International Workshop on Recent Advances in Seismic and Fault
Displacement Hazards Assessment for Nuclear Installations
18-21 June 2024, IAEA Headquarters, Vienna, Austria
Keynote Lectures on Regulatory Challenges and Changes in the Practice after
the 2011 Fukushima Nuclear Accident (Tuesday, 18 June 2024, IAEA, Vienna)

Recent Nuclear Regulations, Reevaluations, and Backfits in Japan to
Cope with Natural Hazards
Akira Ishiwatari, Commissioner
Nuclear Regulation Authority (NRA), Japan
1

Contents

page

Introduction (my experience of 2011 Earthquake-Tsunami) 3
NRA’s New Regulations after Fukushima Nuclear Accident 8(1) Tsunamis(2) Capable Faults(3) Earthquakes(4) Volcanic Activities
NRA’s Recent Backfits to cope with Natural Hazards
22(1) Volcanic Ash Density in the Air(2) Volcanic Ash Thickness at NPP sites(3) Tsunamis coming without Warning(4) Standard Spectra for ‘Everywhere Earthquake’
Other improvements: (5) Slope Set-Back for Landslide(6) Barrier for Tsunami Back Flow (retreating current)
Recent Topic (Noto Earthquake) / Conclusions
37/40
2

Introduction: Mar. 11, 2011 East Japan (Tohoku) Earthquake
Mar. 11 to May 7, 2011

Focal distribution of aftershocks in 12-19 Mar. 2011.
Size of the circle indicatesmagnitude, and its color
signifies focal depth.

★ Mainshock(M9.0)

TohokuSendai★

A, B, C, D
“Induced “earthquakes
V
Volcanic
earthquakes

Tokyo

Bosai.go.jp/info/saigai/2010/pdf/20110323_01.pdf
Japan Meteorological Agency:1104tohokuoki.pdf

3Rice paddies inundated by March
11, 2011 tsunami in Sendai City,
Tohoku, Japan (Photos taken on
March 27, 2011 by Ishiwatari）.
[Below] Cemetery attacked bytsunami with drifted debris.
Gravestones may have been fallen
down either by earthquake or bycrash with tsunami debris.

4

Cemetery of Koganji Temple in Otsuchi Town attacked bytsunami fire (Photos taken on July 31, 2011 by Ishiwatari)

Tsunami-devastated town

Destroyed steel-made building

Tsunami-devastated cemetery

No damage in the up-hill area
55

Kadonowaki Primary
School of Ishinomaki City
was burnt by tsunami
fire. Gravestones in theadjacent Saikoji Temple
were rounded bytsunami fire (Photos
taken on Aug. 16, 2011)

6

Distribution of environmental radioactivity (μSv/h)within 80 km from the Fukushima Daiichi NPPs
Dec. 2011by MEXT

Oct. 2022
by NRA

Pacific
Ocean

7

NRA as an independent regulator
To reflect lessons learned from the TEPCO’s Fukushima Daiichi NPS accident, relevant
authorities were integrated as an independent commission (Nuclear Regulation Authority) in
September of 2012.

Promotional

RR: Research Reactors
RI: Radioisotopes

8< After the accident>
Intentional aircraft crash
Suppression of radioactive
materials dispersion

Prevention of CV failure< Before the accident>

Prevention of core damage

Design basis（Based on single failure, etc.)

Internal flooding (NEW)Natural hazards(NEW: Volcano, Tornado, Forest fire, etc.)

Fire protection

Fire protection

Reliability of power supply

Reliability of power supply

Performance of other SSCs

Performance of other SSCs
Seismic/Tsunami resistance(New: Explicit regulation on tsunami)

NSC: Nuclear Safety Commission

Reinforced

Seismic/Tsunami resistanceAccording to the previous 2006 NSC standards, tsunami
hazard was treated as events accompanied with earthquakes
and considered as a part of seismic design.

Reinforced andNEW

Natural hazards(SA Measures)
NEW

Outline of NRA’s enhanced
regulatory requirements

Reference: NRA HP
The 13th NRA Commission Meeting (3 July 2013)
Reference materials (partially modified)
http://www.nsr.go.jp/committee/kisei/data/0013_08.pdf

9Regulatory requirements against natural hazards
NRA regulatory requirements, established after the TEPCO’s Fukushima Daiichi
Nuclear Power Station accident, require that safety-related SSCs maintain theirfunction against the following external natural hazards:➢ Earthquakes➢ Tsunamis➢ Capable Faults

Relevant topics of thispresentation➢ Volcanoes➢ Lightning➢ Biological phenomena➢ Forest fires➢ Landslides➢ Tornadoes➢ Wind (typhoons)➢ Floods➢ Precipitation➢ Freezing➢ Snow fall
(Underline: Hazards explicitly included in NRA’s
requirements but not addressed by the former
regulator.)

Solar flares may also be a natural hazard for NPPs

10

(1) Tsunamis• Define “Design Basis Tsunami” that exceeds the largest in
the historical and archeological records• Requirements for multiple protective measures
Preventing inflow(High-level seismic design)

Limiting theinundation area

Input
▼Tsunami
Seawalls
Tsunamimonitoring
equipment

Watertightdoors▼Design Basis Tsunami(at X kmoffshore)▼Normal level

Water supply for cooling must be available even in caseof lowered water level at tsunami withdrawal.

11
5

Mar. 11 Tsunamis at NPPs of Japan
NPP

Tsunami Height(Mar. 11, 2011)

Input Tsunami(before Mar. 11)

Input Tsunami(after Mar. 11)

Higashidori

4 m [13 m]

6.5 m

11.7 m*Onagawa*

13 m [15 m]*

9.1 m

23.1 mFukushima Daiichi**

15 m [10 m]

5.4 – 5.7 m

14.9 m** (22.6m)***Fukushima Daini**

15 m [12 m]

5.1 – 5.2 m(27.5 m)***Tokai*

5 m [8 m]

5.7 m

17.1 m[ ] Site elevation
Site caused severe*Site subsided 1 m
accidentby the earthquake
Site affected by(Elevation was 14
tsunami*Passed re-evaluation m at tsunami input)**On decommissioning*Currently under re-evaluation**Tsunami from Kuril Trench. Sea wallof 13.5 to 16 m high was alreadyconstructed by March 2024.
***Proposed by TEPCO as the highest
tsunami for future consideration

Data from various sources (Credit: A. Ishiwatari)

127

(2) On-Site Capable Faults• “Capable faults” need to be determined as those whose activities
since the late Pleistocene (approx.120,000 to 130,000 years ago orlater) cannot be denied• Important facilities have to be constructed on the ground without
outcrop of capable faults
Important facilities：for“Shut-down, Cooling,
and Containment”

Risk of loss of safetyfunction by the damageof the buildings andequipment

Movement of afault

○Movement of the fault under important facilities like Reactor Building may result in
the concentration of deadweight onto the spot and cause damage of the building.
○Even in case damage of the building is avoided, safety function can be lost due to thedeformation of the facilities or damages of the internal equipment.
https://www.nsr.go.jp/data/000070101.pdf (2013)813

How to find a capable fault?
1. Covering Bed Method
Geologicalage of bed

younger“Capable fault” is the official term for “active
fault” that is defined in IAEA Safety Standards
Series No. SSG-9 “Seismic hazards in site
evaluation for nuclear installations”. The “120130 ka” is the base age of Upper Pleistocene.

120-130
thousandyears(ka)olderJudge:

Capable Fault

2. Mineral
Vein Method120-130 ka
mineral vein or
igneous dike

Capable Fault
CapableFault

Not Capable Fault
Not Capable
Fault

14
9

Mineral veins cutting fault zones (Sendai NPPs)
D-45 fault zone is cut by a quartz vein (p.109)

D-48 fault zone is cut by a calcite vein (p. 117)

Crossed polarizers view

Single polarizer view

Polarizing microscope viewsof about 1 mm width

Mineral vein & Fault zone

Sketch of the view

Mar. 19, 2014, Assessment Meeting #95 Mineral veins are of 1
to 3 million years age.
Doc. 2-1, Sendai NPPs (Kyushu EPC)

15

On-Site Fault Evaluaion

Current Status

Capable Fault?

Tomari 1, 2 & 3 (PWR)

On Re-Evaluation

No (covering bed method)Oma 1 (ABWR, on construction)

On Re-Evaluation? (covering bed method)

Higashidori 1 (BWR)

On Re-Evaluation

No (mineral vein method)*

Rokkasho (Recycle Facilities)

Passed Re-Evaluation

No (covering bed method)

Onagawa 2 (BWR)

Passed Re-Evaluation

No (mineral vein method)

Tokai Daini 1 (BWR)

Passed Re-Evaluation

No (covering bed method)

Kashiwazaki 6 &7 (ABWR)

Passed Re-Evaluation

No (covering bed method)

Hamaoka 4 & 3 (BWR)

On Re-Evaluation? (covering bed method)

Shika 2 (ABWR)

On Re-Evaluation

No (mineral vein method)*

Tsuruga 2 (PWR)

On Re-Evaluation

Yes (2015 assessment)**

Mihama 3 (PWR)

On Operation

No (mineral vein method)

Ohi 3 & 4 (PWR)

On Operation

No (covering bed method)

Takahama 1, 2, 3 & 4 (PWR)

On Operation

No (mineral vein method)

Shimane 2 (BWR) & 3 (ABWR, o.c.)

Passed Re-Evaluation

No (mineral vein method)

Ikata 3 (PWR)

On Operation

No (mineral vein method)

Genkai 3 & 4 (PWR)

On Operation

No (covering bed method)

Sendai 1 & 2 (PWR)
On Operation
No (mineral vein method)*Evaluation changed by new data. **NRA’s conclusion may be reached in July 2024.

16
11

NRA Categories ofEarthquakes:
Realistic Design Basis Ground Motion (DBGM) Specified Faults(Identified capable
faults):• Survey 3D geological structure of the site 1. Plate Boundary
2. Intra-Plate• Take into consideration of seismic ground 3. In-Land Crustal
Unspecified Faults
motion predication(“Everywhere
Earthquake”):
1. 2004 Rumoi
Seismic
Engineering Basement (Vs>0.7km/s)
Mw5.8
DBGM is set
2. Standard
at this depth
Spectra Mw<6.5
Seismic Basement (Vs>3km/s)
3. 2000 Tottori W
Mw6.7 (local)
4. 2008 Iwatehypocenter
Miyagi Nairiku
Unique underground structure to amplify theMw6.9 (local)
ground motion(3) Earthquakes

https://www.nsr.go.jp/data/000070101.pdf P.14 (2013)17
12

Sites experiencing earthquakes with strong motions
larger than the old DBGMs3)(gal = cm/s2)
NPP site

Earthquake
Name

Date

Magnitude
Mw

PGA
basematDistance
to siteCredit: NRA
Operation
StatusOnagawa

Miyagi-Oki
earthquake

August 16,
2005

7.1

316 gal 1)

84km

SCRAM at Units#1, 2, 3

Shika

Noto Peninsula
earthquake

March 25,
2007

6.7

226 gal 1)

18km

Under periodical
inspection

Kashiwazaki-Kariwa

Chuetsu-Oki
earthquake

July 16,
2007

16km

SCRAM at Units #3, 4,
7. Others; underperiodical inspection

Onagawa

Tohokuearthquake

March 11,
2011

125km

SCRAM at Units #1 &3. Unit 2 was underperiodical inspection

Fukushima
DaiichiTohokuearthquake

Onagawa

Miyagi-Oki
earthquake

6.6

680 gal 2)

9.0

607 gal 2)

March 11,
2011

9.0

550 gal 2)

180km

SCRAM at Units #1, 2,
3. Others: underperiodical inspection

April 7,2011

7.1

398 gal 1)

78km

Under periodical
inspection

1) Response spectra exceeded the design basis ground motion (DBGM, Ss or S2) at some periods
2) Peak ground acceleration (PGA) and response spectra (at some periods) exceeded the DBGM (Ss or S2)
3) Design basis ground motions (DBGMs) before and after the March 11, 2011 Tohoku Earthquake (at 50 Hz):
Site
Onagawa
Shika
Kashiwazaki-Kariwa
Fukushima-Daiichi
Before 580 gal
600 gal450 gal*
600 gal (*Before back check)
After
1000 (intra-plate)
1000 (on evaluation)
1209-2300
900 (for consideration)
184) SCRAM threshold ground acceleration at Kashiwazaki-Kariwa: horizontal =120-185 gal, vertical = 100 gal

Near-Site Capable Faults and Earthquakes
Example of Sendai NPPs, Kyushu
Kumamoto
NagasakiSendai NPPs

Kagoshima

Kyushu EPC’s evaluation of
Futagawa-Hinagu Fault is
93 km long and M8.1,
assuming a full-length rupture.
Equivalent epicenter distancefrom Sendai NPPs is 104 km.
The Futagawa-Hinagu
Fault caused M7.3
Kumamoto earthquake
on Apr. 16, 2016 andassociated numerous
disastrous earthquakes.
(Mar. 12, 2014 Evaluation
Meeting #92. Copyright:
Kyushu EPC)
19

2016 Kumamoto Earthquake

Surface Fault Rupture:
Futagawa: 28 km
Hinagu:6 km

Apr. 14, M6.5 and Apr. 16, M7.3; 50 deaths,>2,000 injuries and >180,000 evacuees.
50 km
Epicenter ofMain ShockBeppu-Haneyama Fault

Fault Length bySatellite-based Ground
Movement:
Futagawa E: 5 km
Futagawa W: 20 km
Hinagu:10 km(Data from Japan
Meteorological Agency)

Futagawa Fault
Kyushu EPC’s
evaluation of the
Futagawa-Hinagu Fault
in the Sendai NPP
Reassessment:
93 km, M8.1
Hinagu Fault

Sendai NPP

Japan Meteorological Agency

20

(4) Volcanoes
The licensee should survey Quaternary volcanoes within 160 km from the NPP,
and assess their eruption histories, geothermal activities, distribution of lavas,
pyroclastic flows and ash.
Evaluation of
If a pyroclastic flow
reached the NPP site
in the geologic past,
the licensee should
give geophysical evidence for improbabilityof caldera eruption in
decades and should
conduct seismic andgeodetic monitoring of
the caldera volcano.
This is the case for
Sendai and Genkai
NPPs and Rokkasho
Recycle Facilities.

R=160 km area

Aso

Kirishima
Sendai NPP
Aira
Ata
Quaternary
volcanoCaldera(not to scale)

Kikai(Apr. 23, 2014 NRA Evaluation Meeting #107)

volcanic ash
Thickness
Ash
NPP
thickness
Sendai15cm**Ikata
15 cm
Takahama 10 cm*
Ohi
10 cm*
Mihama 10 cm*
Tokai Daini 50 cm
Shimane 56 cm*see later backfit**25 cm after 2020
Final Safety Analysis Report of
Kyushu EPC
21

Backfits/Improvements to cope with Natural Hazards:
2017
2021

2017

2019

2023
2021

(1)Higher volcanic ash density in the air (for all sites)
Add a filter unit for aspirators of diesel generators.
(2) Thicker volcanic ash fall (for 3 sites of KEPCO)
The facilities should keep their function to theash thickness about 2 times of the previous value.
(3) Sudden tsunami without warning (for 1 site of KEPCO)
Tsunamis caused by landslides or volcanoes may comewithout warning. Sensitive sea-level observation andtighter operation of water gates are required.
(4) Application of the standard spectra of earthquake byunidentified fault (for all sites) applied in addition toprevious “Rumoi Earthquake”.
Other improvements:(5) Slope set-back in the TEPCO Fukushima Daiichi site
(6) Barrier for tsunami back flow in the JAEA Tokai site
22

Backfit (1): Higher volcanic ash density in the air
In 2013-14, during the first evaluation process to fit NRA’s
new regulation rule, the licensee (Kyshu Electric Co.) took theobserved 3 mg/m3 ash density in the air at 2010 eruption of
Eyjafjallajokull Volcano, Iceland (VEI=4) to keep operation of
their emergency diesel generators.
In 2016, another licensee (Kansai Electric Co.) took the 33
mg/m3 ash density observed in 1980 at Yakima that is 135 km
from the St. Helens Volcano, USA. (Baxter et al. 1983;
Archives of Environmental Health, 38, 138-143)
In 2016, Hattori et al. (Central Research Institute of ElectricPower Industry Report 015004) calculated the ash density inthe air in Tokyo by the 1707 Hoei eruption of Mt. Fuji as highas 1000 mg/m3.
23

The Hoei Crater by 1707
eruption of Mt. Fuji

Backfit 1: Higher
volcanic ash
density in the
air: example of
Mt. Fuji in 1707

Ash Thickness by 1707
Eruption of Mt. Fuji
Based on Volcanic Hazard
Map of Mt. Fuji
Photo taken by A. Ishiwatari

Tokyo

Chiba

Yokohama
https://www.bousai.go.jp/kazan/fuji_map/pdf/fujihm_ir_hr.pdf

Yokosuka24The 1707 Hoei volcanic
ash layer (top >1 m)
that covers eastern
foothills of Mt. Fuji
(Midono, Gotemba City)

Photo taken by A. Ishiwatari

In the 1707 eruption, white ash
came first, and thick black ash
followed. This suggests
magmatic evolution in the
deep magma chamber, andsimilar explosive eruption is
expected for the next time. 25

Calculation of volcanic ash density in the air: an example

Average ash density in the air (g/m3)
16
12
8
4
0

Deposited volcanic ash thickness: 15 cm
Ash size distribution (4 cases):

Case 3 (small grain)

Report of the NRA examination team forassessment of volcanic ash fall (June 22, 2017).

Notes on cloud and health:
Water particle density of a cloud (or thickCase 1 (big grain)fog) is about 100 mg/m3. Volcanic ash
denser than 150 mg/m3 causes heavy0
12 24 26 48
damage for human respiratory system
Time span of ash fall (hours)(Mckie et al. 2017 “Volcanic Ash”, Elsevier).
Note on international air traffic regulation:
26>0.2mg/m3: Caution notice issued, >2mg/m3: Flights permitted forlimited time and airplane types, >4mg/m3: All flights prohibited.

Backfit (2): Thicker volcanic ash fall (for 3 sites of KEPCO)
Volcanic ash thickness evaluated for KEPCO’s Takahama, Ohi and Mihama NPPs
was 10 cm when these NPPs passed re-evaluation in 2015-2017. NRA-fundedstudy of AIST revealed that the Namatake ash bed of the Daisen Volcano is as
thick as 30 cm in Koshihata to the west of Kyoto. The ash thickness to copewith is 27 cm for Takahama, 25cm for Ohi and 22 cm for Mihama as fixed in 2021.

Daisen Volcano(Not active)

Daisen Namatake Tephra (erupted 80 thousand years ago)

KEPCO NPPs

MihamaTakahama
Ohi

Kyoto

Koshihata
Jan. 24, 2020, NRA Evaluation Meeting #827, Book 1-1-1, p. 16, KEPCO

27

Backfit (3): Tsunami coming without warning On Dec. 22, 2018, Anak
Takahama NPP

200m

Water Gate

Krakatau Volcano ofIndonesia erupted andlarge tsunami attacked
coastal areas, caused>400 deaths. Thistsunami came without
warning. Takahama NPP
was not prepared forsuch tsunami coming
without warning, and
NRA ordered backfit in2019.

Possible submarine landslides
in Japan Sea to cause tsunamis

Takahama NPP

50 km

28

Backfit (3): Tsunami coming without warning 2
Takahama NPP

Sea level change of more than 50 cm within 10 minutes
is identified as tsunami arrival and the water gate should be immediately closed.

29

Backfit (4): Standard Spectra for Diffuse Seismicity

pSv(Everywhere Earthquake)➢ Design Basis Ground Motions (DBGMs) are developed from both the identified andunidentified seismic sources (the latter known as diffuse seismicity in IAEA’s SSG-9).
➢ Licensees employed 2004 Rumoi Earthquake for the diffuse seismicity in 2013. NRA
requested them to analyze 13 earthquakes (Mw5.0-6.2), but they did not give any result.
➢ In 2017, the NRA set up the Study Team on Evaluation for Ground Motions without
Identification of Seismic Sources.
➢ After 11 meetings held in 2018 and 2019, the Study Team proposed the Standard Spectra
for ground motions without identification of seismic sources (with Mw below 6.5).
Pseudo-velocity (pSv) response spectra➢ In April 2021, the NRA decided to include theControl points
Standard Spectra into its regulatory
Damping h=5%
Periodrequirements. The utilities are requested to
Horizontal
take into account the Standard Spectra andVertical
to update their DBGMs, if necessary, in
addition to the previous Rumoi Earthquakeof Hokkaido (Dec. 14, 2004; Mw5.8).
Standard Spectra are determined by statistically analysing strong
motion records (a total of 614 horizontal records and 304 vertical
records) from 89 inland earthquakes with moment magnitude
ranging from 5.0 to 6.6.
For the detailed methodology, please refer to the following paper.

PeriodHorizontal

VerticalStandard Spectra

Tajima, R., H. Tanaka, and C. Wu (2021). An Empirical Method for Estimating Source Vicinity Ground-Motion Levels on Hard Bedrock and Annual
Exceedance Probabilities for Inland Crustal Earthquakes with Sources Difficult to Identify in Advance, Bull. Seismol. Soc. Am., doi: 10.1785/0120210065

30

Improvement (5): Slope set-back in the TEPCO
Fukushima Daiichi site: countermeasure for landslide
Pacific Ocean

Reactors 5 & 6

Reactors 1 to 4

Position of
Fukushima
boreholes andDaiichi Sitecross sections
Red circles: Data added after the technical meeting of December 7, 2022. 500 m
2023.04.25. TEPCO’s
NRA Tec. Meeting slide31

Distribution of the weathered part of Tomioka Formation in the Fukushima Daiichi Site
(North-South Section)
Terrace Deposits‘Tomioka Formation’ is TEPCO’s term. Thisgeological unit is called ‘Dainenji Formation’of ‘Sendai Group’ by majority geologists.

Weathered part

Pliocene Tomioka Formation

The weathered part is distributed all over the site at
the top of Tomioka Formation with thickness up to 8 m.

2023.04.25. TEPCO’s
NRA Tec. Meeting slide32

Distribution of the weathered part of Tomioka Formation in the Fukushima Daiichi Site
(East-West Sections)
Terrace Deposits

Weathered part

Pliocene Tomioka Formation

Terrace Deposits

Weathered part

Pliocene Tomioka Formation

2023.04.25. TEPCO’s NRA Tec. Meeting slide
The weathered part (red dashed) is placed at the top of
Tomioka Formation and is thickening toward the sea (east).

33

Set-back operation of the slope
Used-fuel storage pool facility

Fukushima
DaiichiNuclearPower
Plants
The slope to be
removedA

A

Set-back
operation
2023.12.26. TEPCO’s NRA Meeting slide34

Improvement (6): Barrier for tsunami back current
In the JAEA Tokai site
Tokai Daini NPP
1km
JAEA Nuclear
Cycle ResearchInstitute andJ-PARC
Shinkwa River

HAW・TVF

National Route 245
JAEA: Japan Atomic Energy Agency

JAEA Nuclear
Fuel Cycle
Engineering
Laboratories(NCL)

The tsunami flows
into Shinkawa Riverand spreads overthe valleys. Thenthe tsunami waterflows back to oceanwith drifting debris.
原子力規制委員会東海再処理施設安全監
視チーム第54回資料2「再処理施設における代表漂流物の妥当性の検証について」国立
研究開発法人日本原子力研究開発機構（JAEA） p. 10. (2020年12月24日)
35Improvement (6): Barrier for tsunami back flow 2
Shinkawa River
JAEA Nuclear Fuel
Cycle Engineering
Laboratories (NCL)
New barrier fortsunami back flow
added in response
to my proposal on
June 17, 2020.
（JAEA to NRA team,May 18, 2021)

Pacific Ocean
Barriers to protect HAW and TVF
facilities from drifting objects intsunamis (shown on June 17,2020 NRA Commission Meeting).
HAW:
High Activity
WastesTVF:
TokaiVitrification
Facility

原子力規制委員会東海再処理施設安全監視チーム第58回資料7「漂流物の影響防止施設として設ける津波漂流物防護柵について」国立研究開
発法人日本原子力研究開発機構（JAEA） p. 12. (2021年5月18日)

36

Recent Topic: Noto Peninsula Earthquake, Jan. 1, 2024
Magnitude: 7.6
Maximum Intensity: 7 (JMA scale, max. 399 gal in Shika NPP)
Aftershock area length: 150 km
Ground upheaval of >4 m in northern part of Noto Peninsula
Tsunamis of >5 m high along Noto and Niigata coasts
Intense liquefaction in Noto, Kaga, Toyama and Niigata plains
Deaths: 260, Injuries: 1316, Destroyed houses: 8424 (by June 4)
Troubles in Shika NPP (about 20 km from the active fault)===Oil spilled from the transformers (24600 litters) and loss of
2 external power supply lines (other supply lines survived)===Water spilled from used-fuel storage pools (#1: 95 litters,#2: 326 litters)===Small steps and cracks on roads and slopes in the NPP site===Tsunami height 3 m (site ground level: 11 m)
37

Japan Sea

20 km
Noto

Jan. 1, 2024 Noto
Peninsula Earthquake
Epicenter (yellow star)
and active faults
Mar. 27, 2024, NRA Tech. Inf.
Meeting, Book 64-1-2, p. 2-3.

Japan Sea
Sado

50km

Shika NPP
(about 20 km
from the faults;
on re-evaluation)

NiigataNoto
ToyamaMiyashita, Y. et al. 2024 https://www.gsj.jp/hazards/earthquake/noto2024/index.html

38

Vertical and Horizontal Ground Displacement by
2024 Noto Peninsula Earthquake
Vertical Displacement (Upheaval)

4m
Up

Horizontal Displacement (Westing)3m
Westing

Shika
NPP

https://www.gsi.go.jp/common/000254489.jpg
Mar. 27, 2024, NRA Tech. Inf. Meeting Book 64-1-2, p. 10.

39

Conclusions• In 10 years of my term as NRA Commissioner, 17 NPPs
were permitted and 12 are operating, but 10 are stillon re-evaluation in the new regulatory requirements.
• In these 10 years, 4 backfits took place, some otherimprovements were indicated, and continuous efforts
are practiced to cope with natural hazards.
• I thank IAEA for continuous help in improving NRA’s
regulation to keep nuclear safety, security andsafeguards.
• Thank you for your kind attention!
June 18, 2024, Vienna, Akira ISHIWATARI, NRA JAPAN40