ATENA Forum 2023

Activities of ATENA
February, 2023
Atomic Energy Association(ATENA)
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1. Outline of ATENA
2. Past Activities
3. Challenges
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Overview of ATENA○ Four years have passed since ATENA was established in July 2018 with the aim of tackling common
technical issues, conducting technical dialogue with regulatory authorities on behalf of industry, andencouraging operators to introduce effective safety measures.

Board of Directors
Staff

President & CEO Hiroto Uozumi (formerly of Hitachi, Ltd.), 2 directors, and 2 auditors

Experts in each field have been gathered from nuclear operators and plant manufacturers(approx. 30 people)(Areas of expertise) Safety design, external natural events, mechanical/electrical equipment, etc.

Member companies/organizations

11 utilities, 4 plant manufacturers, 4 related organizations

Hokkaido Electric Power Co., Inc., Tohoku Electric Power Co., Inc., Tokyo Electric Power Company Holdings, Inc., Chubu Electric Power Co., Inc.,
The Kansai Electric Power Company, Incorporated, Hokuriku Electric Power Company, Inc., The Chugoku Electric Power Co., Inc.,
Shikoku Electric Power Company, Incorporated, Kyushu Electric Power Company, Inc., The Japan Atomic Power Company,
Electric Power Development Co., Ltd.,
Toshiba Energy Systems & Solutions Corporation, Hitachi, Ltd., Mitsubishi Heavy Industries, Ltd., Mitsubishi Electric Corporation,
The Federation of Electric Power Companies of Japan(FEPC), Central Research Institute of Electric Power Industry(CRIEPI),
Japan Atomic Industrial Forum, Inc.(JAIF), The Japan Electrical Manufacturers’ Association(JEMA)
Observers: Japan Nuclear Safety Institute (JANSI), Japan Nuclear Fuel Limited (JNFL), Japan Atomic Energy Agency (JAEA)（In no particular order）
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Role of ATENA① Develop effective safety measures and request operators implement these safety measures by taking full advantage of
ATEANA ‘s composition which complies of experts not only from utilities but also from manufactures.
Coordinate efforts across the industry in the identification and addressing phase so that effectively utilize theknowledge/resources available in each organization.
② Actively engage in dialogue with the regulatory authority under the common goal of improving safety.
③ Communicate with various stakeholders to improve safety.
Nuclear Regulation
Authority

Experts frominside andoutside Japan②Dialogue

Regulate

Exchange views

ATENA

Plant

Plant

①Request adoption ofeffective safety measures

Plant①Coordinate activities within the nuclear power industry(effectively utilization of knowledge and resources)

Nuclear operators
Evaluate and support
JANSI

Collaborate

JAIF

JEMA

manufacturer
FEPC

Society

Implement safetymeasuresCRIEPI/
NRRC③Communicate with society about initiatives
for improving safety
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ATENA’s approach to common technical issues
ATENA is to address the following common issues based on lessons learned from the Fukushima
Daiichi Accident and subsequent efforts for safety improvement by utilities.

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Structure of handling common regulatory issues➢ At NRA-CNO Meeting in April 2019, major CNOs explained to the Nuclear Regulation Authority (NRA)
how to handle common regulatory issues in a unified manner.
➢ In order to appropriately handle all common regulatory issues, FEPC has transferred the function ofhandling regulatory issues to ATENA.

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ATENA's governance system
ATENA

NRA

ATENA Steering Committee(CNO of Utilities and Manufacturers)
・Selection of themes
・Determination of safety measures

President andDirectors

dialogue

Supervise the meeting
Reporting anddiscussion

・Public
meeting・Dailymeeting・Extracting themes
・Policy for addressing issues
・Stance of discussion with NRA・Creating ATENA Guidelines
・Development of safety measures<Specific Themes><Daily Response to Regulations>

Subject-specific WGs Chair(General Manager of ATENA)

Permanent WGs Chair(experts from utilities)

ATENA Administration Committee
General managers of nuclear divisionof utilities and manufacturers

Report as responsible
experts
Operation of WGs(dedicated ATENA personnel)

Operation of WGs
ATENA/FEPC
concurrent staff
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1. Outline of ATENA
2. Past Activities
3. Challenges
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Activities since the establishment of ATENA
FY

Accomplishments
・Establishment of ATENA (July 2018)2018

・Selected common technical issues as themes and started
review activities

8

Issues・Prepare for starting dialogues with
NRA・Steadily implement technical reviews

・Started dialogues with NRA (April 2019)
・Started producing fruitful results in the review of technicalissueseg. Reduction of incidents due to human factors inemergency diesel generators (EDGs)(FY 2019: 1 incident; FY 2020: 0 incident)

・Establish practices such as conducting
developing safety measures andrequesting utilities to introduce
countermeasures.

・Extract "potential risks" in addition to
current technical issues

2020

・Established a reasonable approach for the grace period forbackfitting (Design basis ground motion formulated
without specifying the epicenter).
・Conducted technical discussions with NRA on aging
management initiatives, then NRA compiled its views on
the operation period rule.

・ATENA actively proposes issues to the
NRA

2021

・Reinforced safety measures at each company in response to
the inappropriate treatments in physical protection
procedures at TEPCO.
・Enhanced cooperation with overseas organizations(Web meetings by senior management)
・A self-review of our efforts to date, four years since theestablishment of ATENA

・Identification of issues to be addressed

2019

2022

・Further efforts to identify issues for more effective
promotion of safety improvement initiatives of the industry

・Conduct active dialogues with NRA・Conduct productive dialogues with
NRA and reinforce communication
with stakeholders

・Building trust with the NRA・Further strengthen cooperation withexternal organizations, such as
overseas organizations

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ATENA’s Activity Policy①Efforts for solving the common technical issues
25
10 ～• ATENA shall address the common technical issues such as utilization of latest knowledge andtechnology and review them with its expertise in order to achieve the effective safety improvementin NPPs. The result of the review shall be assembled and published as technical reports if
necessary.

• ATENA shall formulate effective safety measures independently of varied interests among utilities
and require all utilities to incorporate them into their actual activities through the votes at ATENA’s
Steering Committee meeting even in case there are some utilities who do not agree on themeasures.
• ATENA shall also confirm and publish the status of utilities’ implementation.
～ 29②Proactive dialogue with NRA
26• ATENA shall be a single responsible body to handle regulatory issues common to utilities.

• ATENA shall engage in dialogue with NRA as a representative of the industry.
③Communication with various stakeholders
30• ATENA shall release information on its activities to the public and incorporate feedback from thepublic to improve its activities.
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List of common technical issues (themes) <as of January 2023>
Technical issue① Proactively
utilize newknowledge andadvanced
technologies

10

Theme
Develop a new guideline for Cyber security
Develop a new guideline to adopt measures for common cause failures in digital safety protection system
Pursue efficient and effective operation with appropriate consideration of importance classification of SA equipment
Establishment of improvement measure for “Open Phase Condition”
Establishment of proper management of electromagnetic compatibility (EMC) related to the instrumentation and control system
Propose back-fit processes with appropriate consideration of safety significanceDevelop the advanced methodology of soil liquefaction assessment
Response to the findings from the investigation and analysis of the TEPCO's Fukushima Daiichi Nuclear Power Station Accident
Deployment of new fuel② Preparethoroughly forvariousexternal events【Completed】 Review of the methodology to assess “design basis ground motion formulated without specifying seismic sources”【Completed】 Establish evaluation method to ensure conformance of base isolated buildings housing SA equipment to technicalstandards
Establish optimized approach to natural events with significant uncertainty
Establish reasonable treatment process when updating design basis ground motion (Ss) through new knowledge③ Establish aframework
which promotes
voluntary efforts
for safety
improvement

Develop industry’s guide documents for specific procedure to fulfill the NRA’s inspection reform④ Others

Establishment of further improvement measures for Emergency Diesel Generators(EDG) reliability by analyzing operating experience【Completed】 Establish guideline for responding to incompatibility of manufacturers’ or component suppliers’ productInitiative of aging management for safe long-term operation
Propose incentive mechanism to enhance licensees’ voluntary efforts of improving nuclear safety
Propose more efficient procedures of operation and maintenance of equipment newly installed to conform new regulatory
requirement

Review and improve the current scheme of “Emergency Action Level”
Adoption of extended-cycle operation
Further Investigation Related to the Intergranular Cracking on Stainless Steel Piping of PWR Primary System
Cooperation to NRA’s initiative of continuously improving the regulatory standards by reflecting review experience
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Published technical reports and schedule for reports <as of January 2023>
FY2019〇Improvement Measures Proposed by Assessing Trends in Emergency Diesel Generator Malfunctions in
Domestic Nuclear Power Plants

Publication date(June 21, 2019)[Rev. 1, November 7, 2019]○Guideline Regarding Performance Indicators (PI) Used in Nuclear Regulatory Inspections(June 28, 2019)○Voluntary Guide on Introducing Cybersecurity Measures at Nuclear Power Plants(March 12, 2020)

FY2020Publication date

○Guideline on the implementation of Licensee Inspections(July 31, 2020)○Maintenance Guideline for Long-term Plant Shutdown(September 25, 2020)○Guideline on Assessing Design Obsolescence(September 25, 2020)○Discontinued Product Management Guideline(September 25, 2020)○Design Guideline for the Base-Isolated Buildings Housing Severe Accident Equipment(September 29, 2020)〇Guideline for Deterrence and Adequate Response to Fraudulent Activity by Manufacturer/Component Supplier○Technical Requirements for Mitigation Measures of Software Common Cause Failures of Digital Safety
Protection System
FY2021(October 28, 2020)(December 24, 2020)[Rev. 1, October 5, 2022]
Publication date〇Report of knowledge build-up related to aging for safe long-term operation（March 25, 2022）

FY2022Publication date

〇Operational safety program revision guideline for improving safety through a diverse range of facilities（July 29, 2022）

To be published〇Report on the advancement of liquefaction evaluation methods（working title)○Position paper on electromagnetic compatibility (working title)

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Overview of Safety Measures (1/4)

12Further improvement of the reliability of emergency diesel generator (EDG)
・Although the number of EDG malfunctioning events has not increased since 2011, the proportion of EDG events among all
events became relatively high, and the proportion of EDG events caused by human factors was large among all EDG events.
Therefore, ATENA analyzed past EDG events in detail, summarized the items to be improved, and requested utilities to improve
maintenance activity of EDG.
・In order to confirm and evaluate the status of the site to see whether safety measures have been appropriately implemented,
ATENA continues to confirm the status of improvements by witnessing actual EDG maintenance activities on site.

Introduction of cyber security measures

16

・Given the growing threat of cyber attacks and the strengthening of domestic and overseas guides, ATENA compiled an industry
guideline that proposed utilities and manufacturers to strengthen countermeasures against cyber attacks, and requested utilities
to strengthen countermeasures.
・Following the submission of the implementation plan for safety measures by each utility, ATENA again requested utilities torevise the implementation plan in order to further reinforce the measures. Such safety measures are currently being implemented
by utilities.
Design Specifications for the Base-Isolated Buildings Housing Severe Accident Equipment
・Design specifications for base-isolated buildings housing severe accident equipment were developed and described in the
ATENA guideline document. ATENA requested utilities to use this guideline when they start to design such buildings.

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Overview of Safety Measures (2/4)< Initiative of aging management for safe long-term operation >Maintenance during long-term plant shutdown

17

18

・Considering the aging deterioration during the long-term shutdown period, ATENA collected and organized each utility’s idea of
formulating maintenance plan for shutdown period, then compiled a guideline and requested utilities to improve theirmaintenance plans for shutdown period.
・It is assessed that the maintenance plans of utilities during long-term shutdown have been appropriately revised by reflecting therecommendations provided in the ATENA guideline.
Assessing design obsolescence・Since ATENA decided that it is important to establish a scheme to extract vulnerability due to the obsolescence of plant design
even at the plants which comply the new regulatory requirements, ATENA proposed a new scheme of “Design Obsolescence
Assessment” which assesses the safety with addressing the difference of design between old plant and new plant. ATENA also
requested utilities to start the assessment.
・Assessment is currently being carried out by utilities.
Proper management of discontinued products

・In order to ensure the handling of discontinued products and to maintain the functions of plant system, ATENA proposed thestructure and operation which enables utilities to obtain information on discontinued products systematically and continuously
from manufacturers, suppliers, and subcontractors, and manage in a unified manner with close cooperation between utilities andmanufacturers. ATENA then requested utilities to implement such structure and operation.
・ATENA confirmed that utilities completed necessary documentations and introduced actual collaboration system.
In addition to the above initiatives, ATENA deploys enhanced activities tobuild-up various knowledge on aging management.

19

20

21

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Overview of Safety Measures (3/4)
Deterrence and adequate response to fraudulent activity by manufacturer/component supplier・ATENA developed a guideline to implement measures by utilities and manufacturers to prevent inappropriate conduct at the timeof manufacturing materials, parts, etc. by supplier companies, and to promptly confirm the impact on nuclear safety and system
integrity when inappropriate conducts are identified. ATENA then requested utilities to deploy measures proposed in the guideline.
・After receiving the implementation status of the measures based on ATENA guideline from utilities and confirming the details of
the status, it was evaluated that the preventive measures against inappropriate conduct are properly implemented in accordancewith the guideline.
Mitigation measures of software common cause failure of digital safety protection system

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・Along with the introduction of digital technology to systems of high safety importance, digital safety protection systems have beenequipped with analog backup system which takes into account software common cause failures. In addition to such measures,the industry decided to introduce reinforced measures to the backup system by taking into consideration the situation in othercountries, then ATENA developed a technical requirement document to reinforce measures and requested utilities to implement
such measures.
・NRA presented its thought on this issue in their report as follows.
“NRA decided not to enforce new regulatory requirements on this issue, by letting utilities to voluntarily address this issue withconsidering the “required level of measures” expressed by NRA, confirming implementation status through periodic reports fromutilities, and also monitoring implementation status at the occasions of regulatory inspections. NRA considers this issue as apioneering scheme in which utilities voluntarily implement measures and NRA follows up those activities, with taking into accountthe discussions in “The deliberation team of continuous safety improvement” composed by NRA commissioners/officials andexternal experts.
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Overview of Safety Measures (4/4)
Efficient and effective operation with appropriate consideration of importanceclassification of SA equipment (Improvement of LCO)

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・Safety improvement initiatives that optimizes for the entire plant are being discussed. This takes into consideration severe accident response
equipment (SA equipment) and specialized safety facility (SSF) as additional back-ups in case the plant enters LCO, i.e., safety critical designbasis equipment (DB equipment) failure or SA equipment failure. ATENA compiled the recommendation into guideline and requested utilities toimplement necessary measures when they will revise the operational safety programs.

・Utilities are preparing to apply for the revision of operational safety programs by referring ATENA guideline.

Improvement of detectability of Open Phase Condition
・In response to the reactor trip event occurred at foreign nuclear power plant which was caused by the one-phase open-circuit
failure event (OPC:Open Phase Condition), the industry decided to voluntarily introduce measures to improve the detectability ofOPC (installation of detectors to relevant transformers) in order to improve plant reliability. ATENA formally requested utilities toimplement such measures.
・Utilities are implementing necessary measures of installing detectors.

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Ensuring cybersecurity
Digital control unit•

As nuclear power plants adopt new digital technologies,
the threat of cyber attacks looms large. Latest
knowledge in such as IAEA guides, NEI guides,
recommendations issued by the US NRC was surveyed.

•

A cyber security guideline drafted by a WG comprisedof experts of ATENA, plant manufactures and operators,
that reflected the latest knowledge obtained from abroad,
was published in March 2020.

•

In light of the importance of cybersecurity, ATENA
requested that operators reinforce their safetymeasures implementation plans to accelerate thedeployment of additional cybersecurity measures in
April 2021.

•

Operators will implement safety measures in linewith the guideline by October 2023.

•

ATENA will check on and disclose operator’s progress
accordingly.
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Network

Attacks from inside the plant
Cut off from external networks

Internet

Safety enhancement measures recommended in the
ATENA guideline・Measures for hardware
Ensure separation from external networks
Access control etc.
・Measures for the management process
Organization, training, equipment management

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ATENA aging degradation management initiatives
Issue

Physical degradation

Response to aging
degradation of facilities(Aging degradation events)
Corrosion, SCC, wear,
irradiation embrittlement,
fatigue, etc.

Non-physicaldegradation

Reflection of the latest
knowledge

Operator initiatives (17

includes regulatory response) and ATENA initiatives＜In normal operating conditions＞• Conduct planned maintenance• Conduct periodic aging degradation assessment (aging
degradation assessment: every 10 years after 30 years
in operation)• Apply for approval of operational life extension(assessment of 40 years+ (up to 60 years) operation)• Continuously review aging degradation management
based on the latest knowledge＜Long-term shutdown period＞• Conduct maintenance considering the shutdown state• Conduct aging degradation management (cold shutdown
PLM assessment, aging degradation assessment duringlong-term shutdown)(design obsolescencemanagement)

Gather the latest knowledge every cycle. Review plantsafety based on the analysis results and the plant safetyassessment results.

Response to
discontinued products

Each operator is exploring stable procurement methods
based on the characteristics of part and the service④ATENA has published a report on the issue（published March 2022)
Issues that require further investigation have been
identified to enable safer long-term operation,referencing the example of the 80-year operating life
license in the US as an example.
Investigate intergranular cracking in primary system
of PWRs (being addressed in WG)
The issues has been designated as a common
technical issue identified in OE to be addressed as
the industry

ATENA published guides for each issue（ in September 2020 )<①Long-term shutdown maintenance guide>
Organized each operator’s approach to shutdown
maintenance plan formulation considering aging
degradation in long-term shutdown<②Design obsolescence assessment guide>For building a mechanism to assess plant designfrom a design obsolescence standpoint andcontinuously improve safety<③Discontinued product management guide>For building a mechanism to efficiently share
information about discontinued products and to
stockpile spare parts between plant manufacturers
and operators

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*IAEA Guide “Aging Management and Development of a Programme for Long Term Operation of NuclearCopyrightPower©Plants”（SSG-48）

Efforts for safe long-term operation

18<Background and Results>➢ At the 10th NRA-CNO meeting (December 2, 2019), ATENA presented ATENA’s efforts tomanage aging degradation for safer long-term operation. At the same time, ATENA
requested NRA to set up meeting occasions for technical opinion exchange.
➢ At the 57th meeting of NRA (January 29, 2020), NRA approved the launch of ※１ theTechnical Opinion Exchange Meeting with ATENA on Aging Management by practical level
members.
Results of the Opinion Exchange Meeting
Round

Date and time

The first

March 6 10:00 to 12:00

SecondApril 27th 9:00 to 12:00

Third

May 22 10:00 to 12:00
13:30～16:00

4th

June 1 9:30 to 12:00

5th

June 15 9:00 to 12:00

6th

July 1 16:30 to 18:30※1:Https://www.nra.go.jp/disclosure/committee/ikenkokan/ATENA/index.html of working-level technical meetings with ATENA on ageing control➢ Although NRA has long announced that it is not in a position to express any opinions on
the operation period issue, NRA released a position paper ※２ at the 15th meeting of NRA(July 29, 2020), which was one of the results from technical opinion exchange meetings
with ATENA.
※2:Opinion on the Relationship Between Review of Operation Period Extension Approval and Aging
Degradationof Power
ReactorFacilitiesAllduringLong
Term Shutdown Period
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EnergyAssociation
RightsReserved.
https://www.nra.go.jp/data/000323916.pdf

Identifying issues that require further investigation in aging degradationassessment based on knowledge from Japan and abroad
State of domestic plants
Start ofoperation# of years inoperation

Takahama Unit 1

1974

47 years

Takahama Unit 2

1975

46 years

Mihama Unit 3

1976

45 years

Tokai Daini1978

43 years

Sendai Unit 1

1984

37 years（12 other units, for a total of 17 units have been operating for 30+ years)

State of US plants
Number of years in operation
40 to 50 years … 41 units
50+ years … 8 units
Plants that have been approved for
an 80-year operational service life
Turkey Point-3&4*
6 units
Peach Bottom-2&3*
Surry-1&2
Identify technical challenges that come withlong-term operation(issues that require more information)

Update knowledge through research and reflect onto units

Plant

19

•

Of the 33 nuclear power plants in Japan, 17 have been online
for more than 30 years (4 units for more than 40 years.) In lightof this, to keep on using plants in the long term while maintaining
safety at a high standard, knowledge on aging degradationneeds to be continuously updated and expanded.

•

The US may be a source of useful information as multiple plants
have been in operation for more than 50 years and multiple
plants that have been approved for 80-year operation.

•

Technical challenges for long-term operation (issues that
require further investigation) were identified based on US
efforts to extend the operational service life to 80 years and thelatest domestic knowledge on aging degradation.

•

A technical report summarizing the challenges was
published in March 2022 https://www.atena-j.jp/report/2022/03/atena21me01rev0.html#000225•

ATENA will be making recommendations to the Atomic
Energy Society of Japan, operators, and research agencies
on the issues that require further investigation, and will be
keeping track of developments.

*: On February 24, 2022, the US NRC retracted its approval of the 80-year license for these plants.

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Further investigation related to the intergranular cracking
on stainless steel piping of PWR primary system•

In August 2020, a crack was identified near thepressurizer spray pipe weld at Ohi Unit 3. The pipe was
replaced and similar welds were checked for cracks.

•

These incidents are rare in actual units and there isalmost no data on intergranular cracking in similar
conditions. ATENA identified this as a common
technical issue to be addressed by the industry toensure safety and reliability of nuclear power plants.

•

ATENA formed a WG and broke down the challenge into
three components:
1) clarifying the crack initiation mechanism
2) integrity assessment with crack3) improving inspection technology.

•

ATENA is studying the cause and prevention
measures with the input of external experts.

Steam generator

Pressurizer spray line

20

Primary
coolant pumpPressurizer
Primary coolant pipe

Reactor vessel

Primary coolant system equipment overview

Cross-sectional diagram(overhead view)

Cross-sectional diagram(side view)Nozzle side

Welded metal Pressurizer side

(Outside of the pipe)(Inside of the pipe)

Crack (image)
Depth 4.4mm
Length 60mm

Intergranular cracking of stainless steel in a PWR primary system coolant
environment is extremely rare.

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New initiatives on aging degradation led by ATENA➢ There needs to establish the function that sets and implements directions and strategic goals based on the challenges
identified based on the latest knowledge and OE to implement aging degradation management-related activities (R&D,
formulating standards) in a strategic and systematic manner.

➢ ATENA will establish an Aging Degradation Investigation WG (as a meeting place for related organizations). This WG willcollect and analyze the latest information on aging degradation management and OE information to formulate andimplement activity plans (R&D plans, etc.).
ATENA Aging Degradation Investigation WG

CRIEPI
Plant
manufacturers

Continuous improvement ofmaintenance activities

ATENA

METI

Academiaetc.

Cooperate

Operators

Engage indialogue

NRA

JANSI

Analysis of OE domestic and abroad
Development of technical foundation
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Mitigation measures of software common cause failure of digital safety protection system

Risk of simultaneous loss of function initiated bysoftware failure•

Common understandings were shared with the regulatory authorities
through technical exchanges of opinions on the digital safety protection
system. In addition to existing voluntary equipment that takes into
account software common cause failures, the conclusions were shared
to introduce enhanced measures in consideration of the situation inother countries.
https://www.nsr.go.jp/disclosure/committee/yuushikisya/digital/0700000
44.html•

WG was composed of experts from ATENA, manufacturers, andutilities, and additional safety measures are compiled in the TechnicalRequirements Document based on the latest knowledge of foreigncountries.

•

In December 2020, a technical requirement document was
published.
http://www.atena-j.jp/report/2020/12/atena-20me05rev0.html•

Utilities began to examine necessary safety measures in detail inaccordance with the ATENA document, and deploy thosemeasures from fiscal 2023.

•

ATENA shall confirm the status of implementation of each utility andrelease it to the public.
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Proposed scheme to confirm the progress of software common
cause failure (CCF) measures of digital safety protection system•

ATENA regularly confirms the status of efforts by utilities at each stage of planning and implementation.

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Pursue efficient and effective operation with appropriate considerationof importance classification of SA equipment (Improvement of LCO)•

Safety improvement initiatives that optimizes for the entire plant are being discussed. This takes into
consideration severe accident response equipment (SA equipment) and specialized safety facility（SSF） as additional back-ups in case the plant enters LCO, i.e., safety critical design basis
equipment (DB equipment) failure or SA equipment failure.

<Technical discussions action items>•

Discuss adding SA equipment and specialized safety
facilities as back-ups for DB equipment and SA
equipment<Anticipated deliverables>
•

•

24

ATENA is putting together a guide that allows NRA
reviews to be conducted efficiently when operators
apply to revise operational safety programs
Open discussion will be held with the NRA
regarding the guide【Current】“Copyright of photos: Kansai Electric Power Co.”DB equipment (power supply)

Check on the soundnessof the remaining DG unit
when entering LCO【Future】
DB equipment (power supply)

SA equipment

SSF

恒設
電源
Check the soundness of SA equipment and SSF in
addition to the remaining DG unit when entering LCO
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25

Deployment of new fuelDeployment of 10 by 10 alley fuel assembly＜Characteristics＞➢ Improve the safety and reliability of fuel• Reduce the heat load per rod
９by９ fuel assembly
by increasing the number of fuel rods
➢ Reduce the number of refueling assemblies(reduce the number of spent fuels)• Increase burnup at replacement(From an avg. of 45G to 50G)
• Increase the amount ofloaded uranium per body

• ATENA helps this BWR owners’ efforts byproviding an idea for realizing efficient review
process by NRA, through discussions with NRA
at practical level.

10 by 10 fuel assembly

Deployment of Accident Tolerant Fuel

• PWR owners in Japan are willing to introduce
Accident Tolerant Fuel (ATF), which is about tobe commercially used in the US, to further
improve reactor safety.

<Characteristics>➢ Improve safety in accidents• Reduce the amount ofhydrogen generated• BWR owners in Japan are willing to introduce 10
by 10 alley fuel assembly, which has been
already introduced in the US, to further improvereactor safety.

Cr coating cladding tube

➢ Improve reliability in normal operations• Increase reliability by improving corrosion resistance• ATENA is going to coordinate the industry-wide
efforts to realize efficient process of developing
and introducing ATF.
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② Proactive Dialogue with NRA

26➢ Opinion Exchange Meeting between NRA and CNOs of major utilities

・Discussions on the general issues of nuclear regulation between the NRA Commissioners,
CNOs and ATENA executives. (about two or three times a year)➢ NRA’s open meetings and technical opinion exchanges meetings・Exchange of opinions on specific technical issues at the practical level between experts of NRA
and the industry

e.g., aging management, electromagnetic compatibility (EMC), new inspection system,
software common cause failure of digital safety protection system,working team meeting of reinforcement of regulations by investigating
Fukushima Daiichi accident➢ Regular administrative meetings
・Daily communication on common technical issues (themes) between the Director of the Nuclear
Regulation Planning Division and the ATENA Secretary General(approximately once a week)
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Dialogue with NRA (major results)
28< Meeting for Exchange of Opinions on Inspection System > (Full Year)At the meeting at the beginning of the fiscal year, NRA presents yearly schedule of discussions, so thediscussions can be prepared systematically. In addition, both sides present drafts of the materials, andconfirm in advance the discussion points at the public meeting on the day. These practices enable
constructive and efficient discussions at the public meetings.
< Design basis ground motion formulated without specifying seismic sources > (FY2019)
ATENA proposed the industry’s thought on grace period of the backfit at the NRA’s open meeting. As areasonable conclusion, only the deadline for the installation permit was indicated, and the deadline forconstruction approval and completion of construction work would be set later.

< Software common cause failure of digital safety protection system > (FY2020)
ATENA prepared a technical requirement document and promoted the implementation activities by utilities.
This approach was considered by NRA as a test stone to leave the industry’s voluntary efforts without
backfitting by regulations.
< Efforts for Safe Long-term Operation> (FY2020)
It took some time to share the ideas about the objectives of ATENA Guidelines, their positioning, and theintent to exchange opinions. After sharing these ideas, exchanges of opinions were conducted efficiently,
including prior confirmation of materials. Finally, NRA issued a position paper on the operation period.
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28

NRA’s inspection reform••

After a trial operation period of one and a half years, the new inspection system enteredoperation in April 2020.
ATENA has published necessary guides and, as the responsible organization for dialogues with
NRA, continuously presents opinions
at the NRA's opinion exchange meetings.

Collaboration structure in the industry
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Dialogue with NRA ： Areas for improvement

29●There was a case in which it took some time to reach common understandings on suchas the objective and the intention of the discussion between NRA and the industry, thenfruitful discussions were not accomplished in the early stage of a series of meetings.

●There was a case in which sufficient communication between NRA and ATENA was notinitiated on what kind of discussions is necessary at the initial stage of ATENA’s technicalreview. As a result, when ATENA presented a draft report at the open meeting, NRA
thought it difficult to discuss on it at the time of the meeting.

In order to implement a fruitful discussions, it is necessary for both NRA and ATENA toshare understandings on the objective and appropriate timing of discussions on specificissues from early stage of the issue identification, then to plan necessary meetings instrategic and timely manner.
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Communication with various stakeholders

30〇Hosted the ATENA Forum＜Forum in session＞
・Held in February every year as a public event
・In the 2022 Forum, panelists discussed on the trust between the regulatory bodyand the nuclear industry〇Presented ATENA activities in academic conference
・Planning session of the Fall Meeting of the Atomic Energy Societyof Japan (AESJ) (September 2021)〇Interviewed by newspapers and magazines
・Journal of Japan Society of Maintenology: Guest message at cover page by CEO of ATENA (November 2021)
・Industry Newspaper “Denki Shimbun”: Publication of articles related to the Guide for discontinued products(July 2022)〇Meetings with executives of organization overseas
・Online meeting with the Nuclear Energy Institute (NEI) (July 2022)
・Online meeting with the Nuclear Energy Agency, Organisation for Economic Co-operation and Development(OECD/NEA）(November 2021 and July 2022)
・Meeting with EDF (January 2023)〇Mail magazine
・Started to deliver ATENA mail magazine (January 2023)
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31

1. Outline of ATENA
2. Past Activities
3. Challenges
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32

Challenges〇Further promotion of communication with the NRA◆We have to gain the regulators' confidence in ATENA through continuous
communication on the forthcoming issues to be discussed.
◆ATENA, as a representative of the industry, should proactively share common
understanding of issues with the regulatory authority, and openly discuss such as
the direction of safety improvement, safety significance, implementation scheduleof each issue.
〇Review on ATENA’s Roles (Scope of Operations) in consideration of recent
situations◆Since the establishment of ATENA, we have been mainly focusing on short-term
initiatives to produce actual output, but it is time to review what ATENA should
really address hereafter.
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