Text

SG-SGDA-05-04-NP, Rev. 0, Comanche Peak Steam Electric Station 1RF11 Outage Condition Monitoring Report and Preliminary Cycle 12 Operational Assessment, October 2005
	ML060670447
Person / Time
Site:	Comanche Peak
Issue date:	02/03/2006
From:	Cullen W, Lagally H, Weyandt T; Westinghouse
To:	; Office of Nuclear Reactor Regulation
References
	CPSES-200600312, RP-39, TXX-06031 SG-SGDA-05-45-NP, Rev 0
	Download: ML060670447 (53)
	v • d • e

Enclosure 2 SG-SGDA-05-45-NP Revision 0 (Non-Proprietary)

Comanche Peak Steam Electric Station IRFNI Outage Condition Monitoring Report and Preliminary Cycle 12, Operational Assessment

Westinghouse Non-Proprietary Class 3 SG-SGDA-05-45-NP Revision 0 October 2005 Comanche Peak Steam Electric Station 1 RF11 Outage Condition Monitoring Report and Preliminary Cycle 12 Operational Assessment

Westinghouse

Westinghouse Westinghouse Non-Proprietary Class 3 SG-SGDA-05-45-NP Comanche Peak Steam Electric Station IRFiI Outage Condition Monitoring Report and Preliminary Cycle 12 Operational Assessment October 2005 Prepared by:.

/c* (&1A~-=.I

?/r';;

William K Cullen Verified by:_

H. 0. Lagally

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TXU Review by:

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SG-SGDA-05-45-NP Comanche Peak I RFl; I Condition MNlonitorin, and Preliminary Cycle 12 Operational Assessment

1.0 INTRODUCTION

Per NEI 97-06, a condition monitoring assessment which evaluates structural and leakage integrity characteristics of SG eddy current indication, is to be performed followving each inspection. This evaluation provides an assessment of the Comanche Peak Unit I steam generator tube structural and leakage integrity based on the 2005, EOC-I I eddy current inspection results. Condition monitoring is "backward looking" and compares the observed EOC-I I steam generator tube eddy current indication parameters against structural and leakage integrity commensurate with the NEI 97-06 performance criteria. Additionally, an operational assessment, or "forward looking" evaluation is used to project the inspection results and trends to the next inspection to determine primarily if tube structural or leakage integrity will be challenged at EOC-12. This report documents the condition monitoring of the NDE results from tile Comanche Peak I RFI I Refueling Outage inspection, performed in October 2005. Additionally, this evaluation provides a preliminary assessment of SG tube integrity at EOC-12 that supports SG operability. Note that no steam generator inspections are planned for the I RF 12 outage as the original steam generators are scheduled for replacement at that time.

The Comanche Peak Unit I SGs are Westinghouse Model D4 SGs with mill annealed Alloy 600 tubing, full depth mechanical (hardroll) expanded tube to tubesheet joints, and carbon steel tube support plates with drilled tube holes and drilled flow holes. A small number of tubes in each SG are expanded in the tubesheet using the WEXTEX explosive expansion process.

2.0 OVERALL CONCLUSIONS The IRFI I flaw parameters for existing known degradation mechanisms are consistent with the I RFI0 and I RF09 flaw parameters in severity of the indications based on NDE data. At I RFI 0 the number of affected tubes with circumferential ODSCC was significantly reduced, and this trend continued with the number of tubes affected with circumferential ODSCC at I RFI I being less than IRFIO. Tile I RFI I maximum circumferential ODSCC flaw amplitude from +Pt of 0.27 volts is well below the EPRI In Situ Guideline Revision 2 testing threshold of 0.50 volts. The number of tubes affected with ding ODSCC was slightly reduced while the number of tubes with freespan ODSCC was slightly increased. In general, the signal amplitudes for all mechanisms were consistent with, or bounded by the IRFl0 results suggesting that there were no significant differences in the secondary side ODSCC aggressiveness that will suggest any result difference from past results for the Cycle 12 operational assessment.

Two new degradation mechanisms, oblique PWSCC at large (Row 3 and higher) U-bends, and circumferential PWSCC at the hot leg hardroll expansion transition were reported for the IRFIO outage. Oblique PWSCC was again reported at IRFI 1, however, circumferential PWSCC at the expansion transition was not reported in full depth roll expanded tubes. A total of 8 tubes were affected with oblique PWSCC at large radius U-bends at I RF IO while 4 were reported at I RFI 1.

These numbers are judged low\\, compared to recent inspection results for plants that have observed this mechanism. It should be noted that the Comanche Peak Unit I T-hot of approximately 620"F with 13.12 accumulated EFPY represent the highest PWSCC initiation potential for operating units Page I of4l

SG-SGDA-05-45-NP with mill annealed tubing. The largest +Pt amplitude reported for oblique PWSCC at I RF lO was 2.2 volts, while the largest +Pt amplitude reported for oblique PWSCC at IRFI I was 0.64 volt.

Two tubes were reported with circumferential PWSCC at the tack roll to WEXTEX expansion transition in WEXTEX expanded tubes at IRFI 1. The maximum reported +Pt amplitude was 1.53 volts with a circumferential involvement of 1030.

Collapsed TIG sleeves were also noted in SGs 2, 3, and 4 at I RF IO. No TIG sleeves are installed in SGI. The total number of TIG sleeves that would not pass a 0.500" +Pt probe was 38. An additional 22 sleeves were observed to contain a signature on the +Pt trace that suggested a possible ovalization condition, even though the 0.500" +Pt passes from end to end. These possible ovalized sleeves in SG3 (6), along wvith a set of control sleeves that did not contain this trace were gauged using a 0.540" bobbin probe. It was found that all control sleeves would pass the 0.540" bobbin probe while all potentially ovalized sleeves would not pass a 0.540" bobbin probe. Thus it was concluded that the remaining 16 potentially collapsed sleeves would also not pennit passage of the 0.540" bobbin probe.

All 60 potentially collapsed sleeves wvere plugged. At IRFI 1, 7 additional TIG sleeves were found to be collapsed. A total of 547 Alloy 800 sleeves were installed at lRFIO; none were found to be collapsed at IRFI 1.

Preliminary benchmarking of the observed I RF I I eddy current parameters indicates that the operational assessment methodologies applied wvere conservative. Based on these observations, it is concluded that structural and leakage integrity wvill be maintained at EOC-12.

The AVB and baffle plate wear mechanisms did not show excessive growth, and growth trends were consistent with Cycle 10. One baffle plate wear indication required plugging due to measured wear scar depth of 45%TW (SG2); the measured depth at I RF IO was 39%TW. No AVB wear signals exceeded 40%TW.

During the CPSES I RFI I steam generator tube inspection, no indications exceeding the structural integrity limits for either axial or circumferential degradation (i.e., burst integrity > 3 times nonnal operating primary to secondary pressure differential across SG tubes) were detected. Based on the changes made to the bobbin reporting criteria and the observed signal characteristics for the top of tubesheet ODSCC mechanisms, which will be discussed in detail later, it is expected that all operational assessment structural and leakage integrity requirements will be satisfied at EOC-12 for the degradation mechanisms observed at EOC-I 1.

3.0 PRE-OUTAGE EVALUATION OF SG DEGRADATION STATUS Pre-Outage Degradation Assessment A pre-outage degradation assessment pursuant to EPRI TR-107621 RI and EPRI 1003138 was performed for CPSES IRFI 1. This degradation assessment (Reference 1) identified the degradation modes which could occur at CPSES Unit I and evaluated the adequacy of the eddy current techniques applied for detection and sizing of these mechanisms.

Per EPRI 1003138, "PWR Steam Generator Examination Guidelines: Revision 6", an active degradation mechanism is:

Page 2 of41

SG-SGDA-05-45-N P

1. A combination of ten or more new indications (> 20% TW) of thinning, pitting, wear (excluding loose part wear), or impingement and previous indications that display an average growth rate > 25% of the repair limit in one inspection-to-inspection interval in any one SG or,

2. One or more new or previously identified indications (> 20%TW) which display a growth rate equal to the repair limit in one inspection-to-inspection interval, or

3. Any crack indication (outside diameter intergranular attack/stress corrosion cracking or primary side stress corrosion cracking).

Based upon the likelihood of indications, the degradation assessment classified degradation mechanisms as active, relevant, or potential, with correspondingly decreasing likelihood of initiation and potential impact upon SG tube integrity. The degradation assessment concluded that the following degradation mechanisms were active (as defined by EPRI 1003138) in the CPSES Unit I SGs.

Axial ODSCC at TSP intersections

Circumferential and Axial ODSCC at the hot leg TTS expansion transition

Axial ODSCC at Freespan dings

Axial ODSCC in the freespan not associated wvith dings

Circumferential and Axial PWSCC at the hot leg TTS expansion transition

Oblique PWSCC at Row 3 and higher U-bends Degradation Structural Limits The CPSES IRFI I pre-outage degradation assessment (Reference I) identified length and depth based structural limits for freespan axial and circumferentially oriented degradation. Lower bound length and depth based structural limits were developed for volumetric degradation modes (i.e., AVB wear, TSP wear) based on previously published industry data and correlations. The degradation assessment provides the structural limits and NDE uncertainties to support the condition monitoring and operational assessments of this report.

CPSES I RFI I Initial Inspection Plan The CPSES IRFI I inspection plan exceeded both the Technical Specification minimum requirements as well as the recommendations of EPRI 1003138, PWR Steam Generator Examination Guidelines: Revision 6. The IRFI I initial inspection plan included;

1) 100% full length bobbin examination in Rows 5 and greater in all 4 SGs, 100% bobbin inspection in the hot and cold leg straight sections of Rows I thru. 4

2) 100% Hot Leg top of tubesheet (TTS) +Pt examination in all 4 SGs from +3 to -3" for hardroll expanded tubes from +3 to hot leg tube end for WEXTEX expanded tubes

3) 100% Row I and 2 U-bend mid-range +Pt examination in all 4 SGs

4) 100% Row 3 through Row 16 U-bend mid-range examination in all 4 SGs Page 3 of 41

SC-SGDA-05-45-NP

5) 100% +Pt examination of DSI signals >IV (per GL 95-05)

6)

Rotating probe examination of mixed residuals (> 1.5 volts as measured by bobbin) and hot leg dented intersections > 5 volts (as measured by bobbin) according to the requirements of GL 95-05.

7)

Rotating probe examination of freespan bobbin coil indications for flaw confinnation and characterization.

8) 100% +Pt inspection of all dented TSP intersections at the H3 TSP > 2 volts

9) 100% +Pt inspection of >5V dings (both legs, including U-bend)

10) 100% +Pt inspection of all dents at AVBs, regardless of voltage

11) 20% +Pt freespan paired ding inspection between the top 2 TSPs

12) 20% +Pt examination of non-expanded tube baffle wear in all 4 SGs

13) 25% +Pt exam of expanded cold leg baffles

14) 100% +Pt full length inspection of Alloy 800 sleeves including parent tube 3 inches above and below the sleeve

15) 20% +Pt full length inspection of TIC sleeves including parent tube 3 inches above and below the sleeve

16)

+Pt examination of TIG sleeves +/- 3 inches from top of sleeve in TIG sleeves not +Pt examined full length

17) 1 00% +Pt examination of AVB wear sites

18)

Secondary side FOSAR at top of tubesheet and atop cold leg baffle B (C2 plate)

19)

Tube plug visual inspection

- - For tubes in Rows I thru 4 with installed TIG sleeves the 0.540 inch wide groove bobbin probe was used for inspection of the parent tube above the sleeve to the hot leg U-bend tangent. For tubes in Rowvs I thru 4 with installed Alloy 800 sleeves the 0.520 inch wide groove bobbin probe was used for inspection of the parent tube above the sleeve to the hot leg U-bend tangent.

The inspection plan was developed to specifically address the areas of active degradation as well as areas expected to be affected based on recent industry experience as well as experience from the CPSES IRFIO outage in April 2004.

3.1 IRF1I Identified Degradation Mechanisms Indications suggestive of the following degradation mechanisms were detected in the CPSES IRFI I inspection:

Axial ODSCC at TSP intersections

Circumferential ODSCC at the Hot Leg TTS expansion transition

Axial PWSCC at the Hot Leg TTS expansion transition

Circumferential PWSCC at the Hot Leg tack roll to WEXTEX expansion transition

Oblique PWSCC at large radius (Row 3 and higher) U-bends

Axial PWSCC at large radius (Row 3 and higher) U-bends

Axial ODSCC in the freespan not associated with dings

Axial ODSCC at freespan dings <5V

Freespan Volumetric indications (not associated with operational degradation)

AVB wear

Wear at non-expanded preheater baffle intersections

Wear due to loose parts or foreign objects Page 4 of 41

SG-SGDA-05-45-NP The 90-day report for axial ODSCC at TSP intersections will be documented in a separate ARC report, as part of analyses required per NRC Generic Letter 95-05. Tube support plate ODSCC indications for I RF I I were nearly identical to I RF I0 both in total number of indications and observed bobbin amplitude. Only I indication had bobbin amplitude greater than I volt. This indication, in SG 2, was confirmed by +Pt and plugged.

Table I presents a summary of the number of repaired tubes in each SG and identifies the mechanism that necessitated the repair. A summary of all repaired tubes, including tubes plugged for degradation, tubes preventively plugged, and tubes permitted to remain in service by application of the voltage based alternate repair criteria per GL 95-05, and F*, is provided in Table 2.

Based on the observation of axial PWSCC in a Row 13 tube in SG4, the U-bend inspection program was expanded to include 100% of Rows 17 through 25 in SG4. Oblique PWSCC Indications were observed in Row 5 tubes in SGs I and 2, and a Row 3 tube in SG3, however, no further expansion of the inspection scope was required as these rows are bounded by the critical area redefinition.

At I RF 10 the U-bend inspection scope for dents at AVBs was expanded to include all dings within

+/- 0.75 inch of the AVB. This expansion was necessitated based on observation of ODSCC at a ding detected by +Pt at approximately 0.6" from the AVB. A DNI report was not noted for this tube however close scrutiny of the bobbin data indicates that a DNI signal was present. At I RFI I the base scope included all dings within +/- I inch of AVBs. Only one ding ODSCC signal in the U-bend region was reported at I RFI 1; this signal was reported as DNI from bobbin and was located 1.54 inch from the AVB.

A C-3 condition was reported for SG4 due to the detection of >45 indications of degradation at the top of tubesheet location.

Disposition Techniques for Identified Degradation Mechanisms Depth measurement of AVB wear indications and non-expanded preheater baffle plate wear using the bobbin coil is acceptable per EPRI Appendix H standards, and these indications were sized against the 40% depth repair criteria. ODSCC indications at the TSP intersections were sized based on voltage using the bobbin coil according to guidance contained in GL 95-05. Indications greater than or equal to I volt by bobbin were RPC inspected for flaw confirmation, even though only those DSls

>1 volt are required to be +Pt inspected per GL 95-05. Indications (regardless of bobbin voltage) identified in exclusion zones related to tube collapse potential near TSP wedges were RPC inspected, and if confirmed. are repaired regardless of voltage. No bobbin indications at TSP intersections were reported in exclusion zones. All mix residual signals were inspected with +Pt; none x'ere confirmed.

All crack-like indications in the expansion transition down to the F* distance were repaired upon detection since depth sizing techniques are not acceptable for continued operation justification. All hot leg top of tubesheet circumferential indications were located within the expansion transition region.

To reduce the potential for an axially oriented ODSCC indication to be obscured by baffle wear, all newly reported occurrences of preheater baffle wear by bobbin were RPC inspected. No ODSCC was detected. Through IRFO9, all previously reported baffle wear had been inspected with +Pt.

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SG-SGDA-05-45-NP Indications previously called volumetric, have in the past been reviewed, and determined to be attributed to deposits, MBMs, dings and bulges, or tube material property changes which sometimes occur after power operation. At I RFI I all SVI calls by RPC not able to be dispositioned by F* were repaired by plugging. A bobbin history review was performed for each of these indications to show that the signal had not changed since the IRF l0 inspection. SVI calls can include volumetric tube degradation associated with a non-corrosion related mechanism such as laps or gouges, and loose part wear signals.

Additionally, permeability variations were reported based on bobbin or RPC amplitude > I volt. Prior to the I RFI I inspection, it was defined that permeability variations coincident with regions of the tube where active degradation mechanisms were present should be repaired if it was judged that the penmeability could interfere wvith adequate flaw detection. This resulted in the conservative repair of 4 tubes; 0 in SGl, I in SG2, 1 in SG 3, and 2 in SG4. Additionally, several tubes wvere conservatively repaired due to dent/ding restrictions that prevented acceptable eddy current data from being collected. Zero tubes in SGI, 0 tubes in SG2, I tube in SG3 and 2 tubes in SG4 were plugged for this reason. The tube in SG3 preventively repaired contained a >5V ding in the U-bend above HI I that could not be inspected due to sleeve installation in the hot leg at IRFI0. The two tubes in SG4 preventively plugged had intermittent data collection through the U-bend due to dents at lower elevations that interfered with the probe translation.

Any tube scheduled for a particular test (such as full length bobbin), that could not be tested due to a restriction in the tube or due to poor data quality, was conservatively repaired.

In addition to the mechanisms identified, the mechanisms that were niot identified are also noteworthy. These include:

SCC at dented TSP intersections

Small radius (Roxv I and 2) U-bend PWSCC "Dents" at Comanche Peak Unit I are believed to be related to manufacture, and not to corrosion of the carbon steel TSPs. Comanche Peak Unit I has not operated with secondary side chemistry regimes conducive to traditional denting morphologies. The lack of small radius U-bend PWSCC is related to the in situ heat treatment of the Rowl and 2 U-bends prior to operation. For similar plants that have performed U-bend heat treatment prior to operation, no degradation in the U-bends has been reported.

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SC-SGDA-05-45-NP Table I Summary of I RF 1 I Tube Repair Statistics SGlI Degradation IIL sludge pile IIL TTS Exp.

RI and 2 Hot Leg Freespan Freespan

>Row 2 U-Baffle Plate Cold Leg Total Mode

(>I" above TTS)

Transition and U-bend TSP (no ding)

(ding) bend TTS Expanded Tube Axial ODSCC 0

0 0

0 4

3 0

0 0

7 Axial PWSCC 0

0 0

0 Circ. ODSCC 0

5 0

0 0

5 Circ PWSCC 0

I 0

0 0

0 1

0 0

2 Wear 0

0 0

0 Volumetric 0

0 0

1 1

0 0

1(1) 0 3

Sub Total 0

6 0

1 5

3 I

I 0

17 SG2 Axial ODSCC 0

0 0

1 2

2 0

0 0

l5 Axial PWSCC 0

0 0

0

°0 0

0 0

0 j

0 Circ. ODSCC 0

9 0

0 0

9 Circ. WVCC 0

I 0

j0 0

0 2

0 U

3 Wear 0

0 0

l 0

Volumetric 0

0 0

0 2

0 0

j 2

Sub Total 0

10 0

1 4

2 2

0 0

1 23(2)

SG 3 AxialODSCC 0

0 0

0 Axial PWSCC 0

0 0

0 Circ. ODSCC 0

24 0

0 0

24 Circ PWSCC 0

0 0

0 I

0 0

1 Wear 0

0 0

0 Volumetric 0

2 0

1(1) 0 0

0 0

0 3

SubTotal 0

26 0

I 0

0 1

0 0

l l33 (3)

SG4 Axial ODSCC 0

0 0

1(5) 2 0

0 0

0 3

Axial PWSCC 0

1 0

0 0

0 1

0 0

2 Circ. ODSCC 0

57 0

0 0

57 Wear 0

0 0

1 0

1 1

Volumetric 0

2 0

0 0

2 Sub Total 0

60 0

1 2

0 1

1 0

70 (4)

Ovcrall Total 0

102 0

4 1

5 5

2 0

l 143 Page 7 of 41

SG-SGDA-05-45-NP Notes for Table 1:

(1): Volumetric indications located at TPSs and cold leg baffles are due to foreign object wear.

(2): Includes 3 collapsed TIG sleeves and one PVN signal preventively plugged.

(3): Includes 3 collapsed TIG sleeves, one >5V ding not inspected due to a sleeve in the hot leg, and one PVN signal preventively plugged.

(4): Includes I collapsed TIG sleeve, two restricted tubes in U-bend, and two PVN signals in U-bend preventively plugged.

(5): Indication reported by RPC only Table 2 Summary of Repaired Indications and Indications Justified for Continued Operation by Application of ARCs:

CPSES iRF1l, October 2005 Values Apply to lRFil Inspection Only SG Tubes Repaired Tubes Tubes Repaired Tubes Tubes Permitted Tubes Total Tubes by Plugging Plugged for for Volumetric Preventively to Remain in Permitted to Permitted to Crack-like Signals Including Plugged including Service by TSP Remain in Remain in Service Defects WVear Collapsed Sleeves ARC Service by F*

by ARCs 1

17 14 3

0 32 1

33 2

23 17 2

4 30 0

30 3

33 25 3

5 33 2

35 4

70 62 3

5 220 1

221 Total (1) 143 118 11 14 315 4

319 I

(1) Totals for tubes returned to service does not include indications permitted to remain in service that were subsequently plugged due to repairable indications at other elevations.

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SG-SG DA-05-45-NP 4.0 CONDITION MONITORING EVALUATION 4.1 Condition Monitoring Evaluation of Active Degradation Mlechanismns as Classified by the Pre-Outage Degradation Mechanism The degradation assessment concluded that the followving mechanisms met the criteria to be classified as active mechanisms for the I RF I1 inspection.

Circumferential ODSCC at hot leg top oftubesheet expansion transition

Axial ODSCC at hot leg top of tubeshee: expansion transition

Axial ODSCC in the freespan

Axial ODSCC at hot leg TSP intersections

Axial PWSCC at the hot leg top of tubeshect expansion transition

Axial ODSCC in freespan dings

Oblique PWSCC at Row 3 and greater U-bends

Circumferential PWSCC at the hot leg top of tubesheet expansion transition 4.1.1 TTS Circunmferential ODSCC Condition Monitoring Evaluation Structural integrity of circumferential indications at the TTS is defined by EPRI TR-107197, "Depth Based Structural Integrity of Circumferential Indications". The controlling parameter with regard to structural integrity of circumferential indications is the percent degraded area, or PDA. The PDA represents the percentage of degraded cross sectional area of the tube.

The burst correlation for circumferential indications is documented in EPRI TR-107197, "Depth Based Structural Analysis Methods for SG Circumferential Indications". The burst curve was used to develop the 100%TW' critical crack angle value of 2940 (82% PDA) for CPSES Unit I at 3AP conditions using mean material property values.

Screening of indications for selection as in situ test candidates is performed at CPSES Unit I using a methodology which is consistent with EPRI Report TR-1007904, "Steam Generator In Situ Pressure Test Guidelines Revision 2". Indications are first screened against the maximum +Pt coil amplitude threshold value of 0.50 volts. Indications with a +Pt amplitude exceeding 0.50 volts are screened against the PDA screening limit. The PDA screening limit is developed by reducing the 82% PDA for material properties at the lower tolerance limit (LTL) values and NDE uncertainty at the 95%

probability level. The resultant PDA used for in situ screening purposes is 59.5%. The as-reported PDA values from NDE are then compared against this value. As all circumferential ODSCC indications had +Pt amplitude < 0.50 volts, in situ pressure testing was not required, and screening against the PDA screen limit was not required. For completeness, all circumferential ODSCC indications had PDA values developed using the methodology as described in Reference 3. Tile IRF09 condition monitoring report (Reference 2) provides PDA data developed using both the quick screening method and profiling. When plotted, this data shows a correlation wvith slope of essentially 1.0 with a small y-intercept, indicating that both methods will produce a similar result. Thus, it is concluded that profiling is not required in order to support structural integrity of top of tubesheet circumferential ODSCC indications. All PDAs were found to be less than the screening value, with the maximum as-reported PDA of 33.96%. Using the quick screening method the NDE adjusted Page 9 of 41

SG-SG I)A-05-45-NP PDA at 90% probability, 50% confidence is [

]'. An evaluation of burst pressure of a

[

]a c PDA circ ODSCC indication was performed using a Monte Carlo simulation that included relational error, NDE error, and material property variation. At the upper 95% probability, 50%

confidence, the predicted burst pressure is 6493 psi.

For leak test screening, the first screen is maKimum voltage > 1.00 volt for PWSCC, 1.25 volts for ODSCC. As no ODSCC indications exceeded the 1" screen, leak testing was not required. The largest circumferential ODSCC amplitude reported for IRF1I I was 0.27 volts, which is bounded by the IRFI0 maximum amplitude of 0.43 volt and the IRF09 maximum amplitude of 0.56 volt. The 0.56 volt indication at I RF09 was in situ pressure tested with no leakage or burst. The conservatism of the screening limits is verified by test data developed by Argonne National Laboratories (Reference 7). In this program, sections of tube and tubesheet were removed from a retired SG using 3/4" OD by 0.043" wall thickness tubes, hardiolled through the tubesheet thickness. Maximum +Pt amplitudes ranged from 0.76 to 2.36 volts. No leakage was reported at SLB conditions, with the minimum observed leakage occurring at a pressure greater than 5000 psi, which exceeds the temperature adjusted 3 times normal operating pressure differential for Comanche Peak Unit 1.

Therefore, the circumferential ODSCC reported at IRFI I satisfied the NEI 97-06 performance criteria for structural integrity and leakage.

Maximum +Pt flaw amplitude is a reasonable qualitative assessment tool for determining the relative structural integrity characteristics of circumferential ODSCC indications. Figure I presents a summary of the maximum +Pt amplitude vs burst pressure and PDA for the hardroll ODSCC pulled tube database. The correlations developed satisfy the requirements of Reference 4, and therefore are valid for evaluating tube integrity. In this evaluation, the amplitude correlations are provided as a defense in depth in support of the PDA detennination and in situ testing performed at I RF 10, as well as past inspections. The largest circumferential flaw amplitude reported at IRFI I was 0.27 volt.

Using the lower 90% probability, 50% confidence line relating +Pt amplitude to burst pressure, the estimated burst pressure of this indication is approximately 8000 psi. Using the lower 90%

probability, 50% confidence line relating +Pt amplitude to PDA, the estimated PDA of this indication is approximately 59%. At the lower 95% probability, 50% confidence, this PDA results in a burst pressure of 5793 psi. The quick screening NDE adjusted PDA for this indication is only 37.7% due to the limited arc length of 1500 and maximum depth of 48%TW. It should be noted that the morphology of the circumferential ODSCC mechanism at Comanche Peak Unit I has been established by tube pulls. This morphology has shown numerous (up to 70) non-degraded ligaments exist within the entire flaw network. The flaws are shown to exist within a relatively consistent elevation band. The tubes pulled for characterization of the circumferential ODSCC mechanism at Comanche Peak unit I were burst tested with the expansion transition in an unrestrained mode, that is, no tubesheet simulant was applied to the expansion transition region during burst testing. Burst pressures were >10,000 psi, consistent with the non-degraded tube burst pressure, and the burst occurred in the freespan region, several inches away from the expansion transition. Based on measured PDAs, these indications would have been expected to burst at approximately 7000 to 8000 psi. The numerous non-degraded ligaments clearly added to the burst capability of these indications.

Figure 2 presents a cumulative probability distribution plot of circ ODSCC +Pt amplitudes for the IRF09, IRFIO, and IRFI I outages. This plot shows that the IRFI I amplitude distribution is bounded by the IRFIO and IRF09 amplitude distribution. For the IRFI I outage, a total of 95 tubes Page IOof41

SG-SGDA-05-45-NP were reported with circumferential ODSCC at the hot leg top of tubeshect expansion transition. The breakdown of affected tubes per SG is; 5 in SGI, 9 in SG2, 24 in SG3, and 57 in SG4. This is a significant reduction from the number of 667 reported at the I RF09 inspection and 289 reported at the I RF IO inspection. Figure 3 presents a cumulative probability distribution plot of circ ODSCC PDAs for the IRF09, IRF 10, and IRFI I outages. This figure shows that the PDA distributions for IRFIO and IRFI I are essentially equal which suggests that the applied initiation and growth functions are essentially equal for both operating cycles.

4.1.2 Expansion Transition Axial ODSCC Condition Monitoring Evaluation Structural integrity of axial flaws is established based on reported NDE length and depth. The program used to perform this calculation uses a model consistent wvith the EPRI Flaw Handbook, and uses a Monte Carlo simulation methodology to account for NDE errors, material property variation when specific tube material properties are not known, and burst equation relational uncertainty.

With regard to freespan axial indications, the in situ screening procedure for burst is as follows.

Maximumn +Pt voltage is compared against the initial screening value of 0.50 volts. Indications exceeding this value are screened for crack length and maximum depth. The length screening value is > 0.43" and the maximum depth screening value is > 70%. These values are reduced for eddy current uncertainty. Indications which exceed both screens are depth profiled. The average depth over the crack length is determined from the depth profile. Average depth vs. length is compared against a table of limiting crack length and average depth relationships provided in the degradation assessment which provide for structural integrity at draft RG 1. 121 recommendations. The freespan screening flaw length of 0.43" provides for burst integrity at draft RG 1.121 recommendations for single flaw morphology of 100% TW depth, using LTL material properties. For flaws with I00%TW lengths greater than about 0.1", the +Pt coil is expected to overestimate the true flaw length. The unadjusted I 00%TW flaw length that provides for burst capability at 3AP is 0.48", however, this value wvas conservatively reduced using length measurement uncertainty data for part throughwall flaws.

For transition region indication leakage screening, the first screens used in the EPRI In Situ Guideline Rev 2 are maximum +Point field evaluation voltage > 3.07 volts (2.50 volts for WEXTEX expansions) for ID indications, >1.0 volts for OD indications; the second screen is max depth > 70%.

Freespan OD indications were screened using a +Pt voltage limit of 0.50 volt. If the first screen is not exceeded, leakage testing is not required. If the first and second screens are exceeded the indication is depth profiled to determine length at max depth. Indications with > 0.1" length at the second screen max depth limit are leak tested. Axial indications located below the TTS do not represent a potential for burst. If the 1" leak test screen is not exceeded for all indications, the largest voltage indications are evaluated against the second screen to ensure that all relevant indications are adequately evaluated.

At the CPSES IRFI I inspection, no tubes were reported with axial ODSCC indications at the top of tubesheet. One tube in SG I was reported with an axial ODSCC indication at 2.5 inches below the TTS. The validity of such an indication must be questioned as this location is a full depth roll expanded tube wvith no reported anomalies in the roll or evidence of missing rolls or skip rolls. As this elevation is below the F* distance this tube is permitted to remain in service.

Page II of 41

SG-SGDA-05-45-NP 4.1.3 Freespan ODSCC Condition Monitoring Evaluation The bobbin analysis program conducted at I RF I I was an outcome of the lessons learned from the I RF09 inspection. The most notable aspect is that no lower voltage threshold for reporting of potential axial ODSCC in the freespan was used. As a result, a significant number of bobbin DFI reports were encountered. A supplemental +Pt exam was performed for each of these signals, resulting in a total of only 7 tubes reported with freespan axial ODSCC; 4 in SG I, 2 in SG2, none in SG3, and 2 in SG4.

One notable difference observed on R32 C99 in SG I was that the number of individual axial cracks in the spans with confirmed DFI reports (C7 to C8 and C8 to C9) was larger than observed at previous outages. During the'PID run of this tube, +Pt data was collected through the ClO elevation.

A continuous crack nearly 33 inches long was reported. This location had no corresponding bobbin reports from the production analysis. Burst pressure estimation of this section of tube indicates that the minimum burst pressure for the tube was located within this span. Based on the observations from R32 C99 it was concluded that a supplemental review of the 2005 bobbin data be performed using the automated data screening (ADS) software function of ANSER to ensure that all similar signals had been reported. The screening criteria used a [

]a.C. ADS was applied to the IRFI I bobbin data of R32 C99; a total of 34 bobbin DFI signals were reported xvith multiple signals in the C5, C6, C7, C8, and C9 spans as well as for the HI, H3, and H7 spans. Additionally, the ADS screening reported DFIs for each of the other tubes with freespan axial ODSCC indications except one. The one tube not reported by ADS had a maximum signal amplitude of <0. 15 volt in the 300 kHz channel; the corresponding +Pt amplitude was <0.10 volt, suggesting a shallow depth. The intent of the supplemental ADS screening was to provide a high level of confidence that indications of modest depth and significant length (like R32 C99) were not missed by the production analysis. The supplemental ADS screening identified a total of 167 additional DFI reports, all orwhichl were inspected with the +Pt coil. Of these, only one was confirmed as axial ODSCC by +Pt. This tube, R35 C37 in SG 1, had a maximum +Pt amplitude of only 0.08 volt and a maximum continuous length of 1.28 inch.

Thus, based on the results of the ADS screening there is a high level of confidence that all flaws with a signal amplitude of> 0.15 volt in 300 kHz have been identified by bobbin, validated, and subsequently interrogated with +Pt. As an example, Table 3 presents a summary of the ADS reports for R32 C99 using the I RF I 1, I RFI 0. and I R1F09 bobbin data. As seen from this data, the ADS screening criteria would have resulted in the generation of DFI reports for R32 C99 as early as I RF09. Additionally, manual review of the I RF08 data for some segments of R32 C99 indicates that flaw signals are present. Thus it can be concluded that the freespan axial ODSCC observed at IRFI I is similar to past occurrences in that the mechanism appears to be slow growing.

Page 12 or4l

SG-SGI)A-05-45-NP Table 3 ADS Results for R32 C99 SGI Elevation I RFII ADS Call IRFI0 ADS Call IRF09 ADS Call IRFI I +Pt Confinn?

HI +14.18 X

X Yes HI +17.82 X

X X

Yes H3+13.60 X

=

Yes H3+14.48 X

Yes H7 +8.82 X

Yes H7+35.95 X

X No H10 +29.49 X

No CIO+8.17 X

X Yes C9 +30.47 X

X X

Yes C9+11.32 X

X X

Yes C9 +8.36 X

Yes C9+1.74 X

=

=_

Yes C8 +32.60 X

Yes C8 +24.02 X

X Yes C8+10.07 X

X Yes C8 +7.21 X

X X

Yes C8+2.22 X

X Yes C8-1.99 X

X Yes C7+39.71 X

Yes C7+38.50 X

X X

Yes C7+33.36 X

Yes C7+27.62 X

Yes C7+18.09 X

X Yes C7+12.81 X

Yes C7+3.59 X

X Yes C7 +2.54 X

X X

Yes C6+10.71 X

X Yes C6+5.48 X

X Yes C6+3.20 X

X X

Yes C6+1.25 X

X Yes C5+14.26 X

Yes C5 +13.22 X

Yes C5 +12.83 X

X Yes C5 +9.54 X

X Yes C5 +8.93 X

X Yes Page 13 of41

SG-SGDA-05-45-NP The segment of R32 C99 with the limiting burst pressure was the section between C9 and CIO. This segment contained the longest continuous flaw segments and largest +Pt amplitude responses. Tile flaw depth was determined by profiling. The length versus depth profile was developed both for the phase based depths and amplitude based depths from the +Pt coil. The phase based profile yielded uncharacteristically large depths for the observed signal amplitude. The pulled tube results from I RF09 showed that the mean regression of +Pt amplitude to depth accurately predicted the true flaw depth. Figure 4 presents a comparison of the phase based and amplitude based profile for the C9 location. Both profiles were evaluated for burst capability using a Monte Carlo simulation that included material property variance and burst relational uncertainty. The simulation was performed at 95% probability, 95% confidence, more conservative than required by the EPRI Tube Integrity Guideline. Table 4 summarizes the simulation results for all freespan ODSCC indications that involved significant flaw lengths. Figures 5 and 6 present the length versus depth profiles for the C7 segment of R32 C99. These plots show the amplitude based profile bounds the phase based profile even though the +Pt amplitudes in the C7 and C9 segments were essentially equal but phase based depths varied dramatically.

Based on the phase based profile analysis results and burst pressure prediction, R32 C99 was selected for in situ pressure testing even though analysis of the amplitude based profile developed from the mean amplitude regression showed a burst pressure of 5300 psi. Since R24 C22 had larger +Pt amplitudes compared to R32 C99, R24 C22 was also conservatively selected for in situ pressure testing. Both tubes were tested in a full tube mode. The 3 times normal operating pressure differential in situ test pressure for Comanche Peak using the actual primary to secondary pressure differential just before shutdown is 4266 psi. A 3 times normal operating pressure differential test condition of 4350 psi was selected using the minimum burst pressure based on the calculated burst pressure of 3946 psi for the upper 95 1h percentile amplitude based sizing of R32 C99. The proof test pressure of 4350 psi was developed by applying a 1.08 temperature adjustment factor and adding 100 psi for gauge measurement uncertainty. The in Situ pressure test of R32 C99 included a 300 psi overpressure condition (peak proof test pressure of 4650 psi) to further strengthen the sizing methodology as described below. Post in situ +Pt examination showed little flaw change in either amplitude or width due to the test. As no leakage or burst was reported, and the post in situ pressure test +Pt exam showed little flaw amplitude change even after the 300 psi overpressure condition, it can be concluded that the most accurate method of sizing freespan axial ODSCC continues to be the mean regression of +Pt amplitude to depth. Ilad this flaw contained significant depths as predicted using phase based analysis, the tube would have burst. Had the flaw contained significant depths as predicted by the upper 9511' percentile amplitude based sizing analysis, the flaw would have experienced plastic yielding with imminent burst. As such, the post test flaw amplitudes would have shown significant change in both amplitude and width; neither was observed.

R24 C22 contained significantly higher +Pt flaw amplitudes than R32 C99, and thus deeper flaw depths. The in situ pressure test of R24 C22 did not include an overpressure condition thus the peak in situ proof test pressure was 4350 psi. Consistent with R32 C99, the post in situ RPC data shows essentially no change in flaw amplitude or width. Figure 7 presents a plot of +Pt amplitude for the pre and post ISPT condition and shows little variance in +Pt amplitude between the two cases thus the same judgment can be applied to R24 C22, that plastic deformation of the flaw did not occur, and that the most accurate sizing method remains the mean +Pt amplitude to depth correlation. As R32 C99 and R24 C22 passed the in situ pressure test with no leakage or burst, the performance criteria Page 14 of 41

SC-SGDA-05-45-N P were satisfied. Additionally, the depth assessment using the mean regression of +Pt amplitude to depth, which has been shown by the pulled tube analysis to be the most representative method of sizing, includes burst pressures evaluated at 95% probability, 95% confidence that exceed the three times normal operating pressure differential of 4266 psi. Therefore, condition monitoring is satisfied.

For all other freespan ODSCC signals the flaw lengths and depths were bounded by R32 C99.

This mechanism has been shown to be confined to the straight leg section. R32 C99 was tested from hot leg top of tubesheet to cold leg top of tubesheet using a +Pt probe. Axial ODSCC was not detected in the U-bend region. All other tubes with freespan ODSCC except R35 C37 in SG I and R30 C65 in SG2 were inspected through the U-bends with a +Pt probe as part of the oblique PWSCC inspection program. All tubes with freespan ODSCC except R32 C99 were inspected with a +Pt probe from the hot leg top of tubesheet to HI I and from the cold leg top of tubesheet to C I 1. No other tubes contained extended length indications such as that found on R32 C99.

Table 5 presents a summary of the freespan axial ODSCC NDE parameters. Due to the large number of indications on R32 C99 extending over multiple tube spans, only the largest +Pt amplitude signal for the indicated span is included.

Page 15 of 41

SG-SGDA-05-45-NP Table 4 anrTr ns

- nrccIZ=vnwn~

r~

rce Ota;/

Dro1a1ttAco/

.nl SG Tube Location As Reported As Reported Upper 95' ISPT Peak Phase Analysis Amplitude Percentile Pressure Analysis Amplitude Analysis I

R32 C99 C9 +28" 2718 psi 5327 psi 3946 psi 4650 psi 1

R32 C99 C7 +20" 7788 psi 6113 psi 4965 psi 4650 psi 2

R30 C65 H3 +34" 4561 psi 6177 psi 5049 psi Not Tested 4

R24 C22 C8 +28" 5798 psi 5515 psi 4191 psi 4350 psi Table 5

+Pt 300 kHz Bobbin Bobbin Signal SG Tube Elevation Volts Length Volts Phase Observable in 2004 Data?

I R6 C50 C 10 +4.44 0.11 0.20 0.19 82 Yes 1

R15 C25 C7 +8.8 0.07 0.23 0.11 118 Yes 1

R32 C99 C5 +12.64 0.19 4.23 0.17 78 Yes

=

C6 +5.42 0.24 20.2 0.23 78 Yes C7 +39.71 0.22 0.81 0.17 115 Yes C8 +7.24 0.15 0.42 0.19 129 Yes C9 +18.93 0.24 17.0 0.11 80 Yes 1

R35 C37 C8 +21.6 0.08 0.37 0.07 79 Yes 2

RI I C91 HI O+9.9 0.10 0.55 0.18 129 Yes 2

R30 C65 H3 +33.1 0.24 1.05 0.38 77 Yes 4

R9 C39 C8 +41.4 0.18 0.18 0.24 103 Yes 4

R24 C22 CS +27.7 0.42 3.3 0.29 73 Yes Page 16 or4l

SG-SGDA-05-45-NIP 4.1.4 TSP ODSCC Condition Monitoring Evaluation One DSI signal exceeded the 1.0 volt repair limit; the DSI amplitude was 1.26 volt located at the H5 TSP. A 0.87 volt DSI is observed for this location using the lRFIO data, however, no DSI report was made at this location at I RF 10. The H3 location of the same tube also contained a 0.88 volt DSI at I RF I I with a 0.80 volt DSI shown in the I RFI 0 data base. A noticeable amount of horizontal probe motion was observed in the I RF I I data for this tube, thus the DSI amplitude measurement could involve a modest error. The +Pt amplitude of 0.18 volt suggests a depth of 47%TW. The voltage based structural limit for TSP ODSCC indications is 4.69 volts for a SLB AP of 2560 psi (vith safety factor applied). The largest bobbin DSI voltages and total DSI reports for each SG are provided beloxv in Table 6.

This data shows that SG 4 appears to be the most susceptible SG with regard to ODSCC initiation.

For all SGs, the average absolute voltage growth is 0.04 volt for Cycle I1, or essential zero average voltage growth. The largest single absolute voltage growth was 0.62 volt for Cycle I 1, or 0.44 volt per EFPY. The average percentage voltage growth for SG2 is larger than has been observed for past cycles, however, the average DSI amplitudes are so low that small changes can have a large percentage change.

Mixed residual signals with bobbin voltage > 1.5 volts were RPC inspected. No mixed residuals

>1.5 volts wvere confirmed to contain axial ODSCC.

A complete evaluation per the GL 95-05 requirements will be provided in the ARC 90-day report.

The IRFI I TSP ODSCC bobbin amplitudes are essentially equal to the IRFIO values. Past GL 95-05 analyses have indicated that the projected leak rate at end of next cycle conditions will be approximately 0.001 gpm, and conditional burst probability of several orders of magnitude less than the GL 95-05 burst limit. Using the Addendum 6 relation of burst pressure to bobbin amplitude, the lower 95% confidence burst pressure of a 1.06 volt indication is >5000 psi.

Table 6 I RFI I TSP DSCC Degra ation Summary SG I SG 2 SG 3 SG 4 Number lnd.

32 32 35 259 Number > 1 volt 0

1 0

0 Average IRFI I Voltage 0.23 0.46 0.41 0.45 Max IRFI I Voltage 0.45 1.26 0.94 0.92 Average Absolute Voltage Growth

-0.01 0.05

-0.02 0.03 Cycle 11 (per EFPY)

Average % Voltage Growth Cycle 11

-5.6%

19.6%

-7.7%

5%

(per EFPY)

One additional tube in SG4 was plugged due to detection of a small amplitude axial ODSCC signal at the H I I plate (RI C 100). No bobbin DSI signal was reported for this tube. An Alloy 800 tubesheet sleeve was installed at IRFIO on the hot leg of this tube. Review of the IRFI I bobbin data shows Page 17 of41

SG-SGDA-05-45-NP that the probe snapped at the beginning of the pull, distorting the bobbin response at this elevation and rendering the 520 wide groove bobbin analysis somewhat ineffective. Due to the 100% base scope +Pt examination of Row I through 16 U-bends, all tubes with sleeves in which the hot leg straight sections were inspected with either the 540 or 520 wvide groove probes were inspected at H I I with a +Pt coil. Thus, this issue is not transferable to all tubes with sleeves in which the hot leg straight sections were inspected with the wide groove probes. The issue With probe snap occurs at the initiation of the pull; good data was collected for all other TSP elevations above sleeves. Note that for sleeves installed in Rows 5 and higher that the 610 diameter bobbin coil was used for inspection above the sleeve. In these cases the bobbin data was collected from the cold leg side.

4.1.5 Axial PWSCC at Hot Leg Top of Tubeshect Expansion Transition Structural integrity of axial flaws is established based on reported NDE length and depth.

During the IRFI I inspection, I tube was plugged due to a reported axial PWSCC indication within the F* distance. The maximum flaw amplitude was only 0.66 volt, while the flaw length was reported at 0.17 inch. Review of the 600 kH:z +Pt data suggests that this signal is comprised of 3 closely spaced axial PWSCC indications located within the expansion transition.

When the flaw length error defined by ETSS 2051 1.1 is applied to the 0.17 inch flaw length the NDE adjusted length is less than the 100%TW critical flaw length of 0.43 inch, thus the structural performance criteria is satisfied. The maximum +Pt amplitude of 0.66 volt suggests shallow depth.

The phase angle of the signal is 33°, suggesting a near I 00%TW depth. However, the influence of the carbon steel tubesheet material can act to rotate weak PWSCC signals into the OD flaw plane, which is what is observed here. While the phase based depth suggests near I 00%TW depth, the signal amplitude is well below the in situ leak testing threshold of 3.07 volts for axial PWSCC at hardroll expansion transitions. It should be noted that a review of the I RF IO +Pt data for this location indicates a reduced amplitude of 0.32 volt and phase angle of 37°, further supporting the conclusion that the phase based depth is unreliable. Note that with increased flaw amplitude the signal phase has shifted slightly towards the ID plane.

During the IRFIO inspection, two axial PWSCC indications were reported wvith amplitudes of 1.32 volts and 0.41 volt with a maximum reported flaw length of 0.17 inch. The small number of PWSCC indications at the top of tubesheet location reported for recent outages is attributed application of shot peening prior to operation.

4.1.6 ODSCC at Freespan Dings Axially Oriented Indications:

Ding ODSCC was first reported at Comanche Peak Unit I at the I RFO8 inspection with one confinred DNI signal. The total number of tubes with ding ODSCC at each of the subsequent outages was 16 at I RFO9, 10 at I RFI0, and 5 at I RFI 1. At the I RF09 inspection, the history review criteria looking for change in bobbin signals were performed using the first ISI of the tube. Thus, the number of DNI signals was substantially increased as confirmed DNIs often do not exhibit significant change from one inspection to the next.

Page 18 of41

SG-SGDA-05-45-NP The dings flaws reported at I RE II all had I[) phase angles or OD phase angles suggesting significant depth. This phenomenon has been observed both at other plants and in the laboratory program that developed the bobbin detection technique (Reference 10). The influence of the ding on the +Pt response overpowers the flaw response for short, shallow axial ODSCC. For these cases, the laboratory flaws generally had maximum depths <70%TW, and flaw lengths <0.12". The +Pt lissajous responses for these flaws are consistent with the laboratory ding specimens. Length evaluation of the I RF I I ding axial ODSCC indicates that the maximum reported ding ODSCC length was 0.34 inch (R27 C23 in SGI). The remaining indications had axial length reports ranging from 0.14 inch to 0.24 inch. Performance evaluation of axial length sizing for ding ODSCC indications indicates that the [

]3.

The integrity evaluation of R27 C23 used a conservative maximum depth estimate of 75%TW', with an average depth of 60%TW based on the relation of maximum to average depth of 1.25 for pulled tubes with axial ODSCC. Burst capability was evaluated using a Monte Carlo simulation that included tube material properties and relational error.

The simulation was evaluated at the lower 95% probability, 50% confidence level, or slightly conservative compared to the recommendations of the EPRI Tube Integrity Assessment Guideline.

The estimated burst pressure for this length and depth combination is 5301 psi, well above the performance criterion of 3855 psi.

The extensive data base developed in the laboratory development program shows that as the ding amplitude is reduced below the qualified detection range of < 5 volts, the bobbin phase response migrates to deeper OD depths due to the reduced influence of the ding signal. The +Pt phase response also migrates from the ID plane to the OD plane as the ding amplitude is reduced. As the bobbin phase angles were >109 degrees, +Pt phase angles remained wvell within the ID plane, and ding amplitudes are small, it is judged that all reported ding ODSCC signals identified at I RFI I were shallow and bounded in maximum depth by 7'0%TW.

In summary, structural and leakage performance criteria are satisfied at EOC-I I conditions for axial ODSCC at freespan dings.

With regard to PWSCC, a 20% sample of all hot leg dings from the hot leg top of tubesheet to H3, the first TSP above the flow distribution baffle, and all dents at H3 > 2 volts were +Pt inspected. No degradation was observed.

4.1.7 Oblique PWN'SCC at Row 3 and Higher U-bends This mechanism was first observed at the I RFlIO outage; no large scale inspection of the Row 3 and higher U-bends was performed prior to the I RFHO inspection. A total of 8 tubes were affected at IRF10, with the most significant containing a 2.22V indication. This tube wvas in situ pressure tested in a full tube mode. No leakage or burst was reported at a test pressure of 4266 psi. The maximum depth of this indication wvas reported at 95%TW based on the reported phase angle of the signal. The reported amplitude of 2.22 V using the 0.560 ' +Pt probe was adjusted to a 0.6 10" probe basis by comparing the amplitude responses of the two probes for the axial and circumferential EDM notches of the calibration standard. The average 0.610 to 0.560" amplitude ratio was 0.83 for all notches.

The equivalent 0.610" volts are then 1.84. Using a correlation of +Pt amplitude to maximum depth Page 19of41

SG-SGDA-05-45-NP for pulled tubes and laboratory doped steam samples, the estimated maximum depth of this indication is [

ja". This result is more consistent with the in situ result than is the phase based result. It should be noted that nearly all of the U-bend indications exhibit phase based maximum depth reports that approach the 90%TW minimum through wall range even though the flaw amplitudes range from about 0.3 volts to 1.09 volts. The amplitude based depth reports for this range of amplitudes is

[

]aC At I RFI 1, a total of 4 tubes were affected by this mechanism, with the maximum reported +Pt amplitude of 0.64 volt and the maximum reported arc length of 700 (different tubes). The reduced number of indications and reduced +Pt amplitude compared to IRFI0 suggests that the indications reported at I RF 10 had been present for several cycles before their detection.

As with the previously reported indications at other units with this mechanism, the affected arc lengths are short., approximately 30 to 700 arc. As such, these indications do not represent a structural integrity challenge as the indicated arc lengths are significantly less than the I00%TW circumferential critical flaw arc length of 2940. In Table 8 the calculated burst pressure assumes the limiting flaw to be I00%TW over the maximum reported arc length.

As the limiting indication wxas shown not to represent a leakage potential at well beyond the SLB pressure differential, and no burst occurred during the in situ pressure test, the NEI 97-06 structural and leakage performance criteria are satisfied.

Table 6 presents a summary of the affected tubes and maximum +Pt amplitude. The 0.560" +Pt was Lised for inspection of these tubes. Amplitude responses for the 0.560" +Pt and 0.610" +Pt were compared to determine if the voltage as reported from the 0.560" +Pt is consistent with the 0.610"

+Pt. This comparison indicated that the 0.560" produced larger amplitudes for each of the part throughwall EDM notches of the calibration standard. The average ratio was 0.83. This value was used to adjust the 0.560" voltage responses for estimating depth as a function of +Pt amplitude. The values in Table 7 represent the as-reported 0.560" +Pt amplitudes.

Table 7 Summary of Oblique PWTSCC at Rowv 3 and Higher U-bends SG Tube Elevation of Max Number of Max +Pt Amplitude Indications Amplitude 1

R5 CIO HI 1 +21.9" 3

0.64 2

R5C20 HIl +18.8" 2

0.30 2

R5 C23 HI I +17.3" 2

0.40 3

R3 C15 Hl l +15.7" 1

0.64 4.1.8 Circumfcrcntial PWN'SCC at Hot Leg Top of Tubesheet Expansion Transition No circumferential PWSCC at the hot leg top of tubesheet expansion transitions xwere reported for the I RF I I outage.

Page 20 of 41

SG-SGDA-05-45-N P 4.2 Condition Monitoring Evaluation of Degradation Modes Classified as Relevant in tle Degradation Assessment The degradation assessment concluded that the following mechanisms did not meet the criteria to be classified as active mechanisms, and therefore were categorized as relevant mechanisms for the I RFI I inspection.

Circumferential ODSCC in freespan dings

Axial PWSCC in small radius U-bends

AVB wear

Tube wear at non-expanded preheater baffles

Tube wear due to foreign objects/loose parts

Axial PWSCC in Row 3 and higher U-bends

Freespan Volumetric degradation

Axial or circumferential PWSCC of parent tube behind sleeve hardroll joints 4.2.1 Freespan Volumetric Indications Three freespan indications were reported by bobbin as DFI signals and confirmed by +Pt as volumetric in nature. These indications occurred in the freespan area away from structures, wvith no evidence of foreign objects in either this tube or surrounding tubes. For all of these indications, the 2004 bobbin data showed a similar signal to the IRFI I bobbin data. One of these was reviewed back to the 2002 inspection with essentially no change in the bobbin signal. At the IRFIO outage freespan volumetric indications were reviewed back to the 1996 inspection with no change. Thus it can be concluded that these indications are not representative of an on-going degradation mechanism. The cause of these signals may be attributed to laps or gouges resulting from the tube installation process or manufacturing process. These indications wnhere preventively repaired by plugging. The maximum depth of these indications based on depth sizing using the EPRI volumetric standard and ETSS 21998.1 was 21%TW; the NDE adjusted depth is bounded by 40%TW. The largest axial length report for the freespan voluinetrics was coincident with the largest maximum depth of 21 %TW. [

]a.c Therefore, the structural and leakage performance criteria of NEI 97-06 are satisfied as the best estimate flaw geometry parameters are bounded by the degradation structural limit for AVB wvear.

4.2.2 Circumferential ODSCC at Freespan Dings At the 1999 inspection of a Model E2 SG, 01) circumferential indications were reported in the freespan region several inches below the top cold leg TSP. The indications were reported coincident with a circumferentially oriented ding, known as a ding pair. The ding pair is believed to be resultant from out of plane rotation of the tube while engaged with the top TSP during tube insertion. The geometry of this type of ding has been studied by Westinghouse and found to be significantly different from the dings that have historically resulted in axial ODSCC. Based on this similar plant experience, 20% of the hot and cold leg paired dings between the top two TSPs were inspected with

+Pt at I RF I 1, a practice that has been in place since the I RFOS inspection. No degradation wvas Page 21 of 41

SG-SGDA-05-45-NP observed for the I RF 1 1 outage or any other preceding inspection.

4.2.3 Small Radius U-bend PWNSCC No small radius (Row 1 or Row 2) U-bend PWSCC indications were reported.

4.2.4 Tube Wear at AVBs, Preheater Baffles, and Due to Loose Parts/Foreign Objects Tube wear due to foreign object interaction was reported in SG1 and SG3. These occurrences are all associated with small foreign objects that were wedged between the tube and TSP. In all cases, the wear mechanism could be tracked to the previous inspection. These indications were sized using the EPRI volumetric standard and guidance provided in ETSS 21998.1. The deepest indication was reported at 27%TW, 0.24". The axially longest indication was reported at 0.31".

The wear mechanisms observed by bobbin coil generally had small bobbin amplitudes, i.e., well less than 1.0 volt in the primary mix channel or 300 kHz differential channel for freespan indications. As a comparison, the volumetric wall loss associated with the 40% depth. 0.187" diameter flat bottom hole of the ASME standard gives a signal of approximately 3 volts. Based on flaw geometry characterization with RPC and relation to laboratory wear scars, the axial extents of the wear indications were about 0.16" max, with a maximum circumferential involvement of about 50 degrees.

The uniform thinning burst model of NUREG!CR-0718 can be used to estimate the burst pressure.

At tip to 83% TW degradation for a 0.26" axial involvement, burst pressure using LTL material properties exceeds the Comanche Peak 1 3AP value of 3855 psi. At 85% TW, the bobbin amplitude would be expected to be substantially larger than 3 volts. Using the ETSS 21998.1 depth measurement uncertainties at 90% probability, 50% confidence, maximum depth is estimated to be bounded by 42%TW. At the approximated maximum depth of 42%, a 0.16" axial length uniform thinning flaw with LTL material properties has a predicted burst pressure of 7319 psi.

Tube wear at non-expanded baffles is a low growth mechanism. The largest reported depth at I RF08 was 43% TW with a growth of 6%TW. The largest reported depth at I RF09 was 41 % TW, with a growth of 6%TW. One additional repairable indication was reported at 40%TW. The largest reported depth at I RFI 10 was 44%TW with a growth of 6%TW. The largest reported depth at I RF I I was 45%TW with a growth of 6%TW for Cycle 1 1. If the sizing uncertainty for wear per ETSS 96004.3 is applied, the NDE adjusted depth of this indication is 59%TW, which is below the structural limit of 68%TW for an assumed 3/4" wear axial length (Reference 1). Evaluation of the +Pt data for a sample of baffle wear signals indicates that the axial lengths are significantly less than 1/4" in length. If it is assumed that the baffle wear extends for 0.75", and applying the ETSS 96004.3 uncertainty, the predicted burst capability using lower tolerance material properties and the NUREG/CR-0718 uniform thinning equation is 5000 psi.

Growth was evaluated individually for all SGs; the values were all similar thus it was concluded that the baffle wear growth for all SGs can be combined. The 9 5 th percentile baffle wear growth was found to be 2.1 %TW per EFPY. For a Cycle 12 length of 500 EFPD or 1.37 EFPY, the growth allowance applied for Cycle 12 is 3%TW. The deepest baffle wear scar returned to service was 38%TW in SG2. Thus, with NDE depth measurement applied, the maximum EOC-12 baffle wear depth is estimated to be 56%TW, which is well below the structural limit, thus the structural and leakage performance criteria are satisfied.

Page 22 of41

SG-SGDA-05-45-NP Wear growth statistics for the C2 and C3 plates were essentially equal to the overall value, suggesting that there is not a preferential growth by plate location.

The largest reported AVB wear indication was 32%TW. This location was also the largest AVB wear depth at 1 RF 10 at 34%TW, and also the largest AVB wear depth at I RF09 of 33%TW. The historical data for this indication suggests that the AVB wear growth has essentially arrested, and depths at EOC-12 are not expected to be significantly different from those reported at IRFI 1. The largest reported AVB wear growth reported for Cycle 11 was 4% TW. As only 8 AVB wear indications were reported at I RFI I with 7 containing corresponding depth values in I RF 10, a statistical growth evaluation can not be performed. Instead, a bounding growth of 10% will be used in the operational assessment.

No tubes were judged to contain volumetric signals due to foreign object wvear at the hot leg top of tubesheet attributable to foreign object wear. A total of four volumetric signals were reported at the hot leg top of tubesheet region. Of the 4 volumetric signals reported at this location, three were in the full depth roll expanded portion of tube wvith the location of the indications below the expansion transition. A review of the IRFI 0 +Pt data shows the indications were present, with no change compared to IRFI 1. One indication in SG3 was reported to contain a volumetric indication within the expansion transition. A review of the IRFIO +Pt data shows a modest change however the I RF I I signal parameters of 0.19 volt, axial extent of 0.26 inch, and circumferential extent of 73 degrees arc. This signal could represent a small foreign object wear signal, or possibly a mixed mode ODSCC flaw; no PLP signal was associated with this location and no PLP reports are present for surrounding tubes. Regardless of the true orientation, the signal parameters are bounded by the structural limit flaw models for either axial cracking, circumferential cracking, or uniform thinning.

In summary, structural and leakage performance criteria are satisfied at EOC-I I conditions for preheater baffle wear, AVB wear, and foreign object wear.

4.2.5 Axial PWN'SCC at Row 3 and higher U-bends One tube in Rowv 13 in SG4 was reported to contain an axial PWSCC indication. The maximum +Pt amplitude was 0.38 volt, with a length of 0.37 inch. Estimated depth from phase analysis is 35%TW.

.A length error of 0.12 inch per ETSS 20511.1 is applied to the reported length of 0.37 inch to develop a length for evaluation of 0.49 inch. Maximum depth error per ETSS 20511.1 at 90%

probability, 50% confidence is 8%TW, thus the flaw parameters used for evaluation are 0.49 inch and 43%TW. Using a Monte Carlo simulation of burst pressure that includes material property variance and burst relational error, the burst pressure evaluated at 95% probability, 50% confidence is 6263 psi.

4.2.6 Axial or Circumferential PWNSCC of Parent Tube behind Sleeve Ilardroll Joints At the I RFI0 inspection, 100% of all IRF09 installed TIG sleeves were inspected full length with the

+Pt coil; no indications were detected. At I RF1 1, 20% of the IRF09 installed TIG sleeves were inspected full length with the +Pt coil; no indications were detected. At IRFI 1, 100% of all IRFHO installed Alloy 800 sleeves were inspected with the +Pt coil; no indications were detected.

Additionally, the I RF IO Alloy 800 sleeve installation included an inspection of the parent tube in the Page 23 of 41

SG-SGDA-05-45-NP sleeve to tube hardroll joint region using the +Pt coil prior to installation of the sleeve. No degradation of the parent tube was detected.

4.3 Condition Monitoring Evaluation of Degradation Modes Classified as Potential in the Degradation Assessment The final degradation classification addressed in the degradation assessment is potential degradation modes. Potential degradation modes are modes not seen in CPSES Unit 1, but represent a potential to occur based on experience at other plants or in laboratory testing.

The degradation modes classified as potential for CPSES IRFI I are;

Axial PWSCC at expanded cold leg baffles

Axial PWSCC at freespan dings

SCC degradation of TIG and Alloy 800 sleeves

Axial ODSCC at cold leg baffle and AVB wear sites A 25% +Pt sample of expanded cold leg baffles has been perfonned for several outages. No degradation of tubes at expanded baffles has been reported. A 20% +Pt sample of >2V dings between the hot leg top of tubesheet and H3 has been performed for several outages. No PWSCC degradation has been reported. All TIG sleeves and parent tubes in the pressure boundary region were inspected with +Pt at IRFIO; the test extent was from 3 inches above the sleeve to 3 inches below the sleeve. No degradation of either the TIG sleeve or parent tube was reported. A 20% +Pt sample of TIG sleeves installed at I RF09 was performed; the test extent was from 3 inches above the sleeve to 3 inches below the sleeve. All remaining TIG sleeves were inspected from 3 inches below to 3 inches above the sleeve top to complete the inspection of the parent tube for axial ODSCC in the hop off region above the sleeve that may not be inspectable with the bobbin probe due to the probe design. No parent tube or sleeve indications were reported. At IRFI I all Alloy 800 sleeves installed at IRFIO were inspected fill length, from 3 inches above to 3 inches below the sleeve using a +Pt coil. No degradation of the parent tube or the Alloy 800 sleeves was reported. At I RF I I a 20% +Pt sample of non-expanded cold leg baffles was performed to determine if SCC signals xvere present but overshadowed to the bobbin coil by the amplitude of the wear scar. The signals selected for this sample included the largest depth wear calls in each SG as if SCC were to develop it would likely develop first at indications with the deepest wear scar depths and associated highest stresses due to the thinned material. No SCC indications were detected. Also, as only 8 AVB wear scars were reported at IRFI I, and the base scope inspection included a large number of +Pt tests in the U-bend region addressing >5V dings, a decision was made to inspect all AVB wear sites with the +Pt coil to validate the position that ODSCC coincident with AVB wear sites was not present in the Comanche Peak Unit I SGs. No SCC degradation was reported coincident with AVB wear sites.

4.4 Summary of Limiting Indications Table 8 presents a summary of the limiting indications for the I RF I I inspection. All indications had predicted burst capabilities of greater than the 3APNormOp value of 3855 psi using either material properties consistent with the EPRI tube integrity guideline or actual tube material properties reduced for operating temperature effect. Table 8 also provides the burst pressure assessment per Table 8-I of the EPRI tube integrity guideline, using ND)E sizing uncertainty, material properties, and relation Page 24 of 41

SG-SGDA-05-45-NP error at the lower 90% probability, 50% confidence level. The values listed for max length, max depth, and average depth are the as-reported NDE values.

Page 25 of 41

SG-SGDA-05-45-NP 4.5 SLB Leakage Discussion For all degradation mechanisms observed at I RFI 1, any potential for SLB leakage at end of Cycle I I conditions is judged to be negligible.

The circumferential ODSCC indications at the TTS are of sufficiently low magnitude that no leakage contribution is expected. Past in situ testing of larger amplitude signals confirmed that no leakage was observed. Based on the available industry database, SLB leakage is not expected for maximum

+Pt amplitudes of about 1.25 volt. The +Pt amplitudes of the previous in situ leak tested circumferential flaws ranged from 0.18 to 0.56 volts. The largest +Pt amplitude observed for all SGs at I RF I I was 0.27 volt. No leakage was reported at any of the I RF06, I RFO7, I RF08, or I RF09 in situ testing campaigns for tests of tubes with circumferential ODSCC indications.

The single axial PWSCC flaw at the TTS had a +Pt amplitude of 0.66 volt, but included contribution from 3 closely spaced axial flaws based on evaluation of the 80 mil high frequency coil. The maximum depth from the +Pt phase depth analysis is near 100%TW for the largest amplitude signal.

The depth from the +Pt amplitude correlation for PWSCC is <40%TW (Reference 2). Previous discussion has shown the phase based sizing to be unreliable based on the lack of phase change with modest amplitude change from IRFIO to IRFI 1. The indicated amplitude is well below the in situ leakage test threshold of 3.07 volts. Maximum +Pt amplitudes for axial PWSCC indications at the TTS in 7/8" hardroll expanded tubes of LIP to 6 volts did not leak during in situ test.

The largest circumferential PWSCC flaw at the tack roll to WEXTEX expansion transition had a +Pt amplitude of 1.53 volts. Using the PWSCC --Pt amplitude vs depth correlation, the estimated maximum depth of this indication is [

]a-at the upper 90% probability, 50% confidence. The phase angle response is 130 or 33%TW.

The largest amplitude oblique PWSCC indication in a large radius U-bend was 0.64 volt, and well below the flaw amplitude that was in situ pressure tested at IRFIO in a full tube mode of 2.22 volt.

Volumetric degradation depths were well below potential breakthrough depths, and also do not represent a leakage potential at SLB conditions.

4.6 In Situ Testing Summary The in situ testing performed for the I RFI I outage supports the conclusion that postulated SLB condition primary to secondary leakage will remain below I gpm for all SGs.

4.7 IRFI I Condition Monitoring Conclusion Based on the CPSES I RFI I inspection results, all tubes satisfied the NEI 97-06 structural and leakage performance criteria. The relative severity levels of the observed degradation for existing degradation mechanisms was judged consistent with or bounded by the levels associated with the I RF IO inspection.

In situ pressure testing of showed no potential for the structural integrity or leakage performance criteria of NEI 97-06 to be challenged.

Page 26 or41

SG-SGDA-05-45-NP 5.0 CY'CLE 12 PRELININARY OPERAiTIONAL ASSESSMIENT Circumferential ODSCC at Hardroll Expansion Transition Figure 2 shows that the cumulative probability distribution function for +Pt amplitude for IRFI I is bounded by, the IRFI0 distribution. As all IRFI I and IRFI0 indications satisfied both structural and leakage integrity criteria, a similar result would be anticipated for EOC-1 2 based on the trending shown on Figures 2 and 3. Assuming the probability of detection for both the IRFI I and IRFI0 outages were consistent, Figure 2 suggests that the growth and initiation function for Cycle 11 is reduced compared to Cycle 10. As no chances in the chemistry regime or operating temperature are anticipated for Cycle 12, the EOC-12 +Pt amplitude distribution is expected to be similar to that observed for IRFI 1.

Axial PWSCC at Hardroll Expansion Transition Only one tube was affected at IRFI l; two tubes were affected at IRF 10. The application of shotpeening prior to operation has apparently reduced the potential for initiation of this mechanism.

The consistency between the results for both inspections suggests that no change in growth or initiation trends are occurring with increased operating time. The peak flaw amplitude reported for IRFI I was well below the IRFI0 peak flaw amplitude.

Oblique PWSCC at Row 3 and higher U-bends The observation of 4 tubes with oblique PWSCC at U-bends represents a reduction in the number of indications and is consistent with other plant, that have perforned more than one inspection for this mechanism. Operating history from another unit indicates that this unit had operated with a 100%TW indication due to this mechanism for approximately 4 years prior to the detection of the indication by secondary side pressure test. Stress fields in U-bends at the flank are believed to have limited arc involvement extent. This is shown by the fact that all indications observed at Comanche Peak as well as other units all have limited circumferential extent, bounded by about 60° arc response to the +Pt coil. The observed number of indications and severity at IRF12 is expected to be bounded by the I RF I I results as I RF I I witas the second large scale inspection of this region.

Freespan Axial ODSCC Severity of this mechanism is expected to be bounded by the results from I RF I I based on the supplemental ADS screening performed. The ADS screening results show that DFI reports would have been produced at I RF09 for R32 C99, thus, it can be assumed that similar indications would have been reported at IRFI 1. At 0.15 volt in the 300 kHz bobbin, the depth associated with this amplitude is approximately [

]ac. The +Pt and bobbin amplitudes for approximately 50 I RFI I confirmed indications wvere compiled. A plot of 300 kHz bobbin amplitude versus +Pt amplitude indicates that the mean predicted +/-Pt amplitude is 0.14 volt, while the upper 90%

probability, 50% confidence +Pt amplitude is 0.21 volt. For a +Pt amplitude of 0.21 volt, the predicted maximum depth is [

I". Evaluation of growth based onl the 300 kHz bobbin amplitude response indicates that the 95i' percentile growth is [

]

per cycle. Thus, at EOC-12, a freespan ODSCC depth of [

]aC could be realized. When the 1.25 maximum to average Page 27 of 41

SG-SG DA-05-45-NP depth ratio is applied, this indication could contain average depth of approximately [

a. c For an assumed flaw length of 3 inches, a [

]3,C average depth flaw would retain a burst capability of approximately 5300 psi at the 95% probability, 50% confidence level.

TSP ODSCC The bobbin amplitude distribution for IRFI I is essentially equal to the IRFIO bobbin amplitude distribution. Thus, growth conditions can be assumed to have not changed over this period. The low growth function associated with the TSP ODSCC mechanism at Comanche Peak does not support a potential for a growth exceeding 3 volts, which would then postulate an indication with an amplitude approaching the voltage based structural limit. For each of the last three inspections, only one tube has been required to be plugged due to a bobbin amplitude exceeding I volt.

Ding ODSCC The number of tubes affected with ding ODSCC was reduced for IRFI I compared to I RFIO. All of the ding ODSCC signals reported by bobbin had precursor signals in the IRFIO data, and some had precursors present in the I RF09 data, supporting the previous supposition that ding ODSCC is generally not a mechanism with significant growth rates. In the case of the 0.77" long indication in situ pressure tested at I RF 10, the signal was present at I RF08, although the 130 kliz phase response was less than the reportable value. Thls, the indication depth likely was shallow.

AVB and Baffle Wear AVB and baffle wear growth rates remain low. The single largest baffle wear growth for Cycle 11 was 6%TW. The average baffle wear growth was approximately I %TW, and baffle wear growth rates have not changed for the past several outages. The total number of affected tubes with AVB wear is small, less than 10. The largest growth was 4%TW for Cycle 11.

Conclusion The preliminary evaluation of mechanism growth rates indicates that there is no apparent change in growth rates for Cycles 11 and 10. As eddy current detection conditions remain consistent, there is no basis to conclude that the observed indication severities at IRF12 will vary significantly from that observed at I RF I 1.

6.0 Potential New Degradation Mechanism Assessment The only new degradation mechanism reported at IRFI I was axial PWSCC in large radius U-bends.

The signal parameters were small, and the Row location (Row 13) suggests that this signal could be a false call as no axial indications were reported in Rows with much higher ovality and total strain conditions. The slow growth observed for the oblique PWSCC indications suggests that if real, such indications would also not represent a high growth condition. Previous industry occurrences of axial PWSCC in Row 3 and higher U-bends have been limited to Rows 4 and 5.

Partially collapsed TIG sleeves were again observed in SGs 2, 3, and 4. Again, this mechanism is not new to the industry, or to Comanche Peak Unit 1. This mechanism is addressed here only to capture Page 28 of 41

SG-SGDA-05-45-NP the results of the +Pt inspection of the sleeve lower hardroll for collapsed TIG sleeves at I RFI I which shows that no detectable degradation was observed in the I RF I I collapsed TIG sleeves, either in the parent tube or sleeve at the lower hardroll joint. Reference 8 provides an assessment of potential TIG sleeve collapse for Comanche Peak and concludes that the weld and hardroll joints will retain integrity in the event of a collapse.

In conclusion, the new mechanism observed at Comanche Peak Unit I during the IRFI I outage has been previously reported in the industry, and does not represent a structural or leakage integrity challenge.

7.0 Comanche Peak 1 In Situ Prcssurc Testing History Table 9 presents a summary of the in situ testing history at Comanche Peak Unit 1. The flaw parameters for the tested circumferential ODSCC indications are consistent for each inspection, suggesting that the upper bound flaw severity has not increased over at least 4 inspections.

Page 29 of 41

SG-SGDA-05-45-N P 8.0 References

1. SG-SGDA-05-32, Rev I, "Comanche Peak Steam Electric Station Unit I Steam Generator Degradation Assessment I RF I I Refueling Outage", October 2005 (Westinghouse Proprietary)

2.

SG-SGDA-04-21, Rev 1, "Comanche Peak Steam Electric Station IRFI0 Condition Monitoring Report and Preliminary Cycle II Operational Assessment", April 2004 (Westinghouse Proprietary)

3.

CN-SGDA-02-93, "Circumferential ODSCC Sizing Uncertainties", April 2002 (Westinghouse Proprietary)

4.

EPRI TR-107621R1, "Steam Generator Integrity Assessment Guidelines", March 2000

5.

EPRI 1003138, "PWR Steam Generator Examination Guidelines Revision 6", October 2002

6.

EPRI 1007904, "Steam Generator In Situ Pressure Test Guidelines Revision 2", August 2003

7.

Argonne National Laboratory, February 2003 Monthly Report for Job Code Y6588, "Tube Integrity Program"

8.

LTR-SGDA-04-137, "Evaluation of Collapsed TIG Welded Sleeves at Comanche Peak Unit I," April 2004

9.

SG-SGDA-04-21, Rev 1, "Comanche Peak Steam Electric Station IRFIO Condition Monitoring Report and Preliminary Operational Assessment," April 2004

10. SG-99-03-005, "Appendix H Certification of Bobbin Coil Detection Performance in Freespan Dings", March 1999 Page 30 of 41

SG-SGDA-0545-NP Table 8 Summar of Limiting Indicati ns at IRFI I at Lower 95% Pr bability, 50% Confidence Evaluation Mechanism Tube Max Length Max Depth Avg. Depth Calculated Burst SLB Leakage Pressure gpm Circ ODSCC at hot leg R36 C79 296" 70%

34%

6493 0.00 TTS Oblique PWSCC in Combined Flaws 700

<60% (1)

N/A 6642 0.00 U-bends Freespan Axial ODSCC R32 C99

-36" 53% (2)

From 5300 0.00 I_

profiling Axial ODSCC in Dings R27 C23 0.34" 75% (3) 60%

5301 0.00 Axial PWSCC at TTS R2 C99 0.21"

<40%TW (I)

N/A 4871 0.00 Axial ODSCC at TSP R26 C65 N/A N/A N/A 5300 0.06 gpm (4)

Baffle Wear R48 C39 0.75" (5) 45%

N/A 4706 0.00 AVB Wear R47 C67 0.35" 38%

N/A 6671 0.00 1): Assumed maximum depth for burst pressure analysis is 100%TW 2): Maximum depth is based on +Pt flaw amplitude.

3): Assumed bounding value based on +Pt lissajous response.

4): For the lower 95% tolerance bound from Addendum 6 to the TSP ODSCC database 5): Assumed to be equal to baffle thickness, uniform thinning model applied Page 31 of 41

SG-SGDA-0545-NP Table 9 Comanche Peak Unit I In Situ Pressure Testing History CPSES IRFI I In Situ esting Summaary Tube SG Degradation Location Flaw Max Depth

+Pt Volts Leak Test Proof Test Leakage Burst Mode Lcngth (NDE)

Prcssure Pressure R332 C99 I

Axial ODSCC C9 to CIO

-36" 53%

0.26 2841 4650 No No R24 C22 4

Axial ODSCC C8 to C9

-4" 60%

0.42 2841 4350 No No CPSES I RFIO In Situ Testing Summarv Tube SG Degradation Location Flaw Max Depth

+Pt Volts Leak Test Proof Test Leakage Burst Mode Length (NDE)

Pressure Pressure RIO C105 I

Oblique HI 1 +8.6" 450

-72%

2.2 4266 4266 No No PWSCC R27 C51 I

Axial ODSCC CIO +36.6" 0.77"

-70%

1.11 4266 4266 No No R7 C12 3

Axial ODSCC H5 +8.6"

-50%

0.20 2841 4266 No No RI 1 C91 4

Circ PWSCC HTS 1060

-61%

l 1.29

[

2925 l

4480 l

No l

No CPSES I RFO9 In Situ esting Summarv Tube SG Degradation Location Flawv Max Depth

+Pt Volts Leak Test Proof Test Leakage Burst Mode Length (NDE)

Pressure Pressure R41 C55 I

Axial ODSCC H10 +38" 0.10"

-70%

0.93 4070 4070 No No R41 C75 I

Axial ODSCC CIO +38" 0.23"

-70%

0.48 4070 4070 No No R42 C59 1

Axial ODSCC AV3 +1.6" 0.27"

-70%

0.52 4070 4070 No No R45 C24 I

Axial ODSCC AV3 +1.7" 0.20"

-70%

0.43 4070 4070 No No R5 C70 2

Circ ODSCC HTS -0.29" 3600 61%

0.18 2970 4375 No No R7 C73 2

Circ ODSCC HTS -0.29" 3300 76%

0.32 2970 4375 No No RI 1 C42 2

Axial ODSCC H5 +10.63" 1.63" 64%

0.21 2841 N/A No N/A R41 C71 2

Axial ODSCC AV3 +26" 0.91" 100%

6.5 2150 N/A Ycs N/A R44 C83 2

Axial ODSCC AV2 +27" 0.25"

-70%

0.45 4070 4070 No No R7 C17 3

Axial ODSCC H5 +11.73" 1.14" 68%

0.26 4070 4070 No No R4 C51 3

Axial ODSCC H9 +9" 0.89" 71%

0.24 2841 4070 No No R2 C77 3

Circ ODSCC HTS -0.3 1" 2700 60%

0.38 2970 l

4375 No No Page 32 of 41

SG-SGDA-0545-NP R38 C77 3

Circ ODSCC HTS -0.25" 2700 76%

0.42 2970 4375 No No R7 C90 3

Axial ODSCC H3 +29.2" 2.81" 60%

0.26 2841 4070 No No R23 C90 3

Circ ODSCC HTS -0.29" 1200 76%

0.44 2970 4375 No No R36 C93 3

Circ ODSCC HTS -0.14" 2100 82%

0.22 2970 4375 No No R7 Cl 12 3

Axial ODSCC H8 +8.56" 2.88" 62%

0.81 2841 4070 No No R32 C65 4

Circ ODSCC HTS -0.46" 3300 76%

0.56 2970 4375 No No R4 C77 4

Circ ODSCC HTS -0.25" 3300 48%

0.26 2970 4375 No No

=U CPSES I RF08 In Situ Testing Sumn ary Tube SG Degradation Location Flaw Max Depth

+Pt Volts Leak Test Proof Test Leakage Burst IMode Length (NDE)

Pressure Pressure R18 C84 4

Circ ODSCC HTS -0.28" 2700 91%

0.19 2955 4395 No No R2 C72 4

Circ ODSCC HTS -0.02" 2700 42%

0.31 2955 4395 No No CPSES I RF07 In Situ Testing Summ ar Tub-e I

rIaDegaduvio M

Location IFaw Max Depth

+Pt voits Leak Test Proof Test Leakage Burst Mode l

Length (NDE)

Pressure Pressure R22 C89 4

Cire ODSCC

-HTS

-0.23" 3390 69%

0.23 2925 4385 No No R32 C77 4

Circ ODSCC FHTS -0.14" 2920 63%

0.32 2925 4385 No No R38C78 4

Circ ODSCC HTS +0. 1" l 2650 71%

0.17 2925 4385 No No CPSES lRF06 In Situ Testing Summary (limiting indications)

Tube SG Degradation Location Flawv Max Depth

+Pt Volts Leak Test Proof Test Leakage Burst Mode Length Pressure Pressure RI C69 2

CircODSCC HTS+0.12" 2960 61%

0.43 2925 4315 No No RI C73 2

Circ ODSCC HTS -0. 17" 3260 67%

0.47 2925 4315 No No RI C95 2

Circ ODSCC HTS -0.32" 3370 64%

0.44 2925 4315 No No R3 C96 l 2 Circ ODSCC HTS -0.25" l3500 71 0.38 2925 4315 No No R3 C103 l 2 CircODSCC HTS-0.14" 360° 71%

0.43 2925 4315 No No Page 33 of 41

SG-SGDA-05-45-NP Notes:

1. R41 C71 leaked at a maximum rate of 0.03 gpm at pressure differential of 1439 psi (normal operating temperature adjusted). Leak test was stopped at 2150 psi due to leakage exceeding pump capacity of 2.6 gpm. Burst could not be established. Predicted burst pressure is approximately 2727 psi.

2. All axial ODSCC tests were conducted using full tube setup, thus leak and proof test pressures are equal. Ri 1 C42 was leak tested only to 2841 psi. This tube was pulled for destructive exam. Laboratory burst pressure was 8177 psi.

3. All maximum depths based on phase analysis for most reliable depth points.

Page 34 of 41

Figure I SG-SGDA-05-45-NP axc Page 35 of 41

SG-SGDA-05-45-NP Figure 2 Comanche Peak IRF09, 1RFI0, and 1RF11 Circ ODSCC +Pt Amplitude Distribution Frequency 1 RF09 Frequency 1 RF1 0 m

Frequency I RF1 I Cumulatiwe% IRF09

.. o--- Cumulate % IRFiO

-Cumulative

% 1RF1I 100.00%

90.00%

80.00%

70.00%

60.00%

50.00%

40.00%

30.00%

20.00%

10.00%

.00%

I*

0 E

C.

LLILL

-_ I a..._

0.1 0.15 0.2 0.25 0.3 0.35 0.4

+Pt Volts Bin 0.45 0.5 More CO0 Page 36 of 41 I

SG-SGDA-05-45-NP 160 140 120 Figure 3 Comanche Peak IRF09, 1RFI0, and IRFI1 Circ ODSCC PDA Distribution at 90% Probability, 50% Confidence including NDE Uncertainty Frequency 1 RF10 Frequency 1 RF09 Frequency I RF1I Cumulative % 1 RF1 0

--- E- -

C-urrulative % 1 RFO9 Cunulative % 1 RF 1 100.00%

90.00%

80.00%

70.00%

60.00%

50.00%

X

/ 40.00%

30.00%

20.00%

IL

.10.00%

.00%

0*

r-.

U-100 80 60 40 20 i

30 33 36 39 42 45 48 51 54 57 60 63 66 69 Nbre PDA Bin (%)

Page 37 of 41

SG-SGDA-05-45-NP Figure 4 axc Page 38 of 41

SG-SGDA-05-45-NP Figure 5 ax Page 39 of 41

SG-SGDA-05-45-NP Figure 6 ax Page 40 of 41

SG-SGDA-05-45-NP Figure 7 R24 C22 Pre vs Post In Situ

-4+-Pre ISPT e

Post ISPT 0.6 0.5 0.4 a 0.3 0.2 0.1 0~

20 21 22 23 24 25 26 27 28 29 30 Elevation P4 3o Page4l of 41 CAW-06-2096 "APPLICATION FOR WITHHOLDING PROPRIETARY INFORMATION FROM PUBLIC DISCLOSURE" PROPRIETARY INFORMATION NOTICE AND COPYRIGHT NOTICE

Westinghouse U.S. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555-0001 Westinghouse Electric Company Nuclear Services P.O. Box 355 Pittsburgh, Pennsylvania 15230-0355 USA Directtel: (412) 374-4419 Direct fax: (412) 374-4011 e-mail: maurerbf~westinghouse.com Our ref: CAW-06-2096 February 7, 2006 APPLICATION FOR WITHHOLDING PROPRIETARY INFORMATION FROM PUBLIC DISCLOSURE

Subject:

SG-SGDA-05-45-P, "Comanche Peak Steam Electrie Station IRFI I Outage Condition Monitoring Report and Preliminary Cycle 12 Operational Assessment," dated October 2005 (Proprietary)

The proprietary information for which withholding is being requested in the above-referenced report is further identified in Affidavit CAW-06-2096 signed by the owner of the proprietary information, Westinghouse Electric Company LLC. The affidavit, which accompanies this letter, sets forth the basis on which the information may be withheld from public disclosure by the Commission and addresses with specificity the considerations listed in paragraph (b)(4) of 10 CFR Section 2.390 of the Commission's regulations.

Accordingly, this letter authorizes the utilization of the accompanying affidavit by TXU Power.

Correspondence with respect to the proprietary aspects of the application for withholding or the Westinghouse affidavit should refercnce this letter, CAW-06-2096, and should be addressed to B. F. Maurer, Acting Manager, Regulatory Compliance and Plant Licensing, Westinghouse Electric Company LLC, P.O. Box 355, Pittsburgh, Pennsylvania 15230-0355.

Very truly yours, B. F. Maurer, Acting Manager Regulatory Compliance and Plant Licensing Enclosures cc: B. Benney L. Feizollahi A BNFL Group company

CAW-06-2096 bcc: B. F. Maurer (ECE 4-7A) IL R. Bastien, IL (Nivelles, Belgium)

C. Brinkman, IL (Westinghouse Electric Co., 12300 Twinbrook Parkway, Suite 330, Rockville, MD 20852)

RCPL Administrative Aide (ECE 4-7A) 1, I A (letter and affidavit only)

A BNFL Group company

CAW-06-2096 AFFIDAVIT COMMONWEALTH OF PENNSYLVANIA:

ss COUNTY OF ALLEGHENY:

Before me, the undersigned authority, personally appeared B. F. Maurer, who, being by me duly sworn according to law, deposes and says that he is authorized to execute this Affidavit on behalf of Westinghouse Electric Company LLC (Westinghouse), and that the averments of fact set forth in this Affidavit are true and correct to the best of his knowledge, information, and belief:

A-B. F. Maurer, Acting Manager Regulatory Compliance and Plant Licensing Sworn to and subscribe before this 7

day of 2006 Notary Public Notadal Seal Sharon L Foed, Notary Pubric Monroevile Boro, Allegheny County My Comnission Expires January 29, 2007 nember, Pennsytvania Asscriarfon Of Nouanas

2 CAW-06-2096 (1) 1 am Acting Manager, Regulatory Compliance and Plant Licensing, in Nuclear Services, Westinghouse Electric Company LLC (Westinghouse), and as such, I have been specifically delegated the function of reviewing the proprietary information sought to be withheld from public disclosure in connection with nuclear power plant licensing and rule making proceedings, and am authorized to apply for its withholding on behalf of Westinghouse.

(2)

I am making this Affidavit in conformance with the provisions of 10 CFR Section 2.390 of the Commission's regulations and in conjunction with the Westinghouse "Application for Withholding" accompanying this Affidavit.

(3)

I have personal knowledge of the criteria and procedures utilized by Westinghouse in designating information as a trade secret, privileged or as confidential commercial or financial information.

(4)

Pursuant to the provisions of paragraph (b)(4) of Section 2.390 of the Commission's regulations, the following is furnished for consideration by the Commission in determining whether the information sought to be withheld from public disclosure should be withheld.

(i)

The information sought to be withheld from public disclosure is owned and has been held in confidence by Westinghouse.

(ii)

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The application of that system and the substance of that system constitutes Westinghouse policy and provides the rational basis required.

Under that system, information is held in confidence if it falls in one or more of several types, the release of which might result in the loss of an existing or potential competitive advantage. as follows:

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The information reveals the distinguishing aspects of a process (or component, structure, tool, method, etc.) where prevention of its use by any of Westinghouse's competitors without license from Westinghouse constitutes a competitive economic advantage over other companies.

3 CAW-06-2096 (b)

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The use of such information by Westinghouse gives Westinghouse a competitive advantage over its competitors. It is, therefore, withheld from disclosure to protect the Westinghouse competitive position.

(b)

It is information that is marketable in many ways. The extent to which such information is available to competitors diminishes the Westinghouse ability to sell products and services involving the use of the information.

(c)

Use by our competitor would put Westinghouse at a competitive disadvantage by reducing his expenditure of resources at our expense.

(d)

Each component of proprietary information pertinent to a particular competitive advantage is potentially as valuable as the total competitive advantage. If competitors acquire components of proprietary information, any one component may be the key to the entire puzzle, thereby depriving Westinghouse of a competitive advantage.

4 CAW-06-2096 (e)

Unrestricted disclosure would jeopardize the position of prominence of Westinghouse in the world market, and thereby give a market advantage to the competition of those countries.

(f)

The Westinghouse capacity to invest corporate assets in research and development depends upon the success in obtaining and maintaining a competitive advantage.

(iii)

The infonnation is being transmitted to the Commission in confidence and, under the provisions of 10 CFR Section 2.390, it is to be received in confidence by the Commission.

(iv)

The information sought to be protected is not available in public sources or available information has not been previously employed in the same original manner or method to the best of our knowledge and belief.

(v)

The proprietary information sought to be withheld in this submittal is that which is appropriately marked in SG-SGDA-05-45-P, "Comanche Peak Steam Electric Station IRFI I Outage Condition Monitoring Report and Preliminary Cycle 12 Operational Assessment," dated October 2005 (Proprietary), being transmitted by TXU Power letter and Application for Withholding Proprietary Information from Public Disclosure, to the Document Control Desk. The proprietary information as submitted by Westinghouse for the Comanche Peak Steam Electric Station Unit I is expected to be applicable for other licensee submittals in response to certain NRC requirements for justification of plant operation with the condition of the steam generators as determined from the inspection during the outage.

This information is part of that which will enable Westinghouse to:

(a) Provide information in support of steam generator licensing submittals.

(b) Provide plant specific calculations.

(c) Provide licensing documentation support for customer submittals.

Further this information has substantial commercial value as follows:

5 CAW-06-2096 (a)

Westinghouse plans to sell the use of similar information to its customers for purposes of meeting NRC' requirements for licensing documentation associated with steam generator submittals.

(b)

Westinghouse can sell support and defense of the technology to its customers in the licensing process.

(c)

The information requested to be withheld reveals the distinguishing aspects of a methodology which was developed by Westinghouse.

Public disclosure of this proprietary information is likely to cause substantial harm to the competitive position of Westinghouse because it would enhance the ability of competitors to provide similar calculations, evaluations, analyses and licensing defense services for commercial power reactors without commensurate expenses. Also, public disclosure of the information would enable others to use the infornation to meet NRC requirements for licensing documentation without purchasing the right to use the information.

The development of the technology described in part by the information is the result of applying the results of many years of experience in an intensive Westinghouse effort and the expenditure of a considerable sum of money.

In order for competitors of Westinghouse to duplicate this information, similar technical programs would have to be perfonned and a significant manpower effort, having the requisite talent and experience, would have to be expended.

Further the deponent sayeth not.

PROPRIETARY INFORMATION NOTICE Transmitted herewith are proprietary and/or non-proprietary versions of documents furnished to the NRC in connection with requests for generic and/or plant-specific review and approval.

In order to conform to the requirements of 10 CFR 2.390 of the Commission's regulations concerning the protection of proprietary information so submitted to the NRC, the information which is proprietary in the proprietary versions is contained within brackets, and where the proprietary information has been deleted in the non-proprietary versions, only the brackets remain (the information that was contained within the brackets in the proprietary versions having been deleted). The justification for claiming the information so designated as proprietary is indicated in both versions by means of lower case letters (a) through (f) located as a superscript immediately following the brackets enclosing each item of information being identified as proprietary or in the margin opposite such information. These lower case letters refer to the types of information Westinghouse customarily holds in confidence identified in Sections (4)(ii)(a) through (4)(ii)(f) of the affidavit accompanying this transmittal pursuant to 10 CFR 2.390(b)(1).

COPYRIGHT NOTICE The reports transmitted herewith each bear a Westinghouse copyright notice. The NRC is permitted to make the number of copies of the information contained in these reports which are necessary for its internal use in connection with generic and plant-specific reviews and approvals as well as the issuance, denial, amendment, transfer, renewal, modification, suspension, revocation, or violation of a license, permit, order, or regulation subject to the requirements of 10 CFR 2.390 regarding restrictions on public disclosure to the extent such information has been identified as proprietary by Westinghouse, copyright protection notwithstanding. With respect to the non-proprietary versions of these reports, the NRC is permitted to make the number of copies beyond those necessary for its internal use which are necessary in order to have one copy available for public viewing in the appropriate docket files in the public document room in Washington, DC and in local public document rooms as may be required by NRC regulations if the number of copies submitted is insufficient for this purpose. Copies made by the NRC must include the copyright notice in all instances and the proprietary notice if the original was identified as proprietary.

ML060670447

Text

1.0 INTRODUCTION

Subject:

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