O N T A R I O P O W E R G E N E R A T I O N

Progress in NDE Inspection Qualification for Steam

Generator Tubes at Ontario Power Generation

O N T A R I O P O W E R G E N E R A T I O N

2

by

P. Kwan, S. Sullivan, T. Malkiewicz

and

A. Chen, J. Huggins

5th International CANDU In-Service Inspection /

NDT in Canada 2014 Conference,

Toronto, Ontario, Canada June 17-18, 2014

Progress in NDE Inspection Qualification for Steam

Generator Tubes at Ontario Power Generation

O N T A R I O P O W E R G E N E R A T I O N

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� OPG Overview

� Inspection Qualification Background

� Qualification Body

� Qualification Process

� OPG Nuclear Steam Generators and Active Degradation

Mechanisms

� Inspection Methods to be Qualified

� Qualification Packages

� Experience with Qualifying Body and Process

� Summary

Presentation Outline

O N T A R I O P O W E R G E N E R A T I O N

OPG Overview

� More than 19000 MW of generation capacity

� 2 Nuclear Stations

� 5 Thermal Stations

� 65 Hydro Electric Stations

� In-house NDE Inspection and Specialized Maintenance

Organization (IMS)

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O N T A R I O P O W E R G E N E R A T I O N

OPG Nuclear Fleet

� Pickering Nuclear

� 6 CANDU Reactor Units, 515 MW Each

� Darlington Nuclear

� 4 CANDU Reactor Units, 900 MW Each

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O N T A R I O P O W E R G E N E R A T I O N

Inspection Qualification Project at OPG

� Multi-year project (2008-2016) to qualify NDE

systems governed by CSA-N285.4, Periodic

Inspection of CANDU Nuclear Power Plants

� Reactor Fuel Channels

� Steam Generators

� Reactor Feeder Piping

� Piping Welds

� Dry Storage Containers for Spent Fuel

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O N T A R I O P O W E R G E N E R A T I O N

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� Inspection qualification of NDE systems is a requirement under CSA-

N285.4, Periodic Inspection of CANDU Nuclear Power Plant

Components, clause 3.6(e) requires that the Owner “demonstrate

the adequacy of the procedures and the proficiency of the assigned

personnel using the assigned equipment to detect and size flaws in

representative samples.”

� Compliance with the standard is a requirement of the Power Reactor

Operating Licenses for the Darlington and Pickering Stations.

� CSA N285.4 Clause 3.6e has been part of the standard since 1994.

Inspection Qualification Background

O N T A R I O P O W E R G E N E R A T I O N

SG IQ Work to Date

� Until recently, NDE flaw characterization performance has been

documented in various engineering reports within OPG, by CANDU

Owners Group (COG) project documents, and by individual contracts

with external vendors. As a result, there has not been a uniform,

consistent, approach to NDE qualification.

� Various technical reports on ET/UT probe capability are based on

pulled tubes and simulated flaws

� UT results are used to validate the ET for volumetric type flaws

� Certified Analysts (CGSB or equivalent)

� SSPD Training and Testing

� Written Inspection procedures/instructions

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O N T A R I O P O W E R G E N E R A T I O N

IQ Background […continued]

� A pilot study completed by OPG in 2001 reviewed the optimal

approach to demonstrate compliance with CSA N285.4 clause 3.6(e).

� Pilot study proposed a process based on Recommended Practices

followed by the European Network for Inspection Qualification

(ENIQ) to complete inspection qualification.

� ENIQ invokes an engineering approach to address qualification.

� The benefits of ENIQ method are its flexibility to include a variety of

evidence in addition to performance demonstration to qualify

inspections. For example, lab studies, mathematical modeling, and

other technically supported arguments.

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O N T A R I O P O W E R G E N E R A T I O N

CANDU Inspection Qualification Bureau (CIQB)

� CANDU Inspection Qualification Bureau (CIQB) was established

within the CANDU Owners Group (COG) which acts as a qualifying

body to provide independent assessment of qualification document

package for participating COG members

� CIQB will also facilitate the development of Inspection Specifications

when requested by two or more participants.

� CIQB facilitates Peer Reviews of NDE qualification documentation

that verifies that the documented NDE Performance meets or

exceeds requirements of the Engineering Inspection Specifications

for various degradation mechanisms.

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O N T A R I O P O W E R G E N E R A T I O N

CIQB Qualification Process

Inspection Specification

Inspection Procedure

Technical Justification

Training and Personnel Qualification Material

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IQ Package

Reviewed by team of experts

assembled by CIQB in field of

NDE suited to submission

Collaborative approach

between ISP and

review team to

disposition feedback

Typically Submitted by

Inspection Service

Provider (ISP) to CIQB

Approval Given

by CIQB after all

disposition is

accepted

CIQB

O N T A R I O P O W E R G E N E R A T I O N

Inspection Specification

� Describes the component and environment

� Observed or Postulated Degradation mechanism(s)

� Inspection Requirements

� Defines the requirement for the Inspection Technique to

detect and quantify the degradation

� Probability of Detection (POD)

� Flaw sizing capability, depth, length…,

� Guidelines for Inspection personnel and qualification

requirements

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O N T A R I O P O W E R G E N E R A T I O N

Inspection Specification […continued]

� Generic Inspection Specification (IS) for

CANDU Steam Generator Tube was

produced as a COG Joint Project on IQ

� Utility Engineering specifies the specific

degradation mechanisms and level of

qualification per the generic IS and any

supplemental requirements

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O N T A R I O P O W E R G E N E R A T I O N

Technical Justification

� Provides justification that the procedure/technique and

training plan meet the requirements of the Inspection

Specification

� Analyzes and documents the essential parameters

� Provides the required evidence (such as field results, lab studies,

mathematical modeling and/or physical reasoning) to demonstrate

that Inspection Procedure and training plan meets the intent of

the Inspection Specification

� The Inspection Service Provider typically produces the

Technical Justification document .

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O N T A R I O P O W E R G E N E R A T I O N

Pickering Units 1 & 4 Steam Generators:

Typical Degradation Mechanisms

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� 12 Steam Generators per

Reactor Unit

� 2600 tubes in each Steam

Generator

� Tube diameter nominally

12.6 mm [0.5”]

� Tube wall thickness

nominally 1.25 mm [0.049”]

� Tube material is High

Magnetic Permeability

Monel 400 (Unique!!)

O N T A R I O P O W E R G E N E R A T I O N

Pickering Units 5 to 8 Steam Generators:

Typical Degradation Mechanisms

� 12 Steam Generators per

Reactor Unit

� 2573 tubes in each Steam

Generator

� Tube diameter nominally

12.6 mm [0.5”]

� Tube wall thickness

nominally 1.25 mm [0.049”]

� Tube material is Variable

(Low to High) Magnetic

Permeability Monel 400

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O N T A R I O P O W E R G E N E R A T I O N

Darlington Steam Generators: Typical Degradation Mechanisms

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� 4 Steam Generators per

Reactor Unit

� 4663 tubes in each Steam

Generator

� Tube diameter nominally

15.88 mm [0.625”]

� Tube wall thickness

nominally 1.13 mm [0.044”]

� Tube material is Incoloy 800

O N T A R I O P O W E R G E N E R A T I O N

Inspection Methods to be Qualified

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Eddy Current Testing (ET) using

Zetec Probes and Equipment

Bobbin Probe

and Array (X-Probe)

Ultrasonic Testing (UT)

Tiny Rotating Ultrasonic Tube

Inspection Equipment (TRUSTIE™)

Magnetic Biasing Bobbin and X-Probes for

Pickering SG Tubes

O N T A R I O P O W E R G E N E R A T I O N

Inspection Methods

� Eddy Current Testing (ET) is the primary method due to

its high acquisition speed.

� Ultrasonic Testing (UT) using TRUSTIE is a supplemental

method

� High-resolution characterization of flaws

� Accurate flaw imaging

� UT results provide evidence on field flaws to validate ET for

Inspection Qualification of Volumetric Flaws

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O N T A R I O P O W E R G E N E R A T I O N

Ultrasonic Inspection using TRUSTIE

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O N T A R I O P O W E R G E N E R A T I O N

TRUSTIE Probes

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Typical UT probe connected to a flexible drive shaft.

Straight-leg Probe U-bend Probe

O N T A R I O P O W E R G E N E R A T I O N

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TRUSTIE Probe Types

Planar (Crack-like) Flaws

Volumetric Flaws

O N T A R I O P O W E R G E N E R A T I O N

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Eddy Current and Ultrasonic Inspection

UT C-Scan Image

Photograph of Flaw in

Pulled Tube

ET Signal from Preheater Volumetric Flaw

• ET for Basic Detection and Sizing

• UT for Enhanced diagnosis and sizing with

higher accuracy – similar to Metallography

O N T A R I O P O W E R G E N E R A T I O N

IQ Package Summary

IQ Packages Qualified

� ET Pickering B OD pitting (qualified 2012)

� UT Darlington OD support fretting (qualified 2012)

� UT Darlington OD pitting (qualified 2012)

� UT Pickering OD pitting (qualified 2012)

� UT Pickering Volumetric Flaws (qualified 2013)

� UT Darlington Volumetric Flaws (qualified 2013)

� ET Darlington OD support fretting (qualified 2014)

Submitted and in review with CIQB

� ET Pickering Volumetric Flaws (submitted Q1 2013)

� ET Darlington Volumetric Flaws (submitted Q1 2014)

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O N T A R I O P O W E R G E N E R A T I O N

IQ Technical Justifications and

Submission Packages in Development

Eddy Current

� Pickering: ET Crack

� Pickering: ET IGA

� Darlington: ET Crack

UT

� Pickering: UT Crack

� Darlington: UT Crack

Procurement of cracked specimens will be beneficial for Qualification of ET

and UT crack packages

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O N T A R I O P O W E R G E N E R A T I O N

Qualification of ET Volumetric Flaws

� Based on comparison of ET flaw signals

with destructive evaluation (DE) of pulled

tube flaws, simulated flaws, and

comparison with UT Results.

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O N T A R I O P O W E R G E N E R A T I O N

ET Detection Capability for Hydrodynamic Flaws in Darlington

SG Tubes

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0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 10 20 30 40 50 60

PO

D

Flaw Depth [% through-wall]

Darlington X-Probe & Bobbin Preheater Volumetric Flaws POD

X-Probe Bobbin X-Probe POD Bobbin POD

Bobbin &

X-Probe: 111

Data Points

O N T A R I O P O W E R G E N E R A T I O N

ET Sizing Accuracy for Hydrodynamic Volumetric Flaws in

Darlington SG Tubes

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0

10

20

30

40

50

60

70

0 10 20 30 40 50 60 70

X-P

rob

e D

ep

th E

stim

ate

(%

th

rou

gh

-wa

ll)

UT Depth Measurement (% through-wall)

Ideal Sizing Reference

Data Points

O N T A R I O P O W E R G E N E R A T I O N

Qualification of UT Volumetric Flaws

� Qualification of UT Volumetric Flaws is based on:

� Pulled Tube Information

� Performance on Simulated Flaws

� Mathematical Modeling (COG R&D study)

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O N T A R I O P O W E R G E N E R A T I O N

y = 0,9908xR² = 0,9916

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0% 20% 40% 60% 80% 100%

Meta

llu

rgy M

easu

rem

en

t (%

tw

)

UT Measurement (% TW)

UT versus Metallurgy - Volumetric flaws in DNGS & PNGS removed tubes

DNGS & PNGS Volumetricflaws

Linear (DNGS & PNGSVolumetric flaws)

UT Results – Depth Sizing Volumetric Flaws

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O N T A R I O P O W E R G E N E R A T I O N

UT Results – Length Sizing Abrupt Flaws in Darlington and

Pickering SG Tubes

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y = 0,9051x + 1,0663

R² = 0,9832

0,0

5,0

10,0

15,0

20,0

25,0

30,0

0,0 5,0 10,0 15,0 20,0 25,0 30,0 35,0

De

stru

ctiv

e E

xa

min

ati

on

Le

ng

th M

ea

sure

me

nt

(mm

)

UT Length Measurement (mm)

UT Length Versus DE Measurements

Met Length (mm)

Linear (Met Length (mm))

O N T A R I O P O W E R G E N E R A T I O N

Experience with CIQB IQ Process

� Packages were reviewed by a very knowledgeable team assembled by the

CIQB with expertise in the field of NDE and its application to Steam

Generator tube inspection.

� Initial ET and UT packages submitted in 2011 took over a year to qualify.

Large number of comments needed disposition as well as competing

priorities with field work.

� Recent UT submission for Pickering Volumetric Flaws was qualified more

quickly due to the experience gained from previous UT submissions.

� Independent expert review by CIQB review team has resulted in

improvements to Inspection procedures overall.

� Collaborative discussions with review team has provided a deeper

understanding of technique and capabilities.

� The Technical Justifications developed to date provide useful summaries of

Essential Parameters.

� A better approach has been established to deal with impact of changes to

procedures/equipment on qualified procedures.

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O N T A R I O P O W E R G E N E R A T I O N

Summary

� OPG in a multi-year project to qualify steam generator tube NDE

� IQ is a requirement of CSA N285.4 Periodic Inspection of CANDU

Nuclear Power Plants

� CIQB established within COG to act as qualifying body

� Provides Licensees/Inspection Service Providers with a consistent

process for IQ (ENIQ adopted by CIQB and accepted by CNSC) for

inspection procedures required for N285.4

� Overall the IQ process is healthy for verifying the capabilities of NDE

techniques

� 7 SG IQ Packages have been Qualified so far

� Future submissions are planned for Volumetric Flaws, Cracking and

IGA.

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