wall thickness measurements under welds with …...–grayloc hub welds –fitting-to-fitting welds...

UNRESTRICTED / ILLIMITÉ

Wall Thickness Measurements

Under Welds

with CAPT and FAATS-COG

Wall Thickness Measurements

Under Welds

with CAPT and FAATS-COG

H. Hébert, G.C. Longhurst

and K.R. Chaplin

Presenter: Hélène Hébert

Outline

• Degradation mechanism under welds

• CAPT and FAATS-COG

–Description of these tools

–Advantages of the technique

• The path to CIQB qualification

2UNRESTRICTED / ILLIMITÉ

Degradation Mechanism Under

Feeder Welds


• Destructive examination of removed Pickering A feeders revealed areas of localized thinning (also knows as blunt flaws) under weld caps

–Grayloc Hub welds

–Fitting-to-fitting welds

Picture of Reactor Face


Feeder Welds

UNRESTRICTED / ILLIMITÉ 4

Grayloc

Hub

1st Fitting/

Bend

Grayloc Hub

Weld

FlangeBolt

1st Fitting-to-fitting

Weld



Feeder Welds

• Characteristics of blunt flaws:

- Abrupt, localized wall thickness changes

• Over regions ~10-20 mm axially

• With various circumferential lengths

- Appearance of a ridge on the inside surface


Feeder Welds

• Localized thinning can be:

– Under weld cap

– Adjacent to weld

Example of localized thinning found at fitting-to-fitting welds


Normal Blunt flaw1st fitting 2nd fitting

Cross Section


Feeder Welds


View from inside of feeder pipes

Localized thinning in Feeder B12W Localized thinning in Feeder B09E



Feeder Welds

• Causes of thinning:

- Variation of chromium content:

• High content in the Grayloc hub

• Medium content in the weld

• Low content in the feeder material

- Could have been exacerbated by grinding that took place during

fit-up and localized turbulence caused by the root geometry

9

CAPT

• Composite Angle Profiling Tool (CAPT)

- Delivery tool developed for COG members

- Adapted from the Header Nozzle Weld Inspection Tool developed by AECL

- Wall thickness measurements under and adjacent to welds

- Based on Phased Array Ultrasonic Testing



CAPT


- Circumferential scanning

- Region covered:

- The entire circumference

- The entire weld

- At least 10 mm of feeder pipe

adjacent to the weld

Region at Grayloc Hub Weld


CAPT

Region at Fitting-to-fitting Weld


- Circumferential scanning

- Region covered:

- The entire circumference

- The entire weld

- At least 10 mm of feeder pipe

adjacent to the weld


CAPT and FAATS-COG

*Patent Pending

CAPT (Mark 1)

13

CAPT on Bruce “A” Mock-up


CAPT


Advantages of CAPT

• CAPT inspects the same region as 6-Probe/GAIT and the entire weld

• CAPT has found minimum thickness on feeder pipes in a region

that is not covered by METAR or 6-Probe/GAIT combined

• CAPT performs measurements every:

- 0.8 mm axially

- 1.5 to 1.9 mm circumferentially

• This measurement grid is adequate for detection of blunt flaws

under welds

15

Advantages of CAPT


• CAPT can detect 3 mm diameter flat bottom holes

The calibration specimen contains:- 3 flat bottom holes- 4 steps

WT and Sensitivity Calibration Specimen

Assembly

16

Advantages of CAPT


• Simple tool…the size of a small loaf of bread

• Easy and quick calibration checks

• Easy manipulation

• Measurements highly repeatable

• CAPT remains stable on the feeder

during use

Calibration Check with CAPT

Advantages of CAPT

• Portable acquisition station, small footprint

CAPTEntire Inspection System,

Including Acquisition Station

18

Advantages of CAPT


• Use a small amount of demineralized water as couplant

(reduces slipping hazards during inspections)

• Compatible with current data acquisition systems used for METAR,

6-Probe and GAIT inspection

• Maintains coupling over complex topography with weld cap,

even in the intrados of tight radius fittings/bends

19

FAATS-COG


• Software used to analyse CAPT data

- Measurement of minimum thickness on feeder pipe and under the weld

- Two-dimensional wall thickness maps

- Localized thinning patterns under welds (blunt flaws)

• Aid to the qualified data analyst

Advantages of FAATS-COG

• Quick calibration checks (performed under 1 min)

• High resolution (1 µm)

• Improved coverage using phased array

• Faster analysis using new software features


21

Advantages of

CAPT and FAATS-COG


• Improved coverage (even in the intrados of tight-radius bends)

• Detection of localized thinning under welds and on feeder pipes

Ex-service Feeder P1E19W

The Path to CIQB Qualification

Experience

• First field trial at Pickering A in 2009:

– Inspection procedure tested

–Areas of improvement identified for CAPT and FAATS-COG

• NRU Calandria vessel leak and repair:

–Extensive use of similar inspection technique and

software at NRU since 2009

–Continuous improvement of these tools

–CIQB qualified techniques

• CAPT Mark 1 and FAATS-COG 3.0 were produced for COG




ACQUISITION OF CAPT DATA

Inspection Procedure

Training Procedure

Training material

ANALYSIS OF CAPT DATA

Analysis Procedure

Training Procedure on Analysis

Training Material on Analysis

Technical Justification





Training Procedure

Training material


Analysis Procedure




Submitted to the CIQB

in 2011 March

Documents were reviewed

by an independent panel

of ultrasonic testing

experts





Training Procedure

Training material


Analysis Procedure




Submitted to the CIQB

in 2011 March

Documents were reviewed

by an independent panel

of ultrasonic testing

experts

Improved procedures

and training material

CAPT is the first COG thinning inspection

technique to undergo CIQB qualification!

26

Acknowledgements


• COG NDE Team and FIJP

• CIQB and their reviewers

• CAPT and FAATS-COG development teams

• B&W for use of their mock-up

• OPG for the first field trial

• Malcolm Clark for the pictures of blunt flaws

PROTECTED - SENSITIVE / PROTÉGÉ - DÉLICAT 27UNRESTRICTED / ILLIMITÉ 27

QUESTIONS?