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Presentation Slides - Technical Justification for the Ghent Version 2 Probe Qualification and Probability of Detection - May 26, 2020 (Non-Proprietary Version)
	ML20143A042
Person / Time
Site:	Beaver Valley
Issue date:	05/22/2020
From:	Raschiatore J, James Smith; Energy Harbor Nuclear Corp, Westinghouse
To:	; Division of Operating Reactor Licensing
	Tobin J
References
	Download: ML20143A042 (31)
	v • d • e

Westinghouse Non-Proprietary Class 3 1

Jay Smith, WEC Fellow Engineer Jeff Raschiatore, WEC Corporate Level III May 26, 2020 Technical Justification for the Ghent Version 2 Probe Qualification and Probability of Detection

- - This record was final approved on 5/21/2020 5:22:23 PM. (This statement was added by the PRIME system upon its validation)

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Background

NRC Safety Evaluation Report (SER) for approval to extend the Nickel Band Tubesheet Sleeve to 8 Cycles stated that the following would need to be addressed for permanent approval. (ML18348B206)

- Qualified Inspection Technique for the parent tube behind the nickel band

- Resolution of questions regarding the POD for the inspection technique

The Ghent Version 2 probe was developed and designed to provide enhanced flaw detection capabilities in the parent tube behind the nickel band region in the lower tubesheet joint.

- - This record was final approved on 5/21/2020 5:22:23 PM. (This statement was added by the PRIME system upon its validation)

3 Westinghouse Non-Proprietary Class 3

Ghent Version 2 Probe Design

Ghent Version 2 probe is a magnetically biased rotating transmit-receive probe.

Strong rare earth magnets suppress the effects of the nickel

- Improves ability to saturate the nickel material

- Improves inspection capability of parent tube behind the nickel

- [

]a,c,e mega gauss oersted (MGO) strength of the Version 1 probe

- - This record was final approved on 5/21/2020 5:22:23 PM. (This statement was added by the PRIME system upon its validation)

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Ghent Version 2 Probe a,c,e a,c,e

- - This record was final approved on 5/21/2020 5:22:23 PM. (This statement was added by the PRIME system upon its validation)

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Ghent Version 2 Probe Qualification

The Ghent Version 2 probe was fully qualified for flaw detection in accordance with the EPRI Steam Generator Examination Guidelines Appendix H, Revision 8

Testing program completed to study the probability of detection capabilities Additional details of each program are provided in the next two Sections

- - This record was final approved on 5/21/2020 5:22:23 PM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 6

Jeff Raschiatore WEC Corporate Level III May 26, 2020 Ghent Version 2 Probe Site-Specific Appendix H Qualification

- - This record was final approved on 5/21/2020 5:22:23 PM. (This statement was added by the PRIME system upon its validation)

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Sleeves at Beaver Valley 2

Alloy 800 sleeves contain nickel and microlok bands located within the roll expansion region

- Original qualifications for the Alloy 800 sleeves were performed using a +POINT'1 eddy current coil that addressed various areas of the sleeve assembly, however, excluded the parent tube adjacent to the nickel band region.

- A different inspection technique was required that improves detection through the masking effects attributed to the nickel band.

- The Ghent G3/G4 probe produced the most promising detection improvement during a feasibility study.

+1POINT is a trademark or registered trademark of Zetec, Inc. Other names may be trademarks of their respective owners.

- - This record was final approved on 5/21/2020 5:22:23 PM. (This statement was added by the PRIME system upon its validation)

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Site-Specific Qualification Requirements

Site-specific qualifications (non-EPRIQ techniques) as a minimum, requires an IQDA verify and document compliance with Appendix H of the EPRI SG Examination Guidelines.

The technique being qualified is for DETECTION only.

- Appendix H requires flaw depths ranging from 60% to 100%.

(It is acceptable to use flaw depths below 60%.)

Table H-2 of the EPRI guidelines provides the minimum number of flawed grading units >60% through-wall (TW) that must be detected to meet the technique acceptance criterion of POD > 0.80 at a 90% confidence level

- With a total of flawed grading units = 25, then minimum number that must be detected = 23.

- - This record was final approved on 5/21/2020 5:22:23 PM. (This statement was added by the PRIME system upon its validation)

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Flawed Samples Created for Qualification a,c,e

- - This record was final approved on 5/21/2020 5:22:23 PM. (This statement was added by the PRIME system upon its validation)

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Flawed Samples & Initial Testing Each of the parent tube samples are Alloy 600 material, 0.875 inch in diameter with a wall thickness of 0.050 inch.

The sleeves were installed into the parent tube and positioned with the notches adjacent to the nickel band.

Worked with probe manufacturer [

]a,c,e.

Version 1 Ghent probe had [

]a,c,e.

a,c,e

- - This record was final approved on 5/21/2020 5:22:23 PM. (This statement was added by the PRIME system upon its validation)

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Modification to Ghent Probe Additional probe modifications were performed by Zetec to create the Ghent Version 2 probe

[

]a,c,e were achieved with the Ghent Version 2 probe.

[

]a,c,e Detection requirements for qualification were met

[

]a,c,e.

a,c,e

- - This record was final approved on 5/21/2020 5:22:23 PM. (This statement was added by the PRIME system upon its validation)

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Peer Review Beaver Valley Unit 2 Site-Specific ETSS # DMW-G3/G4-Ni, Revision 0 was created to provided process detail for acquisition and calibration and reporting requirements for analysis Three IQDA analysts were used for the peer review.

Independently they were able to verify the requirements that Appendix H of the EPRI guidelines were met.

A review of the ETSS was performed, with all 3 approving.

Next, a review of the eddy current data for each indication with the intent of determining if the indication was detectable.

Results for the QDA IQDA #1 - [

]a,c,e detectable IQDA #2 - [

]a,c,e detectable IQDA #3 - [

]a,c,e detectable Each IQDA analyst signed that the technique met Appendix H requirements a,c,e

- - This record was final approved on 5/21/2020 5:22:23 PM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 13

Jay Smith WEC Fellow Engineer May 26, 2020 Probability of Flaw Detection in the Alloy 800 Mechanical Sleeve Lower Tubesheet Joint Using the Ghent Version 2 Eddy Current Probe

- - This record was final approved on 5/21/2020 5:22:23 PM. (This statement was added by the PRIME system upon its validation)

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General Approach to POD Development

Obtained parent tube crack samples

Installed parent tube crack samples into tubesheet simulant collars

Installed Alloy 800 nickel band tubesheet sleeves into parent tube/collar assembly

Tested assembly with Ghent Version 2 probe

Destructively tested crack samples to determine crack depth

Evaluated inspection and test results to develop probability of detection (POD) curves

- - This record was final approved on 5/21/2020 5:22:23 PM. (This statement was added by the PRIME system upon its validation)

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Parent Tube Crack Samples

Parent Tube Crack Samples were obtained from EPRI to develop crack based POD Curves

- 4 Tube Samples containing 12 Axial ODSCC Cracks

- 0.875 inch x 0.050 inch Alloy 600 tubing

Each Sample tested without sleeve with +POINT probe to obtain baseline data

The flaw depths ranged from [

]b to [

]b as determined from subsequent destructive examination

- One sample at [

]b depth

- Remaining depths ranged from [

]b to [

]b TW

- - This record was final approved on 5/21/2020 5:22:23 PM. (This statement was added by the PRIME system upon its validation)

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Parent Tube/Sleeve/Collar Assembly

Tubesheet split collar simulants were manufactured with a tube bore closely matching the tube outer diameter

- Minimize flaw deformation when expanded into collar

Parent tube samples were manually hard rolled into tubesheet simulant collar to firm contact

- Minimize flaw deformation when expanded into collar

Each sample tested with Ghent Version 2 probe

Following testing, sleeves were removed and parent tube tested with +POINT probe and standard Ghent probe

- - This record was final approved on 5/21/2020 5:22:23 PM. (This statement was added by the PRIME system upon its validation)

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Ghent Version 2 Test Results

4 of 12 axial ODSCC flaws were detected in the parent tube behind the sleeve nickel band within the tubesheet simulant collar

- The depth size of the detected flaws ranged from [

]b to [

]b

- The depth of flaws not detected ranged from [

]b to

[

]b

All but one flaw not detected were less than [

]b

Post-test eddy current if parent tube with no sleeve and collar showed no change to the flaw sizes

- Successful measures to mitigate flaw deformation

- - This record was final approved on 5/21/2020 5:22:23 PM. (This statement was added by the PRIME system upon its validation)

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Parent Tube/Sleeve/Collar Test Results As-Received Parent Tube Sleeve/Tube/Collar Assembly Post-Test Parent Tube (No Sleeve)

Parent Tube Sample Identification Flaw Number Location (degrees)

Baseline

+POINT Vpp Behind Nickel Ghent Version 2 Vpp Final

+POINT Vpp Final Standard Ghent Vpp DE Exam Depth

%TW J-2-3 1

31 0.71 NDD 0.74 1.20 2

71 1.49 0.35 1.49 2.62 3

102 0.73 NDD 0.70 1.07 4

285 0.21 NDD 0.21 0.27 J-3 1

91 NI NDD 0.44 0.28 2

91 NI NDD 0.44 0.63 3

168 18.07 3.76 20.49 21.60 4

278 0.26 NDD 0.21 0.21 5

354 0.27 NDD 0.26 0.59 J-8 1

46 0.86 0.09 0.86 1.38 2

228 0.40 NDD 0.36 0.63 J-12A 1

312 1.02 0.39 1.41 2.55 NI-Not initially recorded NDD-No degradation detected b

- - This record was final approved on 5/21/2020 5:22:23 PM. (This statement was added by the PRIME system upon its validation)

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Probability of Detection (POD) Development

Industry accepted POD modeling methods were used to develop POD curves from testing program

Generalized Linear Modeling (GLM) binary hit-miss models used in accordance with the EPRI SG Integrity Assessment Guidelines

- Flaw detection (hits) assigned 1

- Flaw non-detection (miss) assigned 0

- Log-logistic POD curves developed

Two types of POD curves developed

- Simple Hit-Miss POD from raw detects/non-detects from testing

- Noise-based POD from simulations of noise and voltage to depth correlations from testing

- - This record was final approved on 5/21/2020 5:22:23 PM. (This statement was added by the PRIME system upon its validation)

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Simple Hit-Miss Curve a,c,e

- - This record was final approved on 5/21/2020 5:22:23 PM. (This statement was added by the PRIME system upon its validation)

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Noise-Based POD Curve

Used Industry Model Assisted POD (MAPOD) methodology

- Voltage amplitude noise distribution

- Flaw depth to flaw voltage correlation (Ahat)

- Signal-to-noise thresholds for flaw detection

Inputs combined through probabilistic simulations to determine hits/misses to produce log-logistic POD curve

Noise distribution developed from Ghent V2 probe Appendix H program and samples

Ahat distribution from POD test program and destructive examination of crack samples

S/N thresholds developed from results of POD test program

- - This record was final approved on 5/21/2020 5:22:23 PM. (This statement was added by the PRIME system upon its validation)

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Noise and Ahat Distributions a,c,e a,c,e

- - This record was final approved on 5/21/2020 5:22:23 PM. (This statement was added by the PRIME system upon its validation)

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Noise-Based POD Curve, Linear Ahat a,c,e

- - This record was final approved on 5/21/2020 5:22:23 PM. (This statement was added by the PRIME system upon its validation)

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Alternate Noise-Based POD

Observations during the test program suggest that the effects of the nickel may introduce unique conditions not accounted for in the noise-based POD method.

Effects of the nickel reduces the flaw voltage amplitude without apparent influence from noise, thus making the noise-based POD result overly conservative

- MAPOD method assumes noise is the only parameter contributing to masking flaws

An alternate noise-based POD curve developed with an adjusted Ahat function to address the voltage reduction caused by the nickel

- - This record was final approved on 5/21/2020 5:22:23 PM. (This statement was added by the PRIME system upon its validation)

25 Westinghouse Non-Proprietary Class 3

Alternate Noise-Based POD Curve a,c,e

- - This record was final approved on 5/21/2020 5:22:23 PM. (This statement was added by the PRIME system upon its validation)

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Ghent V2 Probe POD Comparisons

The results of the three POD methods are

- Simple POD(0.95) = 74.5% TW

- Unadjusted MAPOD POD(0.95) = 93.7% TW

- Alternate MAPOD POD(0.95) = 86.0% TW

Simple Hit/Miss POD considered More True since it is empirically determined by Detections and Depths. Effect of noise and Nickel is inherent.

Unadjusted MAPOD POD considered overly conservative since it includes compounding effects of voltage reduction from nickel and noise effects

Alternate MAPOD POD is more comparable and more conservative to the empirical Simple Hit/Miss POD

- - This record was final approved on 5/21/2020 5:22:23 PM. (This statement was added by the PRIME system upon its validation)

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Applicability of OD Flaw Detection to ID Flaws

PWSCC flaw samples were not available for this test program. ODSCC flaw samples were readily available.

The POD curves developed from this test program provides a conservative estimate of ID flaw detection based on eddy current theory.

- Eddy current test frequency of 70kHz concentrates the magnetic field at the inner surface of the parent tube

- Magnetic field strength is lower at the outer surface of the parent tube - providing lower detection capability for OD originating flaws.

Detection of parent tube ID originating flaws are expected to be significantly better than the POD curves developed.

- - This record was final approved on 5/21/2020 5:22:23 PM. (This statement was added by the PRIME system upon its validation)

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Operational Assessment Using POD Curves

To demonstrate the acceptability of the developed POD curves, an Operational Assessment was performed to show that SG performance criteria will be satisfied after one cycle of operation with potentially undetected flaws

- Fully probabilistic analysis

- EPRI default growth rates used

- Assumed three undetected flaws

- Assumed flaws located in freespan to allow use of burst and leakage equations

Extremely conservative

Burst is actually eliminated due to tubesheet

Leakage is actually reduced due to tubesheet full depth hard roll and sleeve joint

- - This record was final approved on 5/21/2020 5:22:23 PM. (This statement was added by the PRIME system upon its validation)

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Operational Assessment Results

All SG Performance Criteria satisfied using the three developed POD curves Case Applied POD Curve Probability of Burst

(%)

Probability of Leak

(%)

Upper 95th Percentile SLB Leakage (gpm)

Lower 5th Percentile Burst Pressure (psi)

Case A Simple Hit/Miss 1.15 0.034 0

5355 Case B Alternate Ahat 2.25 0.106 0

5025 Case C Unadjusted Ahat 3.53 0.148 0

4746 SG Performance Criteria 5

5 0.10 4525

- - This record was final approved on 5/21/2020 5:22:23 PM. (This statement was added by the PRIME system upon its validation)

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Conclusions

POD curves for detection of parent tube flaws behind nickel band region in the lower tubesheet sleeve joint have been successfully developed based on actual Ghent Version 2 inspection and destructive examination of actual outer diameter stress corrosion crack samples.

The developed POD curves have been demonstrated to support an operational assessment for at least one cycle of operation.

- - This record was final approved on 5/21/2020 5:22:23 PM. (This statement was added by the PRIME system upon its validation)

WAAP-11737-NP Revision 0 Proprietary Class 3

- This page was added to the quality record by the PRIME system upon its validation and shall not be considered in the page numbering of this document.**

Approval Information Author Approval Smith Jay R May-21-2020 17:03:33 Manager Approval Bradley Michael E May-21-2020 17:22:23 Files approved on May-21-2020

- - This record was final approved on 5/21/2020 5:22:23 PM. (This statement was added by the PRIME system upon its validation)

v t e Letter Sequence Request
EPID:L-2020-LRM-0048, Presentation Slides - Technical Justification for the Ghent Version 2 Probe Qualification and Probability of Detection - May 26, 2020 (Non-Proprietary Version) (Open)
Initiation Request Acceptance... Administration Meeting Questions Answers Results Approval... Other:
MONTHYEAR2020-05-22 [Table View]

ML20143A042

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