Presentation at the Consultion Day event about: Scientific and Technical Platforms / Networks: Achievements and Future Goals during the Global Platform for Disaster Risk Reduction GPDRR 2013 in Geneva

1. Meeting of WA5 (Tsunami Safety Area)
for the IAEA-ISSC EBP
Sentido Zeynep Hotel, Antalya, Turkey
2 May 2013
1
A Proposal of
Tsunami Safety Framework for
Nuclear Power Plants toward Successful
Operation of the ISSC-EBP / WA5
- Integration of Hazard, Design, and PRA -
Hiroyuki KamedaHiroyuki Kameda
Professor Emeritus, Kyoto UniversityProfessor Emeritus, Kyoto University
Technical Counsellor, JNESTechnical Counsellor, JNES

2. Contents
2
(Part I) Reforming WA5
1. EBP steps for tsunami safety
2. Critical needs in the post-Fukushima phase raising
a reform of WA5
3. Reforming WA5
4. WG5-2 outputs
5. Technical resources for WG5-2
(Part II) Some technical elaboration
1. Tsunami resistant technology as bases for design
and fragility assessment
2. Risk-informed decision scheme / Design-PRA
integration

3. 3
1. EBP steps for tsunami safety
(1) Tsunami EBP (April 2007-March 2010)
* Tsunami propagation analysis method – computer code
sharing and benchmark testing
* TiPEEZ system implementation
(Succeeded by ISSC-EBP WA5)
(2) ISSC-EBP (2011 ~ )
- Aug. 2010: Project development at ISSC
- Nov. 2010 : Technical elaboration (1st
Kashiwazaki
Symposium)
- Jan. 2011: Project approval (1st
ISSC-EBP Donor Meeting)
/ WA1 ~ WA10
* WA5 Tsunami Hazard (original form): SR draft on
tsunami hazard assessment / SR draft on tsunami PRA /
Techdoc draft on TiPEEZ application
(Part I) Reforming WA5

4. 4
2. Critical needs in the post-Fukushima phase
raising a reform of WA5
(1) Engineering impacts of the Fukushima accident
- March 2011: Fukushima accident (Great East Japan
Earthquake and Tsunami Disaster)
=> Urgent needs for tsunami design and tsunami PRA
guidelines; those based on tsunami resistant technology
and risk assessment methodology
Tsunami safety assurance is realized by integrating design
(deterministic format) and PRA (systematic treatment of
inherent uncertainties), i.e., their feed-back mechanism.
(2) Needs for reforming WA5
- "Tsunami hazard" => "Tsunami safety"
i.e.; Integration of Hazard-Design-PRA

5. 5
3. Reforming WA5
(1) New framework (approved at Donor Meeting, Jan. 2013)
WA5 Tsunami Safety (Leader: Imamura (Tohoku Univ.) = [The keyword
changed from “hazards” to “safety”]
WG5-1 Tsunami hazard (Leader: Imamura (Tohoku Univ.), Co-leader: Jones
(USNRC), Titov (NOAA)) = [minor change with PRA transferred to the new
WG5-2]
-----------------------------------------------
WG5-2: Tsunami design and PRA (Leader: Kameda (Kyoto Univ.), Co-leaders:
TBD = [newly established]
Task 5.2.1 General decision scheme for tsunami safety
Task 5.2.2 Develop guidance on tsunami design, PRA and integration
Subtask 5.2.2.1 Tsunami design
Subtask 5.2.2.2 Tsunami PRA
Subtask 5.2.2.3 Interaction of design and PRA
Task 5.2.3 Develop safety report on integrated tsunami design and PRA procedures
-----------------------------------------------
WG5-3 TiPEEZ application (Leader: Hatayama (Kyoto Univ.)) = [no change
except WG5-2 => WG5-3]

6. WG5-1 Tsunami Hazard
Leader: Imamura
Co leader Jones(NRC),
Titov(NOAA)
Task 5.1.1 Information Exchange
.1 River run-up
.2 Volcano induced tsunami
.3 land slide ditto
.4 Benchmark
.5 Tsunami PRA
Task 5.1.2 Develop detail guidance
.1 Tsunami hazard assessment safety report
.2 ditto case study
.3 Tsunami PSA safety report
WG5-2 New
Tsunami design and PRA
Leader: Kameda (Kyoto Univ.)
Co leaders: TBD
Task 5.2.1 General decision scheme for tsunami safety
Task 5.2.2 Develop guidance on tsunami design, PRA and
integration
Subtask 5.2.2.1 Tsunami design
Subtask 5.2.2.2 Tsunami PRA
Subtask 5.2.2.3 Interaction of design and PRA
Task 5.2.3 Develop safety report on integrated tsunami design and
PRA procedures
WG5-3 TiPEEZ
Leader: Hatayama(Kyoto Univ.)
Task 5.3.3 TiPEEZ
.1 Application
.2 Tech. Doc on TiPEEZ application
new formation
WA5: Tsunami Safety
6

7. 7
(2) Timeframe
* 2 May 2013: Endorsement at WA5 meeting, Antalya
* 27-28 May 2013: Kick-off of WG5-2, Tokyo
+Decision of the framework details
+Assignment of task-subtask leaders, experts and writers
* WG meetings and consultancy meetings as required
* End of 2013: target of SR (main part) draft completion
* End of 2014: target of SR (supplements added) draft
completion (single volume or separate volumes?)
(3) Future orientations
The reform of WA5 will contribute to the IAEA’s scheme of
site safety against external events by
i) consolidation with other external event PRAs (dealt with
in WA2, 7 and 8), and
ii) providing substantial technical information for the Safety
Guides relating to site evaluation (SSG-18), design (NS-G-
1.5) and safety assessment (SSG-3 and 4).

8. 8
4. WG5-2 outputs
(1) Information exchange and context developments
Task 5.2.1 General decision scheme for tsunami
safety
Task 5.2.2 Develop guidance on tsunami design,
PRA and integration
Subtask 5.2.2.1 Tsunami design
Subtask 5.2.2.2 Tsunami PRA
Subtask 5.2.2.3 Interaction of design and PRA
* Drafting of SR chapters to be undertaken within
the Task-Subtask activities.

9. 9
(2) Safety report
Task 5.2.3 Develop safety report on integrated
tsunami design and PRA procedures
* Outline of the Safety Report (tentative)
“Integrated Tsunami Design and PRA
Procedures for Nuclear Safety”
+ Executive statements (IAEA format)
1. Introduction
2. General decision scheme for tsunami safety of
nuclear installations
3. Tsunami design
4. Tsunami PRA
5. Interaction of design and PRA
6. Conclusions
+ (Appendix)

10. 10
(1) Resources from Japan
- NRA: -Basic Concept- “New Regulatory Standard Related
to Earthquakes and Tsunamis for Light Water Nuclear
Power Reactor Facilities” (April 2013: English translation
underway / final full version by July 2013)
- NRA-JNES: Safety Review Guide / Construction Permit
Review Guide (supporting documents for the new
regulatory standard / April 2013)
- JNES: (developments of tsunami design guideline (2012~ )
and tsunami PRA (2007~ ) )
“Guidelines for Structural Design and Risk Evaluation
against Tsunamis” (to be published in June 2013: English
translation underway)
5. Technical resources for WG5-2

11. 11
- JEA (Japan Electric Association): “Technical Guideline for
Tsunami Design of Nuclear Power Plant (Tentative)” (to be
published in 2013)
- JAEE (Japan Association for Earthquake Engineering)
Committee on Tsunami Resistant Technology for Safety of
Nuclear Power Plants (2012-2014)
(2) Resources from USA, Europe, Turkey, etc.
- USA
- Europe
- Turkey
- Other MSs
* Participation in WG5-2 has been proposed by China,
Finland, France, Japan, Korea, Pakistan, U.S.A.

12. 12
1. Introduction
2. Fundamentals of earthquake-tsunami engineering for nuclear safety
3. Accident scenarios at NPPs under earthquake-tsunami actions
4. Performance criteria for nuclear safety under earthquake-tsunami
5. Risk-based earthquake-tsunami protection scheme for nuclear safety
6. Load effects and actions of tsunamis on NPPs
7. Engineering framework for tsunami protection of NPPs
8. Fragility assessment
9. Relevance to disaster reduction including external zones
10.Computer codes for tsunami analysis
11.Framework of tsunami resistant technology
12.Summary and conclusions
1. Tsunami resistant technology as bases for design
and fragility assessment
(Part II) Some technical elaboration
(1) JAEE Committee on Tsunami Resistant Technology for
Safety of Nuclear Power Plants (2012-2014)

13. 13
(2) Load effects and actions of tsunami
1) Inundation height
Inundation at Fukushima I NPS (by TEPCO)
Fukushima I NPS (Unit 1) Onagawa NPS (Unit 2)

14. 14
2) Hydrodynamic forces (impulsive, sustained in push-pull)
Destroyed sea wall gate (Miyako) Bent steel pillars (Onagawa)
Tsunami wall across Fudai River
3) Scouring
Seawalls toppled due to scouring

15. 15
4) Buoyancy and uplift 5) Seawater intrusion through
unanticipated paths
Heat exchanger room at Onagawa NPS
RB basement (by Tohoku EPCO)
6) Debris (particularly,
fine sea sand immixed
in seawater)
* Destroys active equipments
(shaft bearings of motors,
generators, turbines, etc.)
inundation depth

16. *Eliminate "cliff-edge" effects through "smooth fragility"
and/or "safe relocation".
16
(3) Key issues in design and fragility assessment
* Vulnerability of electric devices to water intrusion (switch
boards, motors for seawater pumps, cables, instrumental
sensors, data transmission devices, etc.) should be
drastically improved.
Enhancementof fragility

17. 17
2. Risk-informed decision scheme
/ Design-PRA integration
(1) Critical lessons from the Fukushima accident (Kameda, 2011)
1) Risk-informed decision should be the basis of nuclear safety
measures: Lack of beyond-design tsunami protection was a major
cause of the accident at Fukushima-I. This requires risk-based
scheme, or risk-informed decision.
2) “Scientific imagination” should be a key for establishing risk
models: Historical high have been too widely used in hazard
assessment. Extreme events with very long return periods should
be incorporated in risk modeling if no historical data but sound
scientific bases. There are evidences.
3) Speed in action is critical: The nature does not wait for us. /
i) The case of Tokai II NPP should be positively highlighted
where construction of new side walls with increased height (7m)
to enclose sea water pump areas, nearly completion at the time of
the Great Tsunami, protected the ultimate heat sink function. / ii)
Delay of implementing risk-informed decision should be critically
reviewed.

18. Scheme of seismic/tsunami safety assurance of NPP
inter-
connected
* Quantitative safety assessment of the
entire plant system
(relative to safety goal/ performance goal)
Accountability
to the public
・ Basic safety level (Design point) assured explicitly
* Benchmark assurance by seismic/tsunami design
Deterministic format
* Residual risk assessment
[Seismic/Tsunami PRA]
・ Assurance of low "Residual risk" as
seismic/tsunami margin of the entire plant
system in beyond-DBGM/DBTH ranges
Fragility
・ Design margin as realistic failure point of
individual SSC's relative to design level
* Design margin assessment of SSC
Probabilistic assessment
Note: SSC = structure, system, component
DBGM = design basis ground motion / tsunami height
"Failure" here means functional loss as well as structural failure
hazard level
probabilitydensity
DBGM
DBTH
* covered by "residual
risk" assessment
(entire plant system)
core damage frequency
(residual risk)
* covered by
seismic/tsunami
design
(benchmark
assurance)
* covered by design margin
assessment (SSC)
hazard curve density
(times/Gal ・
yr)
core damage prob. dens.
(times/Gal ・
yr)
PRA, fragility
(2) Risk-informed decision
Hiroyuki Kameda (Kyoto U., JNES)

19. 19

20. 20
(3) Required regulatory framework (Total Process)

21. Management
category
Risk stages in nuclear safety assessment and
SA management requirements
(Japanese trend, April 2013)
Core damage
Frequency
(CDF)
Container
functional failure
Frequency
(CFF-1)
FP control failure
Frequency
(CFF-2)
Status
Occurrence
rate (/yr)
FP release
Design point
* SA mng. II-IV parts conform with NRA’s “Schematic illustration of FP release relative
to occurrence rate” (3 April 2013).
* CDF, CFF-1 and CFF-2 correspond, respectively, to the context of Performance
goal-1, Performance goal-2 and Safety goal.
* Performance goal-1 and Performance goal-2 must be jointly realized (NSC, 2008).
Core damage Controlled release
Uncontrolled
release
Public exposure
Normal operation
Safe shutdown
Prevention /
SA mng. II
(container
functional failure )
Prevention /
SA mng. III
(large scale release )
ll
(container damage )
Mitigation /
SA mng. IV
(diffusion )
Prevention /
SA mng. I
(core damage )
Design
(benchmark assurance)
(Design margin)
100TBq (Cs137
)
H. Kameda and K. Ebisawa, v2: 130427
10-4
10-5
10-6
Design
implications

22. 22
+Key safety parameters:
1) Design point to define benchmark assurance,
2) Design margin of SSC to clarify their beyond-
design capacity, and
3) Residual risk to define design margin of the entire
plant system
+These parameters are connected consistently through
fragility concepts and PRA integration.
(4) Scope of integration of design-PRA interaction in
WG5-2
+ Treatments depending on tsunami hazard levels (high,
moderate, low)

23. Conclusions
23
(Part I)
* Reforming WA5, approved at the Donors’ Meeting
in March 2013, was presented for developing a
consensus among all WA5 members.
* Motivations, expected outputs and anticipated
resources were discussed.
(Part II)
* For technical elaboration, perspective to tsunami
resistant technology developments, and design-
PRA integration for risk-informed decision
scheme were proposed