai Dai-ni, TEPCO Fukushima Dai-ichi, and Dai-ni. Conclusions
and potential lessons for improvement of nuclear safety are derived as are areas for future
IAEA work, including issues that need further exploration or assessment. The detailed
findings and further information upon which these main findings are based are provided in theform of ‗Finding Sheets‘ provided in the Appendices. The findings are the result of meetings
the Mission had with various Japanese agencies, including questions and answers, site visitsand examination of documents.

3.2

CONTEXTOn 11 March 2011 Japan suffered its largest ever recorded earthquake, and within an hour aseries of associated tsunami waves hit the east coast of Japan. These caused massive
devastation. The infrastructure (roads, electrical supply, communications, etc.) was severely
impaired. Whole towns were destroyed or swept away.

Against this background the operators of nuclear facilities in this part of Japan and authorities
were faced with securing the safety of nuclear facilities and people. There are several nuclear
power plants along the East Coast of Japan that were affected.

The worst affected sites are TEPCO Fukushima Dai-ichi and Fukushima Dai-ni. Fukushima
Dai-ni lost some safety related equipment but off-site and on-site power remained available
albeit somewhat degraded. On the other hand, Fukushima Dai-ichi lost much of its safety
related equipment from the tsunami and all off-site and on-site power except for one diesel

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generator serving Unit 6. This led to a loss of cooling for the reactors of Units 1, 2 and 3 andthe spent fuel pool of Unit 4; in addition cooling of other safety related equipment was
unavailable or inaccessible. All these resulted in accident conditions at four units ofFukushima Dai-ichi NPP.

The response on the sites to the impact of the earthquake and tsunami, particularly at
Fukushima Dai-ichi, was in unprecedented circumstances and has at times required
exceptional levels of leadership and dedication by workers on the sites and elsewhere. At
Fukushima Dai-ichi they were presented with a more or less complete prolonged loss ofelectrical power, compressed air and other services, with little hope of immediate outside
assistance, and having to work in darkness with almost no instrumentation and control
systems to secure the safety of six reactors, six nuclear fuel pools, a common fuel pool anddry cask storage facilities.

To date no confirmed health effects have been detected in any person as a result of radiation
exposure from the associated nuclear accident. A realistic assessment of doses to individuals
would require the establishment and implementation of appropriate health monitoring
programmes, especially for the most exposed groups of population. Japan has created anexpert group to deal with dose assessments and health surveys of residents. This group
includes staff from the Fukushima Prefecture and Medical Universities, including Hiroshima
and Nagasaki Universities.

It is understood that around 30 workers at the Fukushima plant have been exposed to radiation
exposures of between 100 and 250 mSv, although very recent information indicates that somehigher internal doses may have been incurred by some workers in the early days. Doses
between 100 and 250 mSv, although significant, would not be expected to cause any
immediate physical harm, although there may be a small percentage increase in their risk ofeventually incurring some health effects. Monitoring programmes of workers, especially thosein the group of higher doses and for internal exposures, are necessary as soon as possible toassist in eliminating any uncertainties and to reassure workers.

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Three workers are reported to have suffered suspected radiation burns (non-stochastic effects)
on their feet/legs from inadvertent exposure to heavily contaminated water in a turbine
basement. After hospital treatment they were released after four days with reported no longterm likelihood of significant harm. Early on two workers on site were confirmed as dead(from other than radiation exposure) and several injured. A further worker was reported on
14 May 2011 to have died.

To avert potential radiation exposure to the public, the Japanese authorities took the
precautionary action of instructing those within the first 3 km, then 10 km and finally 20 kmof the plant to evacuate and those between 20 km and 30 km to shelter and get ready toevacuate. This instruction remains in place after several weeks. Information on the likely
exposure of the public is not yet available, although evacuation and sheltering would have
limited exposure. Any early exposure to the public before evacuation or sheltering is also not
yet clear.

While there appear so far to have been few radiological health consequences the societal andenvironmental impacts of the accident have been extensive and far reaching, with tens of
thousands of people being evacuated from around the plant, some foodstuffs and drinking
water restrictions, and significant contamination of the sea. In addition there has been great
public anxiety, both in Japan and internationally, about the possible health and other impactsof the radioactivity released. Finally, the economic impact of the failure of the plant is verysignificant.

Ten weeks after the accident there is much that is not yet known about the accident and others
will in due course examine the sequence of events in detail. In particular, the Japanese
government has set up an independent Investigation Committee, consisting of scientists,
lawyers and others who have no significant connection with the Japanese nuclear industry to
examine the details and determine responsibilities.

The present IAEA International Fact Finding Expert Mission set out to gather facts andreview them to identify lessons that might be learned to improve nuclear safety worldwide. In
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doing so it recognized that severe accidents can arise from a variety of causes, not necessarily
the direct causes associated with the Fukushima accident, and that therefore the lessons could
have wide applicability.

The IAEA has a system of Fundamental Safety Principles, international safety requirements
and guides and services. The Fundamental Safety Principles are applicable over all areas ofthe peaceful use of nuclear energy and radioactivity whereas the safety requirements andguides are more targeted and constitute the accumulated knowledge and experience of theworld in nuclear safety over the last fifty years, reflecting best practices in Member States.
The IAEA safety services range from engineering safety, operational safety, and radiation,transport and waste safety to regulatory matters and safety culture in organizations. They are
to assist Member States in applying the standards and appraise their effectiveness.

It is in this context that the Mission has come to the following conclusions and lessons toimprove nuclear safety.

3.3

IAEA FUNDAMENTAL SAFETY PRINCIPLES: GENERALThe circumstances of the Fukushima accident and the main conclusions and lessons have been
considered in the context of the application of the IAEA Fundamental Safety Principles tosecuring the highest standards of nuclear safety. In general, it is concluded that:Conclusion 1: The IAEA Fundamental Safety Principles provide a robust basis inrelation to the circumstances of the Fukushima accident and cover all the areas oflessons learned from the accident.

While all principles are relevant, the ones which are most relevant to the circumstances of this
accident, and under which the conclusions and lessons of this Mission are summarized, arediscussed below.

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3.3.1 Fundamental Safety Principle 3: Leadership and Management for Safety
This states that effective leadership and management for safety must be established andsustained in organizations concerned with, and facilities and activities that give rise to,radiation risks.

The Mission had the opportunity to receive detailed presentations of the scenario of theaccident and its technical management. These presentations were mostly given by TEPCO, at
the headquarters and plant levels. Complementary presentations were also given by the
Nuclear and Industrial Safety Agency (NISA), the nuclear regulator, other Government
Ministries and agencies. These presentations were greatly enhanced by site visits whichallowed the Mission to hear and see at first hand the extremely difficult work involved, andhave a concrete view of the practical conditions under which the operators had to manage theaccident and to perform their interventions.

The extreme difficulties that the operators on the site had to face in Fukushima Dai-ichi haveto be once again strongly underlined: loss of all the safety systems, loss of practically all the
instrumentation, necessity to cope with simultaneous severe accidents on four plants, lack ofhuman resources, lack of equipment, lack of light in the installations, and general conditionsof the installation after the tsunami and after damage of the fuel resulted in hydrogen
explosions and high levels of radiation. Access to outside resources and off-sitecommunications dependent on the local telecommunication network were also severely
disrupted, although the TEPCO in-house communications network between the site andheadquarters had been mostly intact.

Understanding in detail the sequences of the accidents in the plants is a very complex anddifficult task which has to be undertaken in the future. Many uncertainties remain today andwill hopefully be resolved in the future. However, in view of the information that wasprovided to the Mission, it is considered that, given the circumstances, the local teams havemanaged the accident in the best possible way they could. Given the resources available on
the site and the difficulty of the situation, it is doubtful at this stage that any better solutions
than the ones actually chosen could have been realistically implemented. It is therefore
concluded that:

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Conclusion 2: Given the extreme circumstances of this accident the local
management of the accident has been conducted in the best way possible andfollowing Fundamental Safety Principle 3.

3.3.2 Fundamental Safety Principle 8: Prevention of Accidents

This states that all practicable efforts must be made to prevent and mitigate nuclear orradiation accidents. A prime aspect of this principle is the concept of ‗defence-in-depth‘.
Successive layers of protection are provided which are as far as possible independent of eachother and each of which is sufficient to prevent harm occurring. Defence-in-depth covers alllayers of protection: management systems and cultures; site selection; design incorporating
safety margins, diversity and redundancy with appropriate attention to quality and reliability
requirements; operating systems; accident and emergency arrangements, etc. Detailed safety
analysis is the basis for determining and ensuring the adequacy of these barriers.

3.3.2.1

External Hazards

External hazards, especially those of a natural origin, can cause widespread long term
disruption both on and off a nuclear installation site, reaching regional and national scales.
This was a particular feature of the Fukushima accident, where the ground motions from one
the most extreme earthquakes that have been recorded in Japan was followed by the
associated large tsunami. It caused a prolonged loss of off-site power with disruption of roads
and communication infrastructure (note, however, that TEPCO‘s in-house communications
network independent from the local telecommunication network was mostly intact after theearthquake and tsunami, and played an instrumental role in securing communication channels
between the site and headquarters, etc.). Although the plant withstood the effects of theearthquake, the tsunami caused the loss of most safety systems for cooling of the reactor
cores, supply of emergency power and control of containment pressures, etc. It is concluded
therefore that:

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Conclusion 3: There were insufficient defence-in-depth provisions for tsunami
hazards. In particular:although tsunami hazards were considered both in the site evaluationand the design of the Fukushima Dai-ichi NPP as described during themeetings and the expected tsunami height was increased to 5.7 m(without changing the licensing documents) after 2002, the tsunami
hazard was underestimated;

thus, considering that in reality a ‘dry site’ was not provided for these
operating NPPs, the additional protective measures taken as result of theevaluation conducted after 2002 were not sufficient to cope with the hightsunami run up values and all associated hazardous phenomena(hydrodynamic forces and dynamic impact of large debris with highenergy);

moreover, those additional protective measures were not reviewed andapproved by the regulatory authority;because failures of structures, systems and components (SSCs) whensubjected to floods are generally not incremental, the plants were notable to withstand the consequences of tsunami heights greater than thoseestimated, leading to cliff edge effects; andsevere accident management provisions were not adequate to cope withmultiple plant failures.

The status of multiple plants affected by the tsunami makes them more vulnerable to any
further extreme natural hazards, even though the reactors are in a shutdown state. It istherefore concluded that:

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Conclusion 4: For the Tokai Dai-ni and Fukushima Dai-ni NPPs, in the shortterm, the safety of the plant should be evaluated and secured for the present stateof the plant and site (caused by the earthquake and tsunami) and the changed
hazard environment. In particular, if an external event PSA model is alreadyavailable, this would be an effective tool in performing the assessment.

Short term immediate measures at Fukushima Dai-ichi NPP need to be planned
and implemented for the present state of the plant before a stable safe state of all
the units is reached. Until that time the high priority measures against external
hazards need to be identified using simple methods in order to have a timely
plan. As preventive measures will be important but limited, both on-site and offsite mitigation measures need to be included in the plan. Once a stable safe stateis achieved a long term plan needs to be prepared that may include physicalimprovements to SSCs as well as on-site and off-site emergency measures.

To ensure that all plants are robust to such external events in the longer term and brought
under greater regulatory control, it is also concluded that:Conclusion 5: An updating of regulatory requirements and guidelines should be
performed reflecting the experience and data obtained during the Great East
Japan Earthquake and Tsunami, fulfilling the requirements and using also thecriteria and methods recommended by the relevant IAEA Safety Standards forcomprehensively coping with earthquakes, tsunamis and external flooding and,in general, all correlated external events. The national regulatory documents
need to include database requirements compatible with those required by IAEA
Safety Standards. The methods for hazard estimation and the protection of theplant need to be compatible with advances in research and development inrelated fields.

From a wider perspective, it is considered that worldwide nuclear safety could be improved in
the context of enhanced protection against external hazards, in particular:

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Lesson 1: There is a need to ensure that in considering external natural hazards:


the siting and design of nuclear plants should include sufficient
protection against infrequent and complex combinations of external
events and these should be considered in the plant safety analysis –specifically those that can cause site flooding and which may have
longer term impacts;

plant layout should be based on maintaining a ‘dry site concept’,
where practicable, as a defence-in-depth measure against site flooding
as well as physical separation and diversity of critical safety systems;common cause failure should be particularly considered for multiple
unit sites and multiple sites, and for independent unit recovery options,
utilizing all on-site resources should be provided;

any changes in external hazards or understanding of them should beperiodically reviewed for their impact on the current plantconfiguration; andan active tsunami warning system should be established with theprovision for immediate operator action.

3.3.2.2

Severe accidents

Traditionally, nuclear safety design has been based on the concept that the plant will be
designed to withstand all normal conditions and reasonably foreseeable abnormal/fault
conditions with a margin. The design basis usually excludes very remote events or
combination of events – those typically with a lesser probability of occurrence than 1 in
10 000 to 100 000 per year. However, the designer is also expected to consider beyond designbasis events to see whether more can reasonably be done to reduce the potential for harm,
especially where major consequences may ensue. Severe accidents, with significant
consequences, require particular attention in design, management and emergency response
arrangements. Normally, special operating procedures, called ‗Severe Accident Management
Guidelines‘ are developed for this. This review of the Fukushima accident has highlighted the

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following matters.

Lesson 2: For severe situations, such as total loss of off-site power or loss of allheat sinks or the engineering safety systems, simple alternative sources for thesefunctions including any necessary equipment (such as mobile power, compressed
air and water supplies) should be provided for severe accident management.

Lesson 3: Such provisions as are identified in Lesson 2 should be located at a safe
place and the plant operators should be trained to use them. This may involve
centralized stores and means to rapidly transfer them to the affected site(s).

This was clearly demonstrated at Dai-ni where the laying of a completely independent power
supply route for provision of cooling in the longer term (involving installing 9 km of heavy
electrical cabling in 16 hours) was effective in curtailing the development of a severe
accident. Similarly, at Dai-ichi fire tenders were used in series to lift sea water into anintermediate pit for further transfer to provide reactor cooling. Additionally, the normal diesel
generators at the Tokai Dai-ni and Fukushima Dai-ni sites were augmented by JAPC‘s and
TEPCO‘s fleet of mobile diesel generators held for loss of power to electrical supply
customers, which may not always available in other countries. From such experiences, NISA
organized a set of immediate measures for existing plants which addresses the matterincluding those identified in Lesson 2 and Lesson 3. NISA, on 30 March 2011, requested allof the utilities to implement them without delay.

The response to severe accidents being outside normal design and operating provisions
presents special resource, management and instrumentation and control arrangements. This isparticularly the case where multiple plants are involved as occurred at Fukushima Dai-ichi. It
was apparent that more resources were required than what was available on site. In addition,
there is a need for dedicated hardened capable facilities to manage and control the event. This
was available and very effective at the Fukushima Dai-ichi and Dai-ni sites. This provides
lessons for improvement of worldwide nuclear safety, viz:Lesson 4: Nuclear sites should have adequate on-site seismically robust, suitably

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shielded, ventilated and well equipped buildings to house the Emergency
Response Centres, with similar capabilities to those provided at Fukushima Daini and Dai-ichi, which are also secure against other external hazards such as
flooding. They will require sufficient provisions and must be sized to maintain thewelfare and radiological protection of workers needed to manage the accident.

Nevertheless, the response at least at Fukushima Dai-ichi was hampered by a lack of reliablesafety related parameters and communications and this may be a general position in othercountries. Thus:

Lesson 5: Emergency Response Centres should have available as far aspracticableessential

safetyrelatedparameters

based

on

hardened

instrumentation and lines such as coolant levels, containment status, pressure,etc., and have sufficient secure communication lines to control rooms and otherplaces on-site and off-site.
There were particular challenges at TEPCO‘s Fukushima Dai-ichi because of the highradiation fields, and with the tsunami and explosions there was considerable debris disrupting
normal routes. Additionally, control room access was limited and safety related
instrumentation was generally not available or unreliable. Severe Accident Management
Guidelines (SAMG) and associated procedures generally assume that instruments, lighting
and power are available. This may not be the case. In addition, these documents do notconsider the possible state of the plant and the local environmental conditions such as theradiation field that may preclude manual actions from being taken. Consequently, it isconsidered that:

Lesson 6: Severe Accident Management Guidelines and associated proceduresshould take account of the potential unavailability of instruments, lighting, power
and abnormal conditions including plant state and high radiation fields.

The assessment performed by the Mission also highlighted several lessons related to thearrangements for severe accident management to improve nuclear safety, viz:

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Lesson 7: External events have a potential of affecting several plants and several
units at the plants at the same time. This requires a sufficiently large resource interms of trained experienced people, equipment, supplies and external support.
An adequate pool of experienced personnel who can deal with each type of unit
and can be called upon to support the affected sites should be ensured.
Particular difficulties were experienced in responding at the TEPCO‘s Fukushima Dai-ichi
site because of the hydrogen explosions. This may not be adequately taken into account in theplant safety case, design and protective measures. Thus, it is considered that:

Lesson 8: The risk and implications of hydrogen explosions should be revisitedand necessary mitigating systems should be implemented.

One air cooled EDG in Unit 6 at Fukushima Dai-ichi survived partially because it was aircooled and partially because it was effectively protected against flooding, It ensured theprotection of Units 5 and 6 (others are seawater cooled or are air cooled but their associatedelectrical panel and cables were inundated). This demonstrates the benefits of diverse
provision of essential safety related services:

Lesson 9: Particularly in relation to preventing loss of safety functionality, therobustness of defence-in-depth against common cause failure should be based onproviding adequate diversity (as well as redundancy and physical separation) for
essential safety functions.

3.3.3 Fundamental Safety Principle 9: Emergency Preparedness and Response

This states that arrangements must be made for emergency preparedness and response fornuclear or radiation incidents.

3.3.3.1

Off-site Emergency Arrangements to Protect the Public and Environment

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The Japanese emergency arrangements involve several layers and different organizations withdecision making at high level. Normally, less complicated arrangements are used anddecisions such as instigating evacuation made at more local level to ensure thatcountermeasures are timely and conducted in an orderly way. The earthquake and tsunami
degraded the ability to implement effective off-site monitoring in the early stages of theaccident. Thus, greater reliance would have had to be placed on understanding the accident,
its likely progression and off-site impact. From the Mission‘s review and observations it isconcluded that:Conclusion 6: Japan has a well organized emergency preparedness and response
system as demonstrated by the handling of the Fukushima accident. Nevertheless,complicated structures and organizations can result in delays in urgent decision
making.

Conclusion 7: Dedicated and devoted officials and workers, and a well organized
and flexible system made it possible to reach an effective response even in
unexpected situations and prevented a larger impact of the accident on the healthof the general public and facility workers.

The fast changing plant circumstances and absence of real time information on the plantconditions led to the need to take several consecutive countermeasures to protect the public
rather than the expected reliance on dose measurements. In the first days after the accident,
the environmental monitoring programme failed due to damage of equipment by theearthquake and tsunami. This indicates the need for hardened instrumentation,communication, etc. to provide necessary information for on-site and off-site responsemanagement and for early off-site monitoring capability.

Lesson 10: Greater consideration should be given to providing hardened systems,
communications and sources of monitoring equipment for providing essential
information for on-site and off-site responses, especially for severe accidents.

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The effectiveness of the Japanese response seemed not to have been impeded by reliancemore on high level laws than detailed emergency plans under them. However, normallyeffective response is sustained for a range of scenarios through having well establishedintervention levels and associated plans. Other systems may not be as effective in responding
to different scenarios and should be assessed against IAEA Safety Standards for ensuring
robust responses to severe accidents.
Lesson 11: The use of IAEA Safety Requirements (such as GS-R-2) and related
guides on threat categorization, event classification and countermeasures, as well
as Operational Intervention Levels, could make the off-site emergency
preparedness and response even more effective in particular circumstances.
A concept of long term indoors sheltering was introduced in some areas to booster long term
countermeasures but this has been found not to be practicable and has been replaced by othermore established measures using guidelines of the International Commission on RadiologicalProtection (ICRP) and IAEA.

Lesson 12: The use of long term sheltering is not an effective approach and has
been abandoned and concepts of ‘deliberate evacuation’ and ‘evacuationprepared area’ were introduced for effective long term countermeasures using
guidelines of the ICRP and IAEA.

The knowledge of the source term involved in an accident is considered of paramountimportance to reach a clear understanding of the event and to determine the possible extent of
its radiological impact on the public and the environment. The Fukushima accident provides aunique opportunity to extend understanding in this area.

Lessons 13: The international nuclear community should take advantage of thedata and information generated from the Fukushima accident to improve andrefine the existing methods and models to determine the source term involved ina nuclear accident and refine emergency planning arrangements.

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A proper assessment of doses could contribute to defining and optimizing the strategy for
individual health monitoring. Direct monitoring of exposure, using suitable equipment (suchas personal contamination equipment), and the use of the results of the environmental
monitoring, could help in achieving a realistic assessment of doses, and so enhance theconfidence of the population, and determine health tracking programmes.

Conclusion 8: A suitable follow up programme on public exposures and healthmonitoring would be beneficial.

3.3.3.2

On-site Emergency Arrangements to Protect Workers

During the Fukushima accident the extensive disruption from the earthquake and tsunami on
and off the sites made the implementation of the nuclear emergency arrangements extremely
challenging, sometimes making it impossible to fully follow well established procedures andpractices on site. However, the ability of the site management to effectively control doses in
exceptional circumstances was commendable. This was further reinforced by the team‘s
experience at the ‗J-Village‘ coordination centre, where it appeared that around 2000 workers
a day were being provided with full face masks and other radioactivity protection in a wellorganized and effective way. Similarly, at all the sites visited by the Mission, including
Fukushima Dai-ichi with its severe problems, effective health physics protection was evident.
The organization, discipline and devotion during the response to this most complex nuclear
multiple accident is an example to all.

After the accident, the operator gradually improved on-site radiological monitoring, andcomprehensive radiation maps of the site are currently available and updated on a periodic
basis. This information is used to classify the radiological areas in terms of exposure risks andto determine the protection equipment and procedures to be employed by workers in theirtasks. Extensive use of the radiological maps to optimize protection of workers, including theestablishment of clear physical barriers between the radiological areas, are used to separate
those in the highest risk category to prevent possible unexpected or unauthorized entries.

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Conclusion 9: There appears to have been effective control of radiation exposures on
the affected sites despite the severe disruption by the events.

Lesson 14: Large scale radiation protection for workers on sites under severe
accident conditions can be effective if appropriately organized and with well led andsuitable trained staff.

Lesson 15: Exercises and drills for on-site workers and external responders in orderto establish effective on-site radiological protection in severe accident conditions
would benefit from taking account of the experiences at Fukushima.

3.4

IAEA SAFETY REQUIREMENTS AND GUIDES

A particular feature of the Fukushima accident was the need to deal with serious events atseveral reactors on the site. This aspect has implications for multi-plant siting, design, layout,
operation and emergency response arrangements. Detailed safety analysis of the progressionof the accidents at each of the units at Fukushima Dai-ichi would provide a basis for
additional lessons for improving IAEA Safety Requirements and Guides, as appropriate.
Lessons should be learned from this experience and it is concluded that:Conclusion 10: The IAEA Safety Requirements and Guides should be reviewed toensure that the particular requirements in design and severe accident
management for multi-plant sites are adequately covered.

3.5

IAEA SAFETY SERVICES

The IAEA has in place a series of services for Member States to use to check and enhancetheir safety arrangements. These have grown over the years and become more comprehensive.
Developments in these services reflect the periodic review and updating of IAEA Safety
Requirements and Guides. Of particular note has been the expansion of capability to provide a
review of provisions for extreme external hazards. The circumstances of the Fukushima

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accident indicate that the use of these services on a periodic basis could be beneficial inensuring that the best international practice is sustained across Member States.

Conclusion 11: There is a need to consider the periodic alignment of national
regulations and guidance to internationally established standards and guidance,
for inclusion in particular of new lessons learned from global experiences of the
impact of external hazards.

Future Missions and Work by the IAEA on Fukushima
3.4.1 Road Map to Restoration
The roadmap towards restoration from the accident was presented to the Mission by TEPCO
and NISA. This roadmap appears to be ambitious but achievable and to include the issues tobe addressed in order to insure sustainable safety as well as protection of the environment.
Some subjects appear to be of particular importance such as the installation of sustainablecooling systems for the reactor cores and spent fuel pools, the treatment of the highly
contaminated water contained in the basements of the buildings as well as the sheltering of thedamaged reactor building in order to protect the environment against further releases. The
Mission acknowledged the importance and relevance of the roadmap and considered that it
could be a subject for extended international collaboration, if so wished by the Japanese
Government, led by the IAEA. It noted that given the circumstances on the site, it may require
modification as new or unexpected circumstances are revealed.

The roadmap could usefully be seen as a vital component of a wider plan that could result in
remediation of the areas off the site affected by the radioactive releases to allow people
evacuated to resume their normal lives. This would be a useful demonstration to the world ofwhat can be achieved in responding to such extreme nuclear events.

3.4.2 External Hazards
There is much to be learned in the area of earthquake preparedness and hazard assessment for
NPPs in Japan. It is therefore concluded that
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Conclusion 12: The Safety Review Services available with IAEA-ISSC would be
useful in assisting Japan’s development in the following areas:External event hazard assessment



Walkdowns for plants that will start up following a shutdown; andPre-earthquake preparedness.

3.4.3 Off-site Emergency Response
There is potentially much to learn from the Japanese experience of operating effective
emergency responses on and off nuclear sites in extreme circumstances. It is worthy of a moredetailed study than was possible in this short Mission. It is therefore concluded that:Conclusion 13: A follow-up mission including EPREV should look in detail at
lessons to be learned from the emergency response on and off the site.

3.4.4 Organization of Large Scale Radiation Protection for Severe Accident Conditions
As noted above, despite the severity of the accident, to date the organization for large scale
radiation protection on and off the site appears to have been very effective. There may be
several lessons for other nations in developing their arrangements in this area and therefore it
is concluded that:Conclusion 14: A follow-up mission should be conducted to seek lessons from theeffective approach used to provide large scale radiation protection in response to
the Fukushima accident.

3.4.5 Follow-up IRRS Mission
The main objective of the Mission was to collect facts and to perform a preliminary
assessment of the Fukushima accident for worldwide learning. Most of the investigations
were therefore directed towards technical issues related to nuclear safety and radiation
protection of the population and the environment. However, the investigations performed by
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the Mission allowed it to perceive more general issues related to the framework for safety inJapan, to the clarity of the allocation of responsibilities and to the independence of theregulator. The different contacts of the team with the key players in the management of theaccident gave the impression of some lack of consideration for the system and mutual
recognition of its participants. Some presentations suggested, for example, that the
government has the direct responsibility for safety, while the IAEA Fundamental Safety
Principle 1 specifies that this responsibility rests with the utility. Nevertheless, fromdiscussions it is apparent that the site directors at Dai-ichi and Dai-ni recognized their prime
responsibilities and acted accordingly.

On the other hand, the local managers of the plants needed to concentrate on effective on-site
response rather than serving the needs of wider stakeholders. More generally, it also seems
that interactions between NISA and TEPCO could benefit from the development of technicaldepth rather than formal regulatory relations. This may need an enhancement of NISA‘stechnical capability.

The respective roles of the Nuclear Safety Commission (NSC) and NISA are formallydefined; however, some clarification seems necessary in their actual fields of intervention andrespective contributions. Finally, the independence of NISA does not appear clearly in theorganization put in place to manage the Fukushima accident. The two last points were alreadyhighlighted as a result of the IRRS Mission performed in Japan in 2007. Additionally, carehas to be exercised in the response to nuclear accidents that the operating organization‘sprime responsibilities for nuclear safety on sites are not transferred to the regulator orgovernment.

Lesson 16: Nuclear regulatory systems should ensure that regulatory independence
and clarity of roles are preserved in all circumstances in line with IAEA Safety
Standards.

IAEA Fundamental Safety Principles 1 and 2 form the basis for effective general nuclear
arrangements in a country. Their application provides for the establishment of three distinct
roles for the utility, the regulator and government. In summary, the utility has prime

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responsibility for safety and as such has to ensure that it takes appropriate decisions andactions. The regulator oversees the activities of the utility and ensures that it meets its legal
obligations through assessment, inspection and enforcement (which can include advice) but indoing so it should not take decisions that make it effectively responsible for safety. Similarly,
the government‘s role is to ensure that there are appropriate laws and regulations in place, thatthe regulator has the means (resources, technical capabilities, powers, etc.) to provide
effective oversight of the utility, and that the regulator is effectively independent of thelicensee and of any other body, so that it is free from any undue pressure from interested
parties. These roles and responsibilities should not be confused, even in emergency situations.
However, in such circumstances close cooperation is required to ensure that optimum
protection of the public is ensured and that relevant information is available. This is especially
important in severe accidents when off-site countermeasures may be required over extensive
areas and need to be enacted through various agencies or departments.

The implementation of a follow-up IRRS Mission would be a good occasion to assess thecurrent situation and its evolution since 2007. Such a mission could provide a useful andindependent input to the Japanese Government as a complement to the conclusion of the
independent Investigation Committee, set up by the Japanese Government to assess the
management of the Fukushima accident.

Conclusion 15: A follow-up mission to the 2007 IRRS should be conducted inlight of the lessons to be learned from the Fukushima accident and the above
conclusions to assist in any further development of the Japanese nuclear
regulatory system.

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4.

ACKNOWLEDGEMENTS

In conducting this Mission we have been greatly humbled by the fortitude, stoicism andnature of the Japanese people in responding to their terrible loss from the effects of theearthquake and associated tsunami. Our sympathy goes out to them in their suffering.

Throughout the Mission, the IAEA team received excellent cooperation from all the Japanesecounterparts and organizations involved. Questions asked by the IAEA team were fully
answered with expert explanations. Where required, additional documentation was provided.
The Mission benefited greatly from the visits to the three sites which were greatly facilitatedby staff on-site and off-site who put aside time and effort despite the extreme pressures they
had had and were under in responding to the accident.

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APPENDICES

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Appendix 1

IAEA International Fact Finding Expert Mission of
the Fukushima Dai-ichi NPP Accident Following theGreat East Japan Earthquake and Tsunami
Japan

FINDING SHEETS

External Hazards

IAEA 2011

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FINDINGS SHEET
Finding Number:

1. FINDING IDENTIFICATION
Assessment Area:

A1 - EXTERNAL EVENT OF NATURAL ORIGIN

Facility:

FUKUSHIMA DAI-ICHI NPPUnit:

UNITS 1 TO 6

Finding Title:

EARTHQUAKE HAZARDS

A1-01

2. FINDINGS
2.1 - FINDING DESCRIPTION: BACKGROUND
The site of a nuclear installation shall be adequately investigated with regard to all
characteristics that could be significant to safety and possible external natural and humaninduced hazardous phenomena.
In this context, earthquakes pose a significant hazard to nuclear installation and they are oneof the most important natural events to be adequately investigated and evaluated. In thatregard, ―…the seismological and geological conditions in the region and the engineering
geological aspects and geotechnical aspects of the proposed site area shall be evaluated.‖ Site
Evaluation for Nuclear Installations, NS-R-3, 2003, paragraph 3.1. states the following key
requirements:
―Information on prehistorical, historical and instrumentally recorded earthquakes in
the region shall be collected and documented‖;―The hazards associated with earthquakes shall be determined by means ofseismotectonic evaluation of the region with the use to the greatest possible extent of
the information collected.‖ (Ref. [1], para. 3.3.);

―Hazards due to earthquake induced ground motion shall be assessed for the site withaccount taken of the seismotectonic characteristics of the region and specific site
conditions. A thorough uncertainty analysis shall be performed as part of theevaluation of seismic hazards.‖(Ref. [1], para. 3.4.);

―The potential for surface faulting (i.e. the fault capability) shall be assessed for thesite. . . .‖(Ref. [1], para. 3.5.)

The above mentioned IAEA Safety Requirements are supported by the detailed
recommendations provided in the newly revised Safety Guide SSG—9 in which
methodologies and criteria for assessing the seismic hazards and, particularly, the seismic
ground motions and the potential for fault capability are provided.
The general approach to seismic hazard evaluation should be directed towards reducing theuncertainties at various stages of the evaluation process in order to obtain reliable results
driven by data. Experience shows that the most effective way of achieving this is to collect a
sufficient amount of reliable and relevant data. There is generally a trade-off between thetime and effort necessary to compile a detailed, reliable and relevant database and thedegree of uncertainty that the analyst should take into consideration at each step of the
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process. All „pre-instrumental‟ data on historical earthquakes (that is, events for which no
instrumental recording was possible) should be collected, extending as far back in time as
possible. Palaeoseismic and archaeological information on historical and prehistoricalearthquakes should also be taken into account.
Consequently, after detailed hazard characterization is done, the plant shall be designed towithstand the seismic events according to specific design bases determined as result of thishazard assessment, as indicated in IAEA Safety Requirements-Safety of Nuclear Power
Plants: Design, NS-R-1, 2000 Paragraphs 5.16 and 5.17. Moreover, paragraph 5.22 statesthat ―… The seismic design of the plant shall provide for a sufficient safety margin to protect
against seismic events‖.
To comply with such design requirements the IAEA Safety Guide on ―Seismic Design andQualification for Nuclear Power Plants‖, NS-G-1.6, 2003, provide detailed recommendations
for design of systems, structures and components according to their safety significance andfollowing the recognized international engineering practice and consensus at the time.
Finally, the evaluation of the seismic safety of existing power plants should be conducted as
required by:(a) Evidence of a seismic hazard at the site that is greater than the design basis
earthquake arising from new or additional data (e.g. newly discovered seismogenic
structures, newly installed seismological networks or new palaeoseismologicalevidence), new methods of seismic hazard assessment, and/or the occurrence ofactual earthquakes that affect the installation;(b)

Regulatory requirements, such as the requirement for periodic safety reviews, thattake into account the ‗state of knowledge‘ and the actual condition of theinstallation;(c)

Inadequate seismic design, generally due to the vintage of the facility;(d)

New technical findings, such as vulnerability of selected structures, systems orcomponents;(e)

New experience from the occurrence of actual earthquakes;(f)

The need to address the issue of performance of the installation for beyond designbasis earthquake ground motions in order to provide confidence that there is no‗cliff edge effect’; i.e. if an earthquake were to occur that were slightly greaterthan the design basis earthquake, to demonstrate that no significant failures would
occur in the installation;

2.2. – FINDINGS AT FUKUSHIMA-DAI-ICHI NPPGeneral framework on applicable regulatory requirements and guidelines in Japan- At the time of the construction permit (from 1966 to 1972 for units 1 to 6) of Fukushima
Dai-ichi NPP, the applicable and related regulatory requirements were those indicated in
the Regulatory Guide for Review Nuclear Reactor Site Evaluation and Application
Criteria, issued by the Nuclear safety Commission (NSC) in 1964 and revised in 1990,
and in the Regulatory Guide for Reviewing Nuclear Reactor Safety Design, issued by
NSC in 1970 and revised in 1977, 1981, 1990 and 2001 which provide general
requirements on the need that safety related structures, systems and components (SSCs)
shall be classified/categorized for seismic design on the basis of importance of their safety
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-

-

-

-

functions and the effects of earthquake caused losses of functions should not be affectedby this natural hazards.
Professional associations in Japan issued detailed guidelines for seismic design as theJapan Electric Association, Technical Guidelines for Seismic Design of Nuclear Power
Plants, JEAG 4601-1970, JEA, (1970) and JEAG 4601-1987, JEA, (1987).
In 2006 NSC issued the new Regulatory Guidelines titled ‗Regulatory Guide for
Reviewing Seismic Design of NPP Facilities‘ which provides guidance for adequacy ofthe seismic design for nuclear power plants.
Accordingly, NISA requested that all NPPs should undergo a back check on the basis of
the new 2006 NSC guidelines which include the need to re-evaluate the seismic hazards at
the NPP sites to obtain the new so called ―Design Basis Earthquake Ground Motion‖,
DBGM Ss and to execute the required upgrades. The experience gained from theKashiwazaki-Kariwa case was also part of this process. It should also pointed out herethat the NSC guidelines require to perform a residual risk evaluation to take account of thepossibility of occurrence of an earthquake ground motion that may exceed the DBGM Ss.
As indicated in Finding Sheet on Tsunami Safety, in the meeting with NSC authorities, it
was indicated that the NSC guidelines are not legally binding and they are not―regulations‖ although in the practice they are considered as such. It was also expressedthat these guidelines will be revised in view of recent experiences and lessons learned.

The Great East Japan Earthquake of 11 March 2011
- The Magnitude Mw 9.0 earthquake occurred at 14:46 on 11 March 2011, off the Pacificcoast of the Tohoku region in the subduction zone. The hypocentre was located at 24 km
depth and the epicentre at a distance of about 180 km from Fukushima Dai-ichi NPP site
and 130 km from Onagawa NPP site. Its duration was very long, about 140-160 sec, and2-3 significant pulses are present in the observed records. The following graph shows theobserved records in a number of locations in the coastal zone of east Japan.

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- The JMA Japan seismic intensity, showing the damage produced by the earthquake, attowns near the Fukushima Dai-ichi and Dai-ni sites was 6+ (maximum value of the JMA
scale is 7).
- In Appendix XX of this report see detailed maps and graphs describing the seismic event.
- Regarding the observations of the ground motions at the NPP sites the following
information on the maximum response accelerations at the level of the foundation basemats of the six (6) units at Dai-ichi and the four (4) units at Dai-ni was received during themeetings including comparisons with the original earthquake design basis (i.e. S1 and S2level) and the back check DBGM Ss values. Basically, the following 3 sets of values were
provided:
At Fukushima Dai-ichi NPP:
1.
Maximum acceleration values (gal) at base mat level observed during the 11 March2011 Earthquake, first 3 columns for NS and EW horizontal and UD verticalcomponents, in red.
2.

Maximum response acceleration values (Gals) corresponding to the original design basis:
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

The original design basis, defined according to the criteria valid before theestablishment of the NSC Regulatory Guidelines:
180 Gals as direct input to the basemat of the Reactor Building.
270 Gals for confirming function maintenance.

The Standard Seismic Ground Motion S1 and S2, as defined after theestablishment of the NSC Regulatory Guidelines:
S1= 180 Gals
S2= 270 Gals and 370 Gals
, which were defined at the free surface of the base stratum, located at O.P.-196m
Static Seismic Acceleration
According to the Japanese Building Standard, the static shear force on the base mat
is calculated as follows:
Building Standards: 0.2G * Coefficient * weight =195.8Gal * Coefficient * weightWith the ―Coefficient‖ corresponding to the ―Structural Characteristic
Coefficient‖. In the case of F1, the structural characteristic coefficient is 0.8.
Therefore, for the Reactor Building:
195.8Gal * Coefficient * 3 * weight = 195.8Gal * 0.8 * 3= 470 Gals
3. Maximum response acceleration values (Gals) corresponding to the newly estimated
Design Basis Ground Motion (DBGM) according to the September 2006 NSC―Regulatory Guide for Reviewing Seismic Design of Nuclear Power Reactor
Facilities‖, or back check requirements, noted as Ss at the free surface of the basestratum, which should be the envelope of three different types of seismic sources:
Ss1= 450 gals for inland crustal and interplate earthquakes
Ss2= 600 gals for oceanic deep intraplate earthquakes
Ss3= 450 gals for diffuse seismicity

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The estimated values at base mat levels for the six units are indicated in columns 4-6
following table.

During the Mission, no comparison was made between the observed spectra with the design ones
since they were not made available to the Review Team. Regarding the peak accelerations at thefoundation base mat level, the recorded maximum response accelerations exceeded the originallydesign value for S2 earthquake from 1.13 to 2.2 times, with exception of Unit 6 that shows noexceedance.
Regarding the values adopted for the back check evaluation, it was not clear to the Review Team
whether this comparison with observed values is valid since no detailed information was provided
regarding the physical upgrades effectively executed. The information provided indicated that
only some upgrading on piping supports was performed.
At Fukushima Dai-ni NPP:
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At Tokai Dai-ni NPP:
During the meetings at Tokai Dai-ni NPP it was asked that although the back check has been
completed regarding the seismic hazard assessment of the DBGM and some upgrades were
performed, which is the seismic margin against the original design basis. It was answered that the‗plant is strong enough‘ and no detailed information was provided. Also, it was indicated that no
crack monitoring programme is in place to determine whether or not the earthquake produce a
new cracking in concrete structures.

3 – CONCLUSIONS

01/06/2011

1. Although it appears that the Great East Japan earthquake exceeded the licensing based
design basis ground motion of the 1F plant at the level of the foundation base mat in allunits, according to the information provided by TEPCO and NISA, the operating plants
were automatically shutdown and all plants behaved in a safe manner, during and
immediately after the earthquake. It was also confirmed that in some cases the observed
values even exceeded the recently determined maximum response acceleration values
showing apparently an underestimation of the new DBGM Ss.
2. It was also reported that the three fundamental safety functions of (a) reactivity control, (b)removal of heat from the core and (c) confinement of radioactive materials were available
until the tsunami reached the sites.
3. Based on the reports from Japanese experts and plant personnel, safety related structures,
systems and components of the plant seemed to have behaved well for such a strong
extreme earthquake, possibly due to conservatisms introduced at different stages of thedesign process.
4. The underestimation of the hazard in the original hazard study as well as in more recent
re-evaluations mainly result from the use of recent historical seismological data in the
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estimation of the maximum magnitudes especially associated with the neighbouringsubduction zone east of the sites.

4–LESSONS LEARNED---

01/06/2011

Although not applicable to the 1F case considering the present and future status, for thecases of 2F and Tokai Dai-ni the re-evaluation of the seismic hazard at the site should beagain conducted to take due account of new data and lessons learned from the Great East
Japan earthquake for characterizing the seismogenic sources and perform the necessary
safety upgrading in expedited manner. This will also contribute to assess the risk during
the short and intermediate period at units with prolonged shutdown when safety measures
should be taken for the potential occurrence of future events. Detailed inspection andwalkdown programmes should be conducted.
It should be recognized worldwide the need to consider potential maximum seismic events
greater than those observed or recorded in historical time. Although the need to consider
prehistorical and historical data is well established in the international safety requirements
for assessing the natural hazards at nuclear installations, this has not been followed
especially in older nuclear power plants. The current IAEA safety standards establish aclear time scale (going back to historical and prehistorical eras) as well as tectonic
capacity considerations in the estimation of maximum magnitudes associated withseismogenic structures. There is a need for Member States regulations to reflect these
considerations both for the new build as well as for re-evaluation of existing NPPs.
Japan has undergone a seismic hazard re-evaluation (back check) recently on the basis ofrecent investigations and data. However, it was confirmed that these assessments were
exceeded by the March 2011 event. This experience shows the importance of a permanent
oversight of the potential hazards and of performing all required actions for taking
necessary measures for maintaining and increasing the safety level.

-

An appropriately conservative approach to seismic hazard analysis, such as recommended
in the IAEA Safety Guide SSG-9, would significantly decrease the need for a constantreview and revision of seismic design bases at NPP sites.

-

The Fukushima experience has also shown that there is a need to have in place a consistentand comprehensive pre-earthquake planning and post-earthquake response actions
programme for all NPPs worldwide.

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FINDINGS SHEET
1. EXTERNAL EVENT OF NATURAL ORIGIN

Finding Number:

Facility:

FUKUSHIMA DAI-ICHI NPP

Unit:

UNIT 1 - 6

Assessment Area:

EXTERNAL EVENTS OF NATURAL ORIGIN

Finding Title:

TSUNAMI HAZARDS

A1-02

2. FINDINGS
2.1 - FINDING DESCRIPTION: BACKGROUND
Tsunami waves and associated phenomena may produce severe damage to installations locatedin coastal areas. Current IAEA safety standards require that, the potential for tsunamis that canaffect nuclear power plant safety and the determination of its characteristics shall be assessed,
taking into consideration pre-historical and historical data and all types of associated hazards,
with account taken of any amplification due to the coastal configuration at the site. (IAEA
Safety Requirements-Site Evaluation for Nuclear Installations, NS-R-3, 2003, paragraphs 3.24 to
3.28.)
Consequently, if such potential exists and detailed hazard characterization is done, the plant shallbe designed to withstand the event according to specific design bases determined as result of thistsunami hazard assessment, as indicated in IAEA Safety Requirements-Safety of Nuclear Power
Plants: Design, NS-R-1, 2000 Paragraphs 5.16 and 5.17.
To comply with such requirements the IAEA Safety Guides on ―Flood Hazard for Nuclear
Power Plants on Coastal and River Sites, NS-G-3.5, 2003, and on ―External Events Excluding
Earthquakes in the Design of Nuclear Power Plants‖, NS-G-1.5, 2003, provide detailed
recommendations according to the recognized Member State practice and consensus at the time.
In NS-G-3.5 the need to characterize. run-up, drawn-down and associated phenomena (i.e.
hydrodynamic forces, debris, sedimentation, etc.) is clearly recommended (Paragraphs 11.21 and11.22),
Particularly, in relation to flood events, it is recommended that all items important to safety
should be constructed above the level of the design basis flood with account taken of wind wave
effects and effects of the potential accumulation of debris. This is the so-called ―dry site‖
concept which is preferred in many Member States to the alternative solution of permanent
external barriers such as levees, sea walls and bulkheads, which require periodic inspections,maintenance, monitoring as features important to safety. In both cases, redundant andconservative measures should be taken owing to the intrinsic ―cliff edge‖ characteristics in theovertopping of the protection, such as ensuring the waterproofing and a proper design of items
necessary to provide the capability to shut down the reactor and maintain it in safe shutdown
conditions (paragraphs 13.5 and 13.6 of NS-G-3.5).
Recently, a revision of the Safety Guide NS-G-3.5 was developed to consider new data,
information and lessons learned mainly from the 2004 Indian Ocean tsunami and the draft of thisguide, numbered DS417 has been approved by the IAEA Safety Committees (including theCommission of Safety Standards) and it is ready for publication. This new version maintains theconcepts and recommendations mentioned above and provides more detailed recommendations
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related to the protection of NPPs against the effects of tsunamis. As an Annex to this safety
guide draft –which is not considered as part of the standard- a reference to current practice inMember States is included and Japan and USA are the countries providing such examples.
In addition to the effects produced by variation of water levels (maximum and minimum) the
hazardous effects of tsunami waves are also strong currents in harbours and bays, bores in rivers,
estuaries and lagoons, and huge hydrodynamic forces. Sedimentation phenomena, including
deposition and erosion, may also be generated owing to large forces at the sea floor.
The following parameters should be defined, as illustrated in the diagram. They are included
here for a common understanding of the terminology used in this report:Run up:elevation reached by the tsunami wave at the inundation limit or inundation line
Water level at shoreline
Maximum water level
Inundation area (or horizontal flooding area)

2.2. – FINDINGS AT FUKUSHIMA-DAI-ICHI NPP:
Before 11 March 2011
- The tsunami hazard at Fukushima Dai-ichi NPP site was initially estimated at the time of theconstruction permit (from 1966 to 1972 for units 1 to 6) based on the data and observations
from the tsunami generated by the Magnitude 9.4 Chile Earthquake in 1960. The design
maximum height was defined at +3.122 m over mean sea level (msl) as the observed tidelevels at Onahama port, in Fukushima prefecture, located 50 km South of the site. As
reported in the working group meeting (by NISA) this value still represents the official
licensing design basis for flooding generated by tsunamis. The site level for locating the
SSCs (structures, systems and components) at the water intake area was selected as +4.00 m
while the plant grade level (i.e. elevation of the reactor building) for Units 1-4 wasestablished at +10.00 m and for Units 5-6 at +13.00 m.
- At that time, the applicable and related regulatory requirements were those indicated in the
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-

-

-

-

-

-

Regulatory Guide for Review of Nuclear Reactor Site Evaluation and Application Criteria,
issued by NSC in 1964 and revised in 1990, and in the Regulatory Guide for Reviewing
Nuclear Reactor Safety Design, issued by NSC in 1970 and revised in 1977 and 1990 which
provide very general requirements on the need that safety functions should not be affected bythis natural hazard.
It was indicated by TEPCO that the numerical simulation of tsunamis based on a tectonic
mechanism was carried out only after the mid-1970s. This simulation involved ―earthquakes
which occurred at the bottom of the ocean to cause uplift and subsidence of the sea bed,
subsequently leading to generation of tsunamis. Previously, in the 1960s, i.e. at the time of
the application for the construction permit Fukushima Dai-ichi NPP, it was common practiceto adopt historical tsunami records as design basis tsunami height and in according to suchpractice the value of +3.122 was adopted for licensing purposes.
Later, using the new methodology proposed in 2002 by a professional institution, the Japan
Society of Civil Engineers (JSCE), ―Tsunami Assessment Method for Nuclear Power Plants
in Japan‖, the tsunami hazard water levels (maximum and minimum) were re-evaluatedbased on the data and observations from the Magnitude 7.9 Offshore Shioyazaki Earthquake
in 1938, which resulted in a maximum high water level of +5.7 m. Minimum water level of 3.60 m was calculated on the basis of the 1960 Chile M=9.4 earthquake. It was estimatedthat the run up at the water intake area would not be high enough to reach the plant grade at+10.00/+13.00 m. The JSCE methodology is based on a deterministic approach and theuncertainties in the tsunamigenic data is counted through a process of parameter variation
studies. In this computation TEPCO used a magnitude of 8.0 for the Shioyakazi source.
These values, as presented by TEPCO, were not reviewed or validated by NISA as indicatedin the meetings. The fact that the tsunami estimate increased by a factor of almost two andthe main tsunamigenic source shifted from distant (Chile) to near (Shioyazaki) source would
have required the attention of NISA. As these assessment and countermeasures were
undertaken by TEPCO voluntarily without any instruction from NISA, they were not
pertinent to changes in the licensing documents and thus the officially recognized designbases.
Other important consideration is the run up values. The estimate corresponds to the tsunami
height at what can be called the ―intake point‖, i.e. in the graph above can be assumed as atthe ―shoreline‖ point in the entrance to intake structures level. The run up i.e. the waterheight reached at the maximum inundation point was not indicated in any presentation fromTEPCO. When asked, it was said that it was calculated but did not increase significantly the+5.7 m and it did not reach the main grade level of +10 m. It seems also that the calculationof the run up have not considered the specific and detailed arrangements of plant layout.
The IAEA safety guide, the current one NS-G-3.5 as well as the new draft, indicate the needto consider all associated phenomena as hydrodynamic forces, debris and sand deposition,etc. According to the calculation following the JSCE methodology only the maximum andminimum water levels near the intake structures were calculated. The hydrodynamic forces
due to the tsunami were not considered because the methods for these were still evolving.
The combination of the maximum/minimum water tsunami level with the tide of +1.0 m
which led to the +5.7 m seems insufficient also for considering credible scenarios with otheroceanographic and meteorological phenomena (such as storm surge, wind waves) plus
consideration of aleatory and epistemic uncertainties as well as the consideration of a safetymargin. To add +1.0 m to the calculated tsunami value seems too low.
In 2006 NSC issued the new Regulatory guidelines titled ‗Regulatory Guide for Reviewing
Seismic Design of NPP Facilities‘ which addresses tsunami safety in Chapter 8 as anaccompanying event of the earthquake stating that ―... safety functions shall not besignificantly affected by the tsunami which could be postulated appropriately to attack but
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very scarcely in the operational period of facilities‘. No detailed or specific requirements or
guidance is available, as reported. Regarding combination with other flooding hazards, it was
indicated that in practice only the high tide is added to the calculated tsunami water levels.
- NISA requested that all NPPs should undergo a back check on basis of the new 2006
guidelines which include the need to re-evaluate the tsunami hazards. TEPCO reported that
although studies have started results are not currently available.
- In the meeting with NSC authorities, it was clarified that the NSC guidelines are not legallybinding and they are not ―regulations‖ although in practice they are considered as such. It
was also expressed that these guidelines will be revised in view of recent experience andlessons learned.
- Regarding the 2002 JSCE Guidelines it should be highlighted that this standard provides
methods for calculating tsunami height but does not include associated effects such ashydrodynamic loads, or missiles from transported debris. The values calculated by TEPCO
were based on only recent historical data.
- Considering the fact that safety related items for removing the reactor decay heat (link to theultimate heat sink) and for cooling the diesel generators for emergency power supply arelocated at +4.00 m, i.e. +1.70 m below the recently estimated inundation level, it was
indicated by TEPCO that the motors of the safety related pumps (RHR system) wereaccordingly elevated to avoid function disruption. However, no additional details were
provided about the sufficiency of these measures to cope with such an event for theprotection of all related mechanical, electrical and I&C components of the RHR System.
After 11 March 2011 Tsunami- The Magnitude Mw 9.0 earthquake that occurred at 14:46 on 11 March 2011 triggered atsunami that reached the site at about 15:30, i.e. ~44 minutes later with run-up heights ofabout 14-15 m, well above the plant main grade. This produced flooding, destruction anddisruption of safety functions in the form of inundation, hydrodynamic forces, impact ofdragged debris, deposition of sand and silt, debris, etc. The observed record at IWATE
Nanbu Oki Tidal Gauge in open sea can be seen in the following graphs.

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-

-

In Appendix XX of this report see pictures and maps showing the areas devastated by theearthquake.
Because of damage to SSCs (mainly mechanical and electrical items) located at the water
intake area, the safety functions of removal of decay heat and emergency power supply wereseverely affected as described in other sections of this report. It should be noted that due tothe earthquake, off-site power at the plant was not available at the time of the tsunami.
The methodology of the JSCE applied by TEPCO does not provide with guidance for
estimating the hydrodynamic forces and impact of large debris. This resulted in theunderestimation of tsunami effects from a system point of view with a thorough andcomprehensive assessment of all effects of water impacting and leaking to buildings,
structures and components, affecting safety related items. It should also be noted that there is
no reference to influence of simultaneous tectonic subsidence which can influence the wave
heights.

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– CONCLUSIONS

01/06/2011

1. After the issuance of the Construction Permit about forty years ago, the Regulatory
Authority did not provide any requirements or guidance regarding tsunami safety. The
guidance provided in 2006 as part of the Seismic Safety Guidelines, does not contain any
concrete criteria or methodology that could be used in re-evaluation. The only re-evaluation
was performed in 2002 by TEPCO on a voluntary basis. Even this work was not reviewed
by NISA. Therefore an effective regulatory framework was not available to provide for thetsunami safety of the NPPs through their operating life.
2. Although tsunami hazards were considered both in the site evaluation and the design of the
Fukushima Dai-ichi NPP as described during the meetings and the expected tsunami height
was later increased (without changing the licensing documents) after 2002, the tsunami
hazard was underestimated.
3. Furthermore, considering that it was not possible to provide for a ‗dry site‘ condition forthese operating NPPs, the additional protective measures taken as result of the evaluation
conducted after 2002 were not sufficient to cope with the unexpectedly higher tsunami run
up values and all associated hazardous phenomena (hydrodynamic forces and debris
impact). Moreover, the re-evaluation of the hazard after 2002 and the adequacy of theprotective actions taken were not reviewed by the Regulatory Authority. Because failures of
SSCs when subjected to floods are generally not incremental, the plants were not able towithstand the consequences of tsunami heights greater than those expected (cliff edge
effect).
4. Apparently, the tsunami warning and notification system, was not available to provide
appropriate and timely response for plant reaction to the event. Japan, and JNES inparticular, has developed the TIPEEZ System which was given to IAEA through EBPTsunami for distributing to member states. This system was not used at 1F plant and theoperators were not aware of the approaching tsunami waves.
5. It is recognized worldwide that Japan has a high level of expertise and also experience
regarding tsunami hazard and provides leadership in this topic worldwide. This is reflectedin the major influence that Japanese academic, scientific and technical institutions have on
the international research and development of this topic. In this regard, the IAEA recognizes
the valuable support received from JNES on tsunami safety for nuclear power plants which
is transferred to Member States through the ISSC. It seems that organizational issues have
prevented this expertise to be applied to practical cases at the three NPPs visited during thisMission.
4–LESSONS LEARNED

01/06/2011

 There is need to incorporate large safety factors to estimate tsunami run up for NPP sites forthe following reasons: (i) large aleatory and epistemic uncertainties in parameters involvedin tsunami hazard particularly the characterization of the tsunamigenic sources, (ii)significant variations in inundation levels at different parts of the site considering thespecific and detailed plant layout and plant sector elevations, (iii) difficulties inincorporating effective tsunami protection measures for operating plants after an increase intsunami height estimation, (iv) intolerance of NPP SSCs to increased flood levels, i.e. toflood related cliff edge effects.
 There is also need to use a systemic approach for dealing with the design and layout of the
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plant SSCs for an effective protection against tsunami hazards. Leak tightness and water
resistance should be assured through a comprehensive evaluation of all potential water
ways. However, this measure can only be used as a redundancy (i.e. in conjunction with adry site or an effective site protection measure).
 For well-defined tsunamigenic (fault controlled) sources, a large earthquake will always
precede the tsunami. If the source is near the site, the vibratory ground motion will provide a
warning. For all tsunamis that may occur at the site, notification from the national tsunami
warning system should be transmitted to the control room for immediate operator actions. A
clear procedure should be followed by plant management in preparing for a possible tsunami
until the warning is lifted.
An updating of regulatory requirements and guidelines should be performed reflecting theexperience and data obtained during the Great East Japan Tsunami, using also the criteria
and methods established in the IAEA related safety standards for comprehensively copingwith tsunamis and in general all correlated external events. The national regulatory
documents need to include data base requirements compatible with those required by IAEA
Safety Standards. The methods for hazard estimation and the protection of the plant need tobe compatible with the advances in research and development in this field. Regulatory
Authorities need to recognize the importance of these advances and need to keep theirregulations in line with IAEA Safety Standards which are updated regularly taking into
account of scientific advances and recent occurred events.
Finally, the potential for scenarios involving flooding hazards and multiple units (andpossible multiple sites) needs to be fully and comprehensively investigated for new andexisting nuclear power plants worldwide and if they cannot be screened out provisions forplant layout, site protection measures, design, accident management and emergency
preparedness and response should be taken in order to adequately protect the installation
against these disasters.

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FINDINGS SHEET
Finding Number:

1. FINDING IDENTIFICATION

A1-03

Assessment Area:

A1 - EXTERNAL EVENTS OF NATURAL ORIGIN

Facility:

FUKUSHIMA DAI-ICHIUnit:

UNITS 1 TO 6
CROSS CUTTING – PROTECTION OF NPPs AGAINSTEXTERNAL HAZARDS DURING EMERGENCY
CONDITIONS AND EXTENDED SHUTDOWN

Finding Title:

2. FINDINGS
2.1 - FINDING DESCRIPTION: BACKGROUND
The present situation at the 1F as well as the neighbouring NPP sites is unique in terms ofplant state, physical plant condition and the hazard environment. The IAEA Safety
Standard NS-R-1 provides the following requirement:
I.18. For the post-event recovery period (of days or longer), additional events mayneed to be taken into account, depending upon the length of the recovery period andthe expected probabilities of the events. For the recovery period, it may be realistic
to assume that the severity of an event that has to be taken in a combination is not as
great as would need to be assumed for the same kind of event considered over a time
period corresponding to the lifetime of the plant. For example, in the recovery
period for a loss of coolant accident, if a random combination with an earthquake
needs to be considered, the severity could be taken as less than the severity of thedesign basis earthquake for the plant.
This paragraph considers the duration of the recovery period but does not explicitly address thedegraded plant state which may actually require considerations of external hazards with lower
frequencies of exceedance compared with those applicable for undamaged plants. For example, anuclear power plant may be well designed against extreme meteorological conditions such as
hurricanes or typhoons but in a degraded state there may be weaknesses and vulnerabilities to
identify and remedy for events even lower than the original design basis.

2.2. – FINDINGS AT FUKUSHIMA-DAI-ICHI NPP:

For all three NPPs under consideration plant conditions have radically changed with respect to anormally operating installation. This is because, (i) the plant states are different from an
operating plant, (ii) physical conditions of the SSCs are radically different, (iii) there issignificant uncertainty regarding plant parameters and physical conditions of the SSCs.
Therefore the three plants are in a much more vulnerable situation than undamaged plants
regarding external hazards.

With the occurrence of a very large earthquake such as the Great East Japan Earthquake of 11
March 2011, the exposure of the three plants to some external hazards will have changed. First,
all the sites will be experiencing aftershocks of varying magnitudes for some more months (upto a year) to come. Some of these aftershocks may be quite strong and one or two may be large
enough to produce tsunamis. While not a proven fact, there may be increased volcanic activity in

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the region. Finally, the deteriorated state of the plants would make them more vulnerable tomore frequently occurring external hazards in general affecting the recovery actions. Therefore,
external events such as typhoons and extreme weather may be of concern to the three plants.
Tokai Dai-ni is the least affected plant of the three and possibly with the best prospects for a
restart. It is outside of the exclusion zone. The plant is in cold shutdown state.

In Fukushima Dai-ni there are four reactor units with start of operation from 1981 to 1986. The
condition of these units after the earthquake and the tsunami show some variations although in
general they have similar physical conditions. The plant (i.e. all the reactor units) is in cold
shutdown state.

In Fukushima Dai-ichi, there are six reactor units with start of operation from 1970 to 1979. The
state of the plant is further complicated with the more extensive flood damage as well as thedamage incurred by three explosions in reactor units 1, 3 and 4. The residual heat removal
process in three units is still on-going. The spent fuel pools are also being cooled by water
injection from outside. Therefore the vulnerability of Fukushima Dai-ichi to short term external
hazards is much more critical than the other two plants.

3 –CONCLUSIONS

01/06/2011

1.

For the Tokai Dai-ni and Fukushima Dai-ni NPPs, in the short term, it is important to evaluate thesafety of the plant for the changed plant conditions and the changed hazard environment. In
particular, if an external event PSA model is already available for the cold shutdown state, thiswould be an effective tool in performing the assessment.

2.

The short term (immediate) measures at Fukushima Dai-ichi need to be planned during the period
before a stable cold shutdown of all the units are attained. Until that time the high priority
measures to protect the plant against external hazards need to be identified using simple methods
in order to have a timely action plan. As preventive measures will be important but limited, bothon-site and off-site mitigation measures need to be included in this plan.

3.

Once a stable cold shutdown state is achieved a long term plan needs to be prepared that should
include the identification of SSCs needed for this state (a shutdown PSA would be helpful in thisregard) and upgrades to these SSCs to ensure their safety function, as well as on-site and off-site
emergency measures.

4.

Any plans for the future outside of decommissioning or removal of all fuel from the site (for thereactor units that experienced severe core damage), need to take extreme external hazards into
consideration for the long term.

4 – LESSONS LEARNED

01/06/2011

After a major disaster which may cause severe disruption to the plant the changed plantstate and physical conditions of the SSCs need to be taken into consideration. Thechanged plant state (degraded systems and degraded physical conditions of the SSCs)
may have lost design robustness and may have degraded defence-in-depth.

The safety profile of the plant needs to be well understood (e.g. the required SSCs) for
different plant states (e.g. shutdown) in order to provide for a consistent protection and aplan for upgrades.

A major natural disaster may temporarily alter the hazard environment. In order toprovide for an uninterrupted recovery process, there is a need for understanding the plant
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vulnerabilities and the new hazard environment and providing protection for the plant andthe recovery action accordingly in a timely manner.

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FINDINGS SHEET
Finding Number:

1. FINDING IDENTIFICATION

A1-04

Assessment Area:

A1 - EXTERNAL EVENTS OF NATURAL ORIGIN

Facility:

FUKUSHIMA DAI-ICHIUnit:

UNITS 1 TO 6

Finding Title:

CROSS CUTTING – LESSONS LEARNED FROM KASHIWAZAKIKARIWA NPP EXPERIENCE

2. FINDINGS
2.1 - FINDING DESCRIPTION: BACKGROUND-

The use of feedback from experience is a common element to all subjects in nuclear
safety. All IAEA safety standards related to the protection of nuclear installations against
external hazards consider lessons learned from recent events in their periodic review
process. This has been the case for the two major events in the last decade, i.e. the 2004
Indian Ocean tsunami and the Niigataken-Chuetsu Oki earthquake which exceeded thedesign basis of the Kashiwazaki-Kariwa NPP. The two IAEA Safety Guides related tothese issues are SSG-9 (2010) and DS417 (in print), related to seismic and flooding(including tsunami) hazards respectively. These two safety guides were developed taking
full account of recent events in order to incorporate the lessons learned from these.

2.2. – FINDINGS AT FUKUSHIMA-DAI-ICHI NPP:--All plants visited benefited from the lessons learned from the experience of K-K NPP. In
particular:
The on-site fire brigade was extremely useful in providing water injection function tovarious locations, using the fire engines available at the site.
The newly built on-site seismically isolated building served a vital function as a technicalsupport service and in general plant emergency response. This building is shielded withcharcoal filtered ventilation and also located at a high elevation to be protected against
tsunamis.
In Kashiwazaki-Kariwa case, the fire extinguishing piping which was located outdoors
and underground suffered severe damage due to soil failures inducing flooding of thereactor building. As a remedial action, all fire extinguishing piping was re-located above
ground with appropriate foundation. This layout solution proved not to be suitable for thetsunami flooding since the above ground piping was severely damaged by the tsunami
induced waves and debris and they would not have been operable in case of fire. This wasobserved, particularly, in case of 2F plant.

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3 –CONCLUSIONS

01/06/2011

1.

Lessons learned from the Kashiwazaki-Kariwa experience provided extremely valuable
improvements to the emergency response at all the plants.

2.

The so called ‗seismically isolated‘ building (which is also has charcoal filteredventilation, shielded and located at a high elevation) provided a safe haven to all plant
personnel during this disaster and expedited emergency and recovery actions.

3.

The on-site fire brigade was also extremely valuable even though there was no fire at thesites. The fire engines were used for injecting water to various structures to provide
cooling.

4.

The re-location of the piping for the firefighting system, on the other hand, turned out tobe a mistake for the particular hazard scenario (tsunami). The fact that there was no fire atthe 2F plant meant that there was no need for this system. Otherwise the on-site firebrigade which had little hands on experience could have been stretched to cope withmulti-tasking (i.e. dealing with fires and providing water injection to various structures).

4 – LESSONS LEARNED

01/06/2011

1.

Lessons learned from the Kashiwazaki-Kariwa experience proved to be extremely useful
in dealing with the on-site emergency situation at the plants. On-site TEPCO personnel
have clearly expressed the view that if it had not been for the on-site fire brigade and theon-site emergency control centre, the situation would have deteriorated much more
rapidly.

2.

By extension, the lessons learned from the Fukushima Dai-ichi experience may prove tobe very important for the international nuclear community in the future. There is need tounderstand the implications of all aspects of this event in order to benefit from theselessons learned.

3.

Due to the nature of this accident lessons learned will cover a very wide area which
involves all findings of this Mission.

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FINDINGS SHEET
Finding Number:

1. FINDING IDENTIFICATION

A1-05

Assessment Area:

A1 - EXTERNAL HAZARDS

Facility:

FUKUSHIMA DAI-ICHI

Unit:

ALL

Finding Title:

CROSS CUTTING- COMPLEX SCENARIO OF EXTREME
EXTERNAL EVENTS AFFECTING ALL UNITS AT MULTIPLE
SITES

2. FINDINGS
2.1 - FINDING DESCRIPTION: BACKGROUND---

The complexity of the events of the Great East Japan Earthquake and Tsunami stems fromthe fact that the hazards were (and still are) multiple and the NPP sites exposed to thesehazards are also multiple (Tokai Dai-ni, Fukushima Dai-ichi, Fukushima Dai-ni, Onagawa
and Tohoku Higashidori). This means that fifteen reactor units at five sites were
simultaneously exposed to extremely high hazards. Although many Member States havemulti unit sites and in some cases neighbouring sites may be exposed a large hazard
simultaneously, guidance regarding multi unit sites with respect to external hazards islacking.
The common cause nature of these hazards plays an important role in off-site emergency
preparedness and response because these natural disasters produce local, regional andnational impact. In this regard NS-R-3 Paragraph 2.29 provides the following requirement:„The external zone for a proposed site shall be established with account of the potential
for radiological consequences for people and the feasibility of implementing emergency
plans, and of any external events or phenomena that may hinder their implementation.‟
For on-site severe accident management, large and complex external hazards also haveserious implications for securing the reactor cooling and containment functions bystretching the available human and material resources. The situation off-site due to thedestruction by the disasters will limit the movement of resources from off-site to the plant.

2.2. – FINDINGS AT FUKUSHIMA-DAI-ICHI NPP:--

Although, the lessons learned from the Kashiwazaki-Kariwa experience were very usefulparticularly for on-site emergency, there was major regional disruption which hampered
immediate recovery actions. The regional nature of the destruction and the damage
incurred at multiple units at multiple sites (eventually leading to severe accidents at the 1F
NPP) caused significant delays and disruptions in recovery actions.
Following the tsunami, 1F1 to 1F5 had fallen into the Station Black Out (SBO) and theseawater systems were totally destroyed and the Ultimate Heat Sink was lost.
Following the Abnormal Operating Procedure (AOP), operation after SBO should beinterchangeable from the neighbour plant. However, the interchangeability was unable tobe conducted since the other plants also lost the power.
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-

After the tsunami, approximately 400 people (about 130 for operation, about 270 for
maintenance) were available for the recovery processes. The number of the operation
people was totally insufficient for the recovery operation of six units.
Only very limited devices and tools were available. Some of which were in thewarehouses of the affiliated companies and difficult to find.
Fukushima Dai-ni:
In Fukushima Dai-ni (2F) the simultaneous loss of ultimate heat sink in Unit-1, 2 and 4 isa typical common mode failure caused by extreme natural phenomena in multi-unit plant.

3 –CONCLUSIONS

01/06/2011

1.

Japan is a country known for high level of awareness of natural disasters and has an
excellent system of warning, preparedness and response to cope with these. In reviewing
the situation at the NPPs after the Great East Japan Earthquake, it was concluded by the
IAEA Mission Team, that the magnitude of the disaster was not anticipated in the originaland revised hazard assessments.

2.

Consequently a contingency plan for the failure of multiple units at multiple sites within aregional disaster context was not available.

3.

For effective mitigation of the common mode failures affecting simultaneously to multi
unit plants at the same time, sufficient large resource in terms of trained experienced
people, equipment, supplies and external support. In addition, an adequate pool ofexperienced personnel is recommended.

4.

The procedures should be prepared for the logistics, human resources, supplies, external
support to rapidly countermeasure severe accident and to reduce the radiation spreading.
Operators and supporting persons like fire fighters should be effectively trained tounderstand their duties and be capable of implementing the procedures for mitigating thesevere conditions.

4 – LESSONS LEARNED

01/06/2011

The interference of the complex scenarios resulting from the natural disasters at 1F and 2F
plants that affected recovery actions and mitigation measures need to be well documented
in order to develop lessons learned for the international nuclear community.
The potential for complex scenarios involving multiple hazards and multiple units (andpossibly sites) need to be fully investigated for new and existing NPPs worldwide and ifthey cannot be screened out, provisions for plant layout, site protection measures, design,accident management and off-site emergency preparedness and response should be taken inorder to adequately protect the plants from these disasters.

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FINDINGS SHEET
Finding Number:

1. FINDING IDENTIFICATION
Assessment Area:

A1 - EXTERNAL EVENTS OF NATURAL ORIGIN

Facility:

FUKUSHIMA DAI-ICHIUnit:

UNITS 1 TO 6

Finding Title:

CROSS CUTTING – EXTERNAL EVENTS PSA

A1-06

2. FINDINGS
2.1 - FINDING DESCRIPTION: BACKGROUND-

It is important for plants to identify and address all means initiating accident, including those thatstem from natural phenomena.

-

Internal events include equipment failures and human errors occurring within the plants such as
pipe breaks, stuck valves, damaged pumps, instrument failures and operator errors. External events
include those of natural and human induced origin generated outside of the plant, such as
earthquakes, severe meteorological and hydrological phenomena, volcanic hazards, aircraft crashes
and explosions.

-

Generally, more attention has been focused on internal events than external events in PSA.

-

The frequencies of internal events are generally better known due to the wealth of operating
experience that has been accumulated throughout the world. In particular, about 15,000 full power
years of plant operation has been accumulated using similar equipment. Additional information
regarding operability of components has been generated through the periodic in-service testing ofthese components required by all regulatory bodies.

-

Human factors including human reliability analysis has been an important focus of study since the1979 accident at Three Mile Island in the United States in which operator error played a key role.
These research programmes and associated techniques allow the prediction and quantification ofhuman error under specific circumstances.

-

Although uncertainty in internal initiating event frequencies remains, most PSAs developed
throughout the nuclear community include a far more thorough analysis of internal event risk than
external event risk. However, depending on the particular site of a plant, external events candominate overall risk.

2.2. – FINDINGS AT FUKUSHIMA-DAI-ICHI NPP:-In May 2002, Japanese licensees reported the accident management measures developed for each
unit together with PSAs of internal events for representative reactor types for the purpose ofquantifying safety. The PSA of internal events for all commercial reactor facilities under operation
were reported to NISA by the licensees in March 2004. No PSAs for external events were requiredby NISA.

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3 –CONCLUSIONS

01/06/2011For the 1F plant an internal events PSA was conducted and the results of the study reported
to NSC and NISA. NSC evaluated the results of the PSA and found them to be reasonable.

For plants in cold shutdown state a ‗shutdown PSA‘ would be very useful to identify the
SSCs needed to keep the plants in a stable safe state. This would also help in theidentification of all items that need to be protected from external hazards in the short term.

4 – LESSONS LEARNED

01/06/2011



There is a need for the nuclear community to increase effort in developing PSA for external
events.



Even in Member States where conduct of external event PSAs is a regulatory requirement,
many external events are screened out using approximate criteria and not included in
rigorous PSA treatment. There is a need to review the screening approaches in order to takefull benefit of PSA.

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Appendix 2

IAEA International Fact Finding Expert Mission of
the Fukushima Dai-ichi NPP Accident Following theGreat East Japan Earthquake and Tsunami
Japan

FINDING SHEETS

Safety Assessment and Management

IAEA 2011

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FINDINGS SHEET
Finding Number:

1. FINDING IDENTIFICATION

A2-01

Assessment Area:

A2 - SAFETY ASSESSMENT AND MANAGEMENT

Facility:

GENERAL

Unit:
Finding Title:

EQUIPMENT LAYOUT, PHYSICAL SEPARATION AND
INTERNAL BARRIERS NEED TO BE REVIEWED

2. FINDINGS
2.1 - FINDING DESCRIPTION: BACKGROUND---The Operation of most of the safety systems of traditional design NPPs depends on the
power supply from off-site power and Emergency Diesel Generators (EDGs) in case ofloss of off-site power. There are 13 emergency DGs at the Fukushima Dai-ichi NPP, mostof them are located in the lower part of the turbine building (B1F). As a result, the DGs
themselves as well as the associated electric panel and cable were submerged and failed
due to the tsunami on 11 March 2011.
The heat transfer path from the core and the spent fuel pool to the ultimate heat sink isvery important to achieve a stable safe state. There are two trains of residual heat removal
system for each unit, but all of them were submerged and failed due to the tsunami on 11
March 2011.
The DC power supply (batteries) must be available to power the control system, somesafety related motor-operated valves, and the post-accident monitoring system. However,the DC power supply failed at Fukushima Dai-ichi after the tsunami of 11 March 2011.

2.2. – FINDINGS AT FUKUSHIMA-DAI-ICHI NPP:-

Most of safety related system and component such as EDGs, DC power supply system,
RHR are failed due to submerged after Tsunami.
The equipment layout and physical separation of safety important equipment need to bereviewed.
Internal barriers need to be reviewed because they are typically design for internal
flooding and fires and they may not be enough to prevent common cause failures causedby severe external flooding.

3 –CONCLUSIONS__/__/2011

Equipment layout, physical separation and internal barriers need to be reviewed andimproved.

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4 – LESSONS LEARNED__/__/2011

Equipment layout, physical separation and internal barriers need to be reviewed andimproved.

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FINDINGS SHEET
Finding Number:

1. FINDING IDENTIFICATION

A2-02

Assessment Area:

A2 - SAFETY ASSESSMENT AND DEFENCE-IN-DEPTH

NPP:

FUKUSHIMA-DAI-ICHI NPPUnit:

UNITS 1 TO 6

Finding Title:

DIVERSITY DESIGN OF ULTIMATE HEAT SINK NEED TO
BE IMPROVED

2. FINDINGS
2.1 - FINDING DESCRIPTION: BACKGROUND--

Generally speaking, the design of Emergency Core Cooling System of Fukushima Dai-ichi
NPPs is good, there are Isolation Condenser (IC, only for Unit 1), Reactor Core Isolation
Cooling system (RCIC, for unit 2-6), Core Spray system (CS, for Unit 1-5), High-Pressure
Coolant Injection system (HPCI, for Unit 1-5), Automatic Depressurization System(ADS), Low-Pressure Core Spray system (LPCS, for Unit 6), Low-Pressure Coolant
Injection system (LPCI, for unit 2-6), and Residual Heat Removal system (RHR). The IC(only for Unit 1), the RCIC (for Unit 2 and 3) and the HPCI (for Unit 1-3), the latter two
are driven by natural circulation have provided the emergency core cooling for the coresof Unit 1-3 at the first phase of Fukushima Accident which was mainly caused by Station
Blackout for long time than expected.
The heat transfer path from the core and the spent fuel pool to the ultimate heat sink isvery important. The ultimate heat sink of Fukushima Dai-ichi NPP units 1-6 is sea waterof Pacific Ocean, there are two trains of heat removal system for each unit, they arelocated in the separated room, but the elevation of the motor of the RHR-S are same, 4-5.7
m above the sea level. Due to 14-m-height Tsunami on 11 March, all of them aresubmerged and damaged, so the path to removal the decay heat in the core and spent fuelpool to the ultimate heat sink (Pacific Ocean) is broken. For recovery of Dai-ichi Units 14, TEPCO is installing air-cooled equipment for each unit to serve as the ultimate heatsink for the cores and spent fuel pools.

2.2 FINDINGS AT FUKUSHIMA-DAI-ICHI NPP-

At Fukushima Dai-ichi, the heat transfer paths to the ultimate heat sink for units 1-6 werelost. For recovery of Dai-ichi units 1-4, TEPCO is constructing an air cooler tower foreach unit to serve as the ultimate heat sink for the cores and spent fuel pools. The original
design of ultimate heat sink lack of consideration for diversity.

3 –CONCLUSIONS-__/__/2011

According to the National and International standards for the design of NPPs, safety
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-

-

-

systems should be designed with high levels of diversity to improve their reliability.
However, the recommended levels of diversity have not been clearly quantified or definedin the same way as the consideration of single failure has been established.
It is common in the traditional designs of NPPs (including PWR and BWR) for the heattransfer path to the ultimate heat sink to have minimal diversity requiring feed and bleed to
be used in many cases which potentially affects the ability to ensure the containment ofradioactivity.
With the consideration to prevent and mitigate Beyond Design Basis Accident
especially caused by extreme natural hazards, diversity of the ultimate heat sink areimportant means to ensure the robustness of a design, and additional attention shouldbe paid to diversity in new NPP designs.
The additional diversity train of RHR could provide defence-in-depth method to
remove the decay heat in the core and in the spent fuel pool. It should be seismicclassified to avoid common cause failure such as due to earthquake, but it may not bedesigned as safety classified system in order to cope with beyond design basis accident
especially caused by external natural hazard.

4 – LESSONS LEARNED__/__/2011

With the consideration to prevent and mitigate Beyond Design Basis Accident
especially caused by extreme natural hazards, diversity of the ultimate heat sink areimportant means to ensure the robustness of a design, and additional attention shouldbe paid to diversity in new NPP designs.

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FINDINGS SHEET
Finding Number:

1. FINDING IDENTIFICATION

A2-03

Assessment Area:

A2 SAFETY ASSESSMENT AND DEFENCE-IN-DEPTH

NPP:

FUKUSHIMA-DAI-ICHI NPP

Unit:

UNIT 1 TO 6
DIVERSITY DESIGN OF EMERGENCY AC POWER NEEDTO BE IMPROVED

Finding Title:

2. FINDINGS
2.1 - FINDING DESCRIPTION: BACKGROUND--

The operation of most of the safety system of traditional design NPP depends on power
supply from off-site power and emergency power supply from emergency Diesel Generator
in case of loss of off-site power.
There are 13 EDGs in Fukushima Dai-ichi NPP, each unit of Unit 1-5 has 2 EDGs, and unit
6 has 3 EDGs, named as DG1A, DG1B, DG2A, DG2B, DG3A, DG3B, DG4A, DG4B,
DG5A, DG5B, DG6A, DG6B, DG6H (HPCS DG), most of them are located in theirrelevant Reactor Building (underground room, B1F) and cooled by sea water except DG2B,
DG4B and DG6B which are located above the ground and cooled by air. All of the EDGs
that were available at the time started up automatically when loss of off-site power due toearthquake during Fukushima Accident, but they all failed after Tsunami, except DG6B.
The investigation results show that DG1A, DB1B, DG2A, DG3A, DG3B, DG4A, DG5A,
DG5B, DG6A and DG6H are submerged and their Emergency high voltage switchboard(M/C) are submerged or water damaged too, DG2B and DG4B are damaged due to theirassociated electric panel and cable are submerged. DG6B is survived due to its M/C islocated in a higher location.

2.2 FINDINGS AT FUKUSHIMA-DAI-ICHI NPP- Fukushima Dai-ichi NPP have a relatively good diversity design of the Emergency Diesel
Generator, compared to other traditional design NPP, but the elevation of some EDGs are
too low, and the physical separation and water-tight sealing of the of EDG room need to be
improved.
- The elevation of Emergency high voltage switchboard (M/C) for most EDGs is too low,
and the physical separation and water-tight sealing of the room need to be improved.
3 –CONCLUSIONS__/__/2011

Diversity of the emergency AC power is an important means to ensure the robustness of adesign, and additional attention should be paid to diversity in new NPP designs.
The equipment layout and physical separation of The Emergency high voltage switchboard
should be improved.

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4 – LESSONS LEARNED__/__/2011

Diversity of the emergency AC power is an important means to ensure the robustness of adesign, and additional attention should be paid to diversity in new NPP designs.
The equipment layout and physical separation of The Emergency high voltage switchboard
should be improved.

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FINDINGS SHEET
Finding Number:

1. FINDING IDENTIFICATION

A2-04

Assessment Area:

A2 - SAFETY ASSESSMENT AND DEFENCE-IN-DEPTH

NPP:

FUKUSHIMA-DAI-NI NPPUnit:

UNITS 1 TO 4
DIVERSITY DESIGN OF ULTIMATE HEAT SINK NEED TO
BE IMPROVED

Finding Title:

2. FINDINGS
2.1 - FINDING DESCRIPTION: BACKGROUND--

Generally speaking, the design of Emergency Core Cooling System of Fukushima Dai-ni
NPPs (BWR-5) is good, there are Reactor Core Isolation Cooling system (RCIC), HighPressure Core Spray system (HPCS), Low-Pressure Core Spray system (LPCS),
Automatic Depressurization System (ADS), Low-Pressure Coolant Injection system(LPCI), and Residual Heat Removal system (RHR). Some of them provided theemergency core cooling for the core during Accident.
The heat transfer path from the core and the spent fuel pool to the ultimate heat sink isvery important. The ultimate heat sink of Fukushima Dai-ni NPP units 1-4 is sea water ofPacific Ocean, there are two trains of heat removal system for each unit, their seawatercooling system (RHR-S) are located in the relevant Heat Exchange Building (Hx/B), themotor of the RHR-S is located in 1F pump room (4 m above the sea level), and theirpower centres are located in the B1F control panel of Hx/B. Due to the tsunami (maximum
run-up height of approximately 14 m) on 11 March, all of them except RHR-S-3B are
submerged and damaged, so the path to removal the decay heat in the core and spent fuelpool to the ultimate heat sink (Pacific ocean) is broken. The survival of RHR-S-3B is justdue to luck that is why unit 3 can reach cold shutdown state more early than Unit 1, 2, 4.
The site superintendent reported the central and local governments nuclear emergency
situation because the temperature of the suppression pools of Unit 1,2,4 became more than
100 ℃ during accident, but afterward with temporary power cable laid and urgent
procurement of motors, one train of RHRS, RHRC, EECW for each unit of Unit 1,2,4 hasrecovered and restarted. Up to now, all units of Fukushima Dai-ni have reached cold shutstates.

2.2 FINDINGS AT FUKUSHIMA-DAI-NI NPPThe Ultimate heat sink of Fukushima Dai-ni NPP units 1-4 is sea water of Pacific Ocean, it
is broken due to Tsunami on 11 March 2011.

3 –CONCLUSIONS__/__/2011

With the consideration to prevent and mitigate Beyond Design Basis Accident especiallycaused by extreme natural hazards, Diversity of the ultimate heat sink are important means
to ensure the robustness of a design, and additional attention should be paid to diversity in
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new NPP designs.

4 – LESSONS LEARNED__/__/2011

With the consideration to prevent and mitigate Beyond Design Basis Accident especiallycaused by extreme natural hazards, Diversity of the ultimate heat sink are important means
to ensure the robustness of a design, and additional attention should be paid to diversity in
new NPP designs.

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FINDINGS SHEET
Finding Number:

1. FINDING IDENTIFICATION

A2-05

Assessment Area:

A2 - SAFETY ASSESSMENT AND DEFENCE-IN-DEPTH

NPP:

FUKUSHIMA-DAI-NI NPPUnit:

UNITS 1 TO 4
DIVERSITY DESIGN OF EMERGENCY AC POWER NEEDTO BE IMPROVED

Finding Title:

2. FINDINGS
2.1 - FINDING DESCRIPTION: BACKGROUND--

The operation of most of the safety system of traditional design NPP is depend on power
supply from off-site power and emergency power supply of emergency Diesel Generator
in case of loss of off-site power.
There are 12 Emergency Diesel Generators (EDGs) in Fukushima Dai-ni NPP (4 units),
each unit has 3 EDGs, named as DG1A, DG1B, DG1H, DG2A, DG2B, DG2H, DG3A,
DG3B, DG3H, DG4A, DG4B, DG4H, all of them are located in the outer area of theirrelevant Reactor Building (underground room B2F) and cooled by sea water (located in
Hx/B building). All of these EDGs startup automatically due to low bus voltage when theearthquake hit the site on 11 March, but they all failed after Tsunami, except DG3B,
DG3H and DG4H due to luck, because all of their associated sea water cooling pumps andinter-cooling pumps were submerged due to the tsunami. The main difference between
Fukushima Dai-ni and Fukushima Dai-ichi is that one 500 kV line was available for
Fukushima Dai-ni (due to higher height and robust electric tower structure), it means that
Fukushima Dai-ni had off-site power supply (Fukushima Dai-ichi was in SBO with blindcondition), so the reactor were kept in a stable safe state for a long time, first by RCIC
followed by MUWC, so that the operator have enough time to repair the heat transfer pathto the heat sink.

2.2 FINDINGS AT FUKUSHIMA-DAI-NI NPP-Most of the EDGs failed due to failure of their associated seawater cooling system andinter-cooling system, even though three EDGs survived due to luck. It seems that thedesign of emergency AC power lack of diversity.

3 –CONCLUSIONS__/__/2011

The Operation of most of the safety system of traditional design NPP is depend on power
supply from off-site power and emergency Diesel Generator in case of loss of off-site
power, Diversity of the emergency AC power is an important means to ensure therobustness of a design, and additional attention should be paid to diversity in new NPP
designs.
4 – LESSONS LEARNED__/__/2011

Diversity of the emergency AC power is an important means to ensure the robustness of a
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design, and additional attention should be paid to diversity in new NPP designs.

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FINDINGS SHEET
Finding Number:

1. FINDING IDENTIFICATION

A2-06

Assessment Area:

A2 - SEVERE ACCIDENTNPP:FUKUSHIMA-DAI-ICHI NPPUnit:

UNITS 1 TO 4
THE CREATION OF A COMMON POOL OF TRAINEDPERSONS TO RESPOND TO ABNORMAL SITUATIONS

Finding Title:

2. FINDINGS
2.1 - FINDING DESCRIPTION: BACKGROUND
Japan has several sites operating BWRs. Each site has a number of BWRs. In order to
optimize the resources in the interest of economy, the number of trained persons for
operation maintenance and other functions are minimized to the extent possible. While thisworks well during normal circumstances, under abnormal circumstances when multiple
units are affected the number of trained persons available are inadequate.
2.2 FINDINGS AT FUKUSHIMA-DAI-CHI NPP
As a consequence of the earthquake followed by a Tsunami all the three operating units
went into a crisis situation as almost all the safety systems became inoperative due to lossof all sources of electric power. Under the circumstances remedial measures were required
to be implemented in all the units. Obviously the available manpower was inadequate.
Since there are several sites having similar Nuclear Power Plants, BWRs in this case, it
can be suggested that such sites can maintain a pool of trained persons that can be
deployed at the NPP site that is going through an event.
3 –CONCLUSIONS__/__/2011

Sites having the same type of plants can develop and maintain a pool of trained people toprovide immediate support to each other when necessary.

4 – LESSONS LEARNED__/__/2011

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FINDINGS SHEET
Finding Number:

1. FINDING IDENTIFICATION

A2-07

Assessment Area:

A2 - SEVERE ACCIDENTNPP:FUKUSHIMA-DAI-CHI NPPUnit:

UNITS 1 TO 4
THE AVAILABILITY OF A SEISMICALLY ROBUSTBUILDINGFORTHE
FUNCTIONINGOF
THE
EMERGENCY RESPONSE CENTRE (ERC)

Finding Title:

2. FINDINGS
2.1 - FINDING DESCRIPTION: BACKGROUND
The Kashiwazaki-Kariwa Earthquake in 2007 affected all the units at the site. Though all
the operating units were safely shut down, the possibility of a significant damage to all thebuildings and structures was highlighted. Based on this experience the creation of aseismically robust building at all the NPP sites was recommended.
2.2 FINDINGS AT FUKUSHIMA-DAI-CHI NPP
Following the earthquake and tsunami on 11 March 2011 three operating units suffered
severe core degradation. Several structures, including the administration building and staff
offices, were damaged. Increased radiation levels around the plant also made those areas
uninhabitable.
Based on the recommendations of the 2007 earthquake affecting Kashiwazaki-Kariwa
NPP, a seismically robust building was built in Fukushima Dai-ichi as well as in
Fukushima Dai-ni. These buildings are not only built to withstand earthquakes but are also
shielded and have filtered ventilation systems to ensure the habitability during accident
conditions involving the spread of radiation. The buildings are provided with
communication facilities with plant control rooms, as well as external agencies, such as
TEPCO Headquarters in Tokyo.
During the accident and its mitigation phase this building provided a safe location tooperate the Emergency Response Centre. The building continues to provide the only safe
place in the vicinity of the NPP to house a large number of persons (over 2000) who are
engaged in the recovery operations.
3 –CONCLUSIONS__/__/2011

It was extremely useful to have on-site a seismically robust, shielded, ventilated and wellequipped building at Fukushima Dai-ichi and Dai-ni NPPs. Such facilities can beconsidered by all NPPs as a means to deal with severe accidents.
4 – LESSONS LEARNED__/__/2011

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FINDINGS SHEET
Finding Number:

1. FINDING IDENTIFICATION

A2-08

Assessment Area:

A2 - SEVERE ACCIDENTNPP:FUKUSHIMA-DAI-NI NPPUnit:

UNITS 1 TO 4
The comparison and assessment of the event progression andoperator actions at different units of Fukushima Dai-ichi and
Dai-ni NPPs

Finding Title:

2. FINDINGS
2.1 - FINDING DESCRIPTION: BACKGROUND-

Following the earthquake and tsunami, the event progression at different units of Dai-ni and Daiichi were considerably different. The plant conditions and operator actions were also
correspondingly different. Given the fact that the units at Dai-ni survived whereas the units at Daiichi suffered severe core degradation it would be quite useful to compare the event progression andimpact of operator actions at different units.

2.2 FINDINGS AT FUKUSHIMA-DAI-ICHI AND DAI-NI NPP-At the time of the earthquake and tsunami three units at Dai-ichi and all the four units at Dai-ni
were in operation. Though the tsunami levels at the two NPPs were different and the off-site power
was available at Dai-ni major safety systems were affected in both NPPs. Though all the four units
at Dai-ni were brought to safe configuration they were perilously close to a serious situation. The
workers of Dai-ni laid several kilometers of cable to get power back to safety systems.

-

At Dai-ichi the events progressed much too fast for operators to respond in an organized manner.
Normally the mission times of IC/RCIC should have given the operators some time before the core
was exposed and radiation levels increased making several reactor areas inaccessible. It is not clear
if and why these systems did not function the way they should have.

-

A detailed comparison of the event progression and operator actions at different units of the same
NPP, as well as between the units of Dai-ni and Dai-ichi could bring out significant inputs for theprevention and management of severe accidents.

3 –CONCLUSIONS__/__/2011

The comparison and assessment of the event progression and operator actions at different
units of Fukushima Dai-ni and Dai-ichi could provide significant inputs for the prevention
and management of severe accidents.
4 – LESSONS LEARNED__/__/2011

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FINDINGS SHEET
Finding Number:

1. FINDING IDENTIFICATION

A2-09

Assessment Area:

A2 - SEVERE ACCIDENTNPP:FUKUSHIMA-DAI-ICHI NPPUnit:

UNITS 1F1 TO 1F6

Finding Title:

EXTERNAL EVENTS HAVING A POTENTIAL OF
AFFECTING MULTIUNITS PLANTS AT THE SAME TIME

2. FINDINGS
2.1 - FINDING DESCRIPTION: BACKGROUND-

The FUKUSHIMA-DAI-ICHI site has a total of 6 NPPs (1 BWR-3, 5 BWR-4, and 1 BWR-5)
Units 1, 2, 3 and 4 are located on the site level of O.P.+10 m, while Unit 5 and 6 are located on thesite level of O.P.+ 13 m. Most EDGs are located under the ground (B1FL) in turbine buildings
except for five EDGs, that are, 2B and 4B DGs on the first floor of the shared pool building. 6A
and HPCS DG on the B1FL in CS, and 6B on the first floor in a dedicated building.

-According to higher tsunami than expected value, most EDGs were submerged or water damaged
except EDG 6B. Most batteries (125 V DC) except 1F3 were also unavailable since they werelocated under the ground level.

2.2 FINDINGS AT FUKUSHIMA-DAI-ICHI NPP-

According to the tsunami, 1F1 to 1F5 had fallen into the Station Black Out(SBO) and the seawater
systems were totally destroyed ( No Ultimate Heat Sink )-Following the Abnormal Operating Procedure (AOP), operation after SBO should beinterchangeable from the neighbor plant. However, the interchangeability was able to be conductedsince the other plants also lost the power.

-

After the tsunami, approximately 400 people (about 130 for operation, about 270 for maintenance)
were available for the recovery processes. The number of the operation people was totally
insufficient for the recovery operation of six units.

-

Only very limited devices and tools were available. Some of which were in the warehouses of theaffiliated companies and difficult to find.

3 –CONCLUSIONS__/__/2011

For effective mitigation of the common mode failures affecting simultaneously to multi
unit plants at the same time, sufficient large resource in terms of trained experienced
people, equipment, supplies and external support. In addition, an adequate pool ofexperienced personnel is recommended.
The procedures should be prepared for the logistics, human resources, supplies, external
support to rapidly countermeasure severe accident and to reduce the radiation spreading.
Operators and supporting persons like fire fighters should be effectively trained tounderstand their duties and be capable of implementing the procedures for mitigating the
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severe conditions.
4 – LESSONS LEARNED__/__/2011

External events have a potential of affecting several plants and several units at the plants atthe same time. This requires a sufficiently large resource in terms of trained experienced
people, equipment, supplies and external support. An adequate pool of experienced
personnel who can deal with each type of unit and can be called upon to support theaffected sites should be ensured.

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FINDINGS SHEET
Finding Number:

1. FINDING IDENTIFICATION

A2-10

Assessment Area:

A2 - SEVERE ACCIDENTNPP:FUKUSHIMA-DAI-ICHI NPPUnit:

UNITS 1F1 TO 1F6

Finding Title:

POTENTIAL UNAVAILABILTY OF INSTRUMENTS AND
LIGHTING

2. FINDINGS
2.1 - FINDING DESCRIPTION: BACKGROUND-

There were particular challenges at Fukushima Dai-ichi with high radiation fields, and with thetsunami and explosions there was considerable debris disrupting normal routes. Additionally,
control room access was very limited and safety related instrumentation was generally notavailable or unreliable.

2.2 FINDINGS AT FUKUSHIMA-DAI-ICHI NPP-

It was found that reactor water level gauges in 1F1 had drifted sometime during the accident
progression when the instrumentation was calibrated in May. It is assumed that water in areference tube for measurement evaporated due to high temperature in the circumstance, whichbrought higher reactor water level than actual value. Similar phenomena might have occurred in
1F2 and 1F3 as well. Limited number of parameters and less reliable measured values of core,
reactor vessel and containment vessel have been used for severe accident management in 1F1 to
1F3.

-

Severe Accident Management Guidelines (SAMG) and associated procedures generally
assume that instruments, lighting and power are available. This may not be the case. In
addition, these documents do not consider the possible state of the plant and the local
environmental conditions such as radiation fields that may preclude manual actions frombeing taken. Some instruments installed in core, reactor vessel and containment in 1F1 to
1F3 are supposed to be unreliable. Level gauges at reactor vessel might be indicating
overly-estimated values as was confirmed in the case for 1F1.

3 –CONCLUSIONS__/__/2011

Robustness of the instruments, lighting and power to countermeasure the accident elevation
was not sufficiently considered in Severe Accident Management Guidelines (SAMG) or
plant specific procedures.
4 – LESSONS LEARNED__/__/2011

Severe Accident Management Guidelines and associated procedures should take account of
the potential unavailability of instruments, lighting, power and abnormal conditions
including plant state and high radiation fields.

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FINDINGS SHEET
Finding Number:

1. FINDING IDENTIFICATION
Assessment Area:

A2 - SEVERE ACCIDENTNPP:FUKUSHIMA-DAI-NI NPPUNITS 2F1 - 2F4

Unit:
Finding Title:

A2-11

EXTERNAL EVENTS HAVING A POTENTIAL OF
AFFECTING MULTIUNITS PLANTS AT THE SAME TIME

2. FINDINGS
2.1 - FINDING DESCRIPTION: BACKGROUND-

The height of tsunami to FUKUSHIMA DAI-NI site ranged from approximately O.P 7 m to O.P
15 m at south of Unit 1-4. All plants are located at the height of O.P 12 m, which is 2m higher than
FUKUSHIMA DAI-ICHI. Even in case of great earthquake accompanying unexpected tsunami,
Station Black Out was not happened. Instead, due to the flooding into heat exchanger building
most residual heat removal seawater systems (RHRS) except Unit-3 were not available, which led
to the loss of ultimate heat sink. By using the mobile power trucks, temporary power cable, andinstalling of procured motors the function of ultimate heat sink was recovered.

2.3 FINDINGS AT FUKUSHIMA-DAI-ICHI NPP-

The simultaneous loss of ultimate heat sink in unit-1, 2 and 4 is a typical common mode failurecaused by extreme natural phenomena in multi-unit plant.

3 –CONCLUSIONS__/__/2011

For effective mitigation of the common mode failures affecting simultaneously to multi
unit plants at the same time, sufficient large resource in terms of trained experienced
people, equipment, supplies and external support. In addition, an adequate pool ofexperienced personnel is recommended.
The procedures should be prepared for the logistics, human resources, supplies, external
support to rapidly countermeasure severe accident and to reduce the radiation spreading.
Operators and supporting persons like fire fighters should be effectively trained tounderstand their duties and be capable of implementing the procedures for mitigating thesevere conditions.
4 – LESSONS LEARNED__/__/2011

External events have a potential of affecting several plants and several units at the plants atthe same time. This requires a sufficiently large resource in terms of trained experienced
people, equipment, supplies and external support. An adequate pool of experienced
personnel who can deal with each type of unit and can be called upon to support theaffected sites should be ensured.

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FINDINGS SHEET
Finding Number:

1. FINDING IDENTIFICATION

A2-12

Assessment Area:

A2 - SEVERE ACCIDENTNPP:FUKUSHIMA-DAI-NI NPPUnit:

UNITS 2F1 - 2F4

Finding Title:

POTENTIAL UNAVAILABILTY OF INSTRUMENTS AND
LIGHTING

2. FINDINGS
2.1 - FINDING DESCRIPTION: BACKGROUND-

The survivability of instrumentations during severe accidents in FUKUSHIMA DAI-NI site could
not be identified since all reactors safely arrived to cold shutdown states within three days without
entering severe accident conditions.

2.4 FINDINGS AT FUKUSHIMA-DAI-NI NPP-The Severe Accident Management Guidelines (SAMG) of FUKUSHIMA DAI-NI plant aresupposed to have similar contents and strategies with DAI-ICHI plant. It is very likely that the
instrumentations installed around reactor and containment vessel would indicate fault values
during severe accident conditions. It could provide operators and decision-makers with incorrect
information to lead them to improperly countermeasure in response of the transients.

-

SAMGs and associated procedures generally assume that instruments, lighting and power areavailable. This may not be the case. In addition, these documents do not considered the possible
state of the plant and the local environmental conditions such as radiation fields that may preclude
manual actions from being taken.

3 –CONCLUSIONS__/__/2011

Robustness of the instruments, lighting and power to countermeasure the accident elevation
was not sufficiently considered in Severe Accident Management Guidelines (SAMG) or
plant specific procedures
4 – LESSONS LEARNED__/__/2011

Severe Accident Management Guidelines and associated procedures should take account of
the potential unavailability of instruments, lighting, power and abnormal conditions
including plant state and high radiation fields.

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FINDINGS SHEET
Finding Number:

1. FINDING IDENTIFICATION
Assessment Area:

A2 - SEVERE ACCIDENT

Facility:

GENERAL

A2-13

Unit:
Finding Title:

SEVERE ACCIDENT MANAGEMENT

2. FINDINGS
2.1 - FINDING DESCRIPTION: BACKGROUND-

An external initiating event of sufficient magnitude may have the potential to directly
cause multiple component failures potentially leading to core damage. The 11 March 2011
tsunami did just that to three operating units at Fukushima Dai-ichi and led tocomplications at four spent fuel pools. Having a clear understanding of external initiating
event risk can assist a utility in having pre-staged portable equipment to successfully carryout the essential safety functions of the plant, including criticality control, core and spent
fuel pool heat removal and maintenance of containment integrity. Generally, in mostboiling water reactors, a large contributor to core damage frequency is station blackout(SBO) which results in the unavailability of both ac and dc power. SBO precludes theoperation of pumps and valves both necessary to perform the essential safety functions.
This situation can be mitigated through the use of portable equipment provided it can beobtained and implemented in a timely manner, typically within a few hours. In order to doso, the equipment should be pre-staged, procedures developed and the operators trained to
execute the plans. The equipment should be stored in a location that limits the probabilityof damage by the external event. It is also vital that adequate equipment be available forall the units on a site, including the spent fuel pool because of the potential for an external
event affecting all units on a site. In addition, adequately trained staff must be available torespond to the event at all units on a site.

2.2. – FINDINGS AT FUKUSHIMA-DAI-ICHI AND FUKUSHIMA DAI-NI NPP:--

Subsequent to the events on 11 March 2011, Fukushima Dai-ichi received such equipment
and it appears that they have been able to halt the severe accident progression, preventing
containment liner melt through and energetic failure of primary containment. The plant is
now attempting to develop more reliable and redundant means to provide the essential
safety functions to the core and spent fuel pool, to ultimately achieve cold shutdown.
The Fukushima Dai-ni plant was less damaged and the plant operators were able tocontinue to provide water to the reactor cores and depressurize the reactors. To aid inachieving a cold shutdown state, the plant superintendent called for mobile power trucks
and mobilized the workers on-site to lay over 9 km of temporary power cables. In
addition, replacement motors were procured for some of the flooded pumps. This allowed
the normal residual heat removal systems to be returned to service 3 days following thetsunami and the units were brought to cold shutdown either on the same day or the day
after RHR had been restored.
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-

Japanese utilities have implemented voluntary measures for preventing severe accidents
and mitigating the impacts based on the NSC guidance document, ―Accident Management
Measures Against Severe Accidents in Light Water Nuclear Power Facilities,‖ dated 28
May 1992 and revised on 20 October 1997. Typical modifications to plants include
installation of alternative pumps or procedures for core flooding using containment spraysystems, water injection using fire pumps, and additional provisions for ac power using atie-line from a neighbouring installation. These measures provide diversity for essential
safety functions but are vulnerable to a large external event since they are located on thesite. Subsequent to the events of 11 March 2011, NISA has taken action to confirm thatlicensees have followed this guidance and has additionally required that some equipment,such as power vehicles and pump trucks are located off-site.

3 –CONCLUSIONS__/__/2011

The lack of adequate supply of pre-staged portable equipment to carry out the essential
safety functions of the plant hindered the ability to respond to the event.

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FINDINGS SHEET
Finding Number:

1. FINDING IDENTIFICATION
Assessment Area:

A2 - SEVERE ACCIDENT

Facility:

GENERAL

A2-14

Unit:
Finding Title:

MANAGEMENT AND PROCEDURE – CONSIDERATIONSFOR SEVERE ACCIDENT MANAGEMENT FOR NEW AND
EXISTING JAPANESE NPPS

2. FINDINGS
2.1 - FINDING DESCRIPTION: BACKGROUND-

Severe Accident Management Guidelines (SAMGs) and associated procedures have beendeveloped and implemented at most power reactors worldwide since the 1990‘s.
Additional operating experience and research has led to the continuous enhancement ofknowledge regarding severe accidents and subsequent improvements in SAMGs.

2.2. – FINDINGS AT FUKUSHIMA-DAI-ICHI NPP:-The Japanese utilities voluntarily implemented SAMGs in the early 1990‘s. Their
programmes include the documentation of procedures and a training programme,
including the conduct of drills at plants on an annual basis. Because no core damage
occurred at Dai-ni or Tokai Dai-ni, the operators were able to execute these plans althoughdamage to the sites complicated their execution. At Dai-ichi, core damage resulted in highradiation levels at the site. There was some loss of inventory from the SFP due to boil off
and there is a possibility of water loss from sloshing. These levels prevented the access tomany areas of the plant, precluding implementation of the procedures.

3 –CONCLUSIONS__/__/2011

The nuclear community worldwide should consider potential radiation levels in theirprocedures. The result may require action being taken earlier in the event than previously
thought and may also necessitate the use of remote-controlled equipment that must be prestaged. Due to the need for radiation protection measures including respirators andprotective clothing, drills should be conducted with this equipment to verify that the actions
can be taken in a timely manner. Additionally, operators must be appropriately trained in
the use of remote-controlled equipment and equipment functionality should be ensured
under severe conditions, including high radiation fields.

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4 – LESSONS LEARNED__/__/2011

The presence of high radiation fields in the plant needs to be considered to ensure manual
actions can be executed under accident conditions.

4 – LESSONS LEARNED__/__/2011

For most severe situations, such as total loss of power or loss of all the engineering safetysystems, the equipment (such as mobile power and water supplies) that is necessary to
manage the accident should be identified. This should be located at a safe place and theplant operators should be trained to use them
External events have a potential of affecting several plants at the same time. This requires
the independence of the safety system. In addition, this requires multiple resources in termsof trained people, equipment, supplies and external support

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Appendix 3

IAEA International Fact Finding Expert Mission of
the Fukushima Dai-ichi NPP Accident Following theGreat East Japan Earthquake and Tsunami
Japan

FINDING SHEETSMonitoring, Emergency Preparedness
and Response

IAEA 2011

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FINDINGS SHEET
Finding Number:

1. FINDING IDENTIFICATION
Assessment Area:
Facility:

A3-01

A3 - MONITORING, EMERGENCY PREPAREDNESS ANDRESPONSE
GENERAL

Unit:
Finding Title:

THE NUCLEAR EMERGENCY RESPONSE SYSTEM IN
JAPAN

2. FINDINGS
2.1 - FINDING DESCRIPTION: BACKGROUND
-

-

-

-

-

The emergency response system in Japan is organized in a three-tier form. The National
Government establishes a Nuclear Emergency Response Headquarters (headed by thePrime Minister), and Nuclear Emergency Response Local Headquarters (headed by the
Senior Vice Minister of METI), prepares national plans and procedures and takes
decisions on important moves and countermeasures. The Local Government operates a
Local Emergency Response Headquarters and is responsible for the implementation of
emergency activities including monitoring, urgent protective actions (sheltering,evacuation, iodine prophylaxis) and long term countermeasures, municipalities also
operate Emergency Response Headquarters. The operator of a nuclear facility (licensee) is
responsible for the on-site emergency response including notification on events to thecompetent minister, to the governor of the prefecture and to the municipalities.
The legal basis of the nuclear emergency preparedness in Japan is the Basic Act on
Disaster Control Measures (related to every type of disasters) and the Act on Special
Measures Concerning Nuclear Emergency Preparedness. The countermeasures are in linewith the Basic Plan of Disaster, which concerns also emergencies different from nuclear
Responsibilities on the governmental level are distributed among several ministries. Thus
METI is responsible for nuclear power plants, fuel cycle facilities and fuel transportation,
whereas MEXT is responsible for research reactors and radiation sources.
During the 11 March earthquake and tsunami the functioning of the emergency
preparedness and response system could not be performed according to the emergency
plans and regulations for the damages caused by the earthquake in the local infrastructure.
Therefore the central headquarter took over certain functions of the local off-site
emergency centre.
There is no formal and legally binding coordination between the responses to various typesof emergencies, although the consequences of the 2007 Kashiwazaki-Kariwa earthquake
event indicated the necessity of such coordination.

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2.2. – FINDINGS AT FUKUSHIMA-DAI-ICHI NPP:
3 –CONCLUSIONS__/__/2011

Japan has established a concise and well organized nuclear emergency preparedness andresponse system. The legal background of the nuclear emergency preparedness andresponse system is sound, the responsibilities are clearly defined. The handling of the
Fukushima accident has demonstrated the capabilities and strength of the Japanese nuclear
emergency preparedness. Nevertheless the system of nuclear emergency preparedness
appears to be complicated in its structure and organization. This may result in unnecessary
delays in taking urgent decisions.

4 – LESSONS LEARNED__/__/2011

Coordination of responses to various types of emergencies may make the protective actions
more effective. Similarly, simplification of the organizational scheme might result inshorter reaction times and smother functioning.
Flexibility and well trained feature of the emergency response system in Japan has made it
possible to reach an effective response even in unexpected situations needing innovative
solutions.

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FINDINGS SHEET
Finding Number:

1. FINDING IDENTIFICATION

A3-02

Assessment Area:

A3 – EMERGENCY PREPAREDNESS AND RESPONSE

Facility:

GENERAL

Unit:
Finding Title:

AUTHORITY, ACTIVITY AND COORDINATION

2. FINDINGS
2.1 - FINDING DESCRIPTION: BACKGROUND
-

-

-

-

-

-

Authority and activity of the various players in the nuclear emergency preparedness inJapan is stipulated in the Act on Special Measures Concerning Nuclear Emergency
Preparedness. The Act defines the roles and obligations of the licensees, and of the local
and national governments
Article 10 of the Act defines the conditions under which the licensee is bound to notify thegovernment and the local authorities on the occurrence of abnormal operational events.
Notification is required if the dose rate exceeds given values in given circumstances or theplant status warrants it. The limiting conditions are given in separate regulations.
Article 15 of the Act defines the conditions under which the licensee is bound to declare
an emergency situation. This is communicated to the national government and the Prime
Minister takes the necessary steps to initiate preventive and response actions. Declarationof an emergency situation is conditioned by the existence of given radiologicalcircumstances or facility states. The limiting conditions are determined in separate
regulations.
In contrast to the practice of some other countries no alert state is defined in the Japanese
nuclear emergency preparedness system and no specific classification of emergencies isdefined. Note also that the notions, definitions and methods of emergency preparedness
and response as recommended by IAEA have found only limited scope application in theJapanese practice.
Coordination of the various players in the nuclear emergency preparedness is defined by
the relevant acts (c.f. A1-06-01). Nuclear facilities bear the sole responsibility for the
emergency response to events in the facility. Nevertheless, actions having impact on thegeneral public (like e.g. venting or water injection in case of the Fukushima accident)
necessitate the approval of higher level response organizations or of the national
government/Prime Minister.
During the Fukushima accident the extreme natural conditions and events have made forthe nuclear emergency preparedness system extremely difficult, sometimes impossible tofollow the well established procedures and practices. In such cases the decision makers
have selected novel solutions in the best interest of the general public, facility workers andenvironment.

2.2. – FINDINGS AT FUKUSHIMA-DAI-ICHI NPP:

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3 –CONCLUSIONS__/__/2011

The authority, functioning and coordination of the various components of nuclear
emergency preparedness and response organizations in Japan have been and are being
demonstrated by the activities in response to the Fukushima accident. Dedicated anddevoted officials and workers, and a well organized and flexible system prevented a stilllarger catastrophe and saved lives among both the general public and the facility workers.
Certain well established techniques, also recommended by IAEA, however, are not in use
in the Japanese nuclear emergency practice.

4 – LESSONS LEARNED__/__/2011

Dedication and devotion of the Japanese emergency response players and their innovative
activity deserve the interest of the international emergency preparedness community.
Use of IAEA guidance on threat categorization, event classification and countermeasures
could make the off-site emergency preparedness and response in Japan still more effective.

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FINDINGS SHEET
Finding Number:

1. FINDING IDENTIFICATION

A3-03

Assessment Area:

A3 – EMERGENCY PREPAREDNESS AND RESPONSE

Facility:

GENERAL

Unit:
Finding Title:

PLANS, PROCEDURES AND GUIDELINES

2. FINDINGS
2.1 - FINDING DESCRIPTION: BACKGROUND---

The activities, duties and actions are described in acts, regulations and manuals of various
levels. No specific national emergency response plan is in use.
The most important requirements related to nuclear emergency preparedness and response
are given in the Act on Special Measures Concerning Nuclear Emergency. It also contains
the essential information, which is included in the national emergency response plans insome other countries.
There exist manuals, commonly compiled by the operators that summarize practicalinformation on the cooperation of various organizations, on preparatory and advisory steps
to assist decision makers. Ministries with various roles in the emergency preparedness
system have specific manuals; the cooperation of the ministries is realized on a working
level. Local level (prefectures, municipalities) plans define the respective duties andactivities.
Licensees have their emergency preparedness plans for every nuclear facility.
No emergency classification system is in use in the sense of the respective IAEA
guidance. A single emergency planning zone has been defined for every nuclear facility;
this is about 8-10 km for a nuclear power plant. Introduction of the notion of Urgent
Protective action planning Zone and the extension of the planning zone to the size asrecommended by IAEA is under consideration.

2.2. – FINDINGS AT FUKUSHIMA-DAI-ICHI NPP:
3 –CONCLUSIONS__/__/2011

Japan relies more on regulations than on nuclear emergency plans in organizing its nuclear
emergency response, this fact, however, seemed not to impede the effectiveness of the
response.

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4 – LESSONS LEARNED__/__/2011

Use of a nuclear emergency planning system as suggested by the respective IAEA
requirements, guides and technical documents may further enhance the capabilities of theemergency preparedness and response organizations in Japan. In this context definition andintroduction of various emergency planning zones and the preparation of emergency
response plans accordingly might reduce the burden on the response organizations in theearly phase of an emergency.

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FINDINGS SHEET
Finding Number:

1. FINDING IDENTIFICATION

A3-04

Assessment Area:

A3 – EMERGENCY PREPAREDNESS AND RESPONSE

Facility:

GENERAL

Unit:
Finding Title:

PROTECTIVE ACTIONS

2. FINDINGS
2.1 - FINDING DESCRIPTION: BACKGROUND
-

-

-

-

-

Rules for protective actions are presented; refer to the administrative
documents/guidelines compiled by NSC. These guidelines give numerical limiting valuesof radiation for sheltering and evacuation, as well as guidance on how to use otherinformation and data
Specifically for evacuation considerations in the Basic Disaster Prevention Plan as well as
the Regulatory Guide: Emergency Preparedness for Nuclear Facilities by NSC are also to
be taken into account
Iodine prophylaxis is to be exercised in case the perceived committed dose exceeds agiven value. This value is unique for all population groups; however the quantity of stableiodine to be administered depends on the age of the patient. Adults over 40 are notsupposed to be involved.
Long term protective actions including food restrictions are regulated in details and take
into account the specific consumption habits in Japan. The action levels are somewhat
different from those generally proposed by IAEA.
Application of Operational Intervention Levels does not appear in the NSC guidelines andis not under consideration either.
The terms of relocation and resettlement are not in use in the Japanese emergency
preparedness practice.

2.2. – FINDINGS AT FUKUSHIMA-DAI-ICHI NPP:
3 –CONCLUSIONS__/__/2011

Application of protective action is properly defined and regulated in Japan. Some of the
IAEA suggested methods are not in use; however, fully equivalent methods are in place.

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4 – LESSONS LEARNED__/__/2011

Consideration on applying Operational Intervention Levels (OILs) for urgent protective
actions is suggested. Application of OILs may ease and make more effective theapplication of urgent protective actions. Revision in line with the IAEA recommendationsof the terms and conditions used for evacuating people from an area might ease the longterm management of the issue.

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FINDINGS SHEET
Finding Number:

1. FINDING IDENTIFICATION

A3-05

Assessment Area:

A3 – EMERGENCY PREPAREDNESS AND RESPONSE

Facility:

GENERAL

Unit:
Finding Title:

PROTECTIVE ACTIONS – IN CASE OF THE FUKUSHIMAACCIDENT

2. FINDINGS
2.1 - FINDING DESCRIPTION: BACKGROUND
-

-

-

-

-

-

All appropriate measures have been taken to save lives. The National Government, the local
government and the operator of the facility promptly took the actions necessary to minimize theconsequences of a nuclear or radiological emergency. Emergency services have been madeavailable to support the response at the facilities and the responders have implemented allpracticable and appropriate actions to minimize the consequences and to protect emergency
workers in accordance with international standards
Urgent protective actions were implemented to prevent to the extent practicable the occurrence ofsevere deterministic health effects and to avert doses. As soon as the Government declared the stateof nuclear emergency on 11 March 2011, radiation monitoring and environmental sampling andassessment have been initiated in order to identify new hazards promptly and to refine the strategy
for response.
On 16 March the local Headquarters instructed the local government that iodine prophylaxis shouldbe performed when the evacuation is ongoing, however by that time the majority of the population
has already left the 20 km area.
Evacuation has been ordered on a gradually increasing area around the Fukushima Dai-ichi power
plant as the situation in the plant aggravated. (For further details on urgent protective actions, see
A1-06-06.)

Agricultural countermeasures and longer term protective measures were taken to avert
doses. In this action the Nuclear Emergency Response Headquarter gave instruction on
restriction of distribution and/or consumption of food on 23 March 2011, in accordancewith the Food Sanitation Act and the Act on Special Measures Concerning Nuclear
Emergency Preparedness. For this decision the standards to be applied have been
determined as late as 17 March, the measurements took two days whereas the decision was
taken in another two days.
Return criteria have so far not been determined, they are expected to be between 1 and 20
mSv/y.
Compensation scheme for the damages has not yet been elaborated, the actual regulation is
not relevant. A provisional guideline to this is expected to be elaborated by July 2011.
Protection of workers and monitoring of contamination are treated in chapter ―RadiologicalConsequences‖

2.2. – FINDINGS AT FUKUSHIMA-DAI-ICHI NPP:

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3 –CONCLUSIONS__/__/2011

Protective actions related to the Fukushima accident proved to be effective and well posed.
Certain delays are to be attributed to the extreme conditions and unusual situations.
Informing the affected population was an important part of the official activity. Exerciseson handling the consequences of multiple disasters have been held in a very limited scope,
yet the actual activities were efficient and saved lives.

4 – LESSONS LEARNED__/__/2011

1.

Organization, discipline and devotion during the response to the largest ever multiple
catastrophes is to be posed as an example to the emergency preparedness and responseorganizations all over the world.

2.

Timely decision making with less players and faster decisions on countermeasures cancontribute to an even more efficient protection of the general public

3.

Exercises and drills assuming multiple catastrophe situations should be included into theemergency exercise programme at sites potentially affected by such events.

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FINDINGS SHEET
Finding Number:

1. FINDING IDENTIFICATION

A3-06

Assessment Area:

A3 – EMERGENCY PREPAREDNESS AND RESPONSE

Facility:

GENERAL

Unit:
Finding Title:

PROTECTIVE ACTIONSACTIONS IN FUKUSHIMA-URGENTPROTECTIVE

2. FINDINGS
2.1 - FINDING DESCRIPTION: BACKGROUND
-

-

-

-

-

-

Notification according to Article 10 of the Act on Special Measures Concerning Nuclear
Emergency Preparedness was sent from the Fukushima NPP to the government and the
local authorities on 15:42, 11 March 2011. The minister of METI had to establish the local
headquarters in 60 minutes.
Emergency has been communicated to the government on 16:36, by 19:03 the national
headquarters reached its active state and declared a nuclear emergency situation
Evacuation of the population in the 2 km radius around Unit 1 of Fukushima Dai-ichi was
decided on 11 March. Normally evacuation decision is based on dose measurements,
however, in this case no reliable measurement was available and the decision was basedon the Unit 1 status (loss of cooling). The same day the radius of the evacuation zone was
extended to 3 km, whereas the next day pressure elevation triggered further extension to
10 km. This is the area of evacuation zone in the emergency plan.
Hydrogen explosion on 12 March lead to the evacuation of residents from the 20 km zone.
On 15 March another explosion struck Unit No. 2 and the residents in the area between 20
and 30 km radii were instructed to stay in-house (sheltering), whereas the same residents
were suggested to take voluntary evacuation.
On 16 March the local headquarters instructed the local government to administer iodine
tablets whenever evacuation is performed. However, by this time the great majority of theevacuation has been completed.
Long term sheltering (―indoors evacuation‖) was in effect for more than a month.
On 23 and 25 March NSC advised the Nuclear Emergency Response Local Headquarters
to implement the survey on thyroid exposure for 1080 juveniles between 0 and 15 years
have measured; in no cases has the 0.2 mSv/h screening level been exceeded. 190 000
inhabitants underwent external contamination measurements, the 100 000 cpm level was
exceeded in 102 times
On 21 April access to the 20 km radius area was prohibited.
Sheltering in the area between the radii of 20 and 30 km has been lifted on 22 April and at
the same time a Deliberate Evacuation Area has been established where there is the threatthat the dose may reach 20 mSv in a year. In such cases the residents are requested toevacuate within one month. The threat was determined from measured and interpolated
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-

dose values. No measured individual data are yet available from these territories. Threeout of the five villages involved have already been evacuated.
Parallel to that an Evacuation-Prepared Area is defined the residents of which need to beprepared for immediate evacuation should another emergency occur.
The facility was little involved in emergency response activities in the classical sense of
the word; its main activity was accident management.

2.2. – FINDINGS AT FUKUSHIMA-DAI-ICHI NPP:
3 –CONCLUSIONS__/__/2011

Unavailability of measurements has resulted in initiating urgent protection action based on
the plant status. The fast changing plant circumstances made it imperative to take several
consecutive measures (mostly evacuations) to protect the residents. Long term sheltering
was not in line with international practice and has been abandoned and the notions of―deliberate evacuation‖ and ―evacuation-prepared area‖ were introduced instead.

4 – LESSONS LEARNED__/__/2011

1. Use of long term sheltering (―in-house evacuation‖) was an unusual and not fully
justified action that will need further analysis in the future.
2. For the sake of a still better organization and efficient functioning of the national
emergency preparedness and response system the facility Emergency Response Teams
should put emphasize on the activities as required by the respective IAEA documents

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FINDINGS SHEET
Finding Number:

1. FINDING IDENTIFICATION

A3-07

Assessment Area:

A3 – EMERGENCY PREPAREDNESS AND RESPONSE

Facility:

GENERAL

Unit:
Finding Title:

ADDRESSING PUBLIC CONCERNS

2. FINDINGS
2.1 - FINDING DESCRIPTION: BACKGROUND---

Public communication is the responsibility of the local authorities. Residents affected by
evacuation have been informed via local loudspeakers, car-messengers and the media. The
central government asked the national and local media to assist in informing the
population. The Prime Minister has called upon the residents via a televised speech.
However, those who were affected the most could not use their television set for lack ofelectricity. Radio proved to be the most efficient means of communication.
Population affected by countermeasures can obtain information and advice from the web
pages of the Japanese Government and the Ministry of Health, Labor and Welfare(MHLW). National medical centres (neurology, psychiatry) are also prepared to advice theresidents affected.
Daily ground monitoring and aerial monitoring results are given to the media and thegeneral public. Translation to English, Korean and Chinese is done as much as possible.
MEXT with JAEA has established a telephone service for the general public on healthconcerns and radiation data. National Institute on Radiation Sciences has established ahotline to respond radiological exposure and health concerns.

2.2. – FINDINGS AT FUKUSHIMA-DAI-ICHI NPP:
3 –CONCLUSIONS__/__/2011

Informing the general public is of primary importance for the Japanese government andlocal authorities. Various means of communication and information are used with success.

4 – LESSONS LEARNED__/__/2011

Open attitude, dedication, factual rightness and sufficient resources are absolutely necessary
to cope with the information needs of the public.

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FINDINGS SHEET
Finding Number:

1. FINDING IDENTIFICATION

A3-08

Assessment Area:

A3 - EMERGENCY PREPAREDNESS AND RESPONSE

Facility:

GENERAL

Unit:
Finding Title:

ADDRESSING INTERNATIONAL CONCERNS

2. FINDINGS
2.1 - FINDING DESCRIPTION: BACKGROUND--

In the early phases of the accident the Japanese Government was not able to supply
sufficient information to the interested international community. It did not want to conceal
anything but had no sufficient information either. E.g. on 4 April TEPCO released low
level radioactive water into the sea, NISA had notified the IAEA before the event,
however, for the fast changes and communication deficiencies the Japanese Government
was unable to provide sufficient information to the neighboring countries. The government
strives for improvements. It has changed its communication, in case of important actions
not only IAEA but also the neighbouring countries are notified.
The government is aware of import restrictions in some countries. It has been providing
explanations on the accident to the diplomatic corps and governments through official
channels. The government understands that the international community has concerns andalso believes that it is important to react using scientific arguments. The government isaware of the fact that Japan‘s inability to provide sufficient information has led to theelevation of restrictions in some countries.

2.2. – FINDINGS AT FUKUSHIMA-DAI-ICHI NPP:
3 –CONCLUSIONS__/__/2011

The Japanese Government strives for open, sincere and complete information of theinternational community. Initial failures had objective reasons and no intention ofconcealing facts has ever occurred to the Japanese officials

4 – LESSONS LEARNED__/__/2011

Information of the general public and especially the international community is a crucial
and very delicate issue in case of a large scale emergency. Information techniques shouldbe elaborated and practiced to cope with this issue.

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FINDINGS SHEET
Finding Number:

1. FINDING IDENTIFICATION
Assessment Area:

A3 – RADIOLOGICAL CONSEQUENCES

Facility:

GENERAL/ FUKUSHIMA DAI-ICHI NPP

A3-09

Unit:
Finding Title:

SOURCE TERM

2. FINDINGS
2.1 - FINDING DESCRIPTION: BACKGROUND-

The knowledge of the radioactive releases to the environment is necessary for the correctunderstanding of the event and for the decision making on countermeasures to protect the
population. The estimation of source term constitutes one the main features in the process
to have a clear estimate of the radioactive releases and to know the behaviour of some
important structures and systems of the plant.

2.2. – FINDINGS AT FUKUSHIMA-DAI-ICHI NPP:-

The current available estimation of the source term was done by NISA (with the support of
JNES) and NSC with the support of JAEA. On 12 April NISA calculated the estimatedvalues for the purpose of rating the event on the INES scale that resulted in a level 7. The
results are presented in the following table:

I-131
…(a)
Cs-137
Converted value
to I-131 …(b)(a) + (b)Assumed amount of the discharge from
Fukushima Dai-ichi NPS
NISA
NSC
Bq
Bq
17
1.3 x 10
1.5 x 1017
15
6.1 x 10
1.2 x 1016
2.4 x 1017
4.8 x 1017
3.7 x 1017

6.3 x 1017

Amount ofdischarge
fromChernobyl
1.8 x 1018
8.5 x 1016
3.4 x 1018
5.2 x 1018

Additionally, TEPCO has estimated that a total amount of 4.7 x 1015 Bq was directly discharged
into the sea as liquid effluents.
All those estimations are found provisional and limited, because they do not consider all the
involved isotopes and the fact that releases have not yet stopped.
The reconstruction of a most realistic source term could include the analysis of the chronologicalevent sequence and real data from environmental monitoring and from meteorological conditions,in an iterative feedback process. This process should consider the dispersion models at different
time and distance ranges. All possible groups of isotopes should be considered in the analysis(Noble Gases, I, Cs, Te, Sr, Pu…), as well as some very indicative isotope ratios (v.gr. Sr-89/Sr-

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90). Differences in isotopic components found inside the Containment Buildings versus thosefound outside could give information on the integrity of the Containment Pressure Vessels during
the discharges.

3 –CONCLUSIONS__/__/2011

The knowledge of the source term involved in the accident is considered of paramount importance toreach a clear understanding of the event and to determine the possible extend of its radiologicalimpact on the public and the environment.

4 – LESSONS LEARNED__/__/2011

International nuclear community should take advantage of the Fukushima accident to improve andto refine the existing methods and models to determine the source term involved in a nuclear
accident and to help decision making in emergency situations.

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FINDINGS SHEET
Finding Number:

1. FINDING IDENTIFICATION
Assessment Area:

A3 – RADIOLOGICAL CONSEQUENCES

Facility:

GENERAL. FUKUSHIMA DAI-ICHI NPP

A3-10

Unit:
Finding Title:

OFF-SITE RADIOLOGICAL CONSEQUENCES.
ASSSESMENT OF PUBLIC DOSES

2. FINDINGS
2.1 - FINDING DESCRIPTION: BACKGROUND--

Assessment of doses to the population is a key factor to conduct a proper management of a
nuclear emergency. This is usually done using Decision Support Systems to predict doses
in different time and distance ranges, while they take feedback from the real data from theenvironmental monitoring. Direct monitoring of exposure to individuals is found crucial
for public confidence.
Regarding the chronological sequence of the Fukushima accident and how radioactive
releases were produced, it was no possible to predict in advance the off-site impact. For
this reason, data from monitoring the individuals and the environment pay a unique role forthe assessment of radiological consequences of the accident.

2.2. – FINDINGS AT FUKUSHIMA-DAI-ICHI NPP:-

Japanese authorities have conducted direct monitoring of persons as well as the results ofthe environmental monitoring to support the assessment of doses. No significant doses
have been concluded as results of the personal contamination measurements.

-

As a result of the accident, significant amounts of radioactive materials were discharged
into the atmosphere, contaminating some areas around the facility. Nevertheless the early
application of the Emergency Plans, such as evacuation (20 Km) and sheltering (2030 km), seems to have prevented significant exposure to the population.

-

Additionally, the authorities have decided to evacuate some towns in the NW area (Planned
Evacuation Zone), beyond the 20 km initial evacuation zone, based on the application of
the 20 mSv-year projected dose criteria (ICRP for relocation) and the real radiologicalconditions (interpolation values were used where no measurements were available).

-

The evacuation of this NW area started several weeks after the accident and has not
finalized yet. Up to now there is not an estimation of real doses received in the Planned
Evacuation Zone, especially taken into account the exposure to I-131 (cloud anddeposition) and not only the deposited long or intermedium lived isotopes (Cs134 and

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Cs137)-For the mentioned purpose, the Japanese authorities have created an especial group in
charged to define and to conduct health surveys and dose assessment of residents,
including those living in the NW area (Planned Evacuation Zone). This group composed by
Fukushima Prefecture and Medical Universities, including Hiroshima and Nagasaki
Universities.

3 –CONCLUSIONS__/__/2011

The proper assessment of doses to population is considered a key issue in the managementof a nuclear emergency, both to give feedback to the decision making process, in order to
optimize protection strategies, and to gain confidence from the public. Additionally, aproper assessment of doses could contribute to define and optimize the strategy for
individual health monitoring. Japanese authorities have conducted direct monitoring of
persons as well as the results of the environmental monitoring to support the assessment ofdoses, and have created an expert group in charged to define and to conduct health surveys
and dose assessment of residents, including those living in the NW area (Planned
Evacuation Zone).

4 – LESSONS LEARNED__/__/2011

Direct monitoring of individual exposure, when possible, and the use of the results of theenvironmental monitoring, could help in achieving a realistic assessment of doses, toenhance the confidence of the population and to determine the individual health tracking
programmes.

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FINDINGS SHEET
Finding Number:

1. FINDING IDENTIFICATION
Assessment Area:

A3 – RADIOLOGICAL CONSEQUENCES

Facility:

GENERAL/ FUKUSHIMA DAI-ICHI NPP

A3-11

Unit:
Finding Title:

ENVIRONMENTAL MONITORING

2. FINDINGS
2.1 - FINDING DESCRIPTION: BACKGROUND-

Environmental radiological monitoring is a key element for the management of a nuclear
emergency, especially in cases with significant radiological releases.
In the Fukushima Dai-ichi accident, the start of the environmental monitoring was delayed
due to the many difficulties found by the Fukushima Prefecture in charge of thismonitoring. Most of the mentioned difficulties were caused by the same original events
that were in the origin of the nuclear accident; i.e. the earthquake, the tsunami and the
SBO. For that reason, at the beginning of the post accidental situation no manyenvironmental data were collected. Only after MEXT became in charge of the monitoring
programme, on 15 March, they started to collect valuable environmental data.

2.2. – FINDINGS AT FUKUSHIMA-DAI-ICHI NPP:-In Japan, the Governments of Prefectures are in charge of emergency environmental
radiological monitoring. After the accident in Fukushima Dai-ichi NPP, the Prefecture of
Fukushima found a lot of difficulties to start the pre-established monitoring programmes,
most of them due to the damages on the equipments caused by the earthquake, the tsunami
and the SBO. As for example, 23 out of 24 monitoring posts were broken down inFukushima prefecture and the off-site centre became not operable.

-

Some actions were adopted to deal with that situation, using monitoring vehicles, but not
many data were collected in the period between the 11 and 15 March.

-

There were not available useful data on environmental monitoring for the evacuation
decision, which was adopted regarding NPP status.

-

On 15 March MEXT became the central agency for environmental monitoring. From 18
March the monitoring has been enhanced and reinforced (aerial, oceanic, land). Some
important support from IAEA and US-DOE contributed to the improvement. Sophisticatedmonitoring equipments are in use (mobile units, aircraft, ships…). The most significant
exposure ways are currently monitored, including land, marine and sky. Monitoring items
include:
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o Dose rate. Fixed post and mobile units, aircrafts and shipso Integrated dose at fixed monitoring postso Radionuclide analyses (mainly I-131 and Cs-137)
 Dust, soil, pond water, weed Drinking water, fallout (47 Prefectures) Sea water and sea bottom soil-

Airborne measurements using aircrafts are conducted in the 80 km environment around theplant. From the obtained data they will decide on extension of the range.

-

Monitoring data were used for the decision on the Planned Evacuation Zone.

-

No summarized maps are yet available for ground monitoring, so far they haveconcentrated on the population. Currently they are in progress to define a mesh and makemapping.

-

The 47 prefectures make measurements every hour and present results to MEXT daily. 54
Universities make measurements. The information is publicly available.

-

A huge effort is being done by the National Government in cooperation with national andinternational specialized institutions to perform an efficient environmental monitoring.
Recently the Government of Japanhas adopted a resolution to strengthen and to optimize
the monitoring capabilities in areas inside the Planned Evacuation Zone (PEZ) and in areas
outside this zone with relatively high dose rates. This includes terrestrial and sea
monitoring.

3 –CONCLUSIONS__/__/2011

Environmental radiological monitoring is a key element for the management of a nuclear
emergency, especially in cases with significant radiological releases.
Environmental radiological monitoring programmes have been enhanced from the
beginning of the event to date. Many difficulties were found to start the pre-establishedmonitoring programmes of local governments, most of them due to the damages on theequipments caused by the earthquake and the tsunami. A huge effort is being done by the
National Government in cooperation with specialized national and international institutions
to perform an efficient environmental monitoring. Recently the Government of Japanhas
adopted a resolution to strengthen and to optimize the monitoring capabilities in areas inside
the Planned Evacuation Zone (PEZ) and in areas outside this zone with relatively high dose
rates. This includes both airborne and sea monitoring.
4 – LESSONS LEARNED__/__/2011

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Results of the environmental monitoring programmes should be useful to give feedback tooptimize the countermeasure strategy and to inform the public.
Emergency environmental radiological monitoring programmes should be defined andexercised in advance (normal conditions) to assure a fast and reliable deployment when an
accident occurs. The design should consider the potential of common cause failures that
could affect the equipments simultaneously with the nuclear accident, such as SBO or
extreme natural events, and the consideration of all resources available at national andinternational levels to deal with such cases.

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FINDINGS SHEET
Finding Number:

1. FINDING IDENTIFICATION
Assessment Area:

A3 – RADIOLOGICAL CONSEQUENCES

Facility:

GENERAL/ FUKUSHIMA DAI-ICHI NPP

A3-12

Unit:
Finding Title:

ON-SITE RADIOLOGICAL CONSEQUENCES. RADIATIONPROTECTION OF WORKERS

2. FINDINGS
2.1 - FINDING DESCRIPTION: BACKGROUND--

Radiation protection of workers in an accident with serious radiological implications, bothon-site and off-site, is a key issue, not only from the view point of preventing radiologicaldiseases to individuals, but to contribute to the proper development of the mitigation
activities on-site. While the radiation protection programme is effective, it will reassure
workers to assume the radiological risks associated to their tasks in a confident atmosphereof protection.
The accident of Fukushima Dai-ichi NPP has challenged the development of a proper
radiation protection programme of workers, due to several facts, such as the damage of thenormal dosimetry system, the loss of dosimeters and especially the extreme radiologicalconditions in some areas of the plant.

2.2. – FINDINGS AT FUKUSHIMA-DAI-ICHI NPP:-

Japanese regulations for Radiation Protection are in line with the recommendations
established by ICRP in publication ICRP-60 (1990). Dose limits for workers are
established in terms of Effective Dose (ED) in 100 mSv for the period of 5 years, with amaximum of 50 mSv in a single year, and for women 5 mSv/3m.

-

For emergency situations predefined individual dose reference levels are used rather thanlimits. At first, an individual dose reference level of 100 mSv was established. After theassessment of the accidental situation, authorities decided to increase the reference level
for individual dose up to 250 mSv ED, for the sum of external and internal exposuresduring the emergency period. This was to permit the needed activities of mitigation in acompatible way with the protection of workers.

-

The operator has established a lesser reference level (200 mSv) to assure the fulfillment of
the one determined by authorities. Internal dose is measured by whole body counter(WBC) for those individuals with external doses above 100 mSv.

-

During the accident the Management system of individual dosimetry became inoperable:

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unable to gather access control information for Radiation Controlled Areas (RCA) and togather personal dose data. Additionally, the Automatic Personal Dosimeter (APD) System
was inoperable and they were unable to use 5,000 dosimeters. At first days, they could
gather only 320 APD.
-

To deal with that problem, they established a provisional approach that included the use ofshared dosimeters for some workers under specific criteria and manual log register ofindividual doses. Gradually situation has enhanced. Now approximately 2,100 APD units
are available.

-

NISA has issued instructions on radiation protection to comply with by TEPCO in thespecific cases of lack of dosimeters and lack of enough whole body counters.

-

Gradually the situation has improved. On 14 April they introduced a simplified access
control system, based on combination of APD and bar-code system. A new system has
been established on 20 May for the management of radiation exposures of workers,
including actions as those defined bellow:
o Management of exposure doses (reporting on some works by TEPCPO to MHLW)o Health checkups establishing a system to connect with individual doses DB
o Introduction of a system to established priorities for the assessment of internal doses,
based on several criteria: accumulated external doses higher than 100 mSv, females
involved in operations and especial cases (injuries, psychological symptoms…)-

Monitoring of dose rates in different areas of the plant is done on a continuous basis andresults are represented in useful radiation maps.

-

Every intervention in RCA is planned. Time of work in RCA for is limited to a maximumof 2 hours for every worker. Gradually especial tools have been introduced to support workin areas with highest radiation levels or serious contamination, such as robots andunmanned equipments.

-

A comprehensive protocol between J-Village and Fukushima Dai-ichi has been established
for a strong coordination of radiation protection controls of all personnel entering the
restricted area and the facility. Around 2,000 workers a day are provided with radiation
protection equipment in J-Village.

-

As for radiation protection of outside workers and first time interveners, TEPCO provides ashort training before entering the NPP on protective clothes, radioactivity and relevant
work processes. J-Village is used for this training. Registration is going on for retroactive
health care.

-

Radiological prophylaxis with Iodine tablets was administered to the personnel working in
the facility first days after the accident.

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-

So far (23 May) 30 workers are over 100 mSv external doses. Until 31 March there were
21 people to receive 100 mSv, the maximum internal dose was less than 40 mSv. Still theyremain concerned and want to do the entire WBC evaluation as soon as possible.

-

The presence of significant amount of very highly contaminated water in some buildings
and trenches continues to be a matter of special concern, both for radiation protection ofworkers and the potential risks of uncontrolled releases to the sea.

-

A number of actions have already been adopted by TEPCO and additional actions areincluded in the recovery road-map for achieving efficient control of the contaminatedwater. In this aim additional consideration should be done to some remarkable matters,such as those presented below:


Minimization of the inventory and production of contaminated water in a way
compatible with the cooling of the Reactors and the Spent Fuel Pools. In minimizing
contaminated water, the final objective should be the establishment of close coolingsystems, and intermediate objectives should consider the reuse and the recycling
contaminated water.



The installation of temporary additional storage and decontamination capabilities
should strengthen the application of specific safety criteria, both to assure highly
reliable and efficient operation of systems and to prevent accidental leaks. The
potential of natural events, such as earthquakes and tsunamis, should be considered in
the design and operation procedures of those systems.

-

At last, TEPCO reported that two workers have received doses that could exceed theestablished reference dose levels (250 mSv) due to exposure to I-131 during the mitigation
activities in Fukushima Dai-ichi. They plan to make an assessment of the internal doses(thyroid gland) received by these workers-

As summary, the established procedures to control the exposure of workers in Fukushima
Dai-ichi NPP seem to be efficient in assuring a high level of protection in a context of
extreme difficulties.

3 –CONCLUSIONS__/__/2011

The established procedures and organizations to control the exposure of workers inFukushima Dai-ichi NPP and J-Village seem to be efficient in assuring a high level ofprotection in a context of extreme difficulties (areas seriously contaminated and very highdose rate levels). A matter of concern is the presence of significant amount of very highly
contaminated water in some buildings.
The individual internal dose controls for all workers are encouraged to be done as soon as
possible, especially for those workers involved in the mitigation activities at the beginningof the accident when releases occurred.

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4 – LESSONS LEARNED__/__/2011

Protection of workers in emergency situations should be considered a key issue to prevent
unnecessary exposures and to support the mitigation activities. In the optimisation process
for exposure of workers in emergency situations consideration should be done to a flexible
application of the dose reference levels and the introduction of practical tools, such as theextensive use of radiological maps of the site or the use of special equipment (robots andunmanned tools). Classification of workers in different groups of risk could help to optimise
the dosimetry and protection resources.
Especial attention should be paid to the outside workers and first responders, in terms ofprevious information and training.
A number of lessons could be learned for the international community from the experienceof Japan in providing large scale radiation protection in response to the accident.

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ANNEXES

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ANNEX I - MISSION PROGRAMME
Tuesday, 24 May 2011:
A.M.: Arrival of experts to Tokyo, Narita Airport, transfer to hotel.
09:00 Briefing and discussion @Main Lobby
12:00 Lunch
13:00 Technical Discussion @Banquet room Prominence (B1 floor) ~18:00
16:40 Transport by bus to METI
17:10 Courtesy visit to Mr Banri Kaieda, Minister of Economy Trade and Industry@Minister Kaieda‘s office (20min)
17:30 Press Contact (doorstep interview) after the courtesy visit (20min)
17:55 Return to hotel by bus
18:10 Working dinner
The room is booked until 24:00
Wednesday, 25 May 2011:08:30 Departure from Hotel ANA by bus
09:00 Arrival at METI
09:00 Technical Discussions @METI conference room (17th floor, Main bldg.)(3h20min)12:20 Lunch (Lunch box)
13:20 Departure from METI
13:50 Arrival at MOFA
13:50 Courtesy visit to Mr Takeaki Matsumoto, Minister of Foreign Affairs, (MOFA)(30min)
14:20 Press contact (Doorstep Interview) (10min)
14:30 Departure from MOFA
14:40 Arrival at NISA/METI
14:40 Technical Discussions @METI (1h20min)
16:00 Departure from METI to the Prime Minister‘s Office (PMO)
16:30 Arrival at PMO
16:30 Courtesy visit to Mr Yukio Edano, Chief Cabinet Secretary (30min)
17:00 Press contact (Doorstep interview) (10min)
17:10 Departure from PMO
17:30 Arrival at MEXT
17:30 Courtesy visit to Mr Yoshiaki Takaki, Minister of Education, Culture, Sports,
Science & Technology (MEXT) (20min)
17:50 Press contact (Doorstep interview) (10min)
18:00 Departure from MEXT
18:10 Arrival at Hotel
18:10 Working Dinner until 24:00
Thursday, 26 May 2011:
07:00 Departure from ANA Hotel
10:00 Arrival at Tokai Dai-ni NPP (Japan Atomic Power Co.)
10:00 Site tour (120min)
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12:00 Departure from Tokai Dai-ni NPP
12:00 Lunch on board
14:00 Arrival at J-Village
14:00 Change clothes ~14:30
14:30 Departure from J-Village by TEPCO‘s bus
15:00 Arrival at Fukushima Dai-ni NPP (Tokyo Electric Power Co.)
15:00 Radiation survey (20min)
15:20 Briefing (30min)
15:50 Plant observation (water intake, heat exchanger building, T/B, R/B from outside)(2hrs 50min)
18:40 Radiation survey (20min)
19:00 Observation of the Joint Conference
19:00 Q&A, Interviews (60min), dinner box (@ TEPCO)
20:00 Departure from Fukushima Dai-ni NPP
20:30 Arrival at J-Village
20:30 Radiation Survey (60min)
21:30 Departure from J-Village
23:00 Arrival and check-in at Hotel Square (Hitachi, Ibaraki Prefecture 0294-22-5531)
Friday, 27 May 2011:
07:00 Departure from Hotel Square Hitachi
07:00 Breakfast on board (snack bought in Tokai Dai-ni)
08:30 Arrival at J-Village
08:30 Change clothes ~09:00
09:00 Departure from J-Village by TEPCO‘s bus
09:30 Arrival at Fukushima Dai-ni NPP (Tokyo Electric Power Co.)
09:30 Radiation survey (30min)
10:00 Briefing, information exchange, interviews, snack lunch (60min)
11:30 Departure from Fukushima Dai-ni NPP
12:00 Arrival at Fukushima Dai-ichi NP
12:00 Plant observation (water intake, other facilities) (2hrs 30min)
14:30 Radiation survey (30min)
15:00 Emergency operation bldg. (seismic isolation bldg.) (30min)
15:30 Departure from Fukushima Dai-ichi NPP
16:00 Arrival at J-Village
16:00 Radiation Survey (60min)
17:00 Departure from J-Village
17:00 Snack on board (bought in Tokai Dai-ni or by stopping at a highway service
station)
20:30 Arrival at ANA Hotel
20:30 Screening at hotel @Banquet room ‗Aurora‘ (B1F)
21:00 Working Dinner room 2400hrs
Saturday, 28 May 2011:08:30 Internal IAEA meeting with experts, split-up into 3 groups (37F, 606, 610)
09:00 Informal technical discussions with Japanese institution @ banquet room ‗Aries‘
(37F)

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12:00 Lunch @Banquet room ‗Aries‘ (37F)
13:00 Informal technical discussions with Japanese institutions @Banquet room ‗Aries‘(37F)
18:00 Finish of discussion
18:00 Team meeting
19:00 Dinner @Banquet room ‗Galaxy III‘ (B1F) –working dinner~24:00
Sunday, 29 May 2011:
09:00 Informal technical discussions @Banquet room ‗Glory‘ (B1F)
12:00 Lunch
13:00 Preparation of Report @Banquet room ‗Glory‘ (B1F)
17:00 Coordination with Admin
19:00 Submitting the draft report to the Government of Japan
19:00 Working Dinner @Banquet room ‗Glory‘ (B1F) ~24:00
Monday, 30 May 2011:
09:00 Departure from ANA Hotel to NISA/METI
09:10 Informal technical discussions
12:00 Lunch
14:00 Review of Report with NISA
18:00 Departure from METI
18:30 Dinner @Hotel, banquet room ‗Glory‘ (B1F)
20:00 Informal technical discussions, review of report
Tuesday, 31 May 2011:
09:00 Departure from ANA Hotel to NISA/METI
09:10 Formal technical discussions, review of Report
12:00 Lunch
18:00 Departure from METI
18:30 Cheese & Wine Reception at Mr Taniguchi‘s
18:30 Dinner @banquet room ‗Glory‘ (B1F)
Wednesday, 1 June 2011:08:30 Departure from ANA Hotel
09:00 Arrival at Prime Minister‘s Office
09:00 Closing Meeting @Prime Minister‘s office
09:30 Press contact: Doorstep interviews
18:00 Hospitalities
Thursday, 2 June 2011:
A.M. Experts return home.

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ANNEX II - LIST OF PARTICIPANTS
A.1

IAEA REVIEW TEAM:TEAM LEADERSHIPMr WEIGHTMAN, Michael William
United Kingdom(Team Leader)

Health and Safety Executive (HSE)
Office for Nuclear Regulation (ONR)
4N.2 Redgrave Court
Merton Road, Bootle
MERSEYSIDE L20 7HS
United Kingdom
Tel: +44 151 951 4168
Fax: +44 151 951 4821
mike.weightman@hse.gsi.gov.uk

Mr JAMET, PhilippeFrance(Deputy Team Leader)

Autorité de Sûrete Nucléaire (ASN)
6 place du Colonel Bourgoin
75572 PARIS Cedex 12
FranceTel: + 33 1 40 19 86 35
Fax : + 33 1 40 19 86 09
Mobile : + 33 6 66 40 09 71
philippe.jamet@asn.fr
INTERNATIONAL EXPERTS

Mr GODOY, Antonio *1
Argentina(Effect of earthquake, tsunami, explosion and aftershocks on SSCs)

Chivilcoy 1178 Castelar (1712)
BUENOS AIRES, Argentina
Tel: +54-11-4627-0762
Mobile: +43 (664) 41 39 328
agodoy@aon.at

Mr GUERPINAR, Aybars *1
Turkey(External Events Assessment)

Tokoglu Mah.
1068 Sok. No. 31
Alacati, CESME, Turkey
Tel: +90 232 7169879
Mobile: +436645385787
aybarsgurpinar2007@yahoo.com

Mr GORYACHEV, Alexander Valentinovich *2
Russian Federation(Spent Fuel Management under severe degradation)

NIIARGroup head, Fuel Research Department
JSC ―State Scientific Center Research Institute ofAtomic Reactors‖
433510 DIMITROVGRAD-10, Ulyanovsk region,
RussiaTel: +7(84235) 65674
Mobile +7 9063943686
Fax: +7(84235) 65663
goryachev@list.ru, jvv@niiar.ru

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Mr CHAI, Guohan *2
People‘s Republic of China(Safety Assessment and Defence-in-Depth)

Chief Engineer, Nuclear and Radiation Safety
Centre, Ministry of Environmental Protection
54 Hong Lian Nan Cun, Haidian District, BEIJING
100082 People‘s Republic of China
Tel: +86-10-8221-2561
Fax: +86-10-6225-7804
chaiguohan@126.com

Ms UHLE, Jennifer *2
United States of America(Severe Accident: Analysis)

US Nuclear Regulatory Commission (USNRC)
21 Church Street, RACHVILLE
MD 20852 USA
Tel: +1-301-251-7402
Jennfer.Uhle@nrc.gov

Mr SUNG, Key Yong *2
Republic of Korea(Severe Accident: Analysis)

Head, Risk Assessment Department
Korea Institute of Nuclear Safety (KINS)
Yousong-ku Kusong-dong 19,
DAEJEON, 305-600
Republic of Korea
Tel: +82-42-868-0158
Mobile: +82-10-8247-4543
k109sky@kins.re.kr

Mr CHANDE, S. K. *2
India(Severe Accident: Management Procedures)

Vice-Chairman,
Atomic Energy Regulatory Board (AERB),
Niyamak Bhavan, Anushaktinagar
MUMBAI
PIN. 400 094, India
Tel: +91-22-2557-4024
Mobile: +91-981-983-2100

vc@aerb.gov.in
Mr LUX Ivan *3
Hungary(Emergency preparedness and response: protective
actions)

Deputy Director General
Nuclear Safety Directorate
Hungarian Atomic Energy Authority (HAEA)
1539 BUDAPEST, P. O. Box 676
Hungary
Tel:+36-1-4364-881

lux@haea.gov.hu
Mr SUMARGO, Dedik Eko *3
Indonesia(Emergency preparedness and response:
governmental infrastructure and communication)

Head for Sub-directorate of Nuclear Emergency
Preparedness
Nuclear Energy Regulatory Agency (BAPETEN)
P.O. Box 400, JI. Gajah Mada No. 8
JAKARTA, Pusat, 10120
Indonesia
Tel: +62 81382198211, +62 2163856518
d.sumargo@bapeten.go.id
de.margo@yahoo.com

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Mr LENTIJO, Juan Carlos *3
Spain(Radiological Consequences)

General Director for Radiation Protection
Consejo de Seguridad Nuclear (CSN)
c/ Pedro Justo Dorado Dellmans, 1128040 MADRID
Spain
Tel: +34-91-346-0622
Fax: +34-91-346-0528
Mobile +34-630-0822-73
jcll@csn.es

INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA) EXPERT TEAMMr LYONS, James Edward

Director
Division of Nuclear Installation Safety (NSNI)
Department of Nuclear Safety and Security
IAEA
Vienna International Centre
P. O. Box 1400, VIENNA, Austria
Tel: +43-1-2600-22520
J.Lyons@iaea.org

Mr SAMADDAR, Sujit Kumar

Head, International Seismic Safety Centre (ISSC)
Division of Nuclear Installation Safety (NSNI)
Department of Nuclear Safety and Security
IAEA
Vienna International Centre
P. O. Box 1400, VIENNA, Austria
Tel: +43-1-2600-22513
S.Samaddar@iaea.org

Mr BRADLEY Jr, Edward Eugene

Nuclear Engineer
Research Reactor Section (RRS)
Division of Nuclear Fuel Cycle and Waste
Technology (NEFW)
Department of Nuclear Energy
IAEA
Vienna International Centre
P. O. Box 1400, VIENNA, Austria
Tel: +43-1-2600-22759
E.Bradley@iaea.org

Ms NAMMARI, Nadia

Project Assistant
Safety Assessment Section (SAS)Division of Nuclear Installation Safety (NSNI)
Department of Nuclear Safety and Security
IAEA
Vienna International Centre
P. O. Box 1400, VIENNA, Austria
Tel: +43-1-2600-25557
N.Nammari@iaea.org

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IAEA PUBLIC INFORMATION TEAMMr WEBB, Gregory Paul

Press and Public Information Officer
Media and Outreach Section
Division of Public Information (MTPI)
Department of Management
IAEA
Vienna International Centre
P. O. Box 1400, VIENNA, Austria
Tel: +43-1-2600-22047
Mobile: 43-699-165-22047
G.Webb@iaea.org

Mr PAVLICEK, Petr

Video Editor/Cameraman
Media and Outreach Section
Division of Public Information (MTPI)
Department of Management
IAEA
Vienna International Centre
P. O. Box 1400, VIENNA, Austria
Tel: +43-1-2600-26390
Mobile: +43-699-165-26390
P.Pavlicek@iaea.org
IAEA LIASION OFFICER

Mr MORITA, Shin

Nuclear Safety Officer
International Seismic Safety Centre (ISSC)
Division of Nuclear Installation Safety (NSNI)
Department of Nuclear Safety and Security
IAEA
Vienna International Centre
P. O. Box 140 0, VIENNA, Austria
Tel: +43-1-2600-22614
S.Morita@iaea.org

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A.2

JAPANESE ORGANIZATIONS

Officials of the GOVERNMENT OF JAPANand governmental advisory committee members,
including from:

Prime Minister‘s Office;Ministry of Foreign Affairs (MOFA);Ministry of Economy, Trade and Industry (METI)

Nuclear and Industrial Safety Agency (NISA);Ministry of Education, Culture, Sports, Science and Technology (MEXT);

Ministry of Agriculture, Forestry and Fishery (MAFF);



Ministry of Health, Labour and Welfare (MHLW);

Nuclear Safety Commission (NSC);



Japan Nuclear Energy Safety Organization (JNES);Japan Atomic Energy Agency (JAEA);Tokyo Electric Power Company Ltd. (TEPCO);Japan Electric Power Company Ltd. (JAPC)The Committee‘s members, academic experts (to be nominated by the Government ofJapan).

PRIME MINISTER’S OFFICE (PMO)Mr EDANO, Yukio

Chief Cabinet Secretary,
Minister of State for Okinawa and Northern Territories Affairs

Mr HOSONO, Goshi

Special Advisor to the Prime Minister

MINISTRY OF FOREIGN AFFAIRS (MOFA)
Mr MATSUMOTO, Takeaki

Minister for Foreign Affairs

Mr MIYAGAWA, Makio

Director General, Disarmament, Non-Proliferation and Science
Department

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Mr KOIZUMI, Tsutomu

Director, Non-Proliferation, Science and Nuclear Energy Division
Disarmament, Non-Proliferation and Science Department

Mr ONISHI, Kazuyoshi

Deputy Director, International Nuclear Energy Cooperation
Division, Disarmament, Non-Proliferation and Science
Department

MINISTRY OF ECONOMY, TRADE AND INDUSTRY (METI)Mr KAIEDA, Banri

Minister for Economy, Trade and Industry

NUCLEAR AND INDUSTRIAL SAFETY AGENCY (NISA)Mr TERASAKA, Nobuaki

Director General

Mr NEI, Hisanori

Deputy Director General for Nuclear Fuel Cycle

Mr BANNAI, Toshihiro

Director, International Affairs OfficeBannai-toshihiro@meti.go.jp

Mr YAMADA, Tomoho

Director, Nuclear Power Licensing Division
Yamada-tomoho@meti.go.jp

Mr MITA, Shunichiro

Senior Safety examiner, Seismic Safety Office
Nuclear Power Licensing Division

Mr SUGIHARA, Yutaka

Safety examiner, Seismic Safety Office
Nuclear Power Licensing Division

Mr YOSHINO, Masaharu

Director for Safety Examination,
Nuclear Power Licensing Division

Mr OHSHIMA, Toshiyuki

Director for Safety Examination,
Nuclear Safety Regulatory Standards Division

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Mr AOYAMA, Katsunobu

Deputy Director, Nuclear Power Plant Aging Management Office
Nuclear Power Inspection Division

Mr TAKASU, Tsuyoshi

Safety examiner, Nuclear Power Licensing Division

Mr MAEKAWA, Yukinori

Director, Nuclear Emergency Preparedness Division

Mr KOSAKA, AtsuhikoDeputy Director, Quality Assurance, Nuclear Power Inspection
Division

Mr NAKAMURA, Koichiro

Deputy Director General for Nuclear Safety

Mr TAKABATAKE, Masaaki

Head of Radiation Group, Emergency Response Centre

Mr ICHIMURA, Tomoya

Head of Coordination Group, Emergency Response Centre

Mr YONEYAMA, Hiromitsu

Chief Nuclear Safety Inspector
Nuclear Power Inspection Division

Mr ONO, Yuji

Deputy Director, Nuclear Safety Regulatory Standard Division

MINISTRY OF EDUCATION, CULTURE, SPORTS AND TECHNOLOGY (MEXT)Mr TAKAKI, Yoshiaki

Minister for Education, Culture, Sports and Technology

Mr SASAKI, Ryuzo

Senior Vice Minister

Mr GODA, Takafumi

Director General, Science and Technology Policy Bureau

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Mr WATANABE, Itaru

Senior Deputy Director General
Science and Technology Policy Bureau
Exec Director for Nuclear Safety
iwatana@mext.go.jp

Mr AKASAKA, Naoaki

Director, Office of International Relations,
Nuclear Safety Division
Science and Technology Policy Bureau
akasaka@mext.go.jp

Mr TANABE, Kuniharu

Deputy Head, Residents‘ Safety Group, Nuclear Sufferers Life
Support Team, Cabinet Office

Mr CHAYAMA, Shuichi

Head of Radiation Group, Nuclear Sufferers Life Support Team,
Cabinet Office

Mr FUKUSHIMA, Yasumasa

Head of Medical Care Group, Nuclear Sufferers Life Support
Team, Cabinet Office

MINISTRY OF AGRICULTURE, FORESTRY AND FISHERY (MAFF):
Mr AKIYAMA, Noritaka

Deputy Director, Food Security Division, Secretariat

Mr ENDO, Hisashi

Director, Ecosystem Conservation Office, Fisheries Agency

Mr MORITA, Takami

Senior Research Coordinator, Fisheries Agency

Mr SATOH, Yuusuke

Fisheries Coordination Division Chief, Fisheries Agency

MINISTRY OF HEALTH, LABOUR AND WELFARE (MHLW)Mr MIYAHARA, Shintaro

Policy Planning Division, Industrial Safety and Health
Department, Labour Standards Bureau

Mr MORI, Tadashi

Industrial Health Division, Industrial Safety and Health
Department, Labour Standards Bureau

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JAPAN NUCLEAR SAFETY COMMISSION (JNSC)
Mr MADARAME, Haruki

Chair

Mr KUKITA, Yukata

Deputy Chair

Ms KUSUMI, Shizuyo

Commissioner

Mr OYAMADA, Osamu

Commissioner

Mr SHIROYA, Seiji

Commissioner

JAPAN NUCLEAR ENERGY SAFETY ORGANIZATION (JNES)Mr NAKAGAWA, Masaki

Director, Emerging Nations Training Centre, Office ofInternational Programmes
Nakagawa-masaki@jnes.go.jp

Mr SAITO, Minoru

Assistant Director General, Nuclear Emergency Preparedness andResponse Division

Mr EBISAWA, Katsumi

Associate Vice President

Mr HAYASHIDA, Yoshihisa

Director, Radiation Safety and Water Chemistry Evaluation
Group, Nuclear Energy System Safety Division

Mr ABE, Hiroshi

Senior Staff, Seismic Safety Division

Mr CHANGJIANG, Wu

Senior Researcher, Seismic Safety Division

Mr SUGINO, Hideharu

Senior Researcher, Seismic Safety Division

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Mr ANZAWA, Tokio

Principal Staff, Nuclear Energy System Safety Division

Mr MOTOHASHI, Shohei

Senior Counsellor, Seismic Safety Division

Mr WATANABE, Atsushi

Senior Staff, Nuclear Energy System Safety Division

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Representatives of Licensees:TOKYO ELECTRIC POWER COMPANY LIMITED (TEPCO)TOKYO HEADQUARTERS

Mr MASUDA, Naohiro

Superintendent, Fukushima Dai-ni NPP
Masuda.naohiro@tepco.co.jp

Mr KAWANO, Akira

General Manager,
Nuclear Power & Plant Siting Administrative Dept.
Kawano.akira@tepco.co.jp

Mr NISHIOKA, Hiroaki

Overseas Business Development Dept.,
International Affairs Dept.
Nishioka.hiroaki@tepco.co.jp

Mr TATEIWA, Kenji

Deputy Manager, Overseas Business Development Dept.,
International Affairs Dept.
tateiwa.kenji@tepco.co.jp

Mr SUZUKI, Akira

Group Manager, Nuclear Power Plant Management Dept.
Suzuki.akilla@tepco.co.jp

Ms KUMANO, YumikoTransport Engineering Group, Nuclear Fuel Cycle Department
kumano.yumiko@tepco.co.jp

Mr ITO, Shinichi

General Manager, Nuclear Power & Plant Siting Administrative
Dept.
Ito.shinichi@tepco.co.jp

Mr MIYATA, KoichiGroup Manager, Nuclear Asset Management Dept.
Miyata.koichi@tepco.co.jp

Mr ONO, MasayukiGroup Manager, Nuclear Quality and Safety Dept.
Ono.masayuki@tepco.co.jp

Mr OTSUKA, Yasuyuki

Deputy Manager, Nuclear Asset Management Dept.
Otsuka.yasuyuki@tepco.co.jp

Mr FUKUDA, Toshihiko

General Manager, Nuclear and Siting Division
Fukuda.toshihiko@tepco.co.jp

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Mr SAKAI, Toshiaki

General Manager, Construction Engineering Center, Construction
Dept.
Sakai.toshiaki2@tepco.co.jp

Mr ASAI, Satoshi

Deputy Manager, Nuclear Asset Management Dept.
Asai.satoshi@tepco.co.jp

Mr MIZUTANI, Hiroyuki

Deputy Manager, Nuclear Asset Management Dept.
Mizutani.hiroyuki@tepco.co.jp

FUKUSHIMA DAI-ICHI NPPMr YOSHIDA, Masao

Superintendent
Yosida.masao@tepco.co.jp

Mr YOSHIZAWA, Atsufumi

Unit Superintendent
Yoshizaawa.a@tepco.co.jp

Mr INAGAKI, Takeyuki

General Manager, Maintenance Dept.
Inagaki.takeyuki@tepco.co.jp

FUKUSHIMA DAI-NI NPPMr MASUDA, Naohiro

Superintendent
Masuda.naohiro@tepco.co.jp

Mr KAWAMURA, Shinichi

Unit Superintendent
Shinichi.kawamura@tepco.co.jp

JAPAN ELECTRIC POWER COMPANY LIMITED (JAPC)Mr ITO, Hiroyasu

Deputy General Manager, Plant Management Dept, Headquarter

Mr KENDA, Hirofumi

Station Manager, TOKAI Dai-ni Power Station

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