1 KNOWLEDGE TRANSFER FOR LONG TERM · PDF fileFourth International Conference on Nuclear Power PlantLife Management 1 Institute of Nuclear Safety System Hideo Tanaka KNOWLEDGE TRANSFER

Fourth International Conference on Nuclear Power Plant Life Management

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Institute of Nuclear Safety System

Hideo Tanaka

KNOWLEDGE TRANSFER FOR

LONG TERM OPERATION


1983: Entered Kansai Electric Power; shift operator of Mihama units 1/2

1985 : Maintenance Section, Fukui Nuclear Power Division

1987 : Nuclear Maintenance Section, Nuclear Power Management Department

1993 : Institute of Nuclear Safety System, Inc. on loan

1995 : Plant Life Management Team, Nuclear Power Construction Department

1998 : Manager of Maintenance Management Section, Mihama NPP

2000 : Nuclear Engineering Ltd. on loan (responsible for transfer of PLM knowledge to other utilities)

2001 : Chief Manager of Maintenance Group, Wakasa District Office

2004 : Manager of Maintenance Management Group, Nuclear Power Division (Mihama 3 accident)

2005 : Chief Manager of Plant Life Management Group, Nuclear Power Division

2014 : Vice Chief Director of Institute of Nuclear Technology, INSS

My Professional Background 2


Overseas Trends Associated with LTO

NS-G-2.12:Ageing Management for NPPs (2017) draft

New chapter is “RELEVANT PLANT DOCUMENTATION AND

PROGRAMMES”

①SAFETY ANALYSIS REPORT AND OTHER CURRENT LICENSING

BASIS DOCUMENTS

②CONFIGURATION/MODIFICATION MANAGEMENT

PROGRAMME INCLUDING DESIGN BASIS DOCUMENTATION

③PLANT PROGRAMMES

The list of technical items include the collection of

necessary information, such as design parameters,

required for life assessment.

In this respect, as the problem of lack of

information draws attention, a focus is placed on

Configuration Management.

At the same time, the management of knowledge ,

that is, knowledge transfer has become a key issue.

SS 26;SALTO Peer Review Guidelines(2014)

The review addresses the six areas

The areas A through E describe the review contents almost

similar to the ageing management technical evaluation

conducted at Japan’s NPPs (including field investigation).

The area F ”Human resources, competence and knowledge

management for LTO (optional area)” confirms if the

program is appropriate to assure that a required level of

technology is maintained throughout an assumed

operational period rather than conducting evaluation of the

current status at the time of review.

Major amendments in ISO9001-2015

Knowledge in an organization, and its acquisition, accumulation and utilization

Potential deviation from the standard due to an unintentional error

Configuration Management

Change Control

Management of outsourcing

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ISO：International Organization for standardization


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1. Analysis of Current Status of Technology Transfer for NPPs

1) Efforts made by the Japanese nuclear industry

2) Technology transfer by plant manufacturers

3) Technology transfer by Regulatory body

4) Current status of Japanese Nuclear Institute

2. Experience through Plant Life Management and Establishment of

Knowledge Base/Network

1) Overlapping of knowledge

2) Skill of the artisan

3) Development of knowledge base/network

CONTENTS


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1) Efforts made by the Japanese nuclear industry

Steam generator (SG) tube rupture at Mihama unit 2 (SGTR)

⇒Component fabrication during the plant construction stage and

immediately formulating a new procedure to cool the reactor

Safety valve blew out due to a pressure below the setpoint.

⇒Skilled field engineers checked for the state of finishing of the

valve mating face with the naked eye

Primary Water Stress Corrosion Cracking (PWSCC) of Alloy 690 in

the hard-worked material

⇒Observation of cracks both in inner and outer surfaces of carbon

steel pipes in CANDU plants


Crack initiation case of carbon steel pipeInside surface（heavy water)

Outer surface (atmosphere)

Ref: J. P. Slade and T. S. Gendron, ”Proceedings of 12th International Conference on Environmental Degradation of Materials in Nuclear Power Systems-Water Reactors, TMS, 2005, 773-782

Header

Feed water PipeSCC

Creep

Material： Carbon steel

70 degree bending cold worked

Temperature：～ 310 ºC

Initiation time： 12.5（FPY）

CANDU Heat Transport Feeder System

Tight radius

FPY: Full power year

Steam Generator

Header

Fuel Channels

6


200 µm

420°C x 1,000 h 410°C x 1,433 h

200 µm

7

420°C x 1,000 h 410°C x 1,433 h420°C x 1,000 h 410°C x 1,433 h420°C x 1,000 h

7

Crack seems to initiate from just below the surface of notch.

410°C x 1,433 h

Crack Initiation at the notch( 20%CW Steel, in Air )

420°C x 1,000 h

ICG-EAC 2014 ( Prague, Czech Republic )7

Fourth International Conference on Nuclear Power Plant Life Management 8

Dependence of population of cavities on stress ( 30%CW steel in pure water at 360˚C)

K. Arioka et al, Corrosion, 69 ( 2013 ) : p.487.

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0.E+00 1.E-03 2.E-03 3.E-03

Area Fraction of Cavities（SC / S0)

Dista

nce

from

Bot

tome

of t

he N

otch

e （mm）

0 200 400 600

Stress ( MPa )

In pure water ( 5,912 h )

In Pure water ( 8,082h )

σ ( MPa )

Vacancies seem to diffuse to high stress area driven by (∂σ /∂z ).

Stress distribution

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1 μm

SCC initiation in PWR water( 20%CW TT690, 20,653h at 360 )

Pre-crack : ~ 0.1 mmK=23 MPa m1/2

Significant cavities were observed ahead of pre-crack.

Cavity play a key role in crack initiation in CW TT690.

Cavities

(black)Carbides

(dark gray)

90 μm

K. Arioka et al, Corrosion, 72 ( 2016 ) : p.1257.

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Fourth International Conference on Nuclear Power Plant Life Management 10

Role of Cavity on GB Bonding Strength ( 20% CW TT 690 , 410˚C x 5,036 h in air ( no crack ) )

(a)

20 µm

1 µm

GB Bonding strength seems to weaken prior to Crack Initiation.

K. Arioka, Corrosion, 71 ( 2015 ) : p.401.

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: Cavity

Cavities seem to result from diffusion of vacancies induced by cold work driven by stress gradient.

∂C /∂t = D (∂2C /∂x2 + ( Ω / RT ) ( C∂2σ/∂x2) )

Cavity

Assumed processes of cavity formation

: Cold work induced vacancy (Cv)

Cv = η εn ε : Strain

H.G. van Beuren, Acta Metal, 3 ( 1955 ) : p.519.

K. Arioka, Corrosion, 71 (2015): p.401.

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Recent laboratory research programs have observed crack growth in hard-worked

Alloy 690 material.

Although the research into the mechanism of PWSCC is still under way, a number of

data have suggested that cracks initiate not on the surface but in sub-surface regions.

Results of laboratory research

S. M. Bruemmer；17th International Conference

on Environmental Degradation of Materials, 2015

SCC initiation

CW TT690 in PWR water

Advanced knowledge about PWR plant specific PWSCC


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PWRVVER

CANDU

BWR

International Generic Ageing Lessons Learned

It is important to utilize the experience in other types of reactors than its own. In this respect, the

manufactures and owners of PWRs, BWRs, CANDUs and VVERs should make an effort to

understand other types of reactors by utilizing the data accumulated in I-GALL run by the IAEA.

We should be consistently asking ourselves if experience in other types of reactors is applicable

to our own reactors and actively work on investigation while keeping a questioning attitude.

The plant manufacturer is also responsible for appreciating the principle of leaning lessons from

others and educate/train personnel who takes over the principle.


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2) Technology transfer by plant manufacturers from the viewpoint

of utility

Operators switched off the isolation condenser at the time of the Fukushima Daiichi

accident ・・・ attempting to meet the limit to the reactor cooling rate Importance of optimized safety analysis ・・・ rather different from the actual phenomena

as shown in the accents at TMI-2 and 1FNPS

Good practices of incorporating research results into plant operation/maintenance (e.g., cavitation, erosion)

Development of mitigation techniques against SCC and cause investigation of fatigue

cracking in pipe elbows

Knowledge transfer during the manufacturing stage ・・・ Issues of hydrogen flakes and carbon segregation in RV

Demonstration through advanced design ・・・ SG tube failure at San Onofre Notes and bases of design manuals ・・・control of torque coefficient of a fastening bolt


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3) Technology transfer by Regulatory body from the viewpoint of

utility

We are given a good opportunity in a sense to sort out the licensing bases in a

well-established manner, because it takes a long time to go through the safety

review process looking back to the licensing bases applied during the

construction stage.

“The regulators should make their own efforts to collect information related to

safety culture, including minor trouble, through daily oversight activities

performed by inspectors in the field. This will help them build an information

base, which will be effective in guiding the plant operators.”(Yamamoto’s report)*1

*1：https://www.jstage.jst.go.jp/article/taesj/16/3/16_J16.002/_article/


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4) Current status of Japanese Nuclear Institute

Nuclear energy-related organizations such as R&D institutions, universities, and

nuclear industry should set up a platform for partnership and collaboration,

where they can exchange information, recognizing and respecting each other’s

roles. Their first initiative should be the development of a deep and broad

knowledge base, through the collection, systemization, and sharing of scientific

information and knowledge.

http://www.aec.go.jp/jicst/NC/about/kettei/kettei170720_e.pdf

JAEA should be transforming itself into an organization that guides

the creation of “seeds” through industry-academia-government

collaboration; improves fundamental technology; constructs a knowledge base by means of the collection, systemization, and sharing of scientific information and knowledge; and the

provision of facilities, equipment, and services that serve as the foundation of R&D.


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Overlapping of knowledge

Skill of the artisan

Development of knowledge base/network




Overlapping of knowledge

TMS

Design

O&M

Decommissioning

UM

Utilities’

Data

Manufacturers

’

Data

U

U

M

M

More Advanced

next-generation LWRs

Construction

Manufacturing

Maintenance Service

Utilities

Next-generation

design・manufacturing・construction

U

M Manufacturers

Mechanism for

efficient data collection

& seamless data

utilization

LWRs

To continue the use of nuclear energy in future, it is

necessary to understand to what extent the knowledge is

overlapped between the areas of safety design, system

design, component/structure design, parts design,

fabrication/installation methods including quality control,

and management methods of safety activities, in the field

of operation, fuel, maintenance, radiation control and

decommissioning.

In building a knowledge base, it is necessary to consider

the gap between generations as well as cross-sectional

relationship.

In this regard, it is also important to develop human

resources with a capability to have a wide perspective,

such as a bird-eye view.




Overlapping of knowledge For the plant manufacturer who possesses a large volume of classified data, it is difficult to take a

proactive action in sharing information although they recognize the importance of knowledge base.

However, they could share only notes or cautions rather than sharing classified information, which

includes their know-how, in order to prevent an incident from occurring.

The regulators used to consider that they are able to exercise an effective oversight over nuclear

power plants by confirming that the plant operator has performed a complete examination.

However, if the regulator looks at carefully if the operator has any missing areas of knowledge, it

would exert good pressure on the operator and lead to a better regulatory system. Different

anomalies may have the same root cause even if they are very small or different in the nature.

Long-term trend monitoring is essential in identifying the common cause between anomalies. We

expect that the regulator will be able to make judgements by directly observing licensee’s

maintenance activities in the field while being consistently cautious about potential correlation

between anomalies.


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Japanese CultureJapanese Culture

Horyu-ji Temple was erected

1,400 years ago

At Ise Jingu, all the shrines

are rebuilt every 20 years.

compatible

Technical-skill

Transfer of

“Miyadaiku”

Miyadaiku is a carpenter specializing in shrines and temples




Skill of the artisan

As more and more skilled workers specialized in individual fields attain the

retirement age, their expertise is being lost. Under such circumstances, it is

essential to make an effort to maintain and sort out their knowledge.

We can expect further enhancement of the maintenance management system

through the utilization of I-GALL established by the IAEA and other measures.

Scattered knowledge and technologies may be put together taking advantage of

advancement in technologies, in particular inspection and monitoring

technologies. Therefore, it is essential to consistently follow up the development

of new technologies.




Development of knowledge base/network The “Basic Concept on Nuclear Energy Use” issued by the Atomic Energy Commission

recommends that the JAEA contribute not only to gathering information from research

activities, but also to organizing and sharing such information in a systematic manner.

As the NRA also agrees with this concept, we expect that the JAEA, which

plays an important role of giving technical support to the NRA, will take

the initiative in building a system of collecting, organizing and sharing

information.

The licensee is required to disclose safety improvement measures

evaluation reports according to the new regulatory requirements. Making

contribution to the establishment of the knowledge base will help develop

human resources on the nuclear industry side.

In addition, it would be rewarding for us to maintain and improve technical

capabilities as an important part of maintenance activities. It is essential to

promote these activities under an international cooperative framework.

NUREG/CR-6042, Rev. 2

SAND 93-0971


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To achieve long-term operation of nuclear power plants, it is

essential to develop a knowledge base covering the total process of

construction, operation and decommissioning. In this regard, three

important factors have been identified; overlapping of knowledge among stakeholders, transfer of skills of the artisan and global cooperative work.

It takes much labor and time to look into past documents and

compare them with the latest knowledge to demonstrate that a

nuclear power plant can be safely operated. However, for long-

term operation, both configuration management and knowledge

management becomes increasingly important.

To collect and organize knowledge based on experience from a

wider range, it is essential to promote a global cooperative work.

3. CONCLUSION


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ICAPP2017

Agency for Natural

Resources and Energy

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Beyond 40y’s of

Japanese Nuclear Power Plants

IAEA PLiM 2012

May 14, 2012

Chief Manager of PLM-Group

Nuclear Power Division

The Kansai Electric Power Co., Inc.

Hideo Tanaka

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3

Technical Evaluation on Ageing Management in Nuclear Powerin Japan - Outline of 40th Year Technical Evaluation

2012

Documents

1 KNOWLEDGE TRANSFER FOR LONG TERM · PDF fileFourth International Conference on Nuclear Power PlantLife Management 1 Institute of Nuclear Safety System Hideo Tanaka KNOWLEDGE TRANSFER