DCL-02-098, Special Report 02-02 - Results of Steam Generator Inspections for Eleventh Refueling Outage

Special Report 02-02 - Results of Steam Generator Inspections for Eleventh Refueling Outage

ML022420012
Person / Time
Site:	Diablo Canyon
Issue date:	08/22/2002
From:	Womack L Pacific Gas & Electric Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
50-275-OL, DCL-02-098, GL-95-005
Download: ML022420012 (131)

Text

PacificGas and Electric Company Lawrence F. Womack Diablo Canyon Power Plant Vice President P0 Box 56 Nuclear Services Avila Beach, CA 93424 August 22, 2002 Augut22,002Fax e8055454600 805 545 4234 PG&E Letter DCL-02-098 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 Docket No. 50-275, OL-DPR-80 Diablo Canyon Unit 1 Special Report 02 Results of Steam Generator Inspections for Diablo Canyon Power Plant Unit I Eleventh Refuelina Outage

Dear Commissioners and Staff:

In accordance with Technical Specifications (TS) 5.6.10.e and 5.6.10.f, Enclosure I provides the 90-day reporting of results of Unit I steam generator (SG) W* alternate repair criteria (ARC) tubesheet inspections and calculated steam line break leakage from application of all ARC.

In accordance with TS 5.6.10.h, Enclosure 2 provides the 120-day reporting of results of Unit I SG primary water stress corrosion cracking ARC inspections at dented tube support plate intersections.

In accordance with PG&E's commitment to NEI 97-06, Revision 1, Enclosure 3 provides the 120-day SG condition monitoring report. This report is required when greater than one percent of inspected SG tubes are classified as defective.

In accordance with PG&E's commitment to Generic Letter 95-05, "Voltage-Based Repair Criteria for Westinghouse Steam Generator Tubes Affected by Outside Diameter Stress Corrosion Cracking," Enclosure 4 provides the 90-day reporting of results of Unit 1 SG voltage-based ARC inspections at tube support plate intersections provided by Framatone ANP.

Sincerely, Lawrence F. Womack A member of the STARS (Strategic Teaming and Resource Sharing) Alfiance Cattaway e Comanche Peak & Diabto Canyon w Pato Verde

• South Texas Project a Wotf Creek

Document Control Desk PG&E Letter DCL-02-098 August 22, 2002 Page 2 ddml/469 Enclosures cc: David L. Proulx Diablo Distribution cc/enc: Ellis W. Merschoff Girija S. Shukla State of California, Pressure Vessel Unit A member of the STARS (Strategic Teaming and Resource Sharing) Alliance Caltaway e Comanche Peak

• Diablo Canyon

• Palo Verde e South Texas Project a Wolf Creek

Enclosure 1 PG&E Letter DCL-02-098 SPECIAL REPORT 02-02 RESULTS OF STEAM GENERATOR W* ALTERNATE REPAIR CRITERIA TUBESHEET INSPECTIONS DIABLO CANYON POWER PLANT UNIT 1 ELEVENTH REFUELING OUTAGE NRC Reporting Requirements Diablo Canyon Power Plant (DCPP) Technical Specification (TS) 5.6.10.e requires that the results of the inspection of Wstar (W*) tubes be reported to the Commission pursuant to 10 CFR 50.4 within 90 days following return to service of the steam generators (SGs). The report shall include:

1. Identification of W* tubes. Per TS 5.5.9.d.1.k, a W* tube is a tube left in service with degradation within or below the W* length.

2. W* inspection distance measured with respect to the Bottom of the WEXTEX Transition (BWT) or the top of tubesheet, whichever is lower.

3. Elevation and length of axial indications within the flexible W* distance and the angle of inclination of clearly skewed axial cracks (if applicable).

4. The total steam line break leakage for the limiting SG per WCAP-14797 ("Generic W* Tube Plugging Criteria for 51 Series Steam Generator Tubesheet Region WEXTEX Expansions").

DCPP TS 5.6.10.f requires that the aggregate calculated steam line break leakage from application of all alternate repair criteria (ARC) be reported to the Commission pursuant to 10 CFR 50.4 within 90 days following return to service of the SGs.

W* Inspections and Results This report implements the DCPP TS reporting criteria. W* ARC was implemented for the third time during the Unit 1 eleventh refueling outage (1Rll). Following 1Rll SG inspections and repairs completed in May 2002, the SGs were returned to service.

One hundred percent of the SG tubes were inspected by bobbin from tube end to tube end. One hundred percent of the hot leg top of tubesheet (TTS) region was inspected by Plus Point. Cold leg TTS inspections by Plus Point were not required.

Table 1 provides a comprehensive list of axial primary water stress corrosion cracking (PWSCC) indications detected in the WEXTEX region during 1Rll Plus Point inspections. The following TS-required reporting information is extracted from the table:

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Enclosure 1 PG&E Letter DCL-02-098

1. Identification of W* tubes. See "W* Tube" column in Table 1. A total of 14 tubes with 16 indications are identified in Table 1. Thirteen tubes, containing a total of 14 single axial PWSCC indications (SAI) and 1 single volumetric indication (SVI) located below the W* length, are categorized as W* tubes and left in service. One tube with axial PWSCC was plugged because of failure to meet W* ARC (upper crack tip was above BWT). There were 6 additional tubesheet indications in non-W*

tubes that were plugged and are not listed in Table 1: five circumferential outside diameter stress corrosion cracking (ODSCC) indications at the top of tubesheet were plugged because the crack type and location excluded application of W*ARC; one circumferential PWSCC indication located below the W* length was plugged due to a pluggable indication at a tube support plate location.

2. W* inspection distance measured with respect to BWT or TTS, whichever is lower.

For the one hundred percent Plus Point hot leg TTS exam, the inspection extent relative to the TTS was specified as +2/-8 inches. Assuming no degradation in the W* length, eight inches below the TTS constitutes the W* inspection distance. This distance bounds W* lengths for Zone A and Zone B (5.2 inch and 7.0 inch, respectively, relative to BWT), and includes margin for a nominal distance from BWT to TTS plus nondestructive examination (NDE) uncertainty in measuring W*

length. If degradation is detected in the W* region, the inspection extent must bound the calculated flexible W* length. The "W*lnsp Dist" column in Table 1 lists the W* inspection distances measured with respect to BWT for tubes in which axial PWSCC was detected (in all cases, BWT was lower than the TTS).

3. Elevation and length of axial indications within the flexible W* distance. See "From To" and "L" columns in Table 1 for elevation and length of axial indications. Five axial PWSCC indications and one volumetric indication (SVI) were located below the flexible W* distance and left in service. The upper elevation of the SVI was treated as an upper crack tip in the W* calculations.

4. Angle of inclinationof clearly skewed axial cracks (if applicable). None of the axial indications were skewed, so this reporting requirement is not applicable.

5. The total steam line break leakage for the limiting SG per WCAP-14797. Steamline break (SLB) leakage attributed to each W* indication at end of the cycle (EOC) 11 (condition monitoring) and projected EOC 12 (operational assessment) are listed in "CM LR" and "OA LR" columns in Table 1. It can be noted that the W* leakage model assumes all W* indications are throughwall cracks. Based on the maximum depths given in Table 1 (largest is 82%), none of the W* indications would be expected to leak at SLB conditions. The total SLB leakage for the limiting SG is listed in Table 2.

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Enclosure 1 PG&E Letter DCL-02-098 Table 2 reports the following SLB leak rates, pursuant to TS 5.6.10.e.4 and 5.6.10.f:

1. Total W* ARC SLB leakage for each SG at EOC 11. The maximum leak rate is 0.0904 gpm (at room temperature) in SG 1-2.

2. Total W* ARC SLB leakage for each SG at EOC 12. The maximum leak rate is 0.05163 gpm (at room temperature) in SG 1-2. This leak rate is less than the condition monitoring leak rate at EOC 11 due to the new indication in SG 11 at R3C38, which extended into the expansion transition (i.e., above BWT), and the indication was plugged.

3. The aggregate calculated SLB leakage from application of voltage-based ARC, PWSCC ARC, and W* ARC at EOC 11. The maximum leak rate is 0.368 gpm (at room temperature) in SG 1-2.

4. The aggregate calculated SLB leakage from application of voltage-based ARC, PWSCC ARC, and W* ARC at EOC 12. The maximum leak rate is 1.115 gpm (at room temperature) in SG 1-1.

For W* ARC, the SLB differential pressure is assumed to be 2560 psi. For PWSCC ARC and voltage-based ARC, the SLB differential pressure is assumed to be 2405 psi.

Axial PWSCC Growth Rates Of the 15 axial PWSCC indications detected in 1 RI 1, 3 were new indications, 2 were in deplugged tubes, and 10 were repeat W* indications that had been left in service in the prior inspection. Of the 3 new indications, 2 had prior inspection data. Based on prior inspection data, one was detectable and one was not detectable, resulting in a total of 11 new growth rate data points. The average growth rate of the 11 indications was 0.015 inch per effective full power year (EFPY) at Thot of 604 degrees F.

After addition of the 11 new data points, the updated W* growth rate distribution now consists of 108 data points from DCPP Units 1 and 2. The updated growth rate at 95 percent cumulative probability is 0.071 inch per EFPY at 604 degrees F. The pre-1R11 growth rate at 95 percent cumulative probability is 0.081 inch per EFPY at 604 degrees F (based on 97 data points), and this value is conservatively used in the operational assessment for DCPP Unit 1 Cycle 12.

The actual length of Unit 1 Cycle 11 was 1.41 EFPY. The projected length of Unit 1 Cycle 12 is 1.61 EFPY.

Insitu Leak Testinq In support of W* leak rate model validation, PG&E letter DCL-01-095 dated September 13, 2001, defined a four step sequential screen process for determining the 1-3

Enclosure 1 PG&E Letter DCL-02-098 need for insitu leak testing of axial PWSCC indications in the WEXTEX region. The 15 axial PWSCC indications detected in 1 RI I were evaluated against the four steps, none exceeded the criteria, and therefore none were leak tested. The criteria and PG&E evaluation are described below. Maximum voltages and maximum depths for each indication are provided in Table 1.

Step 1: Prior leak tested W* indications with maximum Plus Point voltages greater than or equal to 1.25 times the prior leak test voltage are carried to Step 2. W*

indications with no prior leak test are also carried to step 2.

PG&E evaluation: No W* indications had been leak tested in prior outages, so all 15 indication were carried to step 2.

Step 2: Indications with maximum Plus Point voltages exceeding the critical voltage (Vc~t) are leak tested independent of other parameters. Vcrt equals 4.0 volts for nondeplugged indications and 6.0 volts for deplugged indications. Indications with maximum Plus Point voltages less than Vc,,t are carried to Step 3.

PG&E evaluation: The maximum voltage of the 13 nondeplugged axial PWSCC indications was 0.8 volts, less than the 4.0 volt threshold value. The maximum voltage of the 2 deplugged axial PWSCC indications was 1.25 volts, less than the 6.0 volt threshold value. Therefore, since no indications exceeded Vcrt, all indications were carried to step 3.

Step 3: Indications with maximum Plus Point voltages exceeding Vthr are carried to the Step 4 depth evaluation. A minimum of the five largest voltage indications are carried to the depth evaluation if less than five indications exceed the voltage threshold. Vthr equals 2.5 volts for nondeplugged indications and 4.0 volts for deplugged indications.

PG&E evaluation: The maximum voltage of the 13 nondeplugged axial PWSCC indications was 0.8 volts, less than the 2.5 volt threshold value. The maximum voltage of the 2 deplugged axial PWSCC indications was 1.25 volts, less than the 4.0 volt threshold value. Therefore, since no indications exceeded Vthr, the five largest voltage indications are required to be carried to step 4.

Step 4 (depth evaluation): Indications with maximum depths exceeding the maximum depth leakage threshold (MDL-thr) over lengths greater than the deep crack length threshold (LL-min) are leak tested. MDL-thr equals 80% and LL-m,n equals 0.1 inch.

PG&E evaluation: All axial PWSCC indications in the WEXTEX region were depth profiled using the same techniques as axial PWSCC at dented TSP intersections.

The maximum depth of one indication exceeded 80 percent (SG 12 R20C37), but the flaw length greater than 80 percent was much less than the 0.1 inch threshold 1-4

Enclosure 1 PG&E Letter DCL-02-098 value. Therefore, since there were no indications with maximum depth greater than MDL-thr over lengths greater than LL.min, no indications required insitu leak testing.

Tube Integrity Performance Monitoring Condition MonitoringPerformance Criteria to Limit Free Span Cracking: The upper crack tip (UCT) of VV* indications returned to service at EOCIO.under W* ARC shall remain below the TTS at EOC 11 by at least the NDE uncertainty on locating the crack tip relative to the TTS. The "UCT to TSH" column in Table 1 provides the EOC 11 elevation of the upper crack tip relative to the top of tubesheet, accounting for NDE uncertainty in locating the crack relative to the top of tubesheet. In all cases, the EOC 11 crack tip for indications returned to service at EOC 10 is below the top of tubesheet.

Therefore, the performance criterion was satisfied for condition monitoring at EOC 11.

Accident-Induced Leakage Performance Criteria: Calculated W* leak rates under postulated SLB conditions, when combined with calculated leak rates from application of GL 95-05 voltage-based ARC and PWSCC ARC, shall not exceed 12.8 gpm (at room temperature) in the faulted SG for condition monitoring and 10.5 gpm (at room temperature) for operational assessment. The 12.8 gpm condition monitoring limit is the current licensing basis leak rate limit as approved in NRC letter to PG&E dated March 12, 1998. The more conservative 10.5 gpm operational assessment limit is pending NRC approval of license amendment request (LAR) 01-05, which is expected in late 2002 during Unit 1 Cycle 12. The aggregate calculated SLB leakage from application of all ARC at EOC 11 is 0.368 gpm for the limiting SG. The aggregate calculated SLB leakage from application of all ARC at EOC 12 is 1.115 gpm for the limiting SG. In both assessments, SLB leakage is less than the allowable limit.

Therefore, the performance criterion has been satisfied for condition monitoring at EOC 11 and operational assessment at EOC 12.

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Enclosure 1 PG&E Letter DCL-02-098 Table 1 DCPP Unit 1 1R11 Indications in Hot Leg WEXTEX Tubesheet Region (excluding circumferential indications that were plugged)

SG R C Ind +Pt MD From To L UCT W* W* BWT EOC11 UCT UCT EOC UCT W* Insp W" Flex CM LR EOC12 OALR Plug Type volt to Zone L UCT- Below Below 12 Below Tube Ext Insp W L UCT- 1R11 TSH BWT W* BWT UCT TSH at Dist BWT EOC12 11 3 2 SAI 035 47 -1 53 -1 34 0.19 -112 A 532 022 1 28 No Yes -099 Yes Yes -12.8 12.93 5.50 0.00740 1.15 0.00816 No Repeat 11 15 10 SAI 063 40 -903 -888 015 -866 A 532 -024 836 Yes Yes -853 Yes Yes -1057 1024 532 0 8.23 0 No New 11 15 10 ISAI 08 46 -851 -837 0.14 -815 A 532 -024 785 Yes Yes -802 Yes Yes -1057 1024 532 0 772 0 No New 11 20 44 SAI 031 34 -796 -782 014 -76 B2 7.12 -031 723 Yes Yes -747 Yes Yes -1095 1055 7.12 0 7.10 000051 No Repeat 12 3 38 SAI 022 67 -032 -019 013 003 B1 7.12 -031 -04 No No 016 No No -974 934 724 004530 NA NA Yes New 12 7 33 SAI 1 71 -203 -1 103 -078 B2 7.12 -035 037 No Yes -065 Yes Yes -1032 988 8.14 003100 024 003583 No deplug IR11 12 20 37 SAI 1.25 82 -1 9 -1.75 015 -1.53 B3 7.12 -018 129 No Yes -1.40 Yes Yes -1232 1205 726 001410 1.16 001581 No deplug IR11 13 2 14 SVI 059 NA -836 -812 024 -7.9 A 532 -02 764 Yes Yes -7.77 Yes Yes -928 899 532 0 764 0 No deplugIR11 13 31 36 SAI 047 20 -292 -2.77 015 -255 A 5.32 -025 224 No Yes -2.42 Yes Yes -943 909 546 000360 2.11 000385 No Repeat 13 33 37 SAI 053 24 -55 -536 014 -514 A 532 -048 46 No Yes -501 Yes Yes -9.11 854 545 000054 447 000059 No Repeat 13 30 45 SAI 031 20 -1.9 -1.81 009 -1.59 B4 7.12 -027 126 No Yes -146 Yes Yes -93 894 720 001100 1.13 001212 No Repeat 13 39 46 SAI 0.74 26 -2.43 -2.31 0.12 -2.09 A 5.32 -0.27 1.76 No Yes -1.96 Yes Yes -984 948 543 000500 163 000556 No Repeat 14 23 7 SAI 045 41 -821 -8.06 0.15 -7.84 A 532 -0.16 7.62 Yes Yes -7.71 Yes Yes -10.68 10.43 5.32 0 7.49 0 No Repeat 14 28 57 SAI 027 20 -326 -311 015 -289 B4 7.12 -034 249 No Yes -2.76 Yes Yes -1046 1003 7.26 0.00420 2.36 000457 No Repeat 14 28 57 SAI 035 20 -728 -7.13 015 -691 B4 7.12 -034 651 No Yes -678 Yes Yes -1046 1003 7.26 000022 6.38 0.00022 No Repeat 14 39 58 SAI 032 20 -622 -607 0.15 -585 A 5.32 -011 568 Yes Yes -572 Yes Yes -1023 1003 532 0 555 0 No Repeat 1-6

Enclosure 1 PG&E Letter DCL-02-098 Column - Table 1 Legend and Notes for Table 1 SG Steam generator R Row C Column Ind Plus point indication. SAI is single axial indication. SVI is single volumetric indication.

+P Volt Peak voltage from Plus Point coil MD Maximum depth, percent through-wall, using TSP axial PWSCC depth sizing technique From Elevation (inch) of lower crack tip, relative to the top of tubesheet hot leg (TSH)

To Elevation (inch) of upper crack tip, relative to the top of tubesheet hot leg (TSH).

L Length of crack (inch)

UCT to TSH Elevation (inch) of the upper crack tip (UCT) to TSH, including ANDEcT.1rs (Plus Point NDE uncertainty on locating the crack tip relative to the TTS).

None of the indications extended above the top of tubesheet.

W* Zone W* tubesheet zone based on crack location W* L W* length is 7.12 inch for Zone B and 5.32 inch for Zone A, and includes ANDEw (NDE uncertainty in measuring the W* depth)

BWT Bottom of the WEXTEX transition (inch), measured by bobbin relative to TSH.

EOC 11 UCT to BWT Distance (inch) from the upper crack tip (UCT) to BWT at EOC 11, minus ANDEcT-9wr (Plus Point NDE uncertainty on locating the crack tip relative to the BW'F).

UCT below W*? Ifthe UCT is located below the W* length, then the tube is a W* tube Any type of degradation below the W* length is acceptable UCT below BWT? Ifthe UCT is located below BWT, then the tube is a W* candidate.

EOC 11 UCT UCT location (inch) relative to TSH at the end of the next operating cycle, EOC 12, based on growing the UCT at 0 081 nch/EFPY. Unit 1 Cycle 12 is projected to be 1 61 EFPY.

UCT below TSH at EOC 11? Ifthe UCT is below TSH at EOC 12, a free span indication is precluded and the tube is a W* candidate.

W* Tube? Ifthe EOC 11 UCT is below BWT and the UCT is projected to be below TSH at EOC 12, then the tube is a W* tube Insp Ext Inspection extent of Plus Point relative to TSH (inch)

W* Insp Dist W* inspection distance (inch) This is the +Point inspection extent relative to BWT. The W* inspection distance below BWT is equal to the Plus Point inspection extent below TSH, plus measured distance from BWT to TSH, plus bobbin NDE uncertainty in locating BWT relative to TSH The W*

inspection distance must be greater than or equal to the flexible W* length.

Flex W* L Flexible W* length relative to BWT (inch), equal to W* Length + YCI, (total axial crack length) + NcL*ANDEcL (number of indications times Plus Point NDE uncertainty with measunng length of axial cracks) + NcL*ACG (number of indications times crack growth allowance from prior cycle tube integrity assessment, 0 081 inch/EFPY)

CM LR Condition monitoring SLB leak rate at EOC 11 conditions, gpm at room temperature, based on distance of UCT (at EOC 11) to BWT using Figure 6 4 3 of WCAP-14797 Rev 1. No accident leakage is assigned to deplugged indications and an indication with UCT below W* length EOC 12 UCT to BWT Distance (inch) from the upper crack tip (UCT) to BWT at EOC 12, minus ANDEcT.ewr (Plus Point NDE uncertainty on locating the crack tip relative to the BWT), based on growing the UCT at 0.081 Inch/EFPY (95% growth rate).

OA LR Operational assessment leak rate at EOC 12 conditions based on EOC 12 UCT to BWT, gpm at room temperature, using Figure 6 4-3 of WCAP-14797 Rev 1. No accident leakage is assigned to an indication with UCT below W* length.

Plug 1Ri 1? Tube was plugged in 1Ri 1.

Type Identifies the flaw as new, repeat, or deplugged in 1Ri 1.

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Enclosure 1 PG&E Letter DCL-02-098 Table 2 DCPP Unit 1 Steam Line Break Leak Rates for Alternate Repair Criteria EOC 11 Condition Monitoring Leak Rate SG 1-1 SG 1-2 SG 1-3 SG 1-4 (gpm at room temperature) I W*ARC 000740 0.09040 0.02014 000442 Voltage-Based ARC 0.325 0.278 0.153 0.059 PWSCC ARC 0 0 0 0 Aggregate ARC 0.332 0.368 0.173 0063 EOC 12 Operational Assessment Leak Rate SG 1-1 SG 1-2 SG 1-3 SG 1-4 (gpm at room temperature) I W*ARC 0.00868 005163 0.02213 0.00480 Voltage-Based ARC 1.106 (1) 0.861 0.436 0.233 PWSCCARC 0 0 0 0 Aggregate ARC 1.115 0913 0458 0.238 Note 1: SG 1-1 leak rate of 1.106 gpm was calculated using a normal growth rate distribution. Using a more conservative voltage-dependent growth rate distribution, a leak rate of 1.143 gpm is calculated for SG 1-1.

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Enclosure 2 PG&E Letter DCL-02-098 SPECIAL REPORT 02-02 RESULTS OF STEAM GENERATOR PRIMARY WATER STRESS CORROSION CRACKING (PWSCC) ALTERNATE REPAIR CRITERIA INSPECTIONS AT DENTED TUBE SUPPORT PLATE INTERSECTIONS DIABLO CANYON POWER PLANT UNIT 1 ELEVENTH REFUELING OUTAGE NRC Reporting Requirements For implementation of the alternate repair criteria for axial PWSCC at dented TSPs, DCPP TS 5.6.10.h requires that the results of the condition monitoring and operational assessments will be reported to the NRC within 120 days following completion of the inspection. The report will include:

"* Tabulations of indications found in the inspection, tubes repaired, and tubes left in service under the ARC.

"* Growth rate distributions for indications found in the inspection and growth rate distributions used to establish the tube repair limits.

"* Plus Point confirmation rates for bobbin detected indications when bobbin is relied upon for detection of axial PWSCC in less than or equal to 2 volt dents.

"* For condition monitoring, an evaluation of any indications that satisfy burst margin requirements based on the Westinghouse burst pressure model, but do not satisfy burst margin requirements based on the combined Argonne National Laboratory (ANL) ligament tearing and throughwall burst pressure model.

"* Performance evaluation of the operational assessment methodology for prediction of flaw distributions as a function of flaw size.

"* Evaluation results of number and size of previously reported versus new PWSCC indications found in the inspection, and the potential need to account for new indications in the operational assessment burst evaluation.

"° Identification of mixed mode (axial PWSCC and circumferential) indications found in the inspection and an evaluation of the mixed mode indications for potential impact on the axial indication burst pressures or leakage. In addition, as committed in DCL 02-045, performance of a trending analysis to assess the potential for increasing mixed mode affects over time.

"° Any corrective actions found necessary in the event that condition monitoring requirements are not met.

This report implements the DCPP TS reporting criteria. PWSCC ARC was implemented for the first time in DCPP Unit 1 during 1 R11. 1 RI I SG inspections and repairs were completed during May 2002.

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Enclosure 2 PG&E Letter DCL-02-098 Dented TSP Plus Point Inspection Scope The initial 1R11 Plus Point dent inspection scope was based on greater than 2 volt dents called in the prior 1 R10 outage. This initial scope was supplemented by greater than 2 volt dents called in I RI I from three sources: previously unidentified greater than 2 volt dents, expansion scope in SG 1-4 as discussed later, and deplugged tube dents in SG 1-2. The number of dents inspected in I RI I is provided in Table 1.

The dented TSP inspection criteria and expansion plan criteria described below are based on PG&E letter to the NRC dated April 16, 2001, and WCAP-15573, Revision 1, "Depth-Based SG Tube Repair Criteria for Axial PWSCC at Dented TSP Intersections Alternate Burst Pressure Calculation."

Plus Pointinspection criteriafor axial PWSCC left in service Plus Point inspections shall be conducted on 100 percent of axial PWSCC indications at dented TSP intersections that were left in service in Unit 1 Cycle 11. One hundred eleven axial PWSCC indications had been left in service that were less than 40 percent maximum depth.

Plus Point inspection criteriafor >2 and <5 volt dents and for> 5 volt dents On a SG-specific basis, Plus Point inspections shall be conducted on 100 percent of

> 5 volt dented intersections up to and including the highest hot leg TSP elevation where PWSCC (at any size dent), circumferential indications (at any size dent), or axial ODSCC Not Detected by Bobbin (AONDB) (at > 5 volt dent) have been previously detected in that SG in the prior two outages, or current outage (expansion required),

plus 20 percent of > 5 volt dents at the next higher TSP elevation. In each SG where 100 percent hot leg TSP Plus Point inspections are not required, Plus Point inspections shall be conducted on 20 percent of > 5 volt dents at each hot leg TSP. For any 20 percent sample, a minimum of 50 > 5 volt dents shall be inspected. If the population of

> 5 volt dents at that TSP elevation is less than 50, then 100 percent of the > 5 volt dents at that TSP shall be inspected.

On a SG-specific basis, Plus Point inspections shall be conducted on 100 percent of

> 2 and < 5 volt dented intersections up to and including the highest hot leg TSP elevation where PWSCC (at any size dent), circumferential indications (at any size dent), or > 2 inferred volt AONDB (at > 2 and < 5 volt dent) have been previously detected in that SG in the prior two outages, or current outage (expansion required),

plus 20 percent of > 2 and < 5 volt dent at the next higher TSP elevation. If a SG is free from PWSCC (at any size dent), circumferential indications (at any size dent) and > 2 inferred volt AONDB (at > 2 and < 5 volt dent), then Plus Point inspections shall be conducted on 20 percent of > 2 and < 5 volt dents at 1 H. For any 20 percent sample, a minimum of 50 > 2 and < 5 volt dents shall be inspected. If the population of > 2 and 2-2

Enclosure 2 PG&E Letter DCL-02-098

< 5 volt dents at that TSP elevation is less than 50, then 100 percent of the > 2 and < 5 volt dents at that TSP shall be inspected.

The highest TSP where PWSCC or circumferential indications have been found in the prior two outages is 4H for SG 1-1, 6H for SG 1-2, and 3H for SG 1-4. In SG 1-3, no PWSCC or circumferential indications have been detected. Because all inferred bobbin voltages for AONDB indications have been less than 2 volts, AONDB indications do not factor into the inspection scope. Based on this information, the following Plus Point dent inspection criteria was implemented to meet the requirements specified above.

> 5 volt dents:

"* SG 1-1: 100% at 1H to 4H, 20% at 5H to 7H

"* SG1-2: 100% at1H to 6H, 20%at7H

"* SG 1-3: 20% at 1H to 7H

"* SG1-4: 100% at lH to 3H, 20% at 4H to 7H

> 2 and < 5 volt dents:

"* SGI-1: 100%at1Hto4H,20%at5H

"* SG1-2: 100%atlHto6H,20%at7H

"* SG 1-3: 20% at 1H

"* SG1-4: 100%atlHto3H,20%at4H In 1 RI 1, axial PWSCC was detected at TSP 6H in SG 1-4 R26C37 at a 0.62 volt dent.

The indication was originally detected by bobbin as a distorted ID support signal (DIS) indication and was confirmed by Plus Point. Because TSP 6H was a higher elevation than the original inspection scope, the Plus Point inspection scope in SG 1-4 was expanded during 1R11 in accordance with the following revised inspection criteria:

>5 volt dents: 100% at 1H to 6H, 20% at 7H.

> 2 and < 5 volt dents: 100% at 1H to 6H, 20% at 7H In addition to the dent inspection program for active tubes, a dent inspection program for deplugged tubes was implemented because 150 tubes in SG 1-2 were deplugged and inspected in 1RI I for potential return to service under alternate repair criteria. The deplugged tube dent inspection criteria was more conservative than the active tube population, requiring Plus Point inspection of 100% of > 2 volt dents at all hot leg TSP intersections.

Plus Point inspection for less than or equal to 2 volt dents One hundred percent of the tubes were inspected by bobbin coil, and the bobbin coil was relied upon for detection of axial PWSCC in <2 volt dents. As a result, Plus Point inspection of < 2 volt dents was only required if the bobbin coil detected an indication at 2-3

Enclosure 2 PG&E Letter DCL-02-098 the dented TSP intersection. One hundred percent of bobbin indications at dented TSP intersections (DIS indications) were inspected by Plus Point.

Plus Point inspection criteria for detection of circumferentialindications at dents On a SG-specific basis, if a circumferential indication or >2 inferred volt AONDB is detected in a dent of "x" volts in the prior two outages, or current outage (expansion required), then Plus Point inspections shall be conducted on 100 percent of dents greater than "x - 0.3" volts up to the affected TSP, plus 20 percent of dents greater than "x- 0.3" volts at the next higher TSP. "X" is defined as the lowest dent voltage where a circumferential crack or > 2 inferred volt AONDB was detected in that SG. For any 20 percent sample, a minimum of 50 "x - 0.3" volt dents shall be inspected. If the population of "x - 0.3" volt dents at that TSP elevation is less than 50, then 100 percent of the "x - 0.3" volt dents at that TSP shall be inspected.

The smallest dent in which a Unit 1 circumferential crack has been detected in the prior two outages or current outage is 2.45 volts (1R1I circumferential indication in SG 1-2 R35C69). Thus, "x" = 2.45 volts, and "x- 0.3" = 2.15 volts. Since 2.15 volts is greater than 2 volts, the 2 volt dent cutoff for 1 R1 1 Plus Point inspection was sufficient, and no expansion scope was necessary.

Tabulations of indications found in the inspection, tubes repaired, and tubes left in service under the ARC.

Table 5 provides all axial PWSCC indications at dented TSP intersections detected in 1RI I inspections, with the exception of indications that were deplugged and replugged.

The following information is provided for each indication:

"* For plugged indications, the reason for plugging

"* Identifies the indication as repeat, new, or deplugged

"* Adjusted NDE measurements of length, maximum depth, average depth, voltage, and crack location relative to the TSP centerline.

" Operational assessment burst pressure (free span and total length) using the ANL and Electric Power Research Institute (EPRI) burst model. A burst pressure of 6100 psi in Table 5 represents a predicted burst pressure > 6100 psi since all pressures predicted to exceed 6100 psi are grouped at 6100 psi to reduce computer storage requirements in the analysis.

"* Operational assessment SLB leak rate (free span and total length) using the ANL ligament tearing model.

One hundred eleven axial PWSCC indications had been left in service following 1R10 2-4

Enclosure 2 PG&E Letter DCL-02-098 because they were <40% maximum depth in 1R10. Following 1RI 1 Plus Point inspection and sizing and application of PWSCC ARC requirements, all of the repeat axial PWSCC indications were again determined to be acceptable (OA burst pressure exceeded 6100 psi with no SLB leakage). However, 11 required plugging because of PWSCC ARC exclusion criteria (10 for ID/OD flaw combinations and one for a mixed mode flaw combination). Therefore, 100 of the 111 repeat axial PWSCC indications were returned to service.

In 1 R1 1, 20 new axial PWSCC indications were detected in active tubes. Following Plus Point sizing and application of PWSCC ARC requirements, all were determined to be acceptable (OA burst pressure exceeded 6100 psi with no SLB leakage). However, 5 required plugging because of PWSCC ARC exclusion criteria (ID/OD flaw combinations).

One hundred fifty tubes were deplugged in SG 1-2 in 1RII and 164 axial PWSCC indications at dented TSPs were detected in these tubes. Table 5 lists 100 axial PWSCC indications that were returned to service in SG 1-2 following tube deplugging, as the operational assessment (OA) burst pressure exceeded the burst margin requirements. The lowest OA burst pressure returned to service was 4152 psi. Sixty four of the 164 deplugged indications were replugged and are not included in Table 5 because they are not subject to condition monitoring and operational assessment.

In summary, 215 axial PWSCC indications were returned to service in 1R11: one hundred repeat indications, 15 new indications, and 100 deplugged indications.

Condition monitoring and operational assessment for ID/OD flaw combinations in provided in Enclosure 3.

Growth rate distributions for indications used to establish the tube repair limits.

The growth rate distribution used to establish the tube repair limits was based on prior outage growth data. The methodology for establishing the growth rate was established in WCAP-1 5573, Revision 1 as further explained in PG&E letters DCL-02-023 and DCL-02-045.

Because there are less than 200 growth rate data points over the last two Unit 1 cycles (there are 124 data points over Unit 1 Cycles 9 and 10), the methodology used to establish the growth rate distribution is described below. The number of cycles needed to total 200 growth points is determined. In this case, 6 cycles of data (i.e. Unit 1 Cycle 8, Unit 1 Cycle 9, Unit 1 Cycle 10, Unit 2 Cycle 8, Unit 2 Cycle 9, and Unit 2 Cycle 10) are evaluated because 6 cycles are needed to exceed 200 points. The data from each of these cycles was compared for consistency in growth magnitude. If a given cycle has lower growth rates than other cycles, it is not included in the growth distribution. For average depth and maximum depth, Unit 1 Cycle 8 and Unit 1 Cycle 10 data were excluded. For length, Unit 1 Cycle 8, Unit 2 Cycle 8, and Unit 2 2-5

Enclosure 2 PG&E Letter DCL-02-098 Cycle 9 data were excluded. These evaluations for excluding data were documented in DCL-02-023 and DCL-02-045. In addition, if any deleted data points are greater than the 95 percent values in the resulting distribution, they are added back into the distribution (5 data points were added back in this manner).

Table 2 provides the growth rate data at 603 degrees F over the 6 cycles, and indicates if the data was used in the growth distribution for 1 R11 repair decisions based on the above methodology.

Based on the Table 2 data that was not excluded, Table 3 provides the growth rate cumulative distribution fraction (CDF) at 604 degrees F that was used in the 1 RI I Monte Carlo operational assessment calculations for determining the need for tube repair. The average Thot in Unit 1 Cycle 11 was 604 degrees F, and 604 degrees F Thot is also expected for Unit 1 Cycle 12. Unit 1 growth rates were adjusted using the Arrhenius equation to account for differences in Thot between Unit 1 and Unit 2. The 90 percentile growth values per EFPY at 604 degrees F were 0.069 inch length, 12.07 percent maximum depth, and 9.23 percent average depth.

Growth rate distributions for indications found in the inspection, and growth rate distributions to be used in next operational assessment.

In accordance with WCAP-1 5573, Revision 1, growth rates that could impact the upper tail of the growth distribution were evaluated during 1R1I. The methodology requires that if new growth data cause the growth distribution above 90 percent probability to be more conservative, the new data is added to the growth distribution for the operational assessment.

Figures 1, 2, and 3 compare cumulative probability distribution (CPD) growth rate distributions for the operational assessment (pre-1 R11 data), 1R1 I data, and combined pre-1 RI 1 plus 1RI I data. There were 119 growth rate data points from Unit 1 Cycle 11 based on 1 R11 inspections. The 90 percent growth values per EFPY at 604 degrees F of this data set were 0.037 inch length, 7.8 percent maximum depth, and 6.29 percent average depth, which are smaller than the 90 percent values for the pre-I RI 1 data set (0.069 inch length, 12.07 percent maximum depth, and 9.23 percent average depth).

When the pre-1 R11 and the I R11 data sets are combined, the resulting 90 percent values are 0.055 inch length, 9.36 percent maximum depth, and 8.32 percent average depth. Because the pre-I R11 growth rate is more conservative than the combined growth rate, no growth data from 1RI I was added to the growth rate distributions for the Monte Carlo operational assessment.

The number of growth rate data points in 1R10 and 1R1I are 83 and 119, respectively, such that there are 202 points over the last two cycles. Because there are a total of at least 200 points over the last two cycles on Unit 1, the growth distribution used for the next operational assessment in 1 R12 should be the more conservative of 1R10 data, 1R11 data, or 1R10 plus 1R11 combined data.

2-6

Enclosure 2 PG&E Letter DCL-02-098 Figures 1 through 3 compare the 1R10 data, 1R1I data, and the combined 1R10 plus 1 RI I data. For maximum depth and average depth, the growth rate distributions are essentially the same for the 1 R10 data, the 1 R11 data, and the combined 1 R10 plus 1R11 data (the 1 R11 data is slightly more conservative than the other two data sets).

However, for length, the 1R10 data is more conservative than the combined 1R10 plus 1R1I data and the 1R1I data. The IR10 data has the most conservative length growth but the least conservative average depth growth. Average depth and length are linked, such that for the same profile, longer lengths equate to smaller average depths, thereby explaining the 1R10 growth trend. For the next operational assessment in 1R12, the following growth data will be used in accordance with the above criteria: 1R10 length data, 1R1 1 average depth data, and 1RI 1 maximum depth data.

Figures 1 through 3 also compare the pre-I R11 data with the above data. For maximum depth and average depth, the pre-1 RI 1 data set is more conservative than all other data sets. Likewise, for length, the pre-I R11 data set is more conservative than all other data sets, with the exception of the 1R10 data set. As discussed above, the 1R10 data has the most conservative length growth but the least conservative average depth growth. Therefore, it is concluded that the 1 R11 OA predictions using the pre-1 R11 growth rate distribution provides the most conservative assessment for structural and leakage integrity.

Plus Point confirmation rates for bobbin detected indications when bobbin is relied upon for detection of axial PWSCC in less than or equal to 2 volt dents.

In 1RI I, the bobbin coil was relied upon for detection of axial PWSCC in less than or equal to 2 volt dents. As identified in Table 4, there were 537 DIS indications detected by bobbin in non-repeat PWSCC indications. Tracking of Plus Point confirmation rates in repeat PWSCC indications for active and deplugged tubes is not required because these known flaws are inspected by Plus Point regardless of the bobbin call.

All DIS indications were inspected by Plus Point. Only 9 of the 537 DIS indications were confirmed as PWSCC by Plus Point, for a Plus Point confirmation rate of 1.7 percent, or a 98.3 percent bobbin overcall rate. The high bobbin overcall rate is greater than the overcall rate generated during the bobbin coil performance test documented in WCAP-15573, Revision 1. The high bobbin overcall rate ensures that the bobbin coil results are very conservative, and results in a high probability of detecting significant axial PWSCC indications in less than or equal to 2 volt dents.

For condition monitorinq, an evaluation of any indications that satisfy burst margin requirements based on the Westinghouse burst pressure model, but do not satisfy burst mar-gin requirements based on the combined ANL ligament tearing and throughwall burst pressure model.

This item is not applicable, because all indications satisfied condition monitoring burst 2-7

Enclosure 2 PG&E Letter DCL-02-098 margin requirements based on the combined ANL ligament tearing and EPRI throughwall burst pressure model. The total length condition monitoring burst requirement for EOC 11 was 3367 psi, based on 1.4 times the SLB differential pressure of 2405 psi (pressurizer PORV setpoint plus uncertainty). The free span length condition monitoring burst requirement for EOC 11 was 4419 psi, based on 3 times the normal operating pressure differential.

Performance evaluation of the operational assessment methodology for prediction of flaw distributions as a function of flaw size.

Even though the ARC was not in effect in Unit I Cycle 11, benchmarking was performed of the 111 repeat indications that had been left in service in Unit 1 Cycle 11 because (they were less than 40 percent maximum depth in 1 R10). All projected EOC 11 burst pressures for these indications exceeded the default free span and total length burst pressure of 6100 psi, using the ANLIEPRI model. No SLB leakage was projected at EOC 11 for any of these indications, using the ANL ligament tearing leakage model. The EOC 11 projections used a very conservative industry growth rate distribution. The actual EOC 11 condition monitoring burst pressure of these 111 indications also exceeded the default free span and total length burst pressure of 6100 psi using the ANLJEPRI model, and had no SLB leakage using the ANL ligament tearing leakage model. Based on this performance evaluation via benchmarking, the operational assessment methodology is adequately conservative.

Evaluation results of number and size of previously reported versus new PWSCC indications found in the inspection, and the potential need to account for new indications in the operational assessment burst evaluation.

As discussed above, there were 131 axial PWSCC indications detected in 1R1 1: one hundred eleven repeat indications and 20 new indications. Twelve of the new indications had prior Plus Point inspections in 1R10, and 10 were detectable based on a relook of the 1R10 data. Eight of the new indications had no prior Plus Point inspection, and were detected by bobbin in 1R1 1 in less than 2 volt dents. Because the number of new flaws is relatively small (only 15 percent of the 138 indications were new) and all new indications have OA burst pressures well in excess of burst margin requirements, there is no need to account for new indications in the OA burst evaluation.

Identification of mixed mode (axial PWSCC and circumferential) indications found in the inspection and an evaluation of the mixed mode indications for potential impact on the axial indication burst pressures or leakage. In addition, performance of a trending analysis to assess the potential for increasing mixed mode affects (e.g., circumferential crack depths, burst pressure reductions, increased leakage rates) over time.

A mixed mode indication is defined as an axial PWSCC indication and a circumferential indication (either PWSCC or ODSCC) occurring at the same dented TSP intersection.

2-8

Enclosure 2 PG&E Letter DCL-02-098 One mixed mode indication (axial PWSCC and circumferential PWSCC) in an active tube was detected during 1 RI and was plugged. The location was SG 1-2 RI C81 2H. The tube had been unplugged in 1 R10, and 1R10 Plus Point inspection detected an axial PWSCC indication that was subsequently left in service in Cycle 11 because the maximum depth was less than 40 percent. The circumferential PWSCC indication was not detected in 1 R10, but was detectable based on a lookup of 1R10 data. The dent was measured as 3.1 volts.

In 1 RI I, a null distance of 86 degrees (0.58 inch) was measured between the axial and circumferential indications using the 0.080 pancake coil technique at 600 Khz. The 0.58 inch null distance exceeds the 0.25 inch separation distance requirement, and therefore the flaw is not interacting. Even if the flaw was interacting, the NDE average depth of the circumferential flaw is 49 percent, including 95 percent uncertainty, which is less than the 75 percent average depth threshold value for mixed mode affects. In addition, neither the axial or circumferential indication are 100 percent throughwall at any point. The circumferential indication is 69 percent maximum depth, including 95 percent NDE uncertainty. The measured maximum depth of the axial indication is 27 percent, and has no predicted SLB leakage at 95/50 confidence for condition monitoring (CM). The CM burst pressure of the axial indication is in excess of 6100 psi.

Based on this mixed mode assessment, there is no potential impact on the axial PWSCC indication burst pressure or leakage.

There are several conditions that require evaluation to determine the need for corrective actions. These are discussed below.

" If an interacting mixed mode indication is found to have led to a reduction in the axial indication burst pressure by more than 10 percent and to less than 4000 psi, or to have caused an indication to not satisfy burst margin requirements, the burst margin requirements for implementation in the OA at the next and subsequent outages must be increased by the percentage reduction in the burst pressure found for the mixed mode indication. As discussed above, because this condition did not occur, there are no corrective actions needed to adjust burst margin requirements for future operational assessments.

" If an interacting mixed mode indication is found, and the axial indication condition monitoring predicts SLB leakage at 95/50, and the circumferential indication has

> 50 percent average depth including NDE uncertainty, then the CM leak rate for the axial indication must be increased by a leakage factor. In addition, the OA SLB leak rate for each SG must be increased by a leakage factor. As discussed above, because this condition did not occur, there are no corrective actions needed to adjust SLB leak rates for CM or OA.

" If a previously Plus Point inspected TSP intersection is found to have a circumferential indication with average depth > 80 percent after accounting for NDE uncertainty, then the OA SLB leak rate for each SG must be increased by a leakage 2-9

Enclosure 2 PG&E Letter DCL-02-098 factor. All 1RI I circumferential indications were previously Plus Point inspected in 1R10. The deepest 1R11 circumferential indication was 56 percent average depth, including NDE uncertainty, less than the 80 percent average depth threshold.

Therefore, no corrective actions are needed to adjust the OA SLB leak rates.

In response to NRC request for additional information, PG&E letter DCL-02-045 dated April 18, 2002, committed to perform a trending analysis in the 120 day report to assess the potential for increasing mixed mode affects (e.g., circumferential crack depths, burst pressure reductions, increased leakage rates) over time. Since no burst pressure reductions or leakage rate multipliers have been required, there is no data to trend for these parameters. Trending of circumferential depths and number of circumferential indications is provided in Figures 4, 5, and 6. Figure 4 provides all DCPP Units 1 and 2 TSP PWSCC and ODSCC circumferential indication measured average depths versus year detected. The average depths show a fairly flat trend line. Figure 5 data is a subset of Figure 4, showing the mixed mode circumferential indication average depths versus year detected. Only one mixed mode circumferential indication was detected in an axial PWSCC indication that was returned to service (1 R11 R1 I C81, discussed above). The Figure 5 average depths show a decreasing trend line. Figure 6 provides the cumulative distribution of the number of DCPP Units 1 and 2 TSP PWSCC and ODSCC circumferential indications detected over time. The trend does not indicate a large increase in the numbers of circumferential indications in recent inspections.

This trending assessment does not indicate a need to modify the criteria that cause an increase in the burst margin requirements.

Any corrective actions found necessary in the event that condition monitoring requirements are not met.

This item is not applicable because condition monitoring requirements were satisfied.

Condition monitoring requirements for active tubes are satisfied for burst and leakage; therefore no corrective actions are required. All CM burst pressures for active tubes exceeded 6100 psi using the ANL/EPRI throughwall model, at 95 percent probability and 50 percent confidence (95/50). There was no CM SLB free span or total length leakage at 95/50 for active tubes.

Condition monitoring requirements for mixed mode (axial PWSCC and circumferential) indications and circumferential indications were satisfied, and no corrective actions are needed to adjust burst margin requirements or SLB leak rates.

2-10

Enclosure 2 PG&E Letter DCL-02-098 Table I Number of > 2 Volt Dents Inspected in 1RlI TSP SG 1-1 SG 1-2 SG 1-3 SG 1-4 TOTAL 1H 14 254 70 717 1055 2H 75 197 4 206 482 3H 21 160 9 285 475 4H 10 190 7 226 433 5H 11 85 41 121 258 6H 1 26 17 466 510 7H 50 87 50 121 308 TOTAL 182 952 195 2142 3471 2-11

Enclosure 2 PG&E Letter DCL-02-098 Table 2 Axial PWSCC GrowthlEFPY Data Set at 603 Degrees F for I RI I Tube Repair OA Outage SG Row Col Outage~

TSP Crack NoRwCl (in.)

TP~Cac IData?

Length Includet Max

[Depth (%)

Include Data?

Avg. Depth

(%) [Data?

Include Max. Volts V~s 1R8 1 17 39 01H 1 -009 -2558 -1837 0.37 1R8 1 21 42 01H 1 0.02 -1589 -9.82 0.20 1R8 1 21 44 01H 1 -0.02 4.65 339 0.28 1R8 1 18 64 01H 1 005 078 2.08 0.54 1R8 1 18 64 03H 1 001 1.55 1.25 0.29 1R8 2 26 43 02H 1 -0.06 -9.30 0.10 0.17 1R8 2 43 49 03H 1 -0.01 -2.58 -1.05 0.26 1R8 2 35 56 02H 1 -0.07 0.00 -0.77 0.34 1R8 2 5 66 02H 1 0.02 -14.73 -4.98 0.36 1R8 2 35 67 03H 1 0.02 -19.38 -7.27 0.39 1R8 2 7 68 03H 1 -0.02 8 53 8.17 0.19 1R8 2 14 72 02H 1 0.04 -10.85 -8.15 0.23 1R8 2 16 73 01H 1 0.00 -3.10 -1.07 028 1R8 2 14 74 01H 1 -004 -853 -7.05 040 1R8 2 35 77 01H 1 -002 2326 Yes 1285 Yes 030 1R8 2 35 77 01H 2 -0.01 -2558 -1636 0.55 1R8 2 13 81 01H 1 0.00 -2364 -20.30 032 1R8 2 16 82 01H 1 -005 504 7.09 006 1R8 3 32 47 03H 1 004 -7.75 -4.08 065 1R8 4 38 27 01H 1 000 -9.30 -4.36 055 1R8 4 39 58 01H 1 0.00 -18.99 -11.33 032 2R8 2 2 2 01H 1 -0.02 13.58 Yes 1001 Yes -0.01 2R8 2 14 15 01H 1 0.06 1.85 Yes 289 Yes 0.19 2R8 2 19 15 01H 1 0.02 3.09 Yes 4.20 Yes 0.01 2R8 2 18 16 01H 1 0.04 0.93 Yes 3.93 Yes 0.18 2R8 2 6 24 01H 1 0.02 1.85 Yes 015 Yes 0.09 2R8 2 4 28 01H 1 0.05 1.85 Yes 211 Yes 018 2R8 2 12 28 01H 1 0.02 11.73 Yes 12.50 Yes 025 2R8 2 14 29 01H 1 0.01 0.00 Yes -2.64 Yes 0.06 2R8 2 17 36 01H 1 0.02 -19.75 Yes -1348 Yes 0.14 2R8 2 15 42 01H 1 0.00 0.00 Yes 1.98 Yes 0.04 2R8 2 18 44 01H 1 0.02 8.64 Yes 540 Yes 0.11 2R8 2 22 45 01H 1 0.02 0.00 Yes 081 Yes 0.15 2R8 4 34 34 01H 1 0.02 7.41 Yes 4.88 Yes 0.07 2R8 4 4 37 01H 1 -0.01 Yes 926 Yes 4.01 Yes 019 1R9 1 9 6 01H 1 001 Yes 6.17 Yes 3.93 Yes -008 1 R9 1 22 7 03H 1 0.01 Yes 6 79 Yes 6.78 Yes 0.31 1R9 1 23 14 03H 1 0.02 Yes 864 Yes 6.98 Yes 011 1R9 1 19 15 03H 1 003 Yes 3.70 Yes 0.87 Yes 007 2-12

Enclosure 2 PG&E Letter DCL-02-098 Outage SG Row Col TSP Crack Length Include Max. Include Avg Depth Include Max. Volts No. (in.) Data? Depth (%) Data? (%) Data?

I R9 1 24 20 02H 1 -0 01 Yes 4.94 Yes 5.56 Yes 0.07 1R9 1 30 21 02H 1 005 Yes -2.47 Yes -3.28 Yes 0.01 I R9 1 34 24 03H 1 0.07 Yes 4.94 Yes 1.88 Yes 0.03 1R9 1 20 33 01H 1 0.01 Yes 309 Yes 0.11 Yes 001 1R9 1 38 42 03H 1 -0.01 Yes 2.47 Yes 2.78 Yes 004 1R9 1 22 71 02H 1 -0.01 Yes 5 56 Yes 8.52 Yes 0.06 1R9 2 17 9 06H 1 -002 Yes 14.20 Yes 9.61 Yes -001 1R9 2 15 10 01H 1 0.02 Yes -1543 Yes -396 Yes 006 1R9 2 11 27 01H 1 001 Yes 14.20 Yes 14.03 Yes 0.10 1R9 2 26 39 02H 1 0.00 Yes 4.94 Yes 6.64 Yes 0.08 1R9 2 11 45 01H 1 001 Yes 1.23 Yes -0.11 Yes 0.01 1R9 2 6 47 01H 1 002 Yes 3.70 Yes 208 Yes 0.05 1R9 2 11 47 02H 1 -001 Yes 000 Yes -2.58 Yes 0.04 1R9 2 20 48 03H 1 -0.09 Yes -7.41 Yes -203 Yes 0.07 1R9 2 27 50 01H 1 000 Yes 4.32 Yes 1.98 Yes 0.17 1R9 2 35 52 03H 1 011 Yes 4.94 Yes 281 Yes 0.17 1R9 2 7 53 03H 1 -0.07 Yes 12.35 Yes 8.68 Yes 0.03 I R9 2 25 55 02H 1 -0.02 Yes -1.54 Yes -3.29 Yes 0.09 1R9 2 16 57 01H 1 -0.01 Yes 494 Yes 1.20 Yes 020 1R9 2 38 66 01H 1 0.02 Yes 1.23 Yes 4.20 Yes 009 1R9 2 33 68 02H 1 -0.14 Yes 8.64 Yes 5.31 Yes 002 1R9 2 4 69 01H 1 0.01 Yes 000 Yes 4.69 Yes 005 1R9 2 19 74 02H 1 001 Yes 679 Yes 1.58 Yes 0.06 1R9 2 13 75 02H 1 0.01 Yes 000 Yes -1.06 Yes -002 1R9 2 5 77 05H 1 0.01 Yes 802 Yes 594 Yes 007 1R9 2 26 79 01H 1 0.04 Yes 8.02 Yes 6.86 Yes 0.12 1R9 2 8 80 02H 1 004 Yes 0.00 Yes 1.08 Yes 004 1R9 2 23 82 01H 1 000 Yes 3.09 Yes 2.30 Yes 000 1R9 2 5 84 01H 1 -001 Yes 5.56 Yes 4.79 Yes 0.19 1R9 2 9 87 4H 1 -009 Yes -8.02 Yes -9.59 Yes -001 1R9 2 8 90 03H 1 001 Yes 8.64 Yes 8.61 Yes 0.15 I R9 2 2 92 05H 1 0.02 Yes 0.00 Yes -0.34 Yes -0.06 1R9 4 17 24 01H 1 0.03 Yes 0.00 Yes 006 Yes -0.02 1R9 4 20 25 01H 1 -0.02 Yes 000 Yes 1.84 Yes -0.02 1R9 4 46 42 01H 1 0.01 Yes 3.70 Yes 3.93 Yes -0.05 1R9 4 35 68 03H 1 -0.01 Yes 0.62 Yes -020 Yes 0.12 1R9 4 21 76 01H 1 004 Yes 5.56 Yes 460 Yes -0.05 2R9 2 6 3 01H 1 0.02 7.53 Yes 349 Yes 005 2R9 2 18 7 01H 1 0.08 Yes 10.96 Yes 8.09 Yes 023 2R9 2 5 21 01H 1 002 17.81 Yes 14.56 Yes 008 2R9 2 21 23 02H 1 -0 01 7.53 Yes 8.46 Yes -0 04 2R9 2 8 26 01H 1 0.01 -1062 Yes -1069 Yes 0.15 2R9 2 5 33 01H 1 0.00 1 0.00 Yes 045 Yes 0.12 2R9 2 28 38 01H 1 001 6.16 Yes 3.83 Yes 0.01 2-13

Enclosure 2 PG&E Letter DCL-02-098 Outage SG Row Col TSP Crack Length Include Max. Include Avg. Depth Include Max. Volts No. (in.) Data? Depth (%) Data? (%) Data?

2R9 2 16 39 04H 1 -004 4.11 Yes 4.36 Yes 0.09 2R9 2 16 39 04H 2 -002 0.68 Yes 1.75 Yes 0.05 2R9 2 14 40 01H 1 002 -4.79 Yes -0.16 Yes 0.36 2R9 2 21 40 01H 1 -004 2.74 Yes 564 Yes 0.07 2R9 2 22 46 01H 1 -0.01 -068 Yes -0.13 Yes 0.08 2R9 3 21 78 03H 1 0.09 Yes 8.90 Yes 10.81 Yes 0.08 2R9 4 17 31 03H 1 -0.02 411 Yes 068 Yes 0.13 2R9 4 14 53 03H 1 -001 000 Yes 0.33 Yes 0.06 1R10 1 22 7 03H 1 007 Yes 6.71 3.04 0.25 1R10 1 23 14 03H 1 0.01 Yes -4.70 -369 0.09 1R10 1 19 15 03H 1 0.03 Yes 0.67 0.43 0.09 IR10 1 15 16 02H 1 -0.03 Yes 067 1.94 0.09 IR10 1 24 20 02H 1 0.02 Yes 1.34 -5.35 0.00 IR10 1 30 21 02H 1 -0.05 Yes 000 -0.05 -0.04 1R10 1 22 23 02H 1 -0.01 Yes 2.68 3.86 -001 IR10 1 22 23 02H 2 0.00 Yes 000 463 005 IR10 1 34 24 03H 1 008 Yes -4.70 0.75 005 1R10 1 3 28 02H 1 001 Yes 067 4.38 0.21 iR10 1 14 28 02H 1 000 Yes -6.71 -5.61 011 IR10 1 36 30 02H 1 002 Yes -0.67 1.41 0.34 IR10 1 20 33 01H 1 -0.01 Yes -3.36 -0.06 -0.02 IR10 1 4 41 01H 1 0.08 Yes 10.07 10.05 008 IR10 1 24 67 02H 1 004 Yes 000 050 0.10 IR10 1 22 71 02H 1 007 Yes 1.34 -3.73 011 iR10 2 13 10 01H 1 0.01 Yes 2.68 1.71 0.17 1RlO 2 15 10 01H 1 003 Yes -6.71 -6.12 005 1RlO 2 16 12 05H 1 001 Yes 0.67 389 -005 IR10 2 8 15 02H 1 0.01 Yes 4.03 1.66 0.14 IR10 2 14 16 04H 1 0.00 Yes -336 -1.24 0.15 1R10 2 30 16 01H 1 -007 Yes -872 -3.69 023 IR10 2 25 17 02H 1 0.08 Yes -2.01 -2.72 0.14 IR10 2 23 25 03H 1 0.03 Yes 2.68 4.54 0.31 IR10 2 42 28 02H 1 -0.01 Yes 604 6.25 0.17 IR10 2 7 31 01H 1 0.05 Yes -4.70 -5.33 0.13 1R10 2 19 31 04H 1 -0.05 Yes 067 -0.53 0.09 IR10 2 9 34 02H 1 -0.03 Yes 0.67 -1.22 0.11 1R10 2 33 37 01H 1 0.01 Yes 000 -058 0.08 1R10 2 26 39 02H 1 0.03 Yes -0.67 -1.91 0.30 1R10 2 11 45 01H 1 004 Yes 8.72 3.57 026 IR10 2 14 45 01H 1 0.00 Yes 0.00 -0.11 0.02 IR10 2 20 48 03H 1 007 Yes 336 -0.99 0.15 Rl10 2 27 50 01H 1 0.01 Yes 268 1 0.40 024 2-14

Enclosure 2 PG&E Letter DCL-02-098 Outage SG Row Col TSP Crack I Length Include Max. Include Avg. Depth Include Max. Volts No. (in) Data? Depth (%) Data? (%) Data M V IR10 2 29 51 02H 1 0.07 Yes -067 -3.39 020 1R10 2 34 51 06H 1 0.06 Yes -067 0.03 0.15 IR10 2 35 52 03H 1 -001 Yes -2.68 -0.83 0.13 IR10 2 23 54 01H 1 0.04 Yes 000 -006 0.05 1R10 2 25 55 02H 1 -001 Yes -2.01 0.33 -0.08 IR10 2 9 56 01H 1 000 Yes 1.34 1.81 0.17 IR10 2 27 56 01H 1 0.02 Yes 000 1.34 0.15 IRIO 2 4 57 01H 1 -002 Yes 0.00 -038 -001 IR10 2 36 60 04H 1 003 Yes -2.68 -6.09 009 IR10 2 8 61 02H 1 0.05 Yes -5.37 -2.02 021 IR10 2 8 61 02H 2 0.08 Yes 336 0.32 0.10 IR10 2 32 62 01H 1 006 Yes 6.71 7.11 0.01 IR10 2 41 62 01H 1 -005 Yes 4.70 4.21 009 IR10 2 38 63 01H 1 0.06 Yes 1.34 2.63 0.32 IR10 2 39 64 03H 1 000 Yes 5.37 5.97 011 iR10 2 28 66 02H 1 -001 Yes -11.41 -7.59 0.09 1R1O 2 38 66 01H 1 005 Yes 7.38 1.55 0.10 1R10 2 33 68 02H 1 003 Yes -403 -431 0.05 1R10 2 4 69 01H 1 0.01 Yes 0.00 -1.23 008 1R10 2 27 71 01H 1 0.05 Yes 0.67 -1.67 0.12 IR10 2 6 74 03H 1 003 Yes 000 -1.22 006 IR10 2 19 74 02H 1 001 Yes -403 303 0.05 IR10 2 25 74 01H 1 001 Yes 671 5.89 0.13 1R10 2 2 76 02H 1 004 Yes 000 -3.46 0.07 1RIO 2 5 77 05H 1 0.04 Yes 2.01 1.13 0.12 1R10 2 24 77 01H 1 0.05 Yes 336 4.11 0.11 IR10 2 2 78 01H 1 -0.01 Yes -2.01 0.66 0.27 1R10 2 31 78 05H 1 0.07 Yes 4.70 -1.40 0.11 IR10 2 26 79 01H 1 0.01 Yes 000 1.52 0.21 IR10 2 23 82 01H 1 0.03 Yes 336 252 0.03 IR10 2 13 84 01H 1 0.00 Yes -8.05 -7.42 -0 11 iR10 2 13 84 01H 2 0.03 Yes -2.01 -5.69 -023 1R10 2 2 92 05H 1 0.02 Yes 000 0.29 003 IR10 2 2 92 05H 2 0.01 Yes 0.00 -0.37 005 1R10 2 2 92 05H 3 005 Yes 000 -4.53 006 1R10 2 2 93 04H 1 0.02 Yes -1409 -1369 0.00 IR10 2 8 93 01H 1 -0.03 Yes -6.71 -450 0.10 IRIO 4 17 24 01H 1 -003 Yes 0.00 0.95 001 1R10 4 20 25 01H 1 0.02 Yes 0.00 0.43 001 1R10 4 35 36 02H 1 0.01 Yes 0.00 1.09 -003 iR10 4 46 42 01H 1 0.13 Yes 0.67 -3.12 0.01 IR10 4 39 48 03H 1 001 Yes 0.00 042 -003 2-15

Enclosure 2 PG&E Letter DCL-02-098 pCo OSG Row TSP Crack Length Include Max. Include Avg.Depth Include Max. Vo-s

[

O No. (in) Data? Depth (%) Data? (%) Data?

1R10 4 39 58 01H 1 0.11 Yes 000 -0.77 0.16 1R10 4 35 61 02H 1 0.01 Yes 1.34 5.16 0.07 1R10 4 35 68 03H 1 0.03 Yes -2.01 0.27 -009 1R10 4 38 69 02H 1 0.02 Yes 537 842 0.05 IRlO 4 21 70 03H 1 002 Yes 14.09 Yes 883 0.09 1R10 4 21 76 01H 1 -0.01 Yes 336 1.98 -003 1R10 4 21 84 01H 1 0.07 Yes 1.34 378 001 2R10 2 5 3 01H 1 012 Yes 8.33 Yes 4.41 Yes -005 2R10 2 17 12 01H 1 002 Yes 6.94 Yes 485 Yes 0.33 2R10 2 14 15 02H 1 001 Yes 6.25 Yes 8.11 Yes 006 2R10 2 19 15 01H 1 002 Yes 0.00 Yes 045 Yes 002 2R10 2 11 19 01H 1 0.03 Yes 1042 Yes 4.69 Yes 0.13 2R10 2 15 22 01H 1 003 Yes 7.64 Yes 3.79 Yes 0.14 2R10 2 2 23 01H 1 000 Yes 4.86 Yes 4.74 Yes 0.00 2R10 2 21 23 02H 1 0.03 Yes 8 33 Yes 7.22 Yes 0.06 2R10 2 27 23 01H 1 0.00 Yes 14.58 Yes 11.87 Yes -0.03 2R10 2 6 24 01H 1 0.04 Yes -347 Yes -2.79 Yes -0.04 2R10 2 13 25 03H 1 0.01 Yes 4.17 Yes 6.57 Yes 0.08 2R10 2 2 26 01H 1 001 Yes 13.19 Yes 11.62 Yes 0.03 2R10 2 5 26 01H 1 0.02 Yes 625 Yes 4.52 Yes 0.10 2R10 2 8 26 01H 1 001 Yes 18.75 Yes 15.74 Yes -012 2R10 2 7 27 01H 1 0.05 Yes -1.39 Yes -2.13 Yes 0.03 2R10 2 4 28 01H 1 002 Yes 4.86 Yes 384 Yes -010 2R10 2 6 31 01H 1 003 Yes 0.00 Yes 2.70 Yes 0.04 2R10 2 7 32 01H 1 001 Yes 625 Yes 305 Yes 009 2R10 2 9 32 01H 1 -002 Yes 0.69 Yes 087 Yes -0.01 2R10 2 5 33 01H 1 005 Yes 11.81 Yes 828 Yes -002 2R10 2 3 34 01H 1 -001 Yes 6.94 Yes 4 90 Yes 0.10 2R10 2 4 34 04H 1 001 Yes 0.00 Yes -0.87 Yes 0.04 2R10 2 6 36 01H 1 0.03 Yes 7.64 Yes 636 Yes -0.16 2R10 2 28 38 01H 1 0.01 Yes 000 Yes -4.91 Yes -0.01 2R10 2 12 39 01H 1 0.01 Yes 625 Yes 2.71 Yes -0.17 2R10 2 16 39 04H 1 0.03 Yes 7.64 Yes 6.43 Yes 0.05 2R10 2 16 39 04H 2 0.01 Yes 11.11 Yes 6.88 Yes 0.03 2R10 2 21 40 01H 1 0.00 Yes 1.39 Yes 1.95 Yes -0.01 2R10 2 13 41 01H 1 -0.02 Yes 8.33 Yes 6.55 Yes -0.01 2R10 2 21 41 01H 1 0.03 Yes -3.47 Yes -1.71 Yes 0.01 2R10 2 15 42 01H 1 -002 Yes -4.17 Yes -2.42 Yes -0.03 2R10 2 8 43 04H 1 000 Yes 7.64 Yes 564 Yes 001 2R10 2 22 44 04H 1 0.03 Yes 1007 Yes 2.66 Yes -001 2R10 2 25 44 05H 1 0.08 Yes 0.00 Yes -003 Yes -008 2R10 2 14 45 01H 1 0.03 Yes 0.00 Yes -4.00 Yes -006 2-16

Enclosure 2 PG&E Letter DCL-02-098 Outage SG Row Col TSP Crack Length Include Max. Include Avg Depth Include Max. Volts I No. (in.) Data? Depth (%) Data? (%) Data?

2R10 2 22 45 01H 1 004 Yes 9.72 Yes 9.30 Yes -0.06 2R10 2 16 49 01H 1 0.03 Yes 5.56 Yes -050 Yes -006 2R10 2 15 51 01H 1 001 Yes -1.39 Yes -2.45 Yes -003 2R10 2 27 59 01H 1 006 Yes 16.67 Yes 19.26 Yes 0.17 2R10 3 45 56 01H 1 0.01 Yes -556 Yes -5.39 Yes 006 2R10 3 21 78 03H 1 0 02 Yes -5 56 Yes -3.98 Yes 0.03 2R10 4 16 11 03H 1 006 Yes -694 Yes -7.96 Yes 0.03 2R10 4 11 17 03H 1 004 Yes 2.78 Yes 0.28 Yes -0.13 2R10 4 12 17 03H 1 001 Yes 2.08 Yes 2.00 Yes 0.10 2R10 4 14 53 03H 1 0.03 Yes 1.39 Yes -096 Yes 0.05 Average 0.014 1.39 1.26 0.09 95% 0.075 11.81 9.61 033 Max 0.128 233 19.3 06 2-17

Enclosure 2 PG&E Letter DCL-02-098 Table 3 Axial PWSCC GrowthIEFPY Distributions at 604F for IRII Tube Repair OA Length (inch) CDF Max Depth (%) CDF Avg Depth (%) CDF 0.0000 0.287 0.0000 0.299 0.0000 0.250 0 0101 0.386 0.0239 0.402 0.0198 0 397 0.0201 0.532 0.0477 0.513 0.0395 0.552 0 0302 0.661 0 0716 0.692 0.0593 0.741 0.0403 0.760 0.0955 0.846 0.0791 0.836 0.0503 0.836 0.1194 0.889 0.0988 0.914 0.0604 0.877 0.1432 0.932 0.1186 0.931 0.0705 0.918 0.1671 0.966 0.1384 0.966 0.0805 0.947 0 1910 0.983 0.1581 0.983 0.0906 0.971 0.2149 0.991 0.1779 0.991 0.1007 0.977 02390 1.000 0.1980 1.000 0.1208 0988 0.1310 1.000 Table 4 DIS Confirmation Rates SG 1-1 SG 1-2 SG 1-2 SG 1-3 SG 1-4 Total deplugged Number of bobbin DIS (excludes 75 190 23 48 201 537 repeat PWSCC indications)

Number of new PWSCC indications 2 3 2 0 2 9 confirmed by Plus Point Plus Point confirmation rate 2.7% 1.6% 8 7% 0% 1% 1.7%

Bobbin DIS overcall rate 97.3% 98.4% 91.3% 100% 99% 98.3%

2-18

Enclosure 2 PG&E Letter DCL-02-098 Table 5 I RI I Axial PWSCC Indications at Dented Tube Support Plate Intersections - Adjusted NDE PWSCC ARC Operational Assessment Burst and Leakage Monte Carlo Calculations (ANLIEPRI Burst Model)

FS Total Total FS Burst Ynep SG Row Col. TSP Crack Cal Type Reason for IRlI Length MD AD Max. From To Pressure Leakage Length Length Year No Num Plugging inch (%) (%) Volt psi gpm Press psi Lea 2002 1 3 28 02H 1 00051 repeat 0.10 40.0 28 3 048 -0.19 -009 6100 0000 6100 0000 2002 1 4 41 01H 1 00051 repeat 007 20.0 12.4 0.35 -0.04 003 6100 0000 6100 0000 2002 1 14 28 02H 1 00051 repeat 006 260 18.9 0.41 0.16 022 6100 0000 6100 0000 2002 1 14 87 02H 1 00075 new ID-OD 2H 009 300 208 029 009 0.18 6100 0000 6100 0000 2002 1 15 16 02H 1 00051 repeat 016 220 132 042 -0.15 0 01 6100 0000 6100 0.000 2002 1 15 76 02H 1 00051 repeat 007 29 0 190 033 -014 -007 6100 0000 6100 0.000 2002 1 15 81 02H 1 00075 new ID-OD 2H 019 21.5 124 050 -0 03 016 6100 0000 6100 0000 2002 1 16 45 02H 1 00074 new ID-OD 2H 014 340 22.1 0 84 -010 004 6100 0000 6100 0000 2002 1 19 15 03H 1 00051 repeat 020 460 330 096 -008 012 6100 0000 6100 0000 2002 1 20 28 02H 1 00051 repeat 0.12 260 188 072 -023 -011 6100 0000 6100 0000 2002 1 20 29 02H 1 00051 repeat 0.19 370 246 0 60 004 023 6100 0000 6100 0000 2002 1 20 33 01H 1 00051 repeat 0.07 20.0 9.1 0.21 -0.15 -008 6100 0000 6100 0000 2002 1 22 23 02H 1 00051 repeat 009 32.0 21.7 068 -0.27 -0.18 6100 0000 6100 0000 2002 1 22 23 02H 2 00051 repeat 009 29 0 21 0 063 0.12 0.21 6100 0.000 6100 0000 2002 1 22 71 02H 1 00051 repeat ID-OD 2H 011 400 28 6 067 -001 0 10 6100 0000 6100 0.000 2002 1 23 14 03H 1 00074 repeat 0.10 39 0 288 0 58 -013 -003 6100 0000 6100 0000 2002 1 24 20 02H 1 00051 repeat ID-OD 2H 007 430 22.7 0 71 0 01 008 6100 0000 6100 0000 2002 1 24 67 02H 1 00051 repeat 007 260 15.9 0 53 -011 -004 6100 0000 6100 0000 2002 1 25 57 03H 1 00051 repeat 0.19 37.0 29.4 0.49 -0.06 0.13 6100 0000 6100 0000 2002 1 26 25 01H 1 00051 repeat 0.14 37.0 27.9 1.00 0.13 0.27 6100 0000 6100 0 000 2002 1 27 75 02H 1 00051 repeat 009 30 5 21.0 073 -005 0.04 6100 0.000 6100 0000 2002 1 28 27 01H 1 00051 repeat 029 350 206 080 -032 -003 6100 0000 6100 0.000 2002 1 29 37 02H 1 00051 repeat 016 290 21 8 060 007 023 6100 0000 6100 0000 2002 1 30 21 02H 1 00051 repeat 006 260 157 048 -012 -006 6100 0000 6100 0000 2002 1 30 67 02H 1 00051 repeat 0.29 32.0 21.2 0 91 -0.17 0.12 6100 0000 6100 0000 2002 1 33 40 02H 1 00073 new ID-OD 2H 0.26 45.0 28.7 1.13 -0.23 003 6100 0000 6100 0000 2002 1 34 24 03H 1 00051 repeat 1 _1 032 21 0 8 3 0 38 -0 08 0.24 6100 0.000 6100 0000 2-19

Enclosure 2 PG&E Letter DCL-02-098 FS Burst FS Total Total Insp SG Row Col, TSP Crack Calu Type Reason for 1(Rl Length MD AD Max. From To Pressure Leakage Length ea ag Length Year No. Num Plugging inch (%) Volt pBLenth Burt Lenkagt psi gpm Press. psi -- 0 2002 1 35 59 03H 1 00070 new 0.27 28 0 17.1 085 -0 17 0.10 6100 0000 6100 0.000 2002 1 36 30 02H 1 00051 repeat ID-OD 2H 0.17 43,0 305 1.34 -025 -008 6100 0000 6100 0.000 2002 1 38 41 04H 1 00051 repeat 0.10 32.0 22.2 064 -024 -0.14 6100 0000 6100 0000 2002 1 39 57 02H 1 00070 new 0 10 23 0 17.3 0.57 -0.21 -0.11 6100 0000 6100 0000 2002 2 2 10 03H 1 00075 deplug 1R1l 031 450 339 128 -0.16 0.15 6100 0,000 5680 0000 2002 2 2 28 03H 1 00011 deplug IRIl 024 32.0 180 058 -022 002 6100 0.000 6100 0000 2002 2 2 76 02H 1 00006 repeat 013 21 0 97 039 -020 -007 6100 0000 6100 0000 2002 2 2 78 01H 1 00006 repeat 0.11 200 114 045 004 015 6100 0000 6100 0.000 2002 2 2 79 03H 1 00006 repeat 0.41 20.0 11.3 077 -0.19 022 6100 0000 6100 0000 2002 2 2 90 04H 1 00013 deplug IRlI 0.12 41.0 31.7 1.61 -037 -025 6100 0000 6100 0000 2002 2 2 90 04H 2 00013 deplug 1RlI 0 17 56 0 37.4 2.49 -0.13 004 6100 0000 6100 0000 2002 2 2 92 05H 1 00006 repeat 007 200 13.0 0.27 -0.43 -0 36 6100 0000 6100 0000 2002 2 2 92 05H 2 00006 repeat 0.12 200 15.3 0.54 -0.08 004 6100 0000 6100 0000 2002 2 2 92 05H 3 00006 repeat 017 200 136 0 50 007 0.24 6100 0000 6100 0000 2002 2 2 93 04H 1 00006 repeat 013 320 222 051 010 023 6100 0.000 6100 0000 2002 2 4 54 02H 1 00012 deplug 1 _R__1 024 380 25 9 075 -008 0.16 6100 0000 6100 0000 2002 2 4 57 01H 1 00006 repeat 0.12 21.0 135 049 -001 0.11 6100 0000 6100 0000 2002 2 4 58 01H 1 00012 deplug 1Rll 060 660 33.1 1.05 -0.31 029 6100 0000 4976 0000 2002 2 4 58 01H 2 00012 deplug 1Rll 042 500 399 242 -0.10 0.32 6100 0000 4913 0000 2002 2 4 84 01H 1 00006 repeat 017 21 0 11.7 047 -002 0.15 6100 0,000 6100 0000 2002 2 5 39 02H 1 00011 deplug IRll 017 350 187 081 -022 -0.05 6100 0.000 6100 0000 2002 2 5 65 O1H 1 00006 repeat 025 200 11 9 047 -026 -001 6100 0.000 6100 0000 2002 2 5 66 02H 1 00006 repeat 0 10 270 200 072 -011 -001 6100 0.000 6100 0000 2002 2 5 77 05H 1 00006 repeat 018 320 222 078 -030 -012 6100 0000 6100 0.000 2002 2 5 78 01H 1 00013 deplug IRlI 0.25 36.0 252 126 -003 022 6100 0000 6100 0000 2002 2 5 93 OIH 1 00006 repeat 020 21.0 11.8 0.68 -025 -005 6100 0000 6100 0000 2002 2 6 74 03H 1 00006 repeat 019 27.0 142 063 -0.16 003 6100 0000 6100 0000 2002 2 7 31 01H 1 00006 repeat 026 265 137 071 -002 024 6100 0.000 6100 0.000 2002 2 7 53 03H 1 00012 deplug 1R1l 0.18 320 226 070 -005 0 13 6100 0000 6100 0.000 2002 2 7 68 03H 1 00006 repeat 0.12 29.0 16.7 082 010 022 6100 0000 6100 0000 2002 2 8 15 02H 1 00006 repeat 1 037 27.0 13.8 0,96 -0.15 022 6100 0 000 6100 0000 2-20

Enclosure 2 PG&E Letter DCL-02-098 FS Burst F -Total Total Insp. SG Row Col TSP lnsp Cal Crack Type SG owBuLenth Reason for I RI 1 Length MD AD Max. From To Pressure Leakage Length Length Lenkgth Year No Num. Plugging inch (%) (%) Volt pss gpm Burst Leakage I ___ _ _ _ s p Press psi _.22...

2002 2 8 55 01H 1 00012 deplug1Rl1 020 41.0 227 099 -011 009 6100 0000 6100 0000 2002 2 8 57 01H 1 00012 deplugRil _RI1041 560 390 195 -032 009 6100 0000 4972 0000 2002 2 8 61 02H 1 00006 repeat 010 270 167 0 85 -027 -017 6100 0000 6100 0000 2002 2 8 61 02H 2 00006 new 010 380 253 024 -009 0 01 6100 0000 6100 0000 2002 2 8 61 02H 3 00006 repeat 017 380 231 049 003 020 6100 0000 6100 0000 2002 2 8 66 02H 1 00006 repeat 0.10 200 120 048 -034 -024 6100 0000 6100 0000 2002 2 8 67 01H 1 00006 repeat ID-OD 1H 0.20 29.0 169 088 -005 0 15 6100 0000 6100 0000 2002 2 8 93 01H 1 00006 repeat 0 12 27.0 196 0.67 -0.19 -0.07 6100 0000 6100 0000 2002 2 9 27 03H 1 00011 deplug 1Rll 010 200 11 3 028 -0.17 -007 6100 0.000 6100 0000 2002 2 9 30 01H 1 00008 deplug IRll 034 51 0 41 2 211 -0.17 0.17 6100 0000 5071 0.000 2002 2 9 38 02H 1 00008 deplug IRl 039 51 0 384 2 21 -026 013 6100 0000 5069 0000 2002 2 9 45 01H 1 00008 deplug IRl 0.16 450 303 1 27 005 021 6100 0000 6100 0000 2002 2 9 53 01H 1 00012 deplug 1R11 0.29 44.0 286 1.19 -0.15 0.14 6100 0000 6100 0000 2002 2 9 56 01H 1 00006 repeat 0.17 35.0 184 064 -037 -020 6100 0000 6100 0000 2002 2 9 82 03H 1 00013 deplug 1RlI 0.17 42.0 29.7 1.61 0.10 027 6100 0000 6100 0000 2002 2 10 49 03H 1 00008 deplug IRl1 0.09 22.0 15.3 0 69 013 022 6100 0000 6100 0000 2002 2 10 62 01H 1 00072 deplug IR1l 0.29 48.0 35.3 1.08 -010 0.19 6100 0000 5623 0000 2002 2 10 67 01H 1 00006 repeat 017 200 11.0 069 -0.25 -008 6100 0000 6100 0000 2002 2 10 68 01H 1 00013 deplug 1R1l 013 420 325 1.32 -019 -006 6100 0.000 6100 0.000 2002 2 10 69 02H 1 00051 new 006 200 125 047 -022 -016 6100 0000 6100 0.000 2002 2 10 80 01H 1 00052 new 0.13 260 165 037 -030 -017 6100 0000 6100 0000 2002 2 10 85 04H 1 00006 repeat 008 21.0 13.0 0.51 0.18 026 6100 0000 6100 0000 2002 2 11 20 02H 1 00011 deplug IR11 023 470 355 099 -0.10 0.13 6100 0000 5784 0000 2002 2 11 45 01H 1 00006 repeat 046 200 7 8 094 -0.17 0.29 6100 0.000 6100 0000 2002 2 11 66 03H 1 00068 new 021 200 125 090 -021 000 6100 0.000 6100 0.000 2002 2 11 71 01H 1 00013 deplug 1 _R__1 027 390 301 148 -030 -003 6100 0000 6100 0.000 2002 2 11 71 O1H 2 00013 deplug1R11 007 200 116 056 002 009 6100 0000 6100 0.000 2002 2 11 71 01H 3 00013 deplug IRl1 0.10 390 24.1 062 -019 -009 6100 0000 6100 0000 2002 2 11 71 01H 4 00013 deplugIR11 0.12 23.0 12.1 058 005 017 6100 0000 6100 0000 2002 2 11 81 02H 1 00006 repeat Mixed Mode 2H 0.10 27.0 17.8 0.67 0,04 0.14 6100 0000 6100 0000 2002 2 11 84 02H 1 00013 deplug IRlI 0.14 280 208 068 -0.21 -0.07 6100 0000 6100 0000 2-21

Enclosure 2 PG&E Letter DCL-02-098 Insp SG Row Col.

lnsp SG TSP Crack Cal.

Type IReasonfor 11 ength MD AD Max. From To FS FS Burst Bus -S - FS Pressure Leakage Total Legh Length Total ent Length Year No. Num. Plugging inch (%) (%) Volt psi gppm Burstps PrEs Leakage qpm 2002 2 11 84 02H 2 00013 deplug IR1l 0.20 39.0 28.0 1.05 000 020 6100 0000 6100 0000 2002 2 11 87 01H 1 00013 deplug 1Rll 027 53 0 36.7 2.48 -0.19 008 6100 0000 5603 0000 2002 2 12 77 01H 1 00013 deplug 1Rl 033 450 326 1.28 -0.23 0.10 6100 0000 5702 0000 2002 2 13 10 01H 1 00006 repeat 010 320 196 095 -043 -0.33 6100 0.000 6100 0000 2002 2 13 34 01H 1 00008 deplug 1 _R__1 019 45 0 293 1 26 003 022 6100 0.000 6100 0.000 2002 2 13 44 O1H 1 00008 deplugI lR1 1 029 510 424 152 -018 011 6100 0000 5248 0000 2002 2 13 60 02H 1 00012 deplug IR11 0.25 41.0 238 1 48 -018 007 6100 0000 - 6100 0000 2002 2 13 84 01H 1 00006 repeat 007 200 12.8 0.46 -007 000 6100 0000 6100 0000 2002 2 13 84 01H 2 00006 repeat 011 21 0 11 0 0.33 -0.07 0.04 6100 0000 6100 0000 2002 2 14 16 04H 1 00006 repeat 011 290 142 046 -0.07 0.04 6100 0000 6100 0000 2002 2 14 45 01H 1 00006 repeat 010 200 11 6 035 -008 0.02 6100 0000 6100 0000 2002 2 14 68 01H 1 00006 repeat 040 200 123 079 -027 0.13 6100 0.000 6100 0000 2002 2 14 70 01H 1 00006 repeat 007 200 12.1 036 -0.11 -0.04 6100 0.000 6100 0000 2002 2 14 74 01H 1 00013 deplug IR1l 022 230 150 1 29 -026 -0 04 6100 0.000 6100 0.000 2002 2 16 12 05H 1 00064 repeat 006 235 155 060 -009 -003 6100 0000 6100 0.000 2002 2 16 59 02H 1 00012 deplug 1R1l 0.22 53.0 385 184 -008 0 14 6100 0000 5784 0000 2002 2 16 73 01H 1 00006 repeat ID-OD 1H 012 21.0 15.2 064 -0.32 -020 6100 0000 6100 0000 2002 2 16 73 01H 2 00006 repeat ID-OD 1H 015 200 123 0 50 -025 -0.10 6100 0.000 6100 0000 2002 2 16 76 02H 1 00006 repeat ID-OD 2H 0 18 200 9 7 039 -0 13 005 6100 0.000 6100 0.000 2002 2 16 82 O1H 1 00013 deplug1R11 022 200 109 082 -009 013 6100 0000 6100 0.000 2002 2 16 82 04H 1 00013 deplug1R1l 021 340 196 120 -005 0.16 6100 0000 6100 0.000 2002 2 16 85 02H 1 00013 deplug IRIl 009 340 240 083 -024 -015 6100 0000 6100 0000 2002 2 16 85 02H 2 00013 deplugIR1l 0.15 260 158 056 -011 004 6100 0000 6100 0000 2002 2 16 87 02H 1 00013 deplug IRI1 0.21 390 29.3 1 25 032 053 6100 0000 6100 0000 2002 2 16 88 02H 1 00013 deplug 1RIl 0.18 47.0 33.7 1.31 -0.11. 007 6100 0000 6100 0000 2002 2 17 9 06H 1 00011 deplug 1Rl 007 320 160 068 -0.11 -0.04 6100 0000 6100 0000 2002 2 17 54 01H 1 00012 deplug 1Rl 0 31 500 395 0 91 -012 0.19 6100 0.000 5281 0.000 2002 2 17 59 01H 1 00012 deplug 1RIl 024 440 345 1 87 -007 0.17 6100 0000 5863 0000 2002 2 17 66 01H 1 00013 deplug IRIl 0.37 36.0 28.9 268 -023 014 6100 0 000 5809 0000 2002 2 17 67 01H 1 00013 deplug 1RlI 0 15 31.0 22.2 0.97 -0.33 -0.18 6100 0000 6100 0000 2002 2 17 67 01H 2 00013 deplug iRIl 009 200 128 026 -0.32 -0.23 6100 0000 6100 0000 2-22

Enclosure 2 PG&E Letter DCL-02-098 Total Total nsp. SG Row Crack Cal. Ty Reason for 1Rl Length MD AD Max From To FSeBurst FS Length Length Year No. Num. Plugging inch (%) (%) Volt psi gpm e Burst Leakage

- - - - - - - - si pm Press psi: __

2002 2 17 88 02H 1 00013 deplug 1RIl 025 200 106 0.90 -001 0.24 6100 0000 6100 0000 2002 2 18 64 03H 1 00072 deplug 1iRl 0.18 260 167 070 -022 -0.04 6100 0000 6100 0000 2002 2 19 31 04H 1 00006 repeat 0.10 250 152 044 -008 002 6100 0000 6100 0000 2002 2 19 34 02H 1 00008 deplug 1Rll 0.44 51 0 380 260 -020 024 6100 0000 4968 0000 2002 2 19 74 02H '1 00006 repeat 0.13 21 0 11.1 041 -018 -005 6100 0000 6100 0000 2002 2 20 48 03H 1 00006 repeat 0.20 27.0 135 059 -0 19 0 01 6100 0000 6100 0000 2002 2 20 77 01H 1 00013 deplug 1Rll 023 36.0 26.8 1 37 -015 008 6100 0.000 6100 0000 2002 2 21 38 O1H 1 00008 deplug 1Rll 024 450 35.5 1.23 -0.15 009 6100 0000 5921 0000 2002 2 21 57 01H 1 00012 deplug 1Ril 040 560 41 6 2.37 -020 020 6100 0000 4874 0000 2002 2 21 60 02H 1 00006 repeat 024 240 14 8 073 -0.27 -0.03 6100 0000 6100 0.000 2002 2 21 65 02H 1 00013 deplug 1Ril 0.36 560 339 1.34 -0.12 0.24 6100 0000 5432 0000 2002 2 22 42 O1H 1 00008 deplug 1Rll 0.33 450 324 1 81 -007 026 6100 0000 5692 0000 2002 2 22 54 02H 1 00012 deplug IRlI 0.26 53.0 41.4 161 -015 011 6100 0000 5414 0000 2002 2 22 55 03H 1 00068 new 021 40.0 28.5 1 02 -005 0 16 6100 0.000 6100 0000 2002 2 23 25 03H 1 00006 repeat 025 200 12.9 091 -035 -0 10 6100 0.000 6100 0000 2002 2 23 54 01H 1 00006 repeat 011 200 9.8 034 001 012 6100 0.000 6100 0000 2002 2 23 82 01H 1 00006 repeat 0.10 270 17.9 0.48 011 0 21 6100 0000 6100 0000 2002 2 24 77 01H 1 00006 repeat 013 21 0 12.9 0.43 018 0 31 6100 0000 6100 0000 2002 2 25 17 02H 1 00006 repeat 023 290 179 084 -0.36 -0.13 6100 0000 6100 0000 2002 2 25 50 02H 1 00012 deplug IRll 043 530 378 1.76 -0.25 0.18 6100 0000 4953 0.000 2002 2 25 55 02H 1 00006 repeat 0.10 210 134 036 008 0.18 6100 0000 6100 0000 2002 2 25 72 O1H 1 00050 new ID-OD 1H 009 24.0 17.3 048 000 009 6100 0.000 6100 0000 2002 2 25 74 01H 1 00006 repeat 008 350 24.1 067 -035 -027 6100 0000 6100 0000 2002 2 25 85 04H 1 00052 new 020 31 0 25 2 086 -0.17 003 6100 0000 6100 0000 2002 2 25 87 04H 1 00013 deplug 1RIl 020 390 290 136 -0.11 0.09 6100 0000 6100 0.000 2002 2 26 22 04H 1 00011 deplug IRil 027 440 320 168 -009 0.18 6100 0000 6100 0000 2002 2 26 39 02H 1 00006 repeat 0.10 270 17.8 075 -010 000 6100 0000 6100 0000 2002 2 26 73 O1H 1 00013 deplug 1RI1 0.23 42.0 290 1 52 -014 009 6100 0,000 6100 0000 2002 2 26 79 01H 1 00006 repeat 029 32.0 22.5 079 -0 12 0 17 6100 0.000 6100 0000 2002 2 27 50 01H 1 00006 repeat ID-OD1H 01i 27.0 17.4 088 -030 -019 6100 0.000 6100 0000 2002 2 27 55 01H 1 00037 new 007 200 12.5 0.61 0 21 028 6100 0000 6100 0 000 2-23

Enclosure 2 PG&E Letter DCL-02-098 Total Total Insp. SG Row Col TSP Crack Cal T Reason for 1R1l Length MD AD Max FF T Burs Length Length Year No. Num. ype Plugging inch (%) (%) Volt rom T ressure psi eaag gpm Burstpsi Leakage Press. pm 2002 2 27 56 O1H 1 00006 repeat 011 240 16.1 0.72 -0.22 -0.11 6100 0.000 6100 0000 2002 2 27 63 02H 1 00012 deplug 1Rll 048 380 25 1 098 -025 0.23 6100 0.000 5822 0000 2002 2 27 63 02H 2 00012 deplug IRlI 015 380 295 0 81 -019 -004 6100 0.000 6100 0,000 2002 2 27 64 03H 1 00006 repeat 0.12 200 102 042 -0.13 -001 6100 0000 6100 0.000 2002 2 27 65 02H 1 00013 deplug 1Rl 024 360 276 060 -009 015 6100 0000 6100 0000 2002 2 27 67 OIH 1 00013 deplug 1R11 0.29 50.0 358 1 54 -031 -002 6100 0000 5535 0000 2002 2 27 67 04H 1 00068 deplug 1R1l 018 230 13.9 0.47 -0.23 -005 6100 0000 6100 0000 2002 2 27 69 01H 1 00013 deplug IRll 0 18 280 14.7 0.79 -0.02 0.16 6100 0000 6100 0000 2002 2 27 69 01H 2 00013 deplug 1R1l 035 530 420 243 -025 0.10 6100 0.000 4981 0000 2002 2 28 47 03H 1 00008 deplug 1Rl1 024 300 21 7 078 -001 023 6100 0.000 6100 0000 2002 2 28 66 02H 1 00006 repeat 0 08 27.0 13 0 0 31 -0 02 0 06 6100 0 000 6100 0.000 2002 2 29 24 03H 1 00011 deplug 1Rll 028 35 0 25 9 0 98 006 034 6100 0000 6100 0.000 2002 2 29 51 02H 1 00006 repeat 0.10 270 188 049 -011 -001 6100 0000 6100 0000 2002 2 29 66 01H 1 00013 deplug1RI1 0.15 650 397 126 -005 010 6100 0000 6100 0000 2002 2 30 16 01H 1 00006 repeat ID-OD 1H 0.15 41.0 28 0 070 -008 007 6100 0000 6100 0000 2002 2 30 56 O1H 1 00012 deplug 1RlI 0.50 56.0 42.7 269 -040 010 6100 0000 4553 0000 2002 2 30 62 O1H 1 00006 repeat 008 20.0 11.2 0.47 -0.15 -007 6100 0000 6100 0000 2002 2 30 62 01H 2 00006 new 008 200 104 0 28 002 0.10 6100 0.000 6100 0000 2002 2 30 67 02H 1 00013 deplug IRIl 019 620 464 1 62 -033 -014 6100 0000 5520 0000 2002 2 31 37 03H 1 00006 repeat 009 240 154 066 -015 -006 6100 0000 6100 0000 2002 2 31 37 03H 2 00006 repeat 0.10 27.0 169 045 -003 007 6100 0000 6100 0000 2002 2 31 47 02H 1 00008 deplug 1R1l 0.42 58.0 48.1 2.35 -028 014 6100 0000 4319 0000 2002 2 31 53 02H 1 00012 deplug IR1l 023 53.0 36.4 1.57 -0.28 -005 6100 0000 5834 0000 2002 2 31 66 04H 1 00013 deplug IRlI 015 280 17.7 1.17 -0.02 0.13 6100 0000 6100 0000 2002 2 31 68 01H 1 00013 deplug1RlI 1 019 245 141 091 -004 0.15 6100 0.000 6100 0000 2002 2 31 78 05H 1 00006 repeat 013 380 28 8 044 048 061 6100 0.000 6100 0000 2002 2 32 30 02H 1 00008 deplug 1 _RI_1 022 330 163 088 -027 -005 6100 0000 6100 0000 2002 2 32 37 03H 1 00006 repeat 0.15 240 17.0 042 -003 012 6100 0000 6100 0000 2002 2 32 44 04H 1 00008 deplug 1R1l 0.21 39.0 260 1 07 -0.19 002 6100 0000 6100 0000 2002 2 32 47 03H 1 00008 deplug IR1l 0.18 48.0 37.3 1.63 -0.24 -006 6100 0 000 6100 0 000 2002 2 32 62 01H 1 00006 repeat 0 10 240 168 044 -0.11 -0.01 6100 0.000 6100 0 000 2-24

Enclosure 2 PG&E Letter DCL-02-098 Total Total SG Row Col. TSP Crack Cal. Reason for IRll Length MD AD Max. FSBurst FS Length Length Year So.wNum. Type From To Pressure psi Leakage gpm Burstpsi Leakage Press gEpm 2002 2 33 57 02H 1 00012 deplug 1Rl 1 0.12 56.0 370 1 04 007 0.19 6100 0.000 6100 0000 2002 2 33 68 02H 1 00006 repeat 008 32.0 17.8 041 000 008 6100 0000 6100 0000 2002 2 33 72 04H 1 00072 deplug IRl 0.18 37.0 23.8 0.96 -009 009 6100 0000 6100 0000 2002 2 34 36 03H 1 00006 repeat 020 200 12.0 064 -0.15 005 6100 0000 6100 0000 2002 2 34 42 02H 1 00030 new 0 12 200 12.1 0.50 002 0.14 6100 0000 6100 0,000 2002 2 34 47 02H 1 00008 deplug 1R1l 014 360 22.7 0.85 -003 011 6100 0000 6100 0.000 2002 2 34 49 02H 1 00008 deplug IRI1 042 75 0 49.7 381 -0.31 0.11 6100 0000 4153 0.000 2002 2 34 51 06H 1 00006 repeat 009 380 206 038 0.04 0.13 6100 0000 6100 0.000 2002 2 34 53 02H 1 00012 deplug 1RIl 0.31 500 409 1 66 -020 0.11 6100 0000 5254 0000 2002 2 34 53 02H 2 00012 deplug 1R1l 0.12 35.0 19.1 038 -0.14 .002 6100 0000 6100 0000 2002 2 34 55 O1H 1 00012 deplug 1R1l 026 530 37.2 1.87 -031 -005 6100 0.000 5637 0000 2002 2 34 57 02H 1 00012 deplug 1RlI 045 590 48 0 3.11 -026 019 6100 0000 4207 0000 2002 2 34 57 02H 2 00012 deplug IR1l 046 590 48 1 2.78 -0.28 018 6100 0000 4199 0.000 2002 2 34 58 02H 1 00012 deplug 1Rl 022 620 42.3 1.36 -0.16 0 06 6100 0000 5686 0,000 2002 2 34 59 02H 1 00012 deplug 1RI1 0 13 320 17.7 0.71 -0.05 008 6100 0000 6100 0000 2002 2 34 65 02H 1 00006 repeat 0 11 200 14 5 0.36 -0.09 002 6100 0000 6100 0000 2002 2 35 49 02H 1 00008 deplug IRl 027 390 256 1.40 -0.18 009 6100 0000 6100 0.000 2002 2 35 52 03H 1 00006 repeat 020 200 12 8 078 -0.16 0.04 6100 0000 6100 0.000 2002 2 35 56 02H 1 00006 repeat 0,21 200 109 0 56 -005 0.16 6100 0.000 6100 0000 2002 2 35 70 02H 1 00068 new 0.17 55.0 35.1 1 08 -0 14 003 6100 0.000 6100 0000 2002 2 36 53 03H 1 00012 deplug 1R1l 024 355 22.9 0.64 -019 005 6100 0000 6100 0000 2002 2 36 60 04H 1 00006 repeat 0.10 290 157 092 -0.20 -0.10 6100 0000 6100 0.000 2002 2 37 53 02H 1 00012 deplug IRl 050 560 41 5 1 52 -029 0.21 6100 0000 4536 0000 2002 2 37 69 03H 1 00013 deplug 1Rl 0.16 23.0 126 089 005 0 21 6100 0.000 6100 0000 2002 2 37 69 O1H 1 00013 deplug 1R1l 0.11 28.0 19.0 083 -018 -007 6100 0.000 6100 0000 2002 2 37 69 01H 2 00013 deplug IR1l 010 360 19.4 1.26 -005 005 6100 0000 6100 0000 2002 2 37 69 01H 3 00013 deplug IRl 1 027 360 258 1.70 004 0 31 6100 0000 6100 0000 2002 2 37 70 01H 1 00013 deplug 1R1l 031 530 405 1.70 -0.18 0.13 6100 0000 5237 0.000 2002 2 37 73 03H 1 00006 repeat 0 18 270 207 083 -0.10 0.08 6100 0 000 6100 0.000 2002 2 37 74 03H 1 00013 deplug 1RIl 036 420 31 6 1.75 -0.13 0.23 6100 0000 5617 0000 2002 2 38 66 01H 1 00006 repeat 0.18 350 22.7 0 86 -001 0.17 6100 0000 6100 0000 2-25

Enclosure 2 PG&E Letter DCL-02-098 FS Burst FS Total Total Insp. SG Row Col TSP Crack Cal. Type Reason fori1Ril Length MD AD Max. From To Pressure Leakage Length Length Year No. Num Plugging inch (%) (%) Voit psi gpm Burstpsi Leakage Press qpm 2002 2 42 28 02H 1 00006 repeat ID-OD 2H 011 320 20.1 088 -007 004 6100 0000 6100 0000 2002 2 43 49 03H 1 00008 deplug 1RIl 024 480 32 6 1.32 -024 0.00 6100 0000 6100 0.000 2002 4 17 24 01H 1 00042 repeat 0.08 20.0 8.1 0.30 0.29 0.37 6100 0.000 6100 0.000 2002 4 20 25 01H 1 00042 repeat 0.15 21.0 14.7 0.22 -066 -0.51 6100 0000 6100 0000 2002 4 21 67 05H 1 00070 new 0.18 360 22.9 0 69 -0.19 -001 6100 0000 6100 0000 2002 4 21 76 01H 1 00042 repeat 0.16 305 20.1 053 018 034 6100 0000 6100 0000 2002 4 21 84 01H 1 00042 repeat 008 350 203 062 000 008 6100 0000 6100 0000 2002 4 26 37 06H 1 00031 new 0.11 480 308 1.41 003 014 6100 0000 6100 0000 2002 4 35 36 02H 1 00042 repeat 010 210 130 039 016 026 6100 0000 6100 0000 2002 4 35 56 03H 1 00042 repeat 009 210 140 023 -0.18 -009 6100 0000 6100 0000 2002 4 35 56 03H 2 00042 repeat 0.12 240 173 036 000 0.12 6100 0000 6100 0000 2002 4 35 61 02H 1 00042 repeat 0.10 26.0 17.7 0.24 -0.11 -0.01 6100 0.000 6100 0000 2002 4 35 68 03H 1 00042 repeat 0.24 47.0 32.3 0.47 -0.20 0.04 6100 0.000 6100 0000 2002 4 38 69 02H 1 00042 repeat 008 350 196 039 000 008 6100 0000 6100 0000 2002 4 38 72 01H 1 00024 new 012 330 21 9 050 022 034 6100 0000 6100 0000 2002 4 39 48 03H 1 00042 repeat 013 200 143 027 003 016 6100 0000 6100 0000 2002 4 39 58 01H 1 00042 repeat 024 350 245 0 86 008 032 6100 0000 6100 0 000 2002 4 46 42 01H 1 00042 repeat 015 290 186 038 -019 -004 6100 0000 6100 0 000 2-26

Enclosure 2 PG&E Letter DCL-02-098 Figure 1 Axial PWSCC Length Growth Rate at 604F CP D 050 0000 0010 0020 0030 0040 0050 0060 0070 0081 0091 0101 0121 0131 Growth Rate (Inch) per EFPY Figure 2 Axial PWSCC Maximum Depth Growth Rate at 604F a

IL 0

00% 24% 48% 72% 95% 119% 143% 167% 191% 215% 239%

Growth Rate per EFPY 2-27

Enclosure 2 PG&E Letter DCL-02-098 Figure 3 Axial PWSCC Average Depth Growth Rate at 604F a

a 0

00% 20% 40% 59% 79% 99% 119% 138% 158% 178% 198%

Growth Rate per E FPY Figure 4 Circumferential Average Depth Trending 70 60 U

50

• U U

• 40 I U U U

U U

• 3 U "C)30

• a

• U U I

.*. 20 U I I 20 I U U U

• IU U U U U 10-0 199W4 1995 1996 1997 1998 1999 2000 2001 2002 2003 Year Detected I n Average Depth -Linear Trend (Average Depth) I 2-28

Enclosure 2 PG&E Letter DCL-02-098 Figure 5 Circumferential Mixed Mode Average Depth Trending 60 50 a

OC40 l 0

30 C

E 20

• 10 0

1995 1996 1997 1998 1999 2000 2001 2002 2003 Year Detected w Circumferental Mixed Mode AD - UnearTrend (Circ Mixed Mode AD)

Figure 6 Cumulative Number of Circumferential Indications 80 70

-60 U

~50 40

~30 E

C* 20 20 S10 -

1995 1996 1997 1998 1999 2000 2001 2002 Year Detected

-h-Number of arc indications 2-29

Enclosure 3 PG&E Letter DCL-02-098 SPECIAL REPORT 02-02 STEAM GENERATOR CONDITION MONITORING REPORT DIABLO CANYON POWER PLANT UNIT I ELEVENTH REFUELING OUTAGE 1.0 Summary During the Unit 1 eleventh refueling outage (1 R1 1), greater than 1 percent of inspected tubes in steam generator (SG) 1-2 were defective and required plugging. If greater than 1 percent of inspected tubes in any SG exceed the repair criteria, Nuclear Energy Institute (NEI) 97-06, Revision 1, requires that a Condition Monitoring (CM) report be submitted to the NRC within 120 days after returning the SG to service. This report provides a SG tube CM assessment for Unit 1 Cycle 11 based on 1 R11 tube inspection results.

For degradation subject to alternate repair criteria (ARC), PG&E follows the tube integrity assessment requirements of Diablo Canyon Power Plant (DCPP) technical specifications (TS) and NRC-approved licensing basis. VW* ARC report, PWSCC ARC report, and voltage-based ARC report are provided in separate enclosures in this letter.

For all other degradation, PG&E follows the tube integrity assessment guidance provided in Electric Power Research Institute (EPRI) Report TR-107621, "Steam Generator Integrity Assessment Guidelines," Revision 1, dated March 2000.

NEI 97-06, Revision 1, structural and leakage performance criteria for condition monitoring were satisfied at the end of Unit 1 Cycle 11 (EOC 11). This conclusion is based on assessing the 1 R11 as-found conditions of the tubing on a degradation specific basis. Unit 1 Cycle 11 had an actual duration of 1.41 effective full power years (EFPY).

"* Structural integrity performance criteria: 3APNO and 1.4APSLB are the burst margin requirements for free span degradation and degradation confined to tube support plate (TSP) crevice, respectively. Structural integrity performance criteria were satisfied at EOC 11.

" Accident-induced leakage performance criteria: Accident-induced leakage assessments are based on the steam line break (SLB) differential pressure. For degradation subject to ARC, the maximum allowable SLB induced leak rate limit is 12.8 gpm in a faulted SG, based on an analysis which uses current licensing basis assumptions and approved by the NRC in License Amendment (LA) 124/122. As described in Enclosure 1, the limiting EOC 11 SLB leak rate is 0.368 gpm in SG 1-2, much less than the 12.8 gpm limit. For degradation not subject to ARC, the maximum allowable SLB-induced leak rate is 1 gpm in a faulted SG per NEI 97-06.

The DCPP-specific non-ARC SLB-induced leak rate limit is 0.18 gpm at room temperature. There is no EOC 11 SLB leakage attributed to any non-ARC 3-1

Enclosure 3 PG&E Letter DCL-02-098 degradation. Therefore, accident-induced leakage integrity performance criteria were satisfied at EOC 11.

Operational leakage performance criterion: Primary-to-secondary leakage through any one SG must be limited to 150 gallons per day (gpd). This limit is reflected in DCPP TS. A small leak was detected in Unit 1 Cycle 11, ranging from about 1 to 3 gpd, which is well below the 150 gpd limit. Therefore, the operational leakage performance criterion was satisfied at EOC 11. The leak was initially detected in Unit 1 Cycle 9 and continued in cycles 10 and 11. Injection of Argon-40 into the Unit 1 reactor coolant system was initiated in Unit 1 Cycle 11. The Argon-40 is activated to Argon-41, which is detectable by gamma spectroscopy. This improves the consistency, sensitivity and accuracy of leak rate calculations due to higher Argon 41 concentrations in the reactor coolant system and the steam jet air ejector (SJAE).

SG 1-4 has the highest tritium concentration and leak rate based on steam generator blowdown sampling. No eddy current indications were detected in 1RI I that could account for primary to secondary leakage, nor was leakage identified during visual examination of the tubesheet and tube plugs. Therefore, the cause of the small leak is not known.

2.0 Introduction Steam GeneratorBackground DCPP Units 1 and 2 use Westinghouse Model 51 SGs with explosively expanded (WEXTEX) transitions. The SGs contain Alloy 600 Mill Annealed (MA) tubing. The nominal outside diameter of the tubing is 0.875 inch with a 0.050-inch nominal wall thickness. The DCPP SGs have historically operated with a nominal hot leg temperature (Thot) of 603 degrees F. Unit 1 Cycle 11 operated at a nominal Thot of 604 degrees F due to an uprate. The commercial operation dates for Units 1 and 2 are May 1985 and March 1986, respectively.

Both units have historically operated on 18-month fuel cycles. However, starting with DCPP Unit 2 Cycle 8 and Unit I Cycle 9, the cycle lengths have been extended to nominal 20-month operation.

PG&E has implemented several initiatives to minimize primary water stress corrosion cracking (PWSCC) and outside diameter stress corrosion cracking (ODSCC). Primary side initiatives include U-bend heat treatment, WEXTEX tubesheet shotpeening, and zinc injection. Secondary chemistry initiatives include: copper removal program; ethanol amine (ETA) to control pH; increased hydrazine levels; molar ratio control program to prevent excess alkalinity; boric acid addition program (including boric acid soaks at startup to mitigate denting and ODSCC at TSPs); tube sheet sludge lancing every outage; SG blowdown is maintained at 1 percent of the main steam flo~v rate; condensate polishers were installed and emergency (plant curtailment) procedures issued to protect against seawater condenser tube leaks.

3-2

Enclosure 3 PG&E Letter DCL-02-098 Technical Specification Repair Criteria DCPP TS require plugging of any tube that has degradation greater than or equal to 40 percent of the nominal tube wall thickness, unless ARC are implemented. Prior to 1 R9, the DCPP TS were revised to allow implementation of ARC for (a) ODSCC at TSPs pursuant to Generic Letter (GL) 95-05, "Voltage-Based Repair Criteria for Westinghouse Steam Generator Tubes Affected by Outside Diameter Stress Corrosion Cracking," and (b) W* repair criteria for axial PWSCC in the WEXTEX tubesheet region.

The ODSCC ARC TS changes were granted by the NRC in LA 124/122 dated March 12, 1998, in response to license amendment request (LAR) 97-03. The W* ARC TS for Cycles 10 and 11 were granted by the NRC in LA 129/127 dated February 19, 1999 (in response to LAR 97-04). The W* ARC TS for Cycles 12 and 13 were granted by the NRC in LA 151 dated April 29, 2002 (in response to LAR 01-03). These two ARC were implemented in Unit 1 starting in 1R9.

Prior to 1R1 1, the DCPP TS were revised to allow implementation of ARC for axial PWSCC at dented TSPs. The PWSCC ARC TS changes were granted by the NRC in LA 152 dated May 1, 2002 (in response to LAR 00-06 Supplement 3). Validated depth sizing of axial PWSCC at dented TSP intersections was previously implemented in 1 R9 and 1R10, such that axial PWSCC less than the TS limit of 40 percent maximum depth limit was allowed to remain in service. The PWSCC ARC was implemented in 1RI 1, allowing greater than 40% indications to remain in service.

Other than degradation subject to ARC, all crack-like indications are required to be plugged on detection by a rotating coil probe, regardless of depth measurements. Cold leg thinning and antivibration bar (AVB) wear are sized by bobbin and allowed to remain in service if less than 40 percent.

NRC Reporting A teleconference with the NRC staff was made on May 20, 2002, to report the findings from SG inspections performed during 1RI 1. The phone call included discussion topics identified in NRC letter to PG&E dated October 12, 2000, TS 5.6.10.d items, and preliminary results of tube inspections performed. Table 1 was sent to the NRC prior to the phone call to provide a description of the eddy current exam scope. No open items were identified.

TS 5.6.10.c requires that a licensee event report (LER) be submitted within 30 days and prior to resumption of plant operation if greater than one percent of inspected tubes in any SG are identified as defective, which fall into TS 5.5.9, Category C-3. SG 1-2 was determined to be in Category C-3 following completion of eddy current testing.

Therefore, LER 1-2002-002 dated May 22, 2002, was submitted via PG&E letter DCL 02-064 to the NRC prior to the SGs return to service.

3-3

Enclosure 3 PG&E Letter DCL-02-098 DegradationAssessment NEI 97-06, Revision 1, requires completion of a degradation assessment (of both existing and potential degradation mechanisms) prior to each inspection. A degradation assessment, inspection/expansion plan, and tube repair plan were prepared and issued before 1 RI I. A summary of the inspection plan and expansion plan is provided in Table 1. The degradation assessment provides a summary of the EPRI nondestructive examination (NDE) techniques used in 1R11, including detection and sizing capabilities.

The SG tube inspection contractor (Framatone) performed a site specific technique qualification to demonstrate that the EPRI techniques are applicable for use at DCPP.

Tube Repairs Following eddy current inspections, 87 active tubes were plugged. Framatome 1-690 roll plugs were used in both legs. Table 3 provides the plugging breakdown for each SG and reasons for plugging.

In SG 1-2, 150 tubes were deplugged and subsequently eddy current inspected for potential return to service under three ARC. For these 150 tubes, Table 2 provides a breakdown of the ARC type and type of plug. The following inspections were performed on recovered tubes:

0 100 percent bobbin inspection.

0 Plus Point inspection of original flawed location.

0 Plus Point inspection of all distorted bobbin tube support plate indications, regardless of voltage.

0 Plus Point inspection of hot leg > 2 volt dented intersections.

• Plus Point inspection of TTS region from plus 2 to minus 8 inches.

Following the tube inspections, 53 of the 150 tubes required replugging because of detected degradation that was excluded by ARC. Framatome 1-690 roll plugs were used in both legs. Ninety-seven tubes were returned to service using ARC.

No tube pulls were required in 1RI I.

Insitu Testing To support condition monitoring, degradation was assessed for leakage and structural integrity against the screening threshold values documented in the degradation assessment. The screening methodology is provided in EPRI Steam Generator In Situ Pressure Test Guidelines (EPRI Final Report TR-107620-Rl dated June 1999). None of the indicat! dtged inI RI I required insitu testing.

YR1 Damage Mechanisms 3-4

Enclosure 3 PG&E Letter DCL-02-098 Tables 3 through 5 provide the number of SG tubes plugged in 1 RI I and historical tubes plugged in Unit 1.

The following degradation mechanisms were detected in 1RI I and are assessed for SG tube integrity in this report:

"* Axial PWSCC at hot leg dented TSP intersections (PWSCC ARC).

"* Axial ODSCC at hot leg TSP intersections (voltage-based ARC).

"* Combined axial ODSCC and axial PWSCC at hot leg TSP intersections (ID/OD).

"* Circumferential PWSCC at hot leg dented TSP intersections.

"* Circumferential ODSCC at hot leg dented TSP intersections.

"* Circumferential PWSCC and Axial PWSCC at Dented TSP Intersections (PWSCC Mixed Mode).

"* Circumferential ODSCC and Axial ODSCC at Dented TSP Intersections (ODSCC Mixed Mode).

"* Axial PWCC in hot leg WEXTEX tubesheet region (W* ARC).

"* Circumferential PWSCC in hot leg WEXTEX tubesheet region.

"* Circumferential ODSCC at hot leg WEXTEX top of tubesheet region.

"* Volumetric indications at hot leg WEXTEX tubesheet region and hot leg TSP intersections.

"* Cold leg thinning at cold leg TSP intersections.

"* AVB wear in U-bend region.

"* TSP ligament thinning.

This report also provides inspection results of the following degradation mechanisms that were not detected in 1 R1 1.

"* PWSCC in Rows 1 and 2 U-bends.

"* Stress corrosion cracking (SCC) at free span dings.

"* Tube damage due to loose parts and foreign objects.

"* SCC in 1-690 mechanical plugs.

3.0 Axial PWSCC in WEXTEX Region Axial PWSCC in the WEXTEX tubesheet region is assessed under W* ARC. Enclosure 1 provides the CM OA for axial PWSCC in the WEXTEX region pursuant to W* ARC requirements.

4.0 Axial PWSCC at Dented TSP Intersections Axial PWSCC at dented TSP intersections is assessed under PWSCC ARC. Enclosure 2 provides the CM OA for axial PWSCC at dented TSP intersections pursuant to PWSCC ARC requirements.

3-5

Enclosure 3 PG&E Letter DCL-02-098 5.0 Axial ODSCC at TSP Intersections Axial ODSCC at TSP intersections is assessed under ODSCC ARC. Enclosure 4 provides the CM OA for axial ODSCC at TSP intersections pursuant to GL 95-05 requirements.

6.0 Combined Axial PWSCC and Axial ODSCC at Dented TSP intersections (IDIOD)

A total of 14 active tubes contained axial PWSCC and axial ODSCC (ID/OD) indications located at the same dented TSP intersection, 7 in SG 11 and 7 in SG 12. These tubes were plugged because this type of flaw combination is excluded from both PWSCC ARC and ODSCC ARC application. Eleven of these intersections had either ID or OD indications that were left inservice in the prior inspection (1R10): two axial ODSCC indications under ODSCC ARC, and nine axial PWSCC indications because they were less than 40 percent maximum depth. The remaining 3 intersections had no indications of either ID or OD degradation in 1R10, and 2 of these 3 intersections had no prior Plus Point inspection.

Based on review of the eddy current data and terrain maps for all 14 intersections, the axial PWSCC and axial ODSCC components are separated by hoop direction ligament gaps in excess of 30 degrees. This separation exceeds the required hoop direction ligament thickness of 2*(1 -dmax/t)*t, as developed in this section. Therefore, the flaws are treated independently for CM, under their respective ARC, for structural and leakage integrity. The basis for treating ID/OD indications independently is described below.

The following paragraphs discuss criteria for ID/OD axial crack interactions. The first criterion is a bounding conservative separation distance such that if this separation distance in the hoop direction is met or exceeded, there is no interaction relative to either burst pressure or leak rate. Figure 1 shows the limiting bounding case. Each crack is 50 percent through wall (TW) and of equal length. Ifthe hoop separation distance, L, is zero the cracks became a single 1 00%TW crack. For L > 0 the ligament between the cracks must fail in shear for the cracks to join. A free body diagram of the Section A-A (Figure 1) reveals two moments, a side force, S and a distributed shear stress, "rR on two of the Section A-A faces. These are second order effects in terms of affecting the onset of plastic collapse and can be neglected.

The hoop force per unit axial length, F, must be balanced by the shear force per unit axial length, V. Here the force V equals tLIG AvG*L. The maximum possible value for F is 0.6*(cyp + cGUTS)*t, where "t" is the wall thickness. This is the maximum hoop force per unit length at the burst pressure of an unflawed tube. This is the maximum possible force that can be transmitted around the circumference of the tube, i.e. from one hoop location to another. The ligament resistance, V, is at the shear flow strength and is equal to 0.5*(0.6*(cyp + acuTS))*L. Equating these forces assures that the maximum 3-6

Enclosure 3 PG&E Letter DCL-02-098 possible hoop force can be transmitted from one crack to another without failure of the separating ligament. Hence, in a bounding argument, if L => 2*t there is no possible IDIOD axial crack interaction.

Given that a dent causes local bending of the tubing wall thickness, initiation of ID and OD axial cracks will be displaced in the hoop direction as the tube dent surface changes in sign of curvature. A review of eddy current inspection results of the 14 ID/OD indications in 1 RI 1 shows that the closest hoop distance of approach of ID and OD cracks is about 0.22" (30 degrees). This distance is greater than 2*t, or 0.1 inch.

Hence, bounding non-interaction conditions are met and ID axial and OD axial cracks may be treated independently.

The hoop separation distance for non-interaction is actually a function of maximum crack depth, dmax. The hoop force that must be transmitted without ligament failure is essentially ((t- dmax)/t)*0. 6 *(uyp + GUTS)*t. Hence, L for no interaction is a function of dmax. Thus L => 2*(1- dmaxlt)*t is a more reasonable criterion for no interaction of ID and OD cracks. Ifthe maximum crack depth is 50 percent TW then L => t becomes the required no interaction distance.

The above analytical results for no interaction distances are supported by burst test results for multiple parallel cracks. Reference 6.1 includes burst test results for 20 evenly distributed TW electro discharge machining (EDM) notches up to about 0.6" long for which the burst pressures for multiple axial indications in tubesheet expansion transitions were the same as a single indication of the same size. Reference 6.2, Appendix C includes Westinghouse burst test results for 7 and 14 parallel axial EDM notches 0.35" long in expansion transitions leading to the same conclusions as found in Reference 6.1.

References 6.1 Cochet, B.; "Assessment of the Integrity of Steam Generator Tubes - Burst Test Data - Validation of Rupture Criteria (Framatome Data)", Electric Power Research Institute, NP-6865-L, Vol. 1, (June, 1991) 6.2 "PWR Steam Generator Tube Repair Limits: Technical Support Document for Expansion Zone PWSCC in Roll Transitions - Rev. 2", Electric Power Research Institute, NP-6864-L, (August 1993) 7.0 Circumferential PWSCC and ODSCC at Dented TSP Intersections Two circumferential PWSCC indications and five circumferential ODSCC indications were detected by Plus Point at > 2 volt dented hot leg TSP intersections, as listed in Table 7. All the circumferential indications (SCI) were plugged. The smallest dent voltage at which circumferential cracking was detected is 2.45 volts.

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Enclosure 3 PG&E Letter DCL-02-098 The SCI were sized using the technique described in Appendix B of WCAP-1 5573, Revision 1. The depth profiles were then processed for corrections in accordance with the depth adjustment rules in Section 4.10.4 of WCAP-1 5573, Revision 1. The adjusted NDE results were corrected for 95 percent NDE uncertainty using the NDE uncertainty regression parameters in Tables 4-19 to 4-21 in WCAP-1 5573, Revision 1.

The adjusted NDE and adjusted NDE with uncertainty results are listed in Table 7.

The 3APNO structural limit for a SCI is about 264 degrees, assuming a 100%

throughwall defect. The longest NDE length was 33 degrees for PWSCC and 48 degrees for ODSCC, and are adjusted to 87 degrees and 180 degrees after applying large 95 percent NDE uncertainties. These lengths are less than the 264 degree structural limit. Therefore, structural integrity was satisfied at EOC 11.

The largest NDE maximum voltages were 0.25 volts for ODSCC and 0.58 volts for PWSCC. These values are much less than the insitu leak testing threshold voltage values of 1 volt for ODSCC and 1.5 volt for PWSCC. In addition, the largest NDE maximum depths were 73 percent for ODSCC and 69 percent for PWSCC, including 95 percent NDE uncertainty. Based on these NDE measurements, the SCI were shallow and no SLB leakage should be postulated for these indications at EOC 11.

Per WCAP-15573, Revision 1, Section 4.13, the largest projected EOC average depths are 54 percent for PWSCC and 64 percent for ODSCC. The largest average depths detected in 1RI I were 35 percent for PWSCC and 40 percent for ODSCC with no NDE uncertainty added and 50 percent and 57 percent with 95 percent NDE uncertainty.

Thus, the projected EOC indications bound the largest indications found in 1 RI 1.

8.0 Circumferential PWSCC and Axial PWSCC at Dented TSP Intersections (PWSCC Mixed Mode)

One dented TSP intersection containing a circumferential PWSCC indication and an axial PWSCC indication, termed PWSCC mixed mode, was detected and plugged in 1Rll. The location was SG 1-2, R1lC81 2H. The CM OA of this degradation is provided in Enclosure 2 pursuant to PWSCC ARC requirements.

9.0 Circumferential ODSCC and Axial ODSCC at Dented TSP Intersections (ODSCC Mixed Mode)

One dented TSP intersection containing a circumferential ODSCC indication and an axial ODSCC indication, termed ODSCC mixed mode, was detected in an active tube and was plugged in 1R11. The location was SG 1-2, R35C69 2H. The dent was measured as 2.45 volts. This was the first occurrence of ODSCC mixed mode in either DCPP unit.

The axial ODSCC indication was previously detected by Plus Point in 1R9 and 1R10 and left in service in cycles 10 and 11 under ODSCC ARC because the bobbin voltage 3-8

Enclosure 3 PG&E Letter DCL-02-098 was less than 2 volts. The circumferential ODSCC indication was not detected in prior inspections, and was not detectable based on a lookup of 1R10 data.

Based on review of the 1 RI 1 data, a return to null between the indications was not discernable, and therefore the indications are treated as interacting based on the mixed mode indication guidance of WCAP-15573, Revision 1. The NDE average depth of the circumferential flaw is 49.5 percent, including 95 percent uncertainty, which is less than the 75 percent average depth threshold value for mixed mode effects as defined for PWSCC ARC mixed mode requirements in WCAP-15573, Revision 1. In addition, neither the axial or circumferential indication are 100 percent throughwall at any point.

The circumferential indication is 64 percent maximum depth, including 95 percent NDE uncertainty. The Plus Point voltage of the axial ODSCC indication is 0.44 volt, indicating a shallow flaw. Based on this ODSCC mixed mode assessment, there is no potential impact on the axial ODSCC indication burst pressure or leakage for condition monitoring.

10.0 Circumferential PWSCC and ODSCC in WEXTEX Region Three circumferential PWSCC indications and 5 circumferential ODSCC indications in the hot leg WEXTEX region were detected by Plus Point in 1Ri 1, as listed in Table 7.

All the SCI were plugged.

The SCI were sized using the technique described in Appendix B of WCAP-1 5573, Revision 1. The depth profiles were then processed for corrections in accordance with the depth adjustment rules in Section 4.10.4 of WCAP-15573, Revision 1. The adjusted NDE results were corrected for 95 percent NDE uncertainty using the NDE uncertainty regression parameters in Tables 4-19 to 4-21 in WCAP-1 5573, Revision 1.

The adjusted NDE and adjusted NDE with uncertainty results are listed in Table 7.

Table 7 provides the location of the SCI relative to the top of tubesheet. All SCI, except two PWSCC indications, are located above BWT. The PWSCC indication in SG 1 -4 R17C39 is located below the W* length and does not contribute to burst or leakage in accordance with W* ARC, and no further condition monitoring assessment is required for this indication. R17C39 was plugged due to a defect at another location.

Table 7 also provides the tubesheet zone location of the SCI. All SCI, with the exception of one PWSCC SCI, are located in WEXTEX Zone 4 (center region) of the top of tubesheet. Zone 4 is noted to have the most tube scale buildup.

The 3APNO structural limit for a SCI is about 264 degrees, assuming a 100 percent throughwall defect. The longest measured length was 23 degrees for PWSCC and 42 degrees for ODSCC, and are adjusted to 77 degrees and 178 degrees after applying large 95 percent NDE uncertainties. These lengths are less than the 264 degree structural limit. Therefore, structural integrity was satisfied at EOC 11.

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Enclosure 3 PG&E Letter DCL-02-098 The largest measured maximum voltages were 0.28 volts for ODSCC and 0.82 volts for PWSCC (excluding R17C89). These values are much less than the insitu leak testing threshold voltage values of 1 volt for ODSCC and 1.5 volt for PWSCC. Based on these voltages, the SCI were shallow and no SLB leakage should be postulated for these indications at EOC 11. Two indications, R27C52 and R17C60, have high NDE estimated maximum depths of 96 percent (0.24 volts ODSCC) and 90 percent (0.34 volts PWSCC), respectively. However, the deep depths at these low voltages are not reliable and are most likely due to difficulties in sizing indications below about 0.5 volts.

11.0 Volumetric Indications at TSP Intersections and at WEXTEX Region Six OD volumetric indications (SVI) were detected by Plus Point in 1 R1 1, as listed in Table 6. The SVI in R2C14 was located within the hot leg tubesheet below the W*

length and was left in service under W* ARC because the tubesheet provides constraint against leakage and burst. The other 5 SVI were located at dented TSP 1H intersections and were plugged. Table 6 provides Plus Point sizing estimates. There is no EPRI quantified sizing technique for volumetric indications at hot leg TSP intersections.

The SVI calls may be attributed to closely spaced axial ODSCC. For example, in 1 R10, axial ODSCC (SAI-OD) was confirmed by Plus Point in R28C50, and was left in service under ODSCC ARC. In 1RI1, the Plus Point signal was similar, but was called as two indications, SVI-OD and SAI-OD, causing the tube to be plugged.

EPRI insitu guidelines state that if the flaw length is greater than 0.125 inch and the extent is greater than 30 degree, then the flaw should be treated as volumetric. Based on the 1RI I SVI sizing estimates, the SVI are treated as volumetric.

The SVI dimensions are bounded by specimen dimensions used in development of a cold leg thinning (CLT) structural model simulating the flaws as elliptical wastage, which show that indications with a length of 0.7 inch and a depth of about 78 percent in tubes with LTL material properties may be expected to meet the requirements of 3APNO. The longest axial length was estimated as 0.23 inches, and the maximum depths were estimated to be less than 40%. These NDE measurements are much less than the structural limit length and depth combination. If the indications were assumed to be axial cracks, the burst pressures would be very high due to the short lengths.

Therefore, structural integrity performance criteria were met for the volumetric indications at EOC 11.

Because the SVI maximum depths of less than 40 percent are too shallow to consider ligament tearing (pop through), SLB leakage at EOC 11 would not be expected.

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Enclosure 3 PG&E Letter DCL-02-098 12.0 Cold Leg Thinning (CLT)

CLT indications at cold leg TSP intersections are detected by bobbin probes as part of the 100 percent full-length bobbin inspection. CLT indications are sized by bobbin using EPRI ETSS 96001.1. CLT indications are plugged if bobbin indicates a depth greater than or equal to 40 percent through-wall.

In 1R1I, bobbin indications at cold leg TSPs were called as distorted OD support (DOS) indications. If the intersection had no prior Plus Point history, it was then inspected using Plus Point. Volumetric indications confirmed by Plus Point in the CLT region were depth sized by bobbin. If Plus Point did not confirm the indication, the DOS indication was left in service.

In 1 R1 1, 135 CLT indications were detected and sized by bobbin, of which 4 were greater than or equal to 40 percent and plugged. 10 new CLT indications were detected. All CLT indications were located at either IC or 2C.

Based on development of a CLT structural model assuming elliptical wastage for the flaws,'the 1.4 APSLB structural limit for a tube with CLT confined to the TSP is about 84 percent. The CLT repair limit is 40 percent, thereby allowing for NDE uncertainty and flaw growth progression.

The deepest indication identified in 1RI I was 46 percent through-wall. In accordance with EPRI ETSS 96001.1, sizing of CLT with bobbin coil has an NDE standard regression error of 16.4 percent at 90/50 confidence. Standard error for analyst uncertainty at 90/50 confidence is 0.89 percent times 1.28, or 1.14 percent (reference "Appendix G Generic NDE Information from CM/OA," extracted from "Capabilities of Eddy Current Analysts to Detect and Characterize Defects in SG Tubes," Doug Harris, presented at November 1996 EPRI NDE workshop). The combined NDE system uncertainty (SRSS) of the analyst and technique uncertainties is 16.4 percent. Adding total NDE uncertainty to the bounding indication results in a CLT flaw of 62 percent, which is less than the CLT structural limit of 84 percent. Therefore, the structural integrity performance criteria were satisfied for this bounding indication at EOC 11.

Because CLT was too shallow to consider ligament tearing (pop through), no leakage is postulated in a faulted SG following a SLB at EOC 11. The largest 1 R11 flaw size was less than the bounding flaw size projected in the prior cycle OA.

13.0 Antivibration Bar (AVB) Wear AVB wear indications are detected by bobbin probes during the 100 percent full-length bobbin inspection. AVB wear indications are sized by bobbin using EPRI ETSS 96004.1. AVB wear indications are plugged if bobbin indicates a depth greater than or equal to 40 percent through-wall.

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Enclosure 3 PG&E Letter DCL-02-098 In 1RI 1, bobbin identified 266 AVB wear indications, of which 5 were greater than or equal to 40 percent and plugged. 18 new indications were detected. Three indications in 1 R11 deplugged tubes were detected.

The 3APNO structural limit for a tube with AVB wear is about 71 percent. The AVB wear repair limit is 40 percent, thereby allowing for NDE uncertainty and flaw growth progression.

The deepest indication identified in 1 RI I was 42 percent through-wall. In accordance with EPRI ETSS 96004.1, sizing of AVB wear with bobbin coil has an NDE standard regression error of 5.74 percent at 90/50 confidence. Standard error for analyst uncertainty at 90/50 confidence is 0.86 percent times 1.28, or 1.1 percent (reference "Appendix G Generic NDE Information from CM/OA," extracted from "Capabilities of Eddy Current Analysts to Detect and Characterize Defects in SG Tubes," Doug Harris, presented at November 1996 EPRI NDE workshop). The combined NDE system uncertainty is SRSS of the analyst and technique uncertainties, 5.8 percent. Adding total NDE uncertainty to the bounding indication results in a AVB wear flaw of 47.8 percent, which is less than the AVB wear structural limit of 71 percent. Therefore, the structural integrity performance criteria were satisfied for this bounding indication at EOC 11. Because AVB wear was too shallow to consider ligament tearing (pop through), no leakage is postulated in a faulted SG following a SLB at EOC 11. The largest 1 RI 1 flaw size was less than the bounding flaw size projected in the prior cycle OA.

14.0 Tube Support Plate (TSP) Ligament Thinning In 1R8, 1R9 and 1R10, PG&E performed eddy current inspections to detect degradation of steam generator TSPs. A summary of this program was previously reported to the NRC in response to GL 97-06 (PG&E Letter DCL-98-046 dated March 27, 1998). Visual inspections performed in I R8 confirmed several missing TSP ligaments. Westinghouse has concluded that the missing TSP ligaments are related to suspected TSP drilled hole manufacturing anomalies. The TSP manufacturing practices employed at the time that the DCPP steam generators were produced used a stacked drilling procedure. Several TSPs were clamped together and drilled simultaneously. A review of the suspect ligament crack (SLC) locations indicates distinct location patterns, indicative of manufacturing anomalies of the automatic drilling equipment.

The eddy current inspection program consists of several steps: bobbin inspection to detect SLC using computerized data screening; Plus Point sample inspection of existing Plus Point confirmed "baseline" indications; and Plus Point inspection of newly detected bobbin SLC indications. Plus Point confirmed indications are called either ligament crack indication (LIC) or ligament gap indication (LIG). The following provides a summary of the 1R11 inspection results.

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Enclosure 3 PG&E Letter DCL-02-098 Baseline Inspection and Results To satisfy 20 percent inspection recommendations in the EPRI guidelines and to ensure that the current TSP condition is not changing, Plus Point inspection of 100 percent of the baseline indications in SG 1-1 and SG 1-4 was performed.

In SG 1-1, Plus Point confirmed 63 baseline indications (43 LIC and 20 LIG). Two baseline indications did not confirm. In SG 1-4, Plus Point confirmed all 20 baseline indications (15 LIC and 5 LIG). For the LIG indications, gap measurements were performed for a growth assessment, and the small changes did not indicate any change in the material condition of the TSPs.

Inspection for New Indications Plus Point confirmed 5 new indications (4 LIC and 1 LIG). Based on a review of the baseline data, the LIG was present, but the LIC indications could not be clearly identified due to the quality of the baseline data.

Based on the I RI 1 inspections, there are now of a total of 236 Plus Point TSP ligament indications in Unit 1.

Assessment of Plugging Criteria The largest measured LIG gap was 120 degrees, less than the 146 degree threshold gap. As such, tube plugging was not required.

15.0 PWSCC in Row I and 2 U-Bends Unit 1 SG tubes in Rows 1 and 2 U-bends were heat treated following two cycles of operation to relieve stresses and mitigate the potential for PWSCC in this location. One hundred percent of Rows 1 and 2 U-bends have been inspected each refueling outage.

Starting in 1R8, a Plus Point probe was used to inspect Rows 1 and 2 U-bends.

In 1R 1, 100 percent of Rows 1 and 2 U-bends in all SGs, and 20 percent of Row 3 U bends in SG 1-1 and SG 1-3, were inspected by 0.680 mid range (MR) Plus Point probe. No indications were detected by Plus Point. Because PWSCC was not detected in 1R1 1, this degradation is not considered active in Unit 1 Cycle 11 and condition monitoring is not required.

In light of lessons learned from the Indian Point (IP2) U-bend tube failure event, data quality requirements were implemented. If questionable data (e.g., excessive noise) was collected from the 0.680 MR, the U-bend was reinspected with a 0.680 high frequency (HF) Plus Point probe. If questionable data was subsequently collected with the 0.680 HF, then the tube was plugged for precautionary measures. This resulted in 9 tubes being plugged.

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Enclosure 3 PG&E Letter DCL-02-098 16.0 Free Span Ding Inspections Plus Point inspection was performed on a 20 percent sample of greater than 2 volt free span dings in the hot leg to verify that no PWSCC or ODSCC is occurring in free span dings. The entire length of free span between the support structures was inspected.

No indications at free span dings were detected by Plus Point. No occurrences of stress corrosion cracking at free span dings has been observed at DCPP Units 1 and 2.

17.0 Possible Loose Part (PLP) Inspections The bobbin and Plus Point data were reviewed for possible loose part (PLP) indications.

In addition, a foreign object search and removal (FOSAR) visual examination of the tube sheet annulus and blowdown lane regions was performed to identify loose parts.

In SG 1-1, a PLP indication was detected by Plus Point at R30C78, 0.2 inch above the hot leg top of tubesheet. The Plus Point inspection was performed after sludge lancing.

Subsequent FOSAR inspection recovered the loose part at this tube location. The loose part was a small (0.25 inch) round piece of weld slag. Eddy current detected no tube wear at the top of tubesheet, such that this loose part was not a tube integrity concern.

In SG'1-1, a repeat PLP indication was detected by bobbin and confirmed by Plus Point between SG 1-1 R30C78 and R31C78, 3 inches above the cold leg top of tubesheet.

The Plus Point inspection was performed after sludge lancing. This PLP indication was previously detected in 1R8, 1R9, and 1 R10, but was not detectable by FOSAR.

Bounding Plus Point inspections were performed on adjacent tubes as required by procedure. This tubesheet area was once again specifically reviewed during FOSAR activities, and once again no foreign object was identified. Based on this result, the PLP may be an anomalous eddy current trace pattern on the secondary side of the tube wall (conductive sludge, for example). No tube wear was detected by Plus Point. Eddy current inspections will be performed on this location again in 1R12, along with FOSAR examinations to detect and remove any potential loose parts. Continued operation during Unit 1 Cycle 12 is acceptable because eddy current detected no tube wear.

In SG 1-3, a foreign object was detected by FOSAR between tubes RIC49 and R1C50 at the hot leg top of tubesheet. The approximate size of the object is 0.4 inch by 0.75 inch. The object appeared to be metallic and is tightly lodged between the two tubes.

Multiple attempts to dislodge the object were unsuccessful. Plus Point data was re reviewed at this location and a PLP signal was detected. The signal was traced to 1R9 and 1R10 Plus Point data, and has not changed. No tube wear was detected by Plus Point. Eddy current inspections will be performed at this location again in 1R12, along with FOSAR examinations to detect and remove any potential loose parts. Continued operation during Unit 1 Cycle 12 is acceptable because no tube wear was detected by 3-14

Enclosure 3 PG&E Letter DCL-02-098 eddy current and because the loose part is adhered to the tubesheet and should not move during plant operation.

PLP indications were detected by Plus Point at SG 1-3 R1C75, 0.5 inch above the hot leg top of tubesheet, and at SG 1-4 R32C17, 0.5 inch above the hot leg top of tubesheet. No tube wear was detected by Plus Point. Subsequent FOSAR inspections at these locations did not locate a loose part. The PLP indications were detected by Plus Point prior to sludge lance tubesheet cleaning, so it is possible that sludge lancing could have removed these objects. Post-sludge lance eddy current inspections were not performed at these locations. Eddy current inspections will be performed at these locations in 1R12, along with FOSAR examinations to detect and remove any potential loose parts. Continued operation during Unit 1 Cycle 12 is acceptable because eddy current detected no tube wear.

18.0 1-690 Mechanical Plug Visual Inspections All mechanical plugs installed in DCPP Unit 1 are fabricated from Alloy 690. There has been no occurrence of stress corrosion cracking in 1-690 plugs in the industry. Two types of 1-690 mechanical plugs are installed in DCPP Unit 1: Westinghouse rib plugs and Framatome roll plugs. A visual inspection of all mechanical plugs was performed to verify they are intact and show no signs of leaking. No abnormalities were identified.

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Enclosure 3 PG&E Letter DCL-02-098 Table I IRlI SG Tube Inspection and Expansion Criteria Area Probe Inspection Criteria [ Expansion Criteria 1 Full Length Bobbin 100% N/A 2 Short Radius U-Bends +Point 100% - Rows 1 and 2 U-bends in If SCC found in Row 2, inspect 20% of Row 3 all SGs in affected SG If SCC found in Row 3, 20% - Row 3 U-bends in SG 11 inspect 100% of Row 3 and 20% of Row 4 in and SG 13 affected SG Continue expansion in this manner until a flaw free 20% sample is obtained in the next row U-bend 3 WEXTEX TTS Region +Point

• 100% of HL l-s If C-3 condition is identified in HL TrS, inspect

• Extent is +2" to -8" 20% of CL TTS in affected SG Ifindications 0 PTE/NTE anomaly extent is found in CL, follow EPRI Tables 3-1 and 3-2

+2 to tube end for further expansion requirements If cracking found in HL tubesheet anomalies, inspect 100% of CL tubesheet anomalies 4 Repeat PWSCC at +Point 0 100% N/A I dents and TTS 5 >5 volt dents +Point

• SG 1-1: 100% at 1H to 4H, IfPWSCC (at any size dent), circumferential 20% at 5H to 7H indications (at any size dent), or AONDB (at

• SG 1-2. 100% at 1H to 6H, >5 volt dent) are detected at a TSP elevation 20% at 7H where 100% inspections were not required,

• SG 1-3" 20% at 1H to 7H expand the Plus Point inspections (in a step

• SG 1-4: 100% at 1H to 3H, wise manner, 100% to affected TSP and 20%

20% at 4H to 7H at next TSP) up through the hot leg side of the 0 For each 20% sample, SG and down the cold leg side until a 20%

inspect at least 50 dents, or sample is obtained that is free from PWSCC, else inspect 100% if there circumferential cracking, or > 2 inferred volt are less than 50 dents AONDB 6 >2 and <5 volt dents +Point

• SG 1-1: 100% at 1H to 4H, If PWSCC (at any size dent), circumferential 20% at 5H indications (at any size dent), or> 2 inferred

• SG 1-2 100% at 1H to 6H, volt AONDB (at >2 and <5 volt dent) are 20% at 7H detected at a TSP elevation where 100%

• SG 1-3 20% at 1H inspections were not required, expand the Plus

• SG 1-4 100% at 1H to 3H, Point inspections (in a step-wise manner, 20% at 4H 100% to affected TSP and 20% at next TSP)

• For each 20% sample, up through the hot leg side of the SG and inspect at least 50 dents, or down the cold leg side until a 20% sample is else inspect 100% if there obtained that is free from PWSCC, are less than 50 dents. circumferential cracking, or > 2 inferred volt AONDB 7 Distorted ID support +Point

• 100% of DIS calls by bobbin If a circ indication or >2 inferred volt AONDB is plate bobbin signals detected in a dent of Yx" volts, then Plus Point (DIS) inspections shall be conducted on 100% of dents greater than "x - 0 3" volts up to the affected TSP, plus 20% of dents greater than "x-0 3" volts at the next higher TSP. "x"is defined as the lowest dent voltage where a circ crack or >2 inferred volt AONDB was detected in that SG Note: For any 20%

sample, a minimum of 50 "x - 0.3" volt dents shall be inspected If the population ofx 0 3" volt dents at that TSP elevation is less than 50, then 100% of the 'x - 0 3" volt dents at that TSP shall be inspected 3-16

Enclosure 3 PG&E Letter DCL-02-098 Area Probe I Inspection Criteria Expansion Criteria 8 Distorted OD support +Point s DOS at < 5 volt dented NIA plate bobbin signals intersections (DOS) and voltage- . > 2 volt DOS based ARC

• DOS with suspected TSP implementation ligament cracking

• DOS in the wedge region exclusion zone

• DOS at 7th TSP exclusion zone

• DOS that extend outside the TSP crevice

• copper signals

• Mix residuals, all HL intersections > 2 3 SPR volts, and minimum of 5 largest HL SPR per SG (CDS determines SPR voltage at each TSP) 9 Suspected TSP +Point

• Plus Point inspect 20% of If active degradation is detected in the 20%

Ligament Cracking existing baseline indications, sample inspection, then the Plus Point (SLC) satisfied by 100% inspection inspection will be expanded to 100 percent of of baseline indications in SG the baseline population. Active degradation is 11 and 14 defined as service-induced TSP ligament

• Plus Point inspect all new erosion-corrosion and/or cracking bobbin SLC indications Bobbin analysis

"* CDS of 1R11 bobbin data to identify SLC

"* Low frequency bobbin review of TSP at intersections with distorted support signals to identify SLC 10 Free Span Dings (> 2 +Point

• In each SG, 20% from TSH If PWSCC is found in 20% sample, then volts) to 7H expand inspections in the affected SG by inspecting 100% of >2 volt dings up to affected free span 11 Mechanical Plugs Visual Visual inspection of all existing plugs to verify they are intact and show no signs of leaking 12 Cold Leg Thinning +Point

• New CLT indications N/A

• CLT indications in the wedge zone 13 Free Span Bobbin +Point 100% of free span bobbin N/A Indications indications that are new or exhibit growth or change (MBI, FSI, DNI) 14 Loose Parts Bobbin 0 Review bobbin data of row N/A

+Point 1&2 and periphery tubes a +Point of PLP and surrounding tubes

• +Point of loose parts I _detected by FOSAR 15a Deplugged Tubes full Bobbin 0 100% N/A length 15b Deplugged Tubes +Point 0 100% of HL TTS NIA WEXTEX region _ Extent is +2" to -8" 15c Deplugged Tubes +Point

• Original flawed TSP N/A TSP 0 100% of DOS and DIS, regardless of voltage

• 100% of >2 volt hot leg dents

• 100% of SLC indications _1 3-17

Enclosure 3 PG&E Letter DCL-02-098 Table 2 Number of Tubes Unplugged in SG 1-2 in 1Rll Reason for Unplug Number of tubes Type of Plug PWSCC ARC 76 Roll PWSCC ARC 61 Rib 95-05 ARC 4 Roll 95-05 ARC 6 Rib W* ARC 2 Rib No degradation 1 Roll Total 150 Table 3 DCPP Unit I Tubes Plugged by Mechanism and SG in 1RlI Active and Deplugged Tubes LOCATION ORIENT [-1 1-2 1-3 1-4 1 ,1MECHANISM Total WEXTEX Region PWSCC Axial 1 1 PWSCC Circ 2 2 ODSCC Circ 4 1 5 Hot Leg TSP PWSCC Axial 5 5 PWSCC Circ 1 1 ODSCC Axial 8 16 7 6 37 ODSCC Circ 2 1 1 4 PWSCC Mix Mode Axial PWSCC/Circ 1 1 2 ODSCC Mix Mode Axial ODSCC/Circ 1 1 2 PWSCC/ODSCC Axial 7 7 44 58 Volumetric OD 1 2 3 Cold Leg TSP Cold Leg Thinning 3 1 4 U-Bends AVB Wear 1 3 2 6 Rows 1 and 2 U-bend Preventive Data Quality 7 2 9 Restriction 1 1 Tubes Plugged 29 38 53 10 10 140 Tubes Unplugged 150 150 Net Plugged 29 38 -97 10 10 -10 3-18

Enclosure 3 PG&E Letter DCL-02-098 Table 4 DCPP Unit I Historical Tube Plugged by Mechanism and SG LOCATION MECHANISM J ORIENT 1 1-1 1 1-2 1-3 1 14 1 Total WEXTEX Region PWSCC Axial 2 3 0 2 7 PWSCC Circ 4 4 0 1 9 ODSCC Circ 7 0 9 0 16 Volumetric 3 0 5 4 12 Hot Leg TSP PWSCC Axial 38 34 0 15 87 PWSCC Circ 1 8 0 0 9 ODSCC Axial 21 32 9 10 72 ODSCC Circ 0 7 0 2 9 PWSCC Mix Mode Ax/Circ 0 3 0 0 3 ODSCC Mix Mode Ax/Circ 0 2 0 0 2 PWSCC/ODSCC Axial 10 65 0 0 75 PWSCC/ODSCC Circ 1 1 Volumetric 1 1 1 3 6 Preventive Data Quality PVN 1 1 Cold Leg TSP Cold Leg Thinning 17 27 1 8 53 Volumetric 2 1 1 1 5 Rows 1 and 2 U-bend PWSCC Axial 6 17 2 1 26 PWSCC Circ 7 5 0 1 13 Preventive Data Quality 8 10 4 9 31 U-bend AVB Wear 5 13 14 16 48 Factory Plug 0 1 0 0 1 Restnction 0 3 0 0 3 Free span SVI or SAI scratch 1 0 2 2 5 Fatigue (88-02) Preventive 5 0 1 0 6 Implant Tubes 16 0 0 0 16 Tubes Plugged 1 154 238 49 75 516

% Plugged 1 45 70 1.4 2.2 38 3-19

Enclosure 3 PG&E Letter DCL-02-098 Table 5 - DCPP Unit I Tubes Pluqmed bv Mechanism and Outaae LOCATION MECHANISM ORIENT I Pre IR1 [ 1R2 1R3 1R4 I1RS 1R6I 1R7 1R8 1R9 I IR10 [1Rli UnPlug Total Cumulative EFPYs 1.25 227 345 449 586 7.14 846 9.75 11.4 1287 1428 Cycle EFPY 1.25 1 02 1.18 1 04 1.37 1.28 1.32 1.29 1 62 1.49 1 41 WEXTEX Tubesheet PWSCC Axial 2 2 1 1 2 1 2 7 PWSCC Circ 1 4 2 2 9 ODSCC Circ 2 9 5 16 Volumetric SVI 1 5 5 1 0 12 Hot Leg TSP PWSCC Axial 31 72 124 20 13 5 178 87 PWSCC Circ 4 1 2 1 1 9 PWSCC Mix Mode Ax/Circ 1 2 3 ODSCC Mix Mode Ax/Circ 2 2 PWSCC/ODSCC Axial 1 3 13 58 75 PWSCC/ODSCC Circ 1 0 1 ODSCC Axial 7 8 44 10 18 37 52 72 ODSCC Circ 5 4 9 Volumetric 2 1 3 6 Cold Leg TSP Thinning 10 14 2 11 12 4 53 SVI 1 4 5 Row 1 and 2 U-bend PWSCC Axial 4 13 4 5 26 PWSCC Circ 4 1 4 4 13 U-bend AVB Wear 2 1 12 8 12 3 1 3 6 48 U-bend or straight leg Probe restriction 1 1 1 3 Free Span SVI or scratch 1 4 5 Factory Plug Preservice 1 1 Possible UB indication 1 1 1 1 1 0 Preventive Plugging Fatigue (88-02) 5 1 6 Preventive Plugging UB Data Quality 23 9 1 31 Preventive Plugging TSP Data Quality PVN 1 1 Implant Tubes 4 2 1 9 16 Tubes Plugged 1 0 1 12 1 29 68 117 199 74 108 140 Tubes Unplugged 1 1 40 43 150 Cum Tubes Plugged 1 1 2 13 14 43 111 228 427 461 526 516 Cum Tubes Plugged (%) 001 001 001 010 010 032 0.82 1.68 3.15 34 39 38 3-20

Enclosure 3 PG&E Letter DCL-02-098 Table 6 1R11 Volumetric Indications SG Row Col Location Ind Orient Dent PP Axial Width Extent EPRI flaw 1R10 PP 1R10 IRlO 1R10 volt Volts Length (inch) (deg) treatment Volts Axial WVidth CA (inch) Length (inch) deg (inch) 12 2 68 1H + 0.23 SVI OD 15 023 023 050 67 Volumetric NDD 12 2 68 1H - 0.20 SVI OD 15 024 019 022 30 Volumetric NDD 12 28 -50 1H+002 SVI OD 17 028 022 061 81 Volumetric 069 (Note 3) 13 2 14 TSH -8 36 to - SVI OD 059 0.23 031 40 Volumetric 045 022 034 45 812 14 8 30 1H - 0 02 SVI OD 54 052 012 042 56 Volumetric NDD 14 17 39 1H1--008 SVI 0D 29 023 014 040 53 Volumetric 0.16 0.16 0.34 44 Notes

1. EPRI insitu pressure test guidelines provide the following pressure test criteria Ifthe length is > 0 125 inch and the crack angle is < 30 degrees, evaluate as an axial flaw.

If length < 0.125 inch and CA:> 30 deg, evaluate as a circumferential flaw. If length > 0 125 and CA > 30 deg, evaluate as a volumetric flaw.

2. 1R10 sizes are based on lookup analysis of eddy current data NDD indicates no detectable degradation based on lookup analysis.

3. SG 12 R28C50 1H was characterized as axial ODSCC in 1R10, with a maximum Plus Point voltage of 0.69 volts. In 1Ri1, it was characterized as two flaws, axial ODSCC and volumetric OD.

4. Max depth of these indications is estimated to less than 40%

3-21

Enclosure 3 PG&E Letter DCL-02-098 Table 7 IR11 Circumferential Indications V *,* T Adjusted for Upper Growth Rate per EFPY Unadjusted NDE Adjusted NDE 95% NDE Uncertainty I MnaAgi Max Det Avg gtAge A Ande Depth Max Det Avg deptepdAngleg Angle Max DeteAvg Angle Max Avg SG Row Col 3rackSupport Supocation L inch Circ Type TS BWT Zone inch Dent volt Mixed Flaw Mode? Volt AgeDepth deg Det Depth degDetDphDthdg Det de Det etphDph et 11 2 6 1 TSH -1.77 PWSCC 3 -020 no 0.82 23.2 440 235 232 440 31 7 770 67.1 47.4 -36 -28 -22 11 6 49 1 TSH -018 ODSCC 4 -035 no 028 417 640 39.7 41.7 64.0 554 1777 819 660 NDD 11 14 68 1 TSH 0.00 ODSCC 4 -026 no 023 30.9 92.0 703 309 786 676 1732 926 736 -03 -38 -24 11 17 58 1 TSH -002 ODSCC 4 -051 no 026 387 830 671 387 753 63.8 176.5 902 712 -55 147 122 11 17 60 1 TSH 000 PWSCC 4 -091 no 034 232 910 72.7 23.2 900 693 770 1000 727 00 -4.3 -4.9 11 18 39 1 TSH 000 ODSCC 4 -061 no 0.13 22.4 540 308 224 420 323 1697 65.8 51.6 4.7 40 61 12 8 84 1 1H 030 ODSCC 21.48 no 015 367 380 194 367 400 26.7 1756 643 482 NDD 12 8 85 1 1H 035 ODSCC 1931 no 013 294 550 22.5 294 400 262 1726 643 478 NDD 12 8 85 2 IH 034 ODSCC 1931 no 0.16 22.1 340 203 22.1 400 295 1696 64.3 49.9 NDD 12 11 81 1 2H 011 PWSCC 3.11 yes 043 297 970 608 297 47.0 348 836 693 495 2.1 46 34 12 35 69 1 2H 0.09 ODSCC 245 yes 0 15 22.7 530 35.0 22.7 400 27.5 1699 643 486 NDD 12 37 34 1 3H 004 PWSCC 8.32 no 058 334 550 277 334 400 19.2 87.4 642 390 12 00 -03 13 27 52 1 TSH 000 ODSCC 4 -019 no 024 391 980 67.8 39.1 960 772 1766 1000 796 30 17.7 13.0 14 17 39 1 TSH -939 PWSCC 4 -029 no 1.21 24.0 460 27.5 240 41 0 285 778 64.9 45.2 -2.8 -35 -3.1 14 43 55 1 2H 027 ODSCC 1 23.84 no 025 480 530 394 480 51.5 39.8 1803 728 563 00 60 53 Note 1: For SG 12 R1IC81 mixed mode, the axial component is PWSCC.

Note 2" For SG 12 R35C69 mixed mode, the axial component is ODSCC. NDE average depth adjusted for upper 95% uncertainty for mixed mode affects evaluation is 50 2%

instead of 48.6%.

Note 3. All locations where circumferential indications were detected In I R1 I were previously inspected in 1 R1 0 If a growth rate is indicated, the 1RI0 lookup evaluation detected degradation. If NDD is indicated, the 1R1 0 lookup evaluation did not detect degradation Note 4: BWT is the location (in inches) of the bottom of the WEXTEX transition relative to the top of tubesheet 3-22

Enclosure 3 PG&E Letter DCL-02-098 Figure 1, IDIOD Flaw Interaction 0

HOOP tttftttt

!l-- d, -- Ii Tube ID T ; A-A Tube OD L;

-;;ý444ý OYHOOP F

ffiŽ~ X TR A-A TLIGAVG V = 'LIG AVG L Y-Vertical Forces = 0 F=V 3-23

Enclosure 4 PG&E Letter DCL-02-098 SPECIAL REPORT 02-02 RESULTS OF STEAM GENERATOR VOLTAGE-BASED ALTERNATE REPAIR CRITERIA INSPECTIONS AT TUBE SUPPORT PLATE INTERSECTIONS (GENERIC LETTER 95-05)

DIABLO CANYON POWER PLANT UNIT I ELEVENTH REFUELING OUTAGE

20697-6 2/2002)

A CALCULATION

SUMMARY

SHEET (CSS)

FRAMATOME ANP Document Identifier 86 - 5019218 - 00 Title DCPP UNIT 1 RI1 90 DAY BOBBIN COIL ARC REPORT PREPARED BY: REVIEWED BY:

METHOD: Z DETAILED CHECK n INDEPENDENT CALCULATION NAME AM BROWN NAME JM FLECK SIGNATURE Vieft".., *.,, SIGNATURE f

TITLE ENGR IV DATE 8/19/02 TITLE MGR, SG INT ENG DATE 8/19/02 TM STATEMENT:

COST CENTER 12742 REF.

PAGE(S) 67-68 REVIEWER INDEPENDENCE C 5 P.. 'c PURPOSE AND

SUMMARY

OF RESULTS:

This report summarizes the Diablo Canyon Unit I - I R11 May 2002 inspection of the steam generator tubing with respect to the implementation of the Voltage-based Repair Criteria as specified in NRC Generic Letter 95-05. This document provides the projected probability of burst and leak rate calculations needed for submittal to the NRC. This report provides a non proprietary summary of the results. The supporting proprietary calculations and necessary code verifications required for safety-related calculations are contained in Ref. 19.

THE FOLLOWING COMPUTER CODES HAVE BEEN USED IN THIS DOCUMENT: THE DOCUMENT CONTAINS ASSUMPTIONS THAT MUST BE VERIFIED PRIOR TO USE ON SAFETY RELATED WORK CODENERSIONIREV CODENERSION/REV BURST97/1.0/01 LEAKER97/2.0/01 r-_ YES Z NO Page 1 of 68

86-5019218-00 Page 2 of 68 RECORD OF REVISIONS Revision Number Affected Page(s) Description of Change(s) 0 All Original Release

86-5019218-00 Page 3 of 68 TABLE OF CONTENTS 1.0 Introduction ..................................................................................................................................... 6 2.0 Executive Sum mary ........................................................................................................................ 6 3.0 EO C-1 1 Inspection Results and V oltage Grow th Rates ............................................................ 7 3.1 EO C-1 1 Inspection Results ..................................................................................................... 7 3.2 V oltage Growth Rates ........................................................................................................ 9 3.3 Probe W ear Criteria .................................................................................................................. 10 3.4 Upper V oltage Repair Limit ................................................................................................ 12 3.5 NDE U ncertainty D istributions ............................................................................................. 12 4.0 Database and Methods Applied for Leak and Burst Correlations ............................................ 43 4.1 Conditional Probability of Burst .......................................................................................... 43 4.2 Conditional Leak Rate .............................................................................................................. 44 5.0 Bobbin V oltage D istributions ................................................................................................... 46 5.1 Probability of Detection ........................................................................................................ 46 5.2 Probability of Prior Cycle D etection .................................................................................... 46 5.3 Calculation of BO C-12 V oltage D istributions ...................................................................... 47 5.4 Predicted EOC-12 V oltage D istributions ............................................................................. 47 5.5 Comparison of Predicted and Actual EOC-1 1 Conditions ................................................... 48 6.0 Tube Leak Rate and Tube Burst Probabilities .......................................................................... 65 6.1 Leak Rate and Tube Burst Probability for EO C-12 ............................................................... 65 6.2 Sum m ary and Conclusions .................................................................................................. 65 7.0 References ..................................................................................................................................... 67

86-5019218-00 Page 4 of 68 LIST OF TABLES Table 3-1: 1R 11 DOS Indications > 2.0 volts (Active Tubes) ............................................................ 13 Table 3-2: 1R1 AONDB Indications ................................................................................................ 14 Table 3-3: Summary of Inspection and Repair for Tubes ................................................................... 17 Table 3-4: Summary of Largest Voltage Growth Rates per EFPY ..................................................... 18 Table 3-5: Voltage and Growth Distribution by TSP .......................................................................... 19 Table 3-6: Summary of Voltage Growth per EFPY ............................................................................ 20 Table 3-7: Voltage Dependent Growth (BOC-1 1 Voltage < 0.50 Volts) ............................................ 21 Table 3-8: Voltage Dependent Growth (BOC-1 1 Voltage > 0.50 Volts) ............................................ 22 Table 3-9: Summary of Growth Used for Monte Carlo Simulations .................................... 23 Table 3-10: Growth Distributions Used for Monte Carlo Simulations ............................................... 24 Table 3-11: Re-tested DOSs > 1.5 Volts that Failed the Probe Wear Check ..................................... 25 Table 3-12: New IRI 1 DOSs >=0.5 Volts In Tubes Inspected With A Worn Probe In IRIO ........... 26 Table 3-13: Summary of New DOS Indications Sorted by Category ................................................. 30 Table 3-14: Percentage of Tubes With New Indications ..................................................................... 31 Table 3-15: Average Growth Rates for Cycle 11 ................................................................................ 31 Table 3-16: NDE Uncertainty Distributions ....................................................................................... 32 Table 4-1: Tube Burst Pressure vs. Bobbin Amplitude Correlation ................................................... 43 Table 4-2: ,7/8" Tube Probability of Leak Correlation ........................................................................ 44 Table 4-3: "Leak Rate Database for 7/8" Tube ARC Applications (2405 psi) ..................................... 45 Table 5-1: Diablo Canyon Unit 1 POPCD Evaluation ....................................................................... 49 Table 5-2: SG 1 As-Found and BOC-12 Voltage Distribution ........................................................... 50 Table 5-3: SG12 As-Found and BOC-12 Voltage Distribution ........................................................... 51 Table 5-4: SG13 As-Found and BOC-12 Voltage Distribution ........................................................... 52 Table 5-5: SG14 As-Found and BOC-12 Voltage Distribution ........................................................... 53 Table 5-6: Projected EOC-12 Distributions with POD=0.6 ................................................................. 54 Table 5-7: EOC-1 1 As-Found vs Projected Voltage Distribution ...................................................... 55 Table 5-8: EOC- 1I Projected vs Actual POB & Leak Rate ................................................................. 56 Table 6-1: Leak Rate and Burst Probability Using 0.6 POD ............................................................... 66

86-5019218-00 Page 5 of 68 Glossary of Acronyms Term Definition AONDB Axial ODSCC Not Detected by Bobbin ARC Alternate Repair Criteria BOC Beginning of Cycle CPDF Cumulative Probability Distribution Function CFR Code of Federal Regulations CLT Cold-Leg Thinning DCPP Diablo Canyon Power Plant DIS Distorted ID Support Signal with possible Indication DOS Distorted OD Support Signal with possible Indication DNF Degradation Not Found EFPD Effective Full Power Day EFPY Effective Full Power Year ECT Eddy Current Test EOC End of Cycle FS Free Span FRA-ANP Framatome Advanced Nuclear Power GL NRC Generic Letter 95-05 GPM Gallons per Minute ISI In-service Inspection LRL Lower Repair Limit MSLB Main Steam Line Break NDE Non Destructive Examination NDD No Degradation Detected NRC Nuclear Regulatory Commission ODSCC Outside Diameter Stress Corrosion Cracking PG&E Pacific Gas and Electric Company POB Probability of Burst POD Probability of Detection POPCD Probability of Prior Cycle Detection POL Probability of Leak PWSCC Primary Water Stress Corrosion Cracking RPC Rotating Pancake Coil RSS Retest Support Plate Signal RTS Return to Service SG Steam Generator SER Safety Evaluation Report TS Technical Specification TSP Tube Support Plate WEXTEX Westinghouse Explosive Tubesheet Expansion

+Point Plus Point Coil

86-5019218-00 Page 6 of 68 1.0 Introduction The Diablo Canyon Power Plant (DCPP) Unit 1 completed the eleventh cycle of operation and subsequent steam generator ISI in May 2002. The unit employs four Westinghouse-designed Model 51 SGs with 7/8-inch OD mill annealed alloy 600 tubing and 3/4-inch carbon steel drilled hole tube support plates.

In accordance with the Generic Letter 95-05, ARC implementation requires a pre-startup assessment (Ref. 1) and a 90-day post-startup tube integrity assessment. The NRC Generic Letter 95-05, Ref. 2, outlines an alternate repair criterion (ARC) for allowing tubes containing ODSCC indications to remain in service if the indications are contained within the TSP structure and the measured Bobbin voltage is <2.0 volts. A complete list of exclusion criteria is provided in section 1.b of Ref. 2 and in Ref. 3. The NRC has approved implementation of the voltage-based repair criteria at both DCPP units per Ref. 3. The steam generator TSP ISI results and the postulated MSLB leak rate and tube burst probabilities are summarized in this report. FRA-ANP uses Monte Carlo codes, as described in Refs. 4 and 5, to provide the burst and leak rate analysis simulations. These evaluations are based on the methods in Ref. 6 (for burst) and the new slope sampling method for calculating the leak rate as defined in Ref. 21. The correlation parameters used in the simulations are taken from the March 2002 update (Ref. 20) to Addendum 4 of the EPRI ODSCC ARC Database (Ref. 10).

2.0 Executive Summary Based on the number of indications and the size of the indications, SG 1-1 is predicted to be the limiting generator for Diablo Canyon Unit 1 at the end of Cycle 12. During Cycle 11, SG 1-1 started experiencing voltage dependent growth, where the larger indications were growing faster as measured by voltage. Of the 270 plus point inspections of DOS (distorted OD support signal) indications, 249 were confirmed yielding an overall confirmation rate of about 92%. Based on the plus point confirmation rate, approximately 800 tubes were saved by the implementation of the ARC during 1R1 1.

The leak rate and burst pressure correlations used were based on the latest NRC approved database for 7/8" tubing (Ref. 20). The limiting EOC-12 SLB leak rates (SG 1-1) predicted with constant POD were 1.11 gpm (Normal growth) and 1.14 gpm (voltage dependent growth), where both predictions meet the limit of 10.5 gpm for a full cycle of operation. The tube burst probabilities with constant POD for the limiting generator (SG 1-1) were 6.89 x 10-5 (normal growth) and 1.17 x 104 (voltage dependent growth), which is well below the NRC reporting guideline of 1.0 x 10.2.

A total of 924 DOS indications were found in active tubes during the EOC- 11 inspection, of which 137 were over 1 volt, and 11 were over 2 volts. All indications over 2 volts were confirmed by plus point inspection and repaired by plugging. 98 additional indications in active tubes were identified as AONDB (axial ODSCC not detected by bobbin). All of the inferred voltages for these indications were less than 1 volt. None of the detected DOS or AONDB indications exceeded the upper repair limit of 6.36 volts.

86-5019218-00 Page 7 of 68 In addition to the indications in the active tubes, there were also indications detected in tubes that were deplugged. During the IR 1I outage, 150 tubes in SG 1-2 were deplugged for potential return to service by applying the various ARCs that are approved for DCPP. A total of 34 DOS and 60 AONDB indications were detected in the deplugged tubes, of which 17 DOS and 10 AONDB indications were returned to service under ARC. 53 of the 150 tubes had to be replugged, mostly due to ID and OD axial indications detected at the same TSP intersection. As a result, only 17 DOS and 10 AONDB indications were deplugged and subsequently returned to service. Only one of the deplugged indications returned to service was greater than 1 volt.

The EOC-1 1 projections for leak rate and probability of burst exceeded the as-found conditions by a relatively wide margin for all steam generators. SG 1-1 experienced voltage dependent growth over the previous cycle; however, it was not significant enough to invalidate the projections from the previous 90-day report.

3.0 EOC-11 Inspection Results and Voltage Growth Rates 3.1 EOC-11 Inspection Results The DCPP 1R 11 bobbin coil inspection consisted of a 100% complete full-length bobbin coil examination of tubes in all four steam generators except Rows 1 and 2 U-bends. 0.720" replaceable feet bobbin probes were used for the straight length examinations including all TSP intersections in the hot and cold legs except for the 07H intersection in SG 1-4 Tube 7-89. This intersection was inspected with a 0.700" bobbin probe because a large dent would not permit a 0.720" probe to pass. There was no DOS indication reported at the intersection. Special interest plus point TSP examinations were conducted as follows in support of the voltage-based ARC, as specified in Reference 9.

• 100% of DOS greater than 2 volts

• 100% of DOS in tubes deplugged in 1RI I

• 100% of DOS in dented intersections)

• 100% of DIS (distorted ID support signal at dented intersection) 0 Greater than 2 volt dent examinations based on NRC-approved criteria

• Other Special Interest programs, such as free span dings that may also inspect TSP intersections Based upon the 100% bobbin inspection of all steam generators, a total of 924 DOS indications and 98 AONDB indications were identified in active tubes. An additional 17 DOS indications and 10 AONDB indications were detected in tubes that were deplugged and returned to service in SG 1-2. The results of the inspections are summarized as follows:

1. Table 3-1 lists the DOS indications that were above the LRL (2.0 volts). Each of the indications was confirmed as ODSCC and was repaired by plugging.

2. Five circumferential ODSCC indications and two circumferential PWSCC indications were detected at dented support plates in active tubes and were plugged. All of the dent voltages exceeded 2 volts.

86-5019218-00 Page 8 of 68

3. Table 3-2 lists the indications that were identified as AONDB (axial ODSCC not detected by bobbin) in active tubes and in deplugged tubes returned to service. These indications have axial ODSCC but with no indication of a bobbin DOS signal. These locations are typically smaller voltage ODSCC, by plus point, and are accompanied by a dent that masks the bobbin voltage with one exception. Tube 27-83 in SG 1-2 has an AONDB associated with an SPR (Support Plate Residual) call. Per Refs. 8 and 9, a methodology has been developed to assign a bobbin voltage based on a correlation to the plus point voltage (Ref. 17). Once the calculated voltages are obtained, the locations are subjected to the same exclusion criteria as the DOS population, per Ref. 12. All of the inferred voltages were less than 1 volt. The repair limits for the AONDB indications are 2.00 volts for the dented intersections and 1.00 volt for the SPR intersections.

4. Seven DOS indications in the cold leg thinning (CLT) region were included in the DOS analysis pool. These indications were inspected with plus point and were not confirmed as CLT or ODSCC.

5. Overall, 65 DOS/AONDB indications in 57 active tubes were repaired during R1R1 (including all damage mechanisms for which tube repair is required).

6. There were additional 17 DOS and 50 AONDB indications that were deplugged and subsequently replugged in SG 1-2. These indications do not factor into this analysis since they were not in service before or after the R1R1 outage and not subject to condition monitoring and operational assessment.

Table 3-3 summarizes the TSP voltage distributions for the as-found condition of the indications, the repaired indications, the indications returned to service that were either confirmed by plus point or not inspected with plus point, and finally, the total indications returned to service.

Eleven confirmed DOS were repaired because they exceeded the 2 volt repair limit. The other main reasons for repair included the wedge exclusion criterion, combined ID/OD degradation at the same intersection, and AONDB at intersections with dents greater than 5 volts.

The plus point inspections required for DOS indications were accomplished as a part of the special interest exams. The 1R1 1 plus point inspection scope also included greater than 2 volt dents based on criteria in the degradation assessment (Ref. 9). 270 plus point inspections were performed where DOS indications were called by bobbin, i.e., excluding the AONDB intersections. Of these inspections, 249 were confirmed yielding an overall confirmation rate of about 92%. Based on the plus point confirmation rate, approximately 800 tubes were saved by the implementation of the ARC during IRI 1.

Figures 3-1 and 3-2 show the actual bobbin voltage distribution for all tubes that were in service during Cycle 11. Figure 3-3 shows the voltage distribution for the indications in the tubes in SG 1-2 which were deplugged and returned to service. Figures 3-4 and 3-5 show the indications removed from service at EOC-1 1. Figure 3-6 and Figure 3-7 illustrate all the indications returned to service following the EOC-1 1 ECT inspection. Note that SG 1-1 and SG 1-2 have larger quantities of indications being returned to service compared to the other steam generators.

Table 3-1 shows all of the indications greater than the 2 volt lower repair limit. All of these indications were confirmed as axial ODSCC and were removed from service by plugging.

86-5019218-00 Page 9 of 68 The TSP voltage distribution is provided in Table 3-5. Table 3-5 and Figure 3-8 show that the ODSCC mechanism is most active at the lower hot leg TSPs, and the number of indications tends to decrease as a function of higher TSP elevations. This distribution shows the temperature dependence of ODSCC.

3.2 Voltage Growth Rates For projection of leak rates and tube burst probabilities at the end of Cycle 12 operations, voltage growth rates were developed from the EOC-1 1 inspection data. For indications not reported during the EOC-10 inspection (i.e. new at EOC-1 1), the indications were sized using the EOC-10 ECT signals based on a lookup review. There were 500 newly reported DOS indications in 1Ril. Of these 500 new indications, 494 were detected during the 1RiO lookup and were assigned a IRIO voltage. The remaining 6 indications were not detectable during the lookup and were, therefore, not included in the growth rate calculations. Table 3-4 provides a summary of indications with the largest growth during cycle 11. Table 3-5 provides the maximum and average voltage growth distribution by TSP. Table 3-6 shows the voltage growth distributions for each SG and the composite for all four SGs. The cumulative probability distribution function is also provided here. Figures 3-9 and 3-10 show the voltage growth distributions depicted in bar charts. For the tube integrity calculations, the negative growth values were included as zero growth rates as required by Generic Letter 95-05. Reviewing the average and maximum voltage growth for all indications for each SG shows that the ODSCC mechanism is most active in SG 1

1. This assumption is also supported by reviewing Table 3-6 and Figures 3-9 and 3-10. As shown in the table and figures, four of the five largest growth rates occurred in SG 1-1.

In order to illustrate any dependency of growth on the BOC voltage, the growth rates were plotted against the BOC voltage for all steam generators. This data is shown in Figures 3-11 and 3-12. Based on the slope of the regression lines in these figures, SG 1-1 is the only steam generator that may be experiencing voltage dependent growth. In accordance with the recommended procedure in Ref. 16, different growth distributions were developed for specific ranges of BOC voltages. Tables 3-7 and 3-8 contain the two different sets of growth rates based on BOC voltages. Figure 3-13 shows the growth rate distributions for three different ranges of BOC voltages (<=0.50V, 0.51V to 1.OOV, and >1.OOV). This figure includes data from all four steam generators. As shown in the figure, there is a consistent shift toward higher growth for the larger BOC voltages. Similar charts were prepared for each steam generator individually. SG I 1 was the only steam generator that showed a bias toward voltage dependent growth. This chart for SG 1-1 is shown in Figure 3-14.

For the voltage dependent growth distributions for SG 1-1, two different categories of BOC voltages were defined (<=0.50V and >0.50V). Using a 0.50 volt breakpoint gives 124 indications in the >0.50V bin. Per Ref. 16, the upper voltage bin should include about 200 indications when a constant POD of 0.6 is being used. For Diablo Canyon's case, however, if the breakpoint is lowered such that 200 indications are in the upper voltage bin, then the voltage dependency effect is lessened. Therefore, 0.50 volts was used since there is still a significant population of indications in this category and the voltage dependency is still evident. In accordance with the recommended procedure in Ref. 16, the three largest growth values among all steam generators should be included in the growth distributions (if not already included in the SG-specific data). For Diablo Canyon Cycle 11, one of the three largest growth values occurred in SG 1-2. Therefore, this growth value (1.1 V/EFPY) was added to the voltage dependent

86-5019218-00 Page 10 of 68 growth distribution for SG 1-1 before running the leak rate and probability of burst calculations.

The other two of the three largest growth values occurred in SG 1-1 and were, therefore, already included in the distribution. Table 5-6 gives a summary of the growth distributions that were used in the Monte Carlo simulations for each steam generator.

There were 14 DOS indications detected in tubes that were deplugged and returned to service in IR1O. Some plants have seen higher growth rates for deplugged tubes in the first cycle of operation compared to the continuously active tube population. This phenomenon has not been observed at DCPP based on past experience: 52 ODSCC indications were deplugged and returned to service in 1R9, and subsequent Cycle 10 growth rates of the indications were bounded by the active population. To once again demonstrate that this phenomenon is not occurring at DCPP, the Cycle 11 growth distributions for the 14 1R10 deplugged indications were compared with the Cycle 11 growth distributions for the active tubes. Figure 3-15 shows these distributions. As shown in the figures, the deplugged tube growth distribution is bounded by the growth distribution for the active tubes. Therefore, the deplugged and active tube growth distributions were combined for the leak rate and probability of burst projections.

Per the Generic Letter, growth distributions should be determined for each of the last two inspection cycles. The most limiting of the two growth distributions should be used. Figure 3 16 shows the growth distributions for the last two inspection cycles for Diablo Canyon Unit 1.

As shown in the figure, the growth distribution for Cycle 10 bounds the growth distribution for Cycle 11. However, the SG-specific growth distributions for Cycle 10 all contain less than 200 indications. Therefore, per the Generic Letter, the growth distributions for the two cycles should be combined. For SGs 1-1, 1-2, and 1-3, the combined growth distributions contain the minimum of 200 indications and were, therefore, used in the leak rate and POB projections.

For SG 1-4, the combined growth distribution from Cycles 10 and 11 contained less than 200 indications. Therefore, the data for all steam generators were combined to obtain a Cycle 10 and a Cycle 11 growth distribution for all steam generators combined. The Cycle 10 growth rate is bounding for the smaller growth bins. However, in the upper tails of the distributions, Cycle 11 is bounding. Therefore, the CPDF values from Cycle 10 were used for growth bins up to 1.1 volts inclusively, and for the growth bins above 1.1 volts, the CPDF values from the Cycle 11 growth distribution were used. Table 3-9 provides a summary of the growth distributions that were used for the EOC-12 leak rate and probability of burst projections. Table 3-10 provides the CPDF values for the growth distributions used in the EOC-12 projections.

3.3 Probe Wear Criteria The first NRC requirement regarding probe wear is to minimize the potential for tubes to be inspected with a probe that had failed the probe wear check. This was accomplished by implementing ETSS #1 (Ref. 11) which required the probe have its feet replaced when failing the probe wear check, or in the case of non-changeable feet probes, the probe discarded.

If the DOS voltage is at the retest threshold (1.5 volts or higher) and the Cal is designated as "ARC Out" on the cal board, the indication code is changed from a DOS to an RSS (retest support plate signal). No new indications were detected in the tubes when inspected with the new probe.

86-5019218-00 Page 11 of 68 The 1RI1 eddy current inspection resulted in 19 bobbin indications in excess of 1.5 volts that were inspected with a worn probe. Those indications are shown in Table 3-11. The RSS and DOS voltage variation was tabulated for each worn probe inspection. The retest voltage values compare reasonably with the worn probe voltages. The largest increase in voltage compared to the worn probe voltage was 15.1%. Figure 3-17 shows a comparison of the worn probe and good probe voltages. This figure shows that the voltages do not change significantly between the worn probes and the good probes. Therefore, continued use of the 1.5 volt retest threshold is justified (Ref. 13).

All RSS bobbin indications were inspected in accordance with the Ref. 11 analysis guidelines.

Review of the probe wear log sheets and the eddy current test results indicate that no tubes were inspected with a probe known to have failed the probe wear check. These reviews in conjunction with the results in Table 3-11 address the NRC requirements listed in Ref. 15.

The next requirement involves monitoring tubes that contain new DOS indications that were inspected with probes that failed the wear check in the previous outage. This evaluation is intended to look for new large indications or a non-proportionately large percentage of new indications in tubes that failed the check in the previous outage. Large is defined as > 0.5 volt DOS. The new IRI I >= 0.5 volt DOS indications in tubes that failed the probe wear check in IR10 are shown in Table 3-12.

Overall there were 924 DOS indications detected in the 1RI 1 inspection of the active tube population. 500 or -54% of the DOS indications were new indications. In order to assess the new indications against the probe wear requirements, Table 3-13 is presented. Of the 500 total new indications, 303 were in tubes inspected with a worn probe in IR1O and 197 were in tubes inspected with a good probe in IR10. The number of new indications _>0.5 volts was determined to be 215. Out of these, 138 were in tubes that were inspected with a worn probe in IR10.

When these numbers are compared to the total number of inspections in 1RI0, the results shown in Table 3-14 are obtained. This table shows the approximate percentage of tubes with new indications. The results are categorized based on whether the previous inspection was performed with a worn probe or a good probe. This table shows that about 2.9% of the 1RIO worn probe inspections yielded new indications in IR1i1. This is slightly less than the 3.3 % rate for the tubes inspected with good probes in 1R1O. For the new indications > 0.5 volts, the rates were the same (1.3% for the both worn and good probes).

Since 494 of the 500 newly reported DOS indications were detected during the lookup review of the 1RIO data, probe wear is not considered to be significantly affecting the quality of the data and, therefore, the ODSCC detection capability. In addition, the fact that the rate of new indications is slightly higher for the tubes inspected with good probes in iR1O suggests that detection of these indications is not affected by probe wear.

New indications are more a result of probability of detection rather than the fact that the tube was inspected with a wom probe in IR1O. These percentages are not considered to indicate that a disproportionate number of new DOSs are present in tubes that were inspected with a worn probe in the previous outage. In summary, the NRC analysis requirements regarding probe wear monitoring were met during the IRI 1 bobbin coil inspection and a more stringent wear tolerance is not required.

86-5019218-00 Page 12 of 68 3.4 Upper Voltage Repair Limit Per Generic Letter 95-05, the upper repair limit must be calculated prior to each outage, and the more conservative of the plant-specific average growth rate per EFPY or 30 percent per EFPY should be used as the anticipated growth rate input for this calculation. The upper voltage repair limit was calculated prior to the 1R11 inspection and was determined to be 6.36 volts (Ref. 12) based on the following formula. This calculation used a 32.8 percent per EFPY growth based on the IR10 90-day report (Ref. 7).

VSL VURL =

% VNDE  % VCG 1+ +

100 100 where: VuRL = upper voltage repair limit, VNDE = NDE voltage measurement uncertainty = 20%,

VcG= voltage growth anticipated between inspections = 32.8%/EFPY x 1.61 EFPY = 52.8%,

VSL = voltage structural limit from the burst pressure - Bobbin voltage correlation, where the limit of 11.0 volts was used based on Ref. 20.

Although the upper repair limit will not be calculated again until shortly before the next inspection, the average growth rates from Cycle 11 are documented in this report to verify the limiting growth rate to be used for the 1R12 outage. Table 3-15 shows the average growth values for each steam generator as well as the average growth for all steam generators combined.

As shown in the table, the average growth for all steam generators combined was 19.8% per EFPY. Since this value is less than the NRC minimum limit of 30% per EFPY, the NRC minimum value should be used when calculating the upper repair limit for 1R12.

3.5 NDE UncertaintyDistributions NDE uncertainties must be taken into account when projecting the end-of-cycle voltages for the next operating cycle. The NDE uncertainties used in the calculations of the EOC-12 voltages are described in Ref. 6. The acquisition uncertainty was sampled from a normal distribution with a mean of zero, a standard deviation of 7%, and a cutoff limit of 15% based on the use of the probe wear standard. The analyst uncertainty was sampled from a normal distribution with a mean of zero, a standard deviation of 10.3%, and no cutoff limit. These uncertainty distributions are shown in Table 3-16 and Figure 3-18.

86-5019218-00 Page 13 of 68 Table 3-1: IRll DOS Indications > 2.0 volts (Active Tubes)

SG Row Col Ind Elev Volts 2 46 DOS 1H 3.23 4 67 DOS 1H 2.64 27 47 DOS 1H 2.26 30 32 DOS 1H 2.4 4 48 DOS 1H 2.8 6 53 DOS 1H 2.11 SG12 20 87 DOS 1H 2.14 22 43 DOS 1H 2.25 40 27 DOS 1H 2.33 SG13 33 40 DOS 1H 2.4 SG14 8 29 DOS iH 2.33

86-5019218-00 Page 14 of 68 Table 3-2: iR1l AONDB Indications Dent Plus Pt Assigned DOS Elev Voltage Voltage Voltage SG11 8 69 1H 1.09 0.1 0.42 SG11 8 69 1H 1.09 0.15 0.47 SG11 8 69 1H 1.09 0.25 0.57 SGII 11 15 3H 2.2 0.17 0.49 SGI1 14 12 2H 9.15 0.11 0.43 SGI1 14 62 2H 0.62 0.14 0.46 SGII 16 79 2H 0.73 0.15 0.47 SGIl 19 61 1H 0.45 0.14 0.46 SGI1 19 61 1H 0.45 0.24 0.56 SGII 22 71 2H 0.83 0.16 0.48 SGI 1 23 58 3H 0.38 0.1 0.42 SG1I1 24 20 2H 1.43 0.22 0.54 SG1I 24 51 1H 0.53 0.21 0.53 SG1I1 27 44 2H 4.39 0.11 0.43 SGII 36 30 2H 0.56 0.18 0.50 SGII 36 30 2H 0.56 0.22 0.54 SG11 38 54 2H 3.16 0.23 0.55 SG11 41 68 2H 0.42 0.11 0.43 SG1I 41 68 2H 0.42 0.18 0.50 SG1I 42 50 4H 0.7 0.12 0.44 SGI2 5 20 6H 2.4 0.13 0.45 SG12 6 49 IH 2.54 0.16 0.48 SGI2 6 81 1H 3.75 0.2 0.52 SG12 7 65 2H 1.46 0.14 0.46 SG12 8 17 1H 3.05 0.16 0.48 SG12 8 67 1H 1.2 0.14 0.46 SG12 8 81 1H 8.02 0.17 0.49 SGI2 9 66 2H 6.4 0.12 0.44 SG12 9 70 11H 6.33 0.23 0.55 SG12 9 70 1H 6.33 0.14 0.46 SG12 10 43 11H 1.64 0.24 0.56 SGI2 10 45 2H 1.62 0.15 0.47 SG12 11 18 2H 3.41 0.22 0.54 SG12 11 75 2H 4.36 0.22 0.54 SG12 12 76 1H 2.92 0.14 0.46 SG12 13 66 2H 3.28 0.17 0.49 SG12 13 83 3H 2.59 0.13 0.45 SG12 13 83 3H 2.59 0.13 0.45 SG12 13 83 5H 2.3 0.28 0.60 SG12 13 83 5H 2.3 0.23 0.55 SG12 14 76 11H 2.27 0.34 0.66 SG12 14 84 2H 2 0.18 0.50 SG12 16 73 1H 18.03 0.19 0.51 SG12 17 45 1H 4.2 0.16 0.48 SG12 18 22 1H 3.13 0.11 0.43

86-5019218-00 Page 15 of 68 Table 3-2: 1R1l AONDB Indications (cont'd) 1 1 Assigned DOS SG SG12

[ Row 19 I

Col 57 I E 2H Dent Voltage 2.15 Plus Pt Voltage 0.32 Voltage 0.64 SG12 19 85 2H 3.06 0.32 0.64 SG12 19 85 2H 3.06 0.15 0.47 SG12 20 72 1H 2.42 0.12 0.44 SG12 20 83 1H 2.69 0.18 0.50 SG12 21 32 1H 2.43 0.22 0.54 SG12 22 54 7H 2.54 0.31 0.63 SG12 22 62 2H 4.38 0.32 0.64 SG12 22 83 1H 2.79 0.12 0.44 SG12 23 71 2H 2.13 0.13 0.45 SG12 23 71 2H 2.13 0.16 0.48 SGI2 25 72 11H 2.06 0.15 0.47 SG12 27 50 1H 1.95 0.19 0.51 SG12 27 66 2H 2.32 0.15 0.47 SG12 27 83 2H SPR/2.17V 0.21 0.53 SG12 28 36 2H 1.77 0.2 0.52 SG12 29 49 3H 2.45 0.14 0.46 SG12 29 69 11H 3.74 0.19 0.51 SG12 30 16 11H 0.9 0.32 0.64 SG12 31 44 4H 2.29 0.12 0.44 SG12 31 62 11H 2.34 0.16 0.48 SG12 31 80 4H 4.84 0.17 0.49 SGI2 32 57 2H 5.15 0.24 0.56 SG12 33 40 1H 0.28 0.2 0.52 SG12 34 57 4H 2.99 0.23 0.55 SG12 36 53 1H 2.82 0.15 0.47 SG12 36 53 1H 2.82 0.2 0.52 SG12 39 70 11H 2.54 0.16 0.48 SG12 41 54 3H 2.47 0.17 0.49 SG12 42 28 2H 1.41 0.28 0.60 SG13 6 36 1H 3.19 0.21 0.53 SG13 8 77 11H 5.52 0.14 0.46 SGI3 11 50 1H 7.21 0.18 0.50 SG13 19 80 11H 3.41 0.12 0.44 SG13 25 82 11H 3.03 0.15 0.47 SG13 27 49 1H1 2.32 0.11 0.43 SG14 2 50 2H 5.57 0.19 0.51 SG14 3 44 11H 0.8 0.16 0.48 SG14 5 72 2H 2.97 0.12 0.44 SG14 7 31 1H 26.33 0.11 0.43 SG14 9 37 1H 2.1 0.25 0.57 SG14 11 46 1H 2.46 0.16 0.48 SG14 11 46 11H 2.46 0.12 0.44 SGI4 13 6 2H 2.92 0.36 0.67 SG14 13 10 2H 1.96 0.13 0.45

86-5019218-00 Page 16 of 68 Table 3-2: 1R1l AONDB Indications (cont'd) w C Dent Plus Pt Assigned DOS SG Voltage Voltage Voltage SG14 13 31 111 2.14 0.09 0.41 SG14 13 51 1H 1.57 0.1 0.42 SG14 14 34 1H 2.58 0.31 0.63 SG14 15 29 1H 2.64 0.19 0.51 SG14 15 47 1H 2.66 0.17 0.49 SG14 16 65 2H 2.51 0.11 0.43 SGI4 17 32 1H 2.3 0.37 0.68 SG14 17 45 1H 9.03 0.25 0.57 SGI4 19 32 IH 4.02 0.32 0.64 SGI4 19 40 1H 3.57 0.11 0.43 SG14 21 51 1H 3.19 0.11 0.43 SG14 22 55 1H 5.93 0.24 0.56 SGI4 24 62 11H 2.03 0.12 0.44 SG14 25 60 1H 2 0.28 0.60 SG14 30 59 1H 2.46 0.21 0.53 SG14 33 58 1H 4.05 0.32 0.64 SG14 36 47 1H 3.66 0.32 0.64 SG14 42 32 1H 8.85 0.18 0.50

86-5019218-00 Page 17 of 68 Table 3-3: Summary of Inspection and Repair for Tubes Liii StiII SU SGI212 SG13 DOSs Returned to Service As -Found uRep C oDOSs n f O DReturned S C C o r to Service Total (I)

Vo ltag e As-F ou nd Repai ren dA R e saired O S eo r vice ( 2)

Bi EOC- I I Tubes Conf OD-SCC or Total () EOC-I Tbes Cf OD-SCC or Total IITubes TotaTube)

Not Insp w (Active) Not Inp wf+Pt Not Imp w t 0__1 9 _ _ _ _1 I_ _

02 9 9 9 8 I 9 9 3 3 3 03 49 1 47 48 21 I 20 20 II II II 04 62 62 62 29 32 32 19 19 19 05 81 3 76 78 71 7 68 70 28 2 24 26 06 66 3 62 63 71 7 71 72 20 2 16 18 07 41 3 37 38 34 2 33 34 16 1 15 15 08 24 1 23 23 32 2 29 31 10 1 9 9 09 21 1 19 20 14 13 16 8 t8 8 1 19 2 17 17 15 2 15 15 7 7 7 11 13 1 12 12 11 10 II 9 9 9 12 8 8 8 5 6 6 5 5 5 13 7 2 5 5 3 3 3 8 8 8 14 6 6 6 9 9 9 2 2 2 15 2 2 2 3 3 3 1 1 1 16 2 2 2 3 3 3 I I 1 17 2 2 2 I I I 18 3 3 3 2 2 2 2 2 2 19 I 1 3 3 3 2 1 I 1 3 3 3 2 1 22 2 2 23 1 11 1 24 1 1 1 1 1 25

>25 2 2 1 1 Total 420 21 393 399 338 29 326 336 158 7 147 151

>IV 48 7 41 41 42 6 36 37 36 1 35 35

>2V 4 4 5 5 1 1

'I - ___ ___..........r

.... - - - - - -- - - i _ _ _ _ _ _ _ _

SG. 14 C*.omp)osite of All *Ss DOSs Returned to Service DOSs Returned to Service Votage B

As-Found I EOC-1 [O-Repaired ue Tubes CofO-C Notf OD-SCC or NBin Nonsp wf+Pt rAs-Found

____n[

Total (1) EOC-i I Repaired Tubes Cn DSCo D-SCCor Not Insp1 w+PtI Total (I) 01 1 I 02 7 7 7 27 I 28 28 03 9 9 9 90 2 87 88 04 20 20 20 130 133 133 05 18 I 17 17 198 13 185 191 06 18 4 14 14 175 16 163 167 07 10 1 9 9 101 7 94 96 08 8 1 7 7 74 5 68 70 09 4 4 4 47 1 44 48 1 1 42 4 40 40 II1 31 3 3 36 1 34 35 12 1 1 1 19 20 20 13 1 I 1 19 2 17 17 14 1 I I 18 18 18 15 ______6 6 6 16 6 6 6 17 1 I I 4 4 4 18 2 2 2 9 - 9 9 19 4 1 3 3 2 1 I I 5 5 5 21 22 2 2 23 2 2 24 1 I 4 4 25 ______

>25 3 3 Total 106 8 98 98 1022 65 964 984

>IV 11 1 ID 10 137 15 122 123

>2V I I II II (1) Total includes all DOS/AONDB indications returned to service (confirmed, not inspected, and not confirmed with Plus Point)

(2) DOSs returned to service for SGI2 includes tubes that were deplugged dunng the IRI I outage

86-5019218-00 Page 18 of 68 Table 3-4: Summary of Largest Voltage Growth Rates per EFPY S ID IRow Col Elev IVolts Prev Volts Growth/ Plus Pt ew? Deplugged In 1 R10?

EFPY Result 1 0(R10)

SGI1 2 46 IH 3.23 0.94 1.624 SAI Repeat No SG11 4 67 IH 2.64 1 1.163 SAI Repeat No SG12 4 48 IH 2.8 1.38 1.007 SAI Repeat No SG11 30 32 IH 2.4 1.09 0.929 SAI Repeat No SGIl 27 47 IH 2.26 1.14 0.794 SAI Repeat No SG14 3 36 1H 1.79 0.69 0.780 Repeat No SG12 40 27 1H 2.33 1.38 0.674 SAI Repeat No SG12 6 53 1H 2.11 1.17 0.667 SAI Repeat No SGI1 6 61 1H 1.67 0.8 0.617 Repeat No SGI1 17 73 IH 1.96 1.11 0.603 Repeat No SGI 1 20 54 IH 1.8 0.98 0.582 Repeat No SG12 22 43 1H 2.25 1.44 0.574 SAI Repeat No SG1I1 31 38 1H 1.31 0.51 0.567 Repeat No SGI 1 10 71 1H 1.75 0.95 0.567 SAI Repeat No SGI I 18 31 2H 1.2 0.43 0.546 SAI Repeat No SG12 17 47 1H 1.48 0.72 0.539 SAI Repeat No SGII 24 31 1H 1.51 0.77 0.525 Repeat No SGI1 20 47 1H 1.17 0.44 0.518 Repeat No SGI1 36 45 IH 1.38 0.65 0.518 Repeat No SGI2 13 56 IH 1.48 0.75 0.518 Repeat No

86-5019218-00 Page 19 of 68 Table 3-5: Voltage and Growth Distribution by TSP

('rnwth iinit* are vcilts/EFPY Tube Steam Generator 1-1 Tube Steam Generator 1-2 Support Plate No. of Maximum N.o aiu vrg Maximum Average aiu Average vrg Support lt Noooof Maximum aiu vrg Maximum Average aiu Average vrg Indications Voltage Voltage Growth Growth Indications Voltage Voltage Growth Growth 1H 274 323 066 1.62 0.15 IH 207 280 0.69 1.01 0 12 2H 100 1.40 0.55 0 55 0.10 2H 132 1.76 0.59 040 009 3H 28 0.86 044 034 0.07 3H 47 1.59 0.58 0.49 006 4H 9 067 043 0 19 0.07 4H 23 106 0.60 020 003 5H 1 0.80 0 80 0 19 0.19 5H 10 0.95 0.58 0.14 002 6H 1 0 57 057 008 008 6H 8 0.57 0.46 006 001 7H 1 029 029 001 001 7H 1 0.63 0.63 CL 6 069 0.50 0.09 -001 CL 4 0.80 0 51 009 0 03 All Inds 420 3.23 0.61 1.62 0 13 All Inds 432 2.80 063 1 01 0 09 Tube Steam Generator 1-3 Tube Steam Generator 1-4 SupportSupr Plate No. of Maximum Average Maximum Average Support No of Maximum Average Maximum Average Indications Voltage Voltage Growth Growth Indications Voltage Voltage Growth Growth IH 78 240 076 0.46 008 IH 66 2.33 060 0.78 0.11 2H 30 1.54 075 050 006 2H 25 1.91 055 0.30 0.07 3H 20 1.30 0.77 043 007 3H 9 1.17 058 0.26 0.03 4H 9 1.48 0.71 0 19 0.10 4H 4 0.80 078 0.10 0.04 5H 7 1.33 071 0.14 0.02 5H 2 040 0.36 0.13 009 6H 7 1.97 058 010 0.02 6H 7H 1 036 036 009 0.09 7H CL 6 066 049 003 -0.02 CL All Inds 158 2.40 073 050 007 All Inds 106 2.33 0.59 078 0.08 Composite of All Four SGs Tube Support No. of IMaximum Average Maximum Average Plate Indications Voltage Voltage Growth Growth 1H 625 3.23 0.68 1.62 0.13 2H 287 1.91 0.59 0.55 008 3H 104 1.59 0.58 0.49 006 4H 45 1.48 060 020 006 5H 20 1.33 062 019 004 6H 16 1.97 052 010 0.03 7H 3 063 043 009 0.05 CL 16 080 050 009 0.00 All Inds 1116 323 063 1.62 0.10

86-5019218-00 Page 20 of 68 Table 3-6: Summary of Voltage Growth per EFPY Delta SG1I SG12 SG13 SG14 Total Volts No. of CPDF No. of CPDF No. of o. of CPDF No. of CPDF Obs. Obs. Obs. Obs. _ Obs.

<-=-0.5 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000

-0.4 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000

-0.3 0 0.000 0 0.000 1 0.007 0 0.000 1 0.001

-0.2 3 0.008 5 0.017 1 0.013 2 0.026 11 0.013

-0.1 4 0.018 11 0.055 2 0.026 1 0.039 18 0.033 0 71 0.196 58 0.253 35 0.258 17 0.260 181 0.230 0.1 128 0.519 104 0.608 73 0.742 31 0.662 336 0.596 0.2 108 0.791 61 0.816 26 0.914 13 0.831 208 0.822 0.3 39 0.889 34 0.932 5 0.947 10 0.961 88 0.918 0.4 24 0.950 11 0.969 5 0.980 0 0.961 40 0.962 0.5 7 0.967 3 0.980 3 1.000 2 0.987 15 0.978 0.6 7 0.985 3 0.990 0 1.000 0 0.987 10 0.989 0.7 2 0.990 2 0.997 0 1.000 0 0.987 4 0.993 0.8 1 0.992 0 0.997 0 1.000 1 1.000 2 0.996 0.9 0 0.992 0 0.997 0 1.000 0 1.000 0 0.996 1 1 0.995 0 0.997 0 1.000 0 1.000 1 0.997 1.1 0 0.995 1 1.000 0 1.000 0 1.000 1 0.998 1.2 1 0.997 0 1.000 0 1.000 0 1.000 1 0.999 1.3 0 0.997 0 1.000 0 1.000 0 1.000 0 0.999 1.4 0 0.997 0 1.000 0 1.000 0 1.000 0 0.999 1.5 0 0.997 0 1.000 0 1.000 0 1.000 0 0.999 1.6 0 0.997 0 1.000 0 1.000 0 1.000 0 0.999 1.7 1 1.000 0 1.000 0 1.000 0 1.000 1 1.000 1.8 0 1.000 0 1.000 0 1.000 0 1.000 0 1.000 1.9 0 1.000 0 1.000 0 1.000 0 1.000 0 1.000 2 0 1.000 0 1.000 0 1.000 0 1.000 0 1.000

>2 0 1.000 0 1.000 0 1.000 0 1.000 0 1.000 Total 397 NA 293 NA1I1 151 1 NA 77 1 NA II 918 1 NA

86-5019218-00 Page 21 of 68 Table 3-7: Voltage Dependent Growth (BOC-11 Voltage < 0.50 Volts)

SG12 SGI3 SG14 Total Delta SGII Volts No. of CPDF No. of CPDF No. of CPDF No. of CPDF No. of CPD Obs. Obs. Obs. Obs. Obs.

<=-0.5 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000

-0.4 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000

-0.3 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000

-0.2 1 0.004 0 0.000 0 0.000 0 0.000 1 0.002

-0.1 3 0.015 3 0.018 0 0.000 0 0.000 6 0.013 0 47 0.187 25 0.169 13 0.194 13 0.277 98 0.190 0.1 103 0.564 72 0.602 42 0.821 23 0.766 240 0.624 0.2 81 0.861 40 0.843 11 0.985 6 0.894 138 0.873 0.3 25 0.952 23 0.982 1 1.000 5 1.000 54 0.971 0.4 8 0.982 3 1.000 0 1.000 0 1.000 11 0.991 0.5 3 0.993 0 1.000 0 1.000 0 1.000 3 0.996 0.6 2 1.000 0 1.000 0 1.000 0 1.000 2 1.000 0.7 0 1.000 0 1.000 0 1.000 0 1.000 0 1.000 0.8 0 1.000 0 1.000 0 1.000 0 1.000 0 1.000 0.9 0 1.000 0 1.000 0 1.000 0 1.000 0 1.000 1 0 1.000 0 1.000 0 1.000 0 1.000 0 1.000 1.1 0 1.000 0 1.000 0 1.000 0 1.000 0 1.000 1.2 0 1.000 0 1.000 0 1.000 0 1.000 0 1.000 1.3 0 1.000 0 1.000 0 1.000 0 1.000 0 1.000 1.4 0 1.000 0 1.000 0 1.000 0 1.000 0 1.000 1.5 0 1.000 0 1.000 0 1.000 0 1.000 0 1.000 1.6 0 1.000 0 1.000 0 1.000 0 1.000 0 1.000 1.7 0 1.000 0 1.000 0 1.000 0 1.000 0 1.000 1.8 0 1.000 0 1.000 0 1.000 0 1.000 0 1.000 1.9 0 1.000 0 1.000 0 1.000 0 1.000 0 1.000 2 0 1.000 0 1.000 0 1.000 0 1.000 0 1.000

>2 0 1.000 0 1.000 0 1.000 0 1.000 0 1.000 Total 273 NA II 166 [NA ]1 67 1 NA k 47] NA 553 NA

86-5019218-00 Page 22 of 68 Table 3-8: Voltage Dependent Growth (BOC-11 Voltage > 0.50 Volts)

SG11 SG12 SGI3 SG14 Total Volts No. of CPDF No. of CPDF No. of C No. 1 Obs. Obs. Obs. _ Ohs.of D No.

Obsof CPDF

<=-0.5 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000

-0.4 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000

-0.3 0 0.000 0 0.000 1 0.012 0 0.000 1 0.003

-0.2 2 0.016 5 0.039 1 0.024 2 0.067 10 0.030

-0.1 1 0.024 8 0.102 2 0.048 1 0.100 12 0.063 0 24 0.218 33 0.362 22 0.310 4 0.233 83 0.290 0.1 25 0.419 32 0.614 31 0.679 8 0.500 96 0.553 0.2 27 0.637 21 0.780 15 0.857 7 0.733 70 0.745 0.3 14 0.750 11 0.866 4 0.905 5 0.900 34 0.838 0.4 16 0.879 8 0.929 5 0.964 0 0.900 29 0.918 0.5 4 0.911 3 0.953 3 1.000 2 0.967 12 0.951 0.6 5 0.952 3 0.976 0 1.000 0 0.967 8 0.973 0.7 2 0.968 2 0.992 0 1.000 0 0.967 4, 0.984 0.8 1 0.976 0 0.992 0 1.000 1 1.000 2 0.989 0.9 0 0.976 0 0.992 0 1.000 0 1.000 0 0.989 1 1 0.984 0 0.992 0 1.000 0 1.000 1 0.992 1.1 0 0.984 1 1.000 0 1.000 0 1.000 1 0.995 1.2 1 0.992 0 1.000 0 1.000 0 1.000 1 0.997 1.3 0 0.992 0 1.000 0 1.000 0 1.000 0 0.997 1.4 0 0.992 0 1.000 0 1.000 0 1.000 0 0.997 1.5 0 0.992 0 1.000 0 1.000 0 1.000 0 0.997 1.6 0 0.992 0 1.000 0 1.000 0 1.000 0 0.997 1.7 1 1.000 0 1.000 0 1.000 0 1.000 1 1.000 1.8 0 1.000 0 1.000 0 1.000 0 1.000 0 1.000 1.9 0 1.000 0 1.000 0 1.000 0 1.000 0 1.000 2 0 1.000 0 1.000 0 1.000 0 1.000 0 1.000

>2 -0 1.000 0 1.000 0 1.000 0 1.000 0 1.000 Total 1 124 NA 11 1271 NA 84] NA 11 30 ] NA 11 365 1 NA

86-5019218-00 Page 23 of 68 Table 3-9: Summary of Growth Used for Monte Carlo Simulations Growth Distribution SG 1-1 1. SG11-Specific Normal Growth (Combined Cycles 10 and 11)

2. SG11-Specific Voltage-Dependent Growth from Cycle 11 (plus one large growth value from SG 1-2)

SG 1-2 1. SG12-Specific Normal Growth (Combined Cycles 10 and 11)

SG 1-3 1. SG13-Specific Normal Growth (Combined Cycles 10 and 11)

SG 1-4 1. Normal Growth; All SGs Combined; I Bounding of Cycles 10 and 11

86-5019218-00 Page 24 of 68 Table 3-10: Growth Distributions Used for Monte Carlo Simulations Delta Volts Normal Growth (CPDF) Voltage Dependent Growth for SG 11 (CPDF) per EFPY SG1I SG12 I SG 13 SG14 [<=0.5V@BOC-11 >0.5V@BOC-11 0 0.1609 0.2104 0.2458 0.1265 0.1868 0.2177 0.1 0.4753 0.5701 0.6695 0.4630 0.5641 0.4194 0.2 0.7550 0.7919 0.8475 0.7208 0.8608 0.6371 0.3 0.8757 0.9072 0.9280 0.8616 0.9524 0.7500 0.4 0.9506 0.9593 0.9534 0.9379 0.9817 0.8790 0.5 0.9689 0.9751 0.9831 0.9666 0.9927 0.9113 0.6 0.9835 0.9864 0.9958 0.9833 1.0000 0.9516 0.7 0.9890 0.9955 0.9958 0.9905 1.0000 0.9677 0.8 0.9909 0.9977 0.9958 0.9928 1.0000 0.9758 0.9 0.9909 0.9977 0.9958 0.9928 1.0000 0.9758 1 0.9927 0.9977 1.0000 0.9952 1.0000 0.9839 1.1 0.9945 1.0000 1.0000 0.9976 1.0000 0.9839 1.2 0.9982 1.0000 1.0000 0.9989 1.0000 0.9919 1.3 0.9982 1.0000 1.0000 0.9989 1.0000 0.9919 1.4 0.9982 1.0000 1.0000 0.9989 1.0000 0.9919 1.5 0.9982 1.0000 1.0000 0.9989 1.0000 0.9919 1.6 0.9982 1.0000 1.0000 0.9989 1.0000 0.9919 1.7 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.8 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.9 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 2 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000

86-5019218-00 Page 25 of 68 Table 3-11: Re-tested DOSs _Ž1.5 Volts that Failed the Probe Wear Check SG Row Col Ind Elev Volts Probe Cal Group ARC Out IRI1  % Diff IH 1.63 720RF 5 Yes 6 61 RSS DOS IH 1.67 720RF 55 2.4%

RSS IH 1.65 720RF 13 Yes 10 71 RSS IH 1.75 720RF 48 Yes DOS 1H I 1.75 720RF 55 5.7%/0.0%

RSS IH 1.81 720RF 14 Yes 17 73 RSS 1H 1.96 720RF 51 Yes DOS 1H 1.96 720RF 62 7.7% / 0.0%

RSS IH 1.75 720RF 14 Yes 17 74 RSS IH 1.71 720RF 51 Yes

-7.4% /-4.9%

SGI I DOS RSS IH IH 1.63 1.61 720RF 720RF 62 6 Yes 20 54 RSS 1H 1.88 720RF 51 Yes DOS 1H 1.8 720RF 62 10.6% / -4.4%

27 47 JRSS I1H J 2.01 720RF [ 6 55 Yes ________

11.1%

DOS 1H 2.26 720RF RSS 1H 2.15 720RF 4 Yes 30 32 RSS 1H 2.32 720RF 48 Yes DOS 1 H 2.4 720RF 55 10.4%/3.3%

RSS 1H 1.52 720RF 4 Yes 42 37 RSS 1H 1.59 720RF 48 Yes DOS 1H 1.58 720RF 55 3.8%/-06%

IH 1.93 720RF 32 Yes 6 53 RSS 1H IRSS DOS 2.11 720RF 51 8.5%

20 87 HJ 2.081 720RF 34 Yes DOS I IH 2.14 720RF 51 2.8%

22143 RSS J IH 2.19 j720RF J 25 Yes J 22 4 DOS 1H 2.25 720RF 51 2.7%

2H 1.81 720RF 30 Yes 26 52 RSS 2H 1.76 720RF 38 -2.8%

SG 12 DOS 281501 MEE IH 12.021 720RF J 29 [ Yes J_ _ _ _

DOS I IH 1.85 720RF 38 -9.2%

311 511 RSS -IH 1.63 ]720RF J 29 38 Yes 7.4%

DOS I 1H 1.76 720RF 37 23 RSS J 3H 1.83 720RF 19 Yes DOS 3H 1.59 720RF 38 _ -15.1%

40 27 RSS IH 2.24 720RF 20 Yes DOS IH 2.33 720RF 38 3.9%

RSS 1H 1.87 720RF 16 Yes SG13 10 71 DOS 1H 1.93 720RF 31 3.1%

1H 1.52 720RF 10 Yes 3 36 RSS 1.79 720RF 54 15.1%

SG14 DOS IH 7 Yes 25 26 I RSS _2H 1.8 720RF I DOS I 2H 1.91 720RF 43 Y 5.8%

86-5019218-00 Page 26 of 68 Table 3-12: New 1R1l DOSs >=0.5 Volts In Tubes Inspected With A Worn Probe In 1R10 SG Row Col Ind Elev Volts Cal ARC Out IR1l ARC Out IR10 SGII 11 40 DOS 2H 1.4 CL-3 Yes Yes SG11 6 31 DOS 1H 1.35 CL-3 Yes Yes SGII 16 45 DOS 2H 1.29 CL-I Yes SG1I 33 40 DOS 2H 1.26 CL-5 Yes SG11 4 54 DOS IH 1.09 HL-10 Yes SGI 1 26 77 DOS IH 1.07 CL-1I Yes Yes SG11 18 39 DOS 2H 0.93 CL-2 Yes Yes SGI 1 30 35 DOS IH 0.84 CL-4 Yes Yes SGI 1 24 20 DOS 2H 0.81 CL-28 Yes SGI 1 10 39 DOS 1H 0.81 CL-3 Yes Yes SG11 32 48 DOS 2H 0.81 CL-5 Yes SGI1 31 41 DOS 1H 0.81 CL-4 Yes Yes SGI1 14 80 DOS 1H 0.81 CL-14 Yes Yes SG1I 6 78 DOS 2H 0.78 CL-14 Yes Yes SGII 12 74 DOS 2H 0.77 CL-13 Yes Yes SG 1I 24 40 DOS 1H 0.77 CL-2 Yes Yes SGI1 20 76 DOS 3H 0.77 CL-1I Yes Yes SGI 1 19 39 DOS 1H 0.76 CL-2 Yes Yes SGI I 7 37 DOS 3H 0.75 CL-3 Yes Yes SG11 26 61 DOS 1H 0.75 CL-9 Yes Yes SG11 6 73 DOS 1H 0.72 CL-14 Yes Yes SGI 1 4 64 DOS 1H 0.71 HL-10 Yes SGI1 33 43 DOS 1H 0.7 CL-4 Yes Yes SGl1 30 31 DOS 1H 0.7 CL-5 Yes SG11 22 69 DOS 1H 068 CL-1I Yes Yes SG1I 25 44 DOS 1H 0.68 CL-2 Yes Yes SGl1 30 58 DOS 4H 0.67 CL-10 Yes SGl1 5 68 DOS 1H 0.67 HL-9 Yes SGI1 12 70 DOS 1H 0.67 CL-13 Yes Yes SG 11 6 25 DOS 2H 0.66 CL-26 Yes Yes SG1I 25 43 DOS 2H 0.66 CL-1 Yes SG11 29 38 DOS 1H 0.65 CL-7 Yes Yes SG11 12 27 DOS 2H 0.62 CL-26 Yes Yes SG 11 11 22 DOS 2H 0.62 CL-25 Yes Yes SG11 41 32 DOS 2H 0.61 CL-5 Yes SG11 19 48 DOS IH 0.59 CL-1 Yes SG1I 28 53 DOS 1H 0.59 CL-10 Yes SGII 19 40 DOS 2H 0.58 .CL-1 Yes SGII 43 48 DOS 3H 0.58 CL-5 Yes SGI1 5 54 DOS 1H 0.57 HL-9 Yes SG1I 19 46 DOS 1H 0.57 CL-2 Yes Yes SGII 22 38 DOS 1H 0.57 CL-2 Yes Yes SGI I 15 30 DOS 2H 0.56 CL-2 Yes Yes SGII 8 42 DOS 1H 0.56 CL-3 Yes Yes SGI1 17 75 DOS 2H 0.56 CL-14 Yes Yes SGI 1 43 47 DOS 2H 0.55 CL-4 Yes Yes

86-5019218-00 Page 27 of 68 Table 3-12: New 1R1l DOSs >=0.5 Volts In Tubes Inspected With A Worn Probe In IR10 (cont'd)

SG Row Col Ind Elev Volts Cal ARC Out 1R1l ARC Out 1R10 SGI 1 8 24 DOS 2H 0.55 CL-25 Yes Yes SG11 30 70 DOS IH 0.55 CL-11 Yes Yes SG11 26 66 DOS 1H 0.54 CL-10 Yes SG1I 21 36 DOS 3H 0.54 CL-2 Yes Yes SGI 1 21 42 DOS 3H 0.54 CL-1 Yes SG1I 19 31 DOS 2H 0.54 CL-1 Yes SG11 13 44 DOS 2H 0.53 CL-3 Yes Yes SGI I 5 49 DOS 2H 0.53 HL-8 Yes SGII 15 24 DOS 1H 0.53 CL-25 Yes Yes SGI 1 37 36 DOS 1H 0.53 CL-5 Yes SG11 17 87 DOS 1H 0.52 CL-17 Yes Yes SG11 14 78 DOS 1H 0.52 CL-13 Yes Yes SG11 10 74 DOS 1H 0.52 CL-13 Yes Yes SG11 7 78 DOS 2H 0.51 CL-14 Yes Yes SGII 10 23 DOS 3H 0.51 CL-26 Yes Yes SGII 46 50 DOS IC 0.5 CL-6 Yes Yes SG12 23 12 DOS IH 1.6 CL-11 Yes SG12 45 42 DOS IH 1.46 CL-24 Yes SG12 20 63 DOS 2H 1.4 CL-31 Yes SG12 21 82 DOS IH 1.21 CL-33 Yes Yes SG12 21 72 DOS 4H 1.06 CL-34 Yes Yes SG12 35 65 DOS 3H 1.02 CL-I Yes SG12 33 71 DOS IH 1.01 CL-34 Yes Yes SG12 4 48 DOS 2H 0.98 HL-5 Yes SG12 27 83 DOS 3H 0.98 CL-34 Yes Yes SG12 35 68 DOS 1H 0.95 CL-29 Yes Yes SG12 3 80 DOS IH 0.95 HL-4 Yes SG12 19 41 DOS IH 0.89 CL-26 Yes SG12 6 87 DOS 2H 0.88 CL-35 Yes SG12 37 35 DOS 2H 0.86 CL-21 Yes Yes SG12 15 66 DOS 2H 0.81 CL-32 Yes Yes SG12 6 56 DOS 2H 0.79 CL-32 Yes Yes SG12 28 63 DOS 1H 0.79 CL-30 Yes Yes SG12 32 55 DOS 2H 0.76 CL-30

• Yes Yes SG 12 38 45 DOS 4H 0.75 CL-23 Yes SG12 32 59 DOS IH 0.75 CL-30 Yes Yes SG12 30 57 DOS 2H 0.72 CL-30 Yes Yes SG12 39 66 DOS 3H 0.72 CL-29 Yes Yes SG12 35 46 DOS 2H 0.71 CL-23 Yes SG12 20 89 DOS 3H 0.66 CL-34 Yes Yes SG12 20 83 DOS 3H 0.65 CL-34 Yes Yes SG12 46 49 DOS IH 0.65 CL-24 Yes SG12 5 51 DOS IH 0.63 HL-4 Yes SG12 33 73 DOS 1H 0.62 CL-33 Yes Yes SG12 32 45 DOS 3H 0.61 CL-23 Yes SG12 26 52 DOS 3H 0.6 CL-30 Yes Yes

86-5019218-00 Page 28 of 68 Table 3-12: New IR1l DOSs >=0.5 Volts In Tubes Inspected With A Worn Probe In 1R10 (cont'd)

SG Row Col Ind Elev Volts Cal ARC Out IR1l ARC Out IR10 SG12 26 52 DOS 3H 0.6 CL-38 Yes SG12 6 49 DOS 2H 0.58 CL-27 Yes Yes SG12 4 49 DOS 1H 0.58 HL-4 Yes SG12 39 37 DOS IH 0.58 CL-21 Yes Yes SG12 37 33 DOS 2H 0.58 CL-21 Yes Yes SG12 17 38 DOS 2H 0.57 CL-25 Yes Yes SG12 17 24 DOS IH 0.57 CL-14 Yes Yes SG12 43 48 DOS 4H 0.56 CL-23 Yes SG 12 6 65 DOS 2H 0.56 CL-32 Yes Yes SG12 10 7 DOS 4H 0.56 CL-16 Yes Yes SG12 30 76 DOS 5H 0.56 CL-33 Yes Yes SG12 29 72 DOS 6H 0.55 CL-34 Yes Yes SG12 12 63 DOS IH 0.55 CL-32 Yes Yes SG12 26 83 DOS IH 0.55 CL-33 Yes Yes SG12 19 48 DOS 1H 0.55 CL-25 Yes Yes SG12 20 43 DOS 3H 0.55 CL-25 Yes Yes SG12 36 33 DOS 2H 0.55 CL-22 Yes SG12 8 86 DOS 3H 0.54 CL-35 Yes SG12 34 61 DOS 1H 0.53 CL-30 Yes Yes SG12 9 3 DOS 3H 0.53 CL-16 Yes Yes SG12 19 39 DOS 2H 0.52 CL-26 Yes SG12 5 57 DOS 1H 0.52 HL-4 Yes SG12 26 64 DOS 2H 0.51 CL-30 Yes Yes SG12 42 61 DOS 2H 0.51 CL-29 Yes Yes SG12 11 82 DOS 2H 0.51 CL-36 Yes SG12 19 65 DOS 2H 0.51 CL-32 Yes Yes SG12 5 50 DOS 3H 0.5 HL-4 Yes SG12 40 66 DOS 3H 0.5 CL-29 Yes Yes SG13 9 63 DOS 1H 1.38 HL-1 Yes SG13 25 81 DOS 1H 1.25 CL-15 Yes SG13 10 10 DOS 2H 1.18 HL-8 Yes Yes SG13 24 41 DOS 1H 1.05 CL-5 Yes Yes SG13 27 32 DOS 2H 1.05 CL-7 Yes SG13 25 76 DOS 1H 1.04 CL-15 Yes SG13 9 58 DOS 1H 1.02 HL-3 Yes SG13 19 90 DOS 1H 0.86 CL-17 Yes Yes SG13 9 67 DOS 4H 0.82 HL-2 Yes SG13 8 6 DOS 3H 0.8 HL-10 Yes SG13 7 75 DOS 2H 0.77 CL-15 Yes SG13 20 68 DOS 1H 0.77 HL-2 Yes SG13 32 40 DOS IH 0.71 CL-8 Yes Yes SG13 20 33 DOS IH 0.62 CL-I Yes SG13 15 73 DOS IH 0.57 CL-15 Yes SG13 9 57 DOS 3H 0.55 HL-4 Yes SG13 19 44 DOS 1H 0.5 CL-5 Yes Yes

86-5019218-00 Page 29 of 68 Table 3-12: New 1Rll DOSs >=0.5 Volts In Tubes Inspected With A Worn Probe In tRIO (cont'd)

SG Row Col Ind Elev Volts Cal ARC Out 1Rl ARC Out IR10 SG14 9 21 DOS 2H 0.75 HL-5 Yes Yes SGI4 29 57 DOS 2H 0.69 CL-7 Yes SGI4 3 74 DOS 1H 0.69 HL-10 Yes Yes SGI4 2 50 DOS 1H 0.61 HL-4 Yes Yes SGI4 27 55 DOS 1H 0.6 CL-7 Yes SG14 11 86 DOS 1H 0.54 CL-14 Yes SG14 13 48 DOS 2H 0.53 CL-5 Yes Yes SG14 28 63 DOS 1H 0.5 CL-9 Yes

86-5019218-00 Page 30 of 68 Table 3-13: Summary of New DOS Indications Sorted by Category New IRll New IRl1 DOil New new Inl Ind. In Ind. Ž0.5 DO 1R1s Tl mde In Tubes New 1R1l Volts in in Not Tubes Insp. Insp. w/ Ind. Ž0.5 Tubes Insp.

Tube (Tubes Detected in 1R10 Prorn PRob Goodin Probe Volts w/ Worn Probe in (Total) 1R10il ______ ti 11110 1R10 SG11 400 238 145 93 92 61 SG12 293 158 106 52 82 54 SG13 152 62 32 30 28 16 SG14 79 42 20 22 13 7 Total 924 500 303 197 j 215 138

86-5019218-00 Page 31 of 68 Table 3-14: Percentage of Tubes With New Indications TWorn Probe In IR10 Good Probe In 1RIO Number of Insnections In 1RI0 10494 5949 New Indications in IRll 303 197 Percentage w/ New Indications 2.9% 3.3%

New Indications >0.5V in 1R11 138 77 Percentage w/ New Indications >0.5V 1.3% 1.3%

Table 3-15: Average Growth Rates for Cycle 11 SG No of Average Average Average Average Average Inds In BOC-11 Voltage Growth per Percent Percent Growth Voltage Growth EFPY Growth for Growth per Dist. Cycle 11 EFPY SG11 397 0.440 0.179 0.127 40.6% 28.8%

SG12 293 0.548 0.128 0.091 23.4% 16.6%

SG13 151 0.653 0.093 0.066 14.2% 10.1%

SG14 77 0.500 0.119 0.085 23.9% 17.0%

Total 918 0.515 0.143 0.102 27.9% 19.8%

86-5019218-00 Page 32 of 68 Table 3-16: NDE Uncertainty Distributions Analyst Uncertainty Acquisition Uncertainty Percent Cumulative Percent Cumulative Variation Probability Variation Probability

-400% 000005 <-150% 000000

-38.0% 000011 -15.0% 001606

-36.0% 0 00024 -14 0% 0 02275

-340% 000048 -130% 003165

-32.0% 0 00095 -120% 0.04324

-30 0% 0.00179 -11 0% 0.05804

-280% 000328 -10 0% 0.07656

-26 0% 000580 -90% 009927

-24 0% 000990 -80% 012655

-22 0% 001634 -7.0% 015866

-20 0% 002608 -60% 019568

-18 0% 004027 -50% 023753

-16 0% 006016 -40% 028385

-140% 008704 -30% 033412

-120% 012200 -20% 038755

-100% 016581 -10% 044320

-80% 021867 00% 050000

-60% 028011 1 0% 0 55680

-40% 034888 20% 061245

-20% 042302 30% 066588 0.0% 0 50000 40% 071615 2.0% 057698 5 0% 0 76247 40% 065112 60% 080432 60% 071989 70% 084134 80% 0.78133 8 0% 0 87345 100% 0.83419 9.0% 0.90073 120% 087800 100% 0.92344 140% 091296 11 0% 0.94196 160% 093984 120% 095676 180% 095973 130% 096835 200% 097392 140% 097725 220% 098366 150% 098394 240% 099010 >150% 100000 260% 099420 280% 099672 Std Deviation = 7 0%

30.0% 0 99821 Mean = 0 0%

32.0% 0 99905 Cutoff = +1-15 0%

340% 099952 360% 099976 380% 099989 40 0% 0 99995 Std Deviation = 10.3%

Mean = 0 0%

No Cutoff

86-5019218-00 Page 33 of 68 Figure 3-1 Voltage Distributions of As-Found DOSIAONDB Indications SG11 & SG12 100 90 80 I 70 0

0 S60

50 50 40 E

z 30 - -_ __ _ __ _ _

204 10 0 , 0 0 1] n

-~

0 o~~~~C

~~~~~ oV

- C l0U ~

- I. 0(

~ ~ l In C) 1-C0 0) m Bobbin Volts USG11 ESG12 Figure 3-2 Voltage Distributions of As-Found DOSIAONDB Indications SG13 &SG14 inn .______ - - -- - -- ______ ____ _

on. I 80 70 60

£Z 0 50

.0 40 E

z 11I~k 30 20 10 0- L o 0 0 0 0--- in I N N NM

, N, M

• r, c) vA It, L L L I L Bobbin Volts E

1111 *SG13 OSG14

86-5019218-00 Page 34 of 68 Figure 3-3 Voltage Distribution of DOSIAONDB Indications In Deplugged Tubes SG12 10 9

Note This chart only Includes indications that were deplugged end returned to 8 - service. I e indications in tubes that were deplugged and subsequently replugged 7 -re not Included FA r

0 6

r 0 5 is 4

E 3

2 1 -----

0 o 0 0 0 0 .- -~ 0 MJ m A Bobbin Volts

• SG12

86-5019218-00 Page 35 of 68 Figure 3-4 Repaired Tube Voltage Distributions SGII & SG12 in 9

8-7 r

0 S6

-5

".4 E

z 3-LI 1

0 o

O C,

o C) 0 0 Wi C) 3 0--

- 3 C, Cl C

O3 N

w1Y-I C, Ifl N

II.

N C)

N C,

I C, sn C-m, Co C)

V' A Bobbin Volts

[SG11 OSG12 Figure 3-5 Repaired Tube Voltage Distributions SG13 & SG14 10 9

8 7

0 6.

r

-5 0

.04 E

z 3 SI-2 ---- j t i II 1

0 11 0

V) kc - a) ~ a N

. t i C , U ~ ) '

0 0 0 , C, C , C fl- Bobbin Volts

• SG13 nSG14

86-5019218-00 Page 36 of 68 Figure 3-6 Voltage Distributions of All DOS/AONDB Indications Returned to Service SG11 & SG12 100 90 80 riI 70 U-,

0 S60 0

50 4--

40 -A-----n I -9 VI I I

-2 LIU Nt E

30 1 I 11 20 10- -

o 0 o o Bobbin Volts ISG11 OSG12 Figure 3-7 Voltage Distributions of All DOSIAONDB Indications Returned to Service SG13 & SG14 1o0 90 80 70

=* 6060 50o 0

• 40 E

z 30 20 -1 10 S hI 0 ih . . -in I L I I . I ý I I

- 0. t-, 0)t M -ý U0 0) --~ 0 0) -f 0 r 0) "r A

o o 0 0 N N CI N4 V) M~ Cl) Cl)

Bobbin Volts

• SG13 nSG14]

86-5019218-00 Page 37 of 68 Figure 3-8 Distribution of Indications by TSP Location 300 250 -

C0 200 S150 0

E 100 50 IJ *~ ~ ~.* .I -

I 7t F1-1.r_ý rl-1HT 2H 3H 4H 5H 6H 7H CL 3SGIl 274 100 28 9 1 1 1 6 DSG12 207 132 47 23 10 8 1 4 OSG13 78 30 20 9 7 7 1 6

• SG14 66 25 9 4 2 Tube Support Plate

86-5019218-00 Page 38 of 68 Figure 3-9 Delta Volts per EFPY SGII & SG12 140 120 100

_80

", 60

.0 E

z 40 20 0

e U0 0 0 (0 0' - C: :!

C!  :! CD N. (0 0) N, Delta Volts per EFPY

[ SGI1 OSG12 Figure 3-10 Delta Volts per EFPY SG13 & SG14 140 120 100 U,

0 80 0

"6* 60 E

40 20 1 A I. ,i,.

90 a

9e" 9 a a}

9 a

a a

o a 0

~ 0 LD (O 0

0n 0 t-)

0 W 0)

M ~ ~ ID C . (0 0 "A Delta Volts per EFPY

• SG13 DSG14

86-5019218-00 Page 39 of 68 Figure 3-11 SG1I & SG12 Growth Rate vs. BOC Voltage 15 EL I,

"05 0

0

-05 0 02 04 06 08 1 12 14 16 18 2 BOC Voltage

• SG11 m SG12 - Linear(SG11) -- Linear(SG12)

LU Figure 3-12 SG13 & SG14 Growth Rate vs. BOC Voltage 15

-0 5 LL "C05 4l 0 E3 0 , 00 0

0 02 04 06 08 1 12 14 16 18 2 BOC Voltage

• SG13 [ SG14 - ULinear (SG13) -- Linear(SG14)

86-5019218-00 Page 40 of 68 Figure 3-13 Voltage Dependent Growth (All SGs) 1 00 0 80 060 IL 0.

040 0 20 0 00 0 01 02 03 04 05 06 07 08 09 1 11 12 13 14 15 16 17 1.8 19 2 >2 Delta Volts per EFPY

--<=0 50V @ BOC -.-- 05lV to I 00V @ BOC ->1 00V @ BOC Figure 3-14 SGII Voltage Dependent Growth 1 00 0 80 0 60 L

C3 Q.

U 040 0 20 0 00 0 01 02 03 04 05 06 07 08 09 1 112 13 14 15 16 17 18 19 2 >2 Delta Volts per EFPY

---

<0 50V@ BOC -- >o 50V BOCF

86-5019218-00 Page 41 of 68 Figure 3-15 Deplugged vs. In-Service Growth Comparison All SGs 500 1 00 450 0 90 400 0 80 350 070 m

0 Cu 300 060 U

0 250 050 1 U

E 200 E

z 150 100 50 0

Delta Volts per EFPY in Deplugged in IRIO [ Active

-- Deplugged in IR10 - U - Active Figure 3-16 DCPP-1 Growth Rate (CPDF) Curves 1 00 0 90 -o-DCPPU1 -OC10 0 80 -- DCPP U1-CIl 070 0 60 S050 U

040 030 020 010 0 00 o0 *- °4 CJ C

• W O* CID t- CD 0) - - (4 C3

• C CD r- CD 0) C' 0 0 000 0 0 0 p0 Delta Volts per EFPY

86-5019218-00 Page 42 of 68 Figure 3-17 Probe Wear Voltage Comparison 3

25

0. 2 a

E 0

15 0

.0

.0 0 1 03 05 0

0 05 1 15 2 25 3 Bobbin Volts (New Probe)

Figure 3-18 NDE Uncertainty Distributions 10 09-08 07

.0 06 2.

'M 0 05 a-t E 04 C.

03 02 01 00

-400% -300% -200% -100% 00% 100% 200% 300% 400%

Percent Variation In Voltage

86-5019218-00 Page 43 of 68 4.0 Database and Methods Applied for Leak and Burst Correlations The leak and burst correlations utilized in the analyses presented in this report are based on the updated databases contained in the May 2002 letter from NEI to the NRC (Ref. 20). This letter contains the latest industry database that includes the Beaver Valley pulled tubes that affected the leak rate correlation and ultimately the methods used to postulate the leak rate. The leak rate correlations used were developed for a MSLB delta P of 2405 psi. The correlations have been developed specifically for the evaluation of ODSCC indications at TSP locations in Model 51 steam generators and relate Bobbin voltage amplitudes, free span burst pressure, probability of leakage and associated leak rates to assess end of next cycle structural integrity.

4.1 ConditionalProbabilityofBurst For the burst pressure versus voltage correlation, the database contained in Ref. 20 meets all GL 95 05 requirements and was used in these calculations. Material properties were also considered as part of the calculations and were obtained from Ref. 6. The FRA-ANP Monte Carlo computer code was utilized to predict the POB at the end of cycle 12 based upon the input parameters shown in Table 4 1 (from Ref. 20, Table 2). This simulation follows the statistical methods presented in Ref. 6.

Table 4-1: Tube Burst Pressure vs. Bobbin Amplitude Correlation PB = ao + a, log(Volts)

Parameter Database 00 7.55184 oXI -2.39285 r2 82.0%

aCEfor 0.82802 N (data pairs) 95 p Value for a 2 I.lx10-36 Reference cr 68.78 ksi

86-5019218-00 Page 44 of 68 4.2 ConditionalLeak Rate The POL and leak rate correlation parameters used in this analysis are shown in Tables 4-2 and 4-3.

The inputs are taken directly from Ref. 20 Tables 3 and 5, respectively. The methodology used in the calculation of these parameters is consistent with the NRC criteria in Ref. 2. The methodology used for the leak rate calculations is referred to as p value sampling method. This method is described in Ref. 21 and supersedes the leak rate method in Ref. 6.

Table 4-2: 7/8" Tube Probability of Leak Correlation 1 2 Pr(Leak) = {1 + e&[1+0 Iog(V)]}-l Parameter Database P3I -4.15642 P2 4.11275 V 110) 0.59110 V 12 -0.52488 V 22 0.53648 DoFI2) 141 Deviance 81.83 Pearson SD 74.7%

Notes:

N (1) Parameters Vj are elements of the covariance matrix of the coefficients, 1 , of the regression equation.

(2) Degrees of freedom.

86-5019218-00 Page 45 of 68 Table 4-3: Leak Rate Database for 7/8" Tube ARC Applications (2405 psi) 5

+ b4 x logwo/ts )ý Q = 10( b3 Parameter Database Intercept, b 3 -0.658481 Slope, b4 0.973499 Index of Deter, r2 11.7%

Residuals, GE,,or (b5) 0.810399 Data Pairs, N 30 Mean of Log(Q) 0.45134 Std Dev of Log(Q) 0.84746 Mean of Log(V) 1.14003 SS of Log(V) 2.57620 p Value for b4 3.2%

86-5019218-00 Page 46 of 68 5.0 Bobbin Voltage Distributions This section describes the prediction of the EOC voltage distribution used for evaluating tube leakage and burst probabilities at the end of the operating period.

5.1 Probabilityof Detection The number of bobbin indications used to predict the tube leak rate and burst probability is obtained by adjusting the number of reported indications to account for the detection capability of the bobbin coil. This is accomplished by using a POD factor. The calculation of the bobbin voltage distribution is a net total number of indications returned to service, defined as:

NEOC 11 NBoc 12 = EOC POD - Nrepared + Ndeplugged where:

NBOC12 = Number of bobbin indications being returned to service for the next operating cycle Number of bobbin indications reported in the current NEOCIl] = inspection POD = Probability of Detection Nrepaired = Number of bobbin indications repaired after the last cycle Number of previously plugged indications whibh are Ndeplugged = deplugged after the last cycle and are returned to service Note that the deplugged tube component of this equation only applies to SG 1-2. No tubes were deplugged and subsequently returned to service in SGs 1-1, 1-3, and 1-4.

The NRC generic letter (Ref. 2) requires the application of a constant POD equal to 0.6 to define the BOC distribution for the EOC voltage projections. The operating cycle length is required for proper voltage projection calculations: Cycle 11 (actual) = 1.41 EFPY and Cycle 12 (estimated)=1.61 EFPY (Ref. 18).

5.2 Probabilityof PriorCycle Detection Per the Generic Letter, the beginning-of-cycle voltage distribution must be developed using a constant POD of 0.6 as mentioned above. In reality, however, the POD is a function of the bobbin voltage. The larger voltage indications should have a higher POD. EPRI has developed a voltage-dependent POD based on data from 19 inspections at plants with 7/8" diameter tubing.

The latest update of the probability of prior cycle detection (POPCD) is documented in Ref. 10.

The POPCD was not used in any of the leak rate and probability of burst projections contained in this document. However, the Diablo Canyon POPCD is documented in this report for comparison to'the EPRI POPCD.

For voltage-based repair criteria applications, the important indications are those that could significantly contribute to EOC leakage or burst probability. These significant indications can be expected to be detected by bobbin and confirmed by the plus point inspection. Thus, the population of interest for POD assessments is the EOC RPC confirmed indications that were or

86-5019218-00 Page 47 of 68 were not detected at the prior inspection. The probability of prior cycle detection (POPCD) is defined as follows:

EOC-11 Plus Pt confirmed + EOC-10 Plus Pt confirmed and POPCD EOC-10 and detected at EOC-10 repaired at EOC-10 (NUMERATOR) + New EOC-1 1 Plus Pt confirmed indications Note that the above definition for POPCD is based on the premise that all indications which contribute significantly to leakage or burst probability are confirmed with Plus Point. However, only a fraction of the bobbin indications are inspected with a Plus Point coil. Therefore, a more realistic definition of POPCD is obtained by replacing the "EOC-1 1 Plus Pt confirmed" category with a category of"EOC-1 1 Plus Pt confirmed plus not inspected".

The POPCD evaluation for the EOC-10 inspection data is summarized in Table 5-1 and Figure 5-1. For the most part, the Diablo Canyon POPCD for the EOC-10 inspection results is slightly below the EPRI POPCD for voltages below about 1.6 volts. The Diablo Canyon POPCD equals 1.0 for bobbin voltages greater than 1.7 volts.

5.3 Calculationof BOC-12 Voltage Distributions The first step in performing the leak rate and probability of burst projections is to determine the number and voltages of the indications being returned to service for the next operating cycle.

The BOC-12 distribution is calculated by dividing the as-found condition of the SG by the probability of detection (POD), subtracting the number of repaired tubes, and adding the number of deplugged tubes that are being returned to service. For this analysis, the BOC-12 distributions for each SG were calculated using the constant POD of 0.6 as required per the Generic Letter.

Tables 5-2 through 5-5 and Figures 5-2 through 5-5 summarize the as-found distribution, repaired tubes, deplugged tubes, and the calculated BOC-12 distributions for SG 1-1, SG 1-2, SG 1-3, and SG 1-4 respectively.

5.4 PredictedEOC-12 Voltage Distributions Once the BOC-12 voltage distribution has been determined, the EOC-12 voltage distributions are obtained by applying a Monte Carlo sampling process to the BOC-12 voltages. This process randomly assigns uncertainty values and a growth value to each of the BOC-12 indications. The EOC-12 voltage distributions are used to calculate a leak rate and probability of tube burst.

Section 3.2 provides information on the growth distributions that were used in the analyses.

Table 5-6 summarizes the projected EOC-12 voltage distributions for 0.6 POD. Figures 5-6 through 5-9 show the calculated BOC-12 and projected EOC-12 voltage distributions using normal growth for SG 1-1, SG 1-2, SG 1-3, and SG 1-4, respectively. Figure 5-10 shows the projected EOC-12 voltage distribution for SG 1-1 using voltage dependent growth.

86-5019218-00 Page 48 of 68 5.5 ComparisonofPredictedand Actual EOC-11 Conditions The as-found EOC-1 1 bobbin voltage distributions and the predicted distributions from the previous 90-day report (Ref. 7) are compared in Table 5-7 and Figures 5-11 through 5-14. As shown in Table 5-7, the number of indications was under-predicted using the 0.6 POD for all steam generators. Figures 5-11 through 5-14 show that the under predictions generally occurred in voltage bins less than about 0.7 volts. For bins exceeding 0.7 volts, the predictions generally exceed the as-found voltages except for the tail of the distribution for SG 1-2, in which there were 5 indications detected that exceeded 2.1 volts, but only 1.75 indications were projected to be above 2.1 volts.

The projected EOC 11 leak rate and POB in Ref. 7 used a SLB dP of 2560 psi, the correlations of Addendum 4, and the leak rate method of Ref. 6. The EOC 11 projected leak rate and POB were recalculated using a SLB dP of 2405 psi, updated correlations of Ref. 20 and the revised leak rate method of Ref. 21 to permit a direct comparison to the EOC 11 as-found leak rate and POB.

These projections replace the Ref. 7 projections and are provided in Table 5-8. The as-found leak rates and probabilities of burst were bounded by the updated projected values. The LR and POB projections are conservative because for voltage bins exceeding 0.7 volts (which tend to drive the leak rate and burst probability), the predictions generally exceed the as-found voltages.

86-5019218-00 Page 49 of 68 Table 5-1: Diablo Canyon Unit 1 POPCD Evaluation Composite of All Steam Generator Data Bobbin Call In First New Indications Both Inspections Inspection POPCD PC RPC RRPC Confirmed Plus Not RPC Confirmed RPC Confirmed Confirmed and Inspected Confirmed Plus Not Confirmed Plus Not Coniged Voltage Bin Inspected Inspected Plugged Frac Count Frac Count

>0 - 0.2 11 63 5 7 0.313 5/16 0.100 7/70 0.2-0.4 29 231 38 117 6 0.603 44/73 0.347 123/354 0.4-0.6 33 112 26 112 4 0.476 30/63 0.509 116/228 0.6 - 0.8 15 41 18 86 4 0.595 22/37 0.687 90/131 0.8-1.0 10 18 10 43 1 0.524 11/21 0.710 44/62 1.0- 1.2 4 10 5 21 1 0.600 6/10 0.688 22/32 1.2- 1.6 3 8 6 25 0.667 6/9 0.758 25/33 1.6-2.0 3 5 1.000 3/3 1.000 5/5 2.0-2.5 1 1.000 1/1 1.000 1/1 2.5-3.2 2 1.000 2/2 1.000 2/2 3.2 -3.5 1 1 1 1 1 TOTAL 105 483 111 416 19 Total >Iv 7 18 14 51 4

86-5019218-00 Page 50 of 68 Table 5-2: SG11 As-Found and BOC-12 Voltage Distribution DOSs/AONDBs Returned to Service Voltage As-Found POD Repaired Calculated Conf. OD-SCC or Bin EOC-11 (0.6) Tubes BOC-12 Not Inspw/+Pt Total 0.1 0.2 9 15 15 9 9 0.3 49 81.67 1 80.67 47 48 0.4 62 103.33 103.33 62 62 0.5 81 135 3 132 76 78 0.6 66 110 3 107 62 63 0.7 41 68.33 3 65.33 37 38 0.8 24 40 1 39 23 23 0.9 21 35 1 34 19 20 1 19 31.67 2 29.67 17 17 1.1 13 21.67 1 20.67 12 12 1.2 8 13.33 13.33 8 8 1.3 7 11.67 2 9.67 5 5 1.4 6 10 10 6 6 1.5 2 3.33 3.33 2 2 1.6 2 3.33 3.33 2 2 1.7 2 3.33 3.33 2 2 1.8 3 5 5 3 3 1.9 2 1 1.67 1.67 1 1 2.1 2.2 2.3 1 1.67 1 0.67 2.4 1 1.67 1 0.67 2.5 2.6 2.7 1 1.67 1 0.67 2.8 2.9 3

3.1 3.2 3.3 1 1.67 1 0.67 3.4 3.5

>3.5 Total 420 700 21 679 393 399

86-5019218-00 Page 51 of 68 Table 5-3: SG12 As-Found and BOC-12 Voltage Distribution DOSs/AONDBs Returned to Service Repaired Deplugged &

Voltage As-Found POD Tubes Returned to Calculated Conf. OD-SCC or Bin EOC-11 (0.6) (Active) Service BOC-12 Not Insp w/+Pt Total 0.1 1 1.67 1 0.67 0.2 8 13.33 1 2 14.33 9 9 0.3 21 35 1 34 20 20 0.4 29 48.33 3 51.33 32 32 0.5 71 118.33 7 6 117.33 68 70 0.6 71 118.33 7 8 119.33 71 72 0.7 34 56.67 2 2 56.67 33 34 0.8 32 53.33 2 1 52.33 29 31 0.9 14 23.33 2 25.33 13 16 1 15 25 2 2 25 15 15 1.1 11 18.33 18.33 10 11 1.2 5 8.33 1 9.33 6 6 1.3 3 5 5 3 3 1.4 9 15 15 9 9 1.5 3 5 5 3 3 1.6 3 '5 5 3 3 1.7 1.8 2 3.33 3.33 2 2 1.9 1 1.67 1 0.67 2

2.1 2.2 2 3.33 2 1.33 2.3 1 1.67 1 0.67 2.4 1 1.67 1 0.67 2.5 2.6 2.7 2.8 1 1.67 1 0.67 2.9 3

3.1 3.2 3.3 3.4 3.5

>3.5 Total 338 563.33 29 27 561.33 326 336

86-5019218-00 Page 52 of 68 Table 5-4: SG13 As-Found and BOC-12 Voltage Distribution DOS/AONDB Returned tn Servwe Voltage As-Found POD I Repaired Calculated Conf. OD-SCC or Bin EOC-II (0.6) Tubes BOC-12 Not Insp w/+Pt Total 0.1 0.2 3 5 5 3' 3 0.3 11 18.33 18.33 11 11 0.4 19 31.67 31.67 19 19 0.5 28 46.67 2 44.67 24 26 0.6 20 33.33 2 31.33 16 18 0.7 16 26.67 1 25.67 15 15 0.8 10 16.67 1 15.67 9 9 0.9 8 13.33 13.33 8 8 1 7 11.67 11.67 7 7 1.1 9 15 15 9 9 1.2 5 8.33 8.33 5 5 1.3 8 13.33 13.33 8 8 1.4 2 3.33 3.33 2 2 1.5 1 1.67 1.67 1 1 1.6 1 1.67 1.67 1 1 1.7 1 1.67 1.67 1 1 1.8 2 3.33 3.33 2 2 1.9 3 5 5 3 3 2 3 5 5 3 3 2.1 2.2 2.3 2.4 1 1.67 1 0.67 2.5 2.6 2.7 2.8 2.9 3

3.1 3.2 3.3 3.4 3.5

>3.5 Total 158 263.33 7 256.33 147 151

86-5019218-00 Page 53 of 68 Table 5-5: SG14 As-Found and BOC-12 Voltage Distribution DOSs/AONDBs Returned to Service Voltage As-Found POD Repaired Calculated Conf. OD-SCC or Bin EOC-11 (0.6) Tubes BOC-12 Not Insp w/+Pt Total 0.1 0.2 7 11.67 11.67 7 7 0.3 9 15 15 9 9 0.4 20 33.33 33.33 20 20 0.5 18 30 1 29 17 17 0.6 18 30 4 26 14 14 0.7 10 16.67 1 15.67 9 9 0.8 8 13.33 1 12.33 7 7 0.9 4 6.67 6.67 4 4 1 1 1.67 1.67 1 1 1.1 3 5 5 3 3 1.2 1 1.67 1.67 1 1 1.3 1 1.67 1.67 1 1 1.4 1 1.67 1.67 1 1 1.5 1.6 1.7 1 1.67 1.67 1 1 1.8 2 3.33 3.33 2 2 1.9 2 1 1.67 1.67 1 1 2.1 2.2 2.3 2.4 1 1.67 1 0.67 2.5 2.6 2.7 2.8 2.9 3

3.1 3.2 3.3 3.4 3.5

>3.5 Total 106 176.67 8 168.67 98 98

86-5019218-00 Page 54 of 68 Table 5-6: Projected EOC-12 Distributions with POD=0.6 Voltage Voltage Normal Growth Dependent Bin Growth SGlII SG12 SGI3 1SG14 SGII

<=0.1 0.12 0.28 0.06 0.07 0.14 0.2 3.32 3.37 1.49 1.44 3.85 0.3 14.33 9.45 5.49 3.72 16.70 0.4 29.96 21.07 12.31 8.16 35.32 0.5 51.22 39.77 20.50 13.64 60.94 0.6 70.89 57.10 26.28 17.53 83.11 0.7 78.75 67.95 27.57 20.26 82.27 0.8 78.98 68.25 25.33 19.42 71.85 0.9 70.57 61.02 21.72 17.65 57.08 1 59.68 51.49 18.50 14.72 45.04 1.1 48.69 41.46 16.06 11.64 36.65 1.2 38.86 32.29 14.32 8.96 33.31 1.3 30.48 24.74 12.67 6.72 29.10 1.4 23.59 19.11 10.65 5.04 23.24 1.5 18.19 15.06 8.51 3.76 19.05 1.6 13.90 11.97 6.56 2.81 15.82 1.7 10.45 9.32 5.14 2.18 12.75 1.8 7.83 7.01 4.25 1.78 10.06 1.9 5.95 5.14 3.73 1.52 7.90 2 4.58 3.75 3.32 1.37 5.96 2.1 3.63 2.75 2.89 1.23 4.58 2.2 2.98 2.09 2.37 1.08 3.86 2.3 2.44 1.66 1.84 0.91 3.30 2.4 1.96 1.26 1.38 0.74 2.86 2.5 1.51 0.95 1.01 0.57 2.57 2.6 1.10 0.72 0.74 0.43 2.11 2.7 0.81 0.55 0.53 0.32 1.57 2.8 0.61 0.43 0.38 0.23 1.18 2.9 0.49 0.33 0.26 0.18 0.90 3 048 0.25 0.17 0.14 0.68 3.1 0.47 0.19 0.11 0.11 0.52 3.2 0.45 0.15 0.07 0.09 0.48 3.3 0.39 0.11 0.05 0.07 0.79 3.4 0.30 0.08 0.03 0.05 0.82 3.5 0.23 0.06 0.02 0.04 0.61 3.6 0.18 0.04 0.02 0.02 0.46 3.7 0.15 0.03 0.01 0.02 0.37 3.8 0.12 0.02 0.01 0.01 0.29 3.9 0.09 0.02 0.00 0.01 0.22 4 0.07 0.01 0.00 0.01 0.16 4.1 0.05 0.01 0.00 0.00 0.12 4.2 0.04 0.01 0.00 0.00 0.09 4.3 0.03 0.00 0.00 0.00 0.07 4.4 0.02 0.00 0.00 0.00 0.06 4.5 0.02 0.00 0.00 0.00 0.04

>4.5 0.05 0.00 0.00 0.01 0.13 Total 679.01 561.32 256.34 168.69 I 679.01

86-5019218-00 Page 55 of 68 Table 5-7: EOC-11 As-Found vs Projected Voltage Distribution POD 0.6 Bin SG1I EOC-11 SGI2 EOC-11 SG- 3 EOC-11 SG14 EOC-1I As-Found Projected As-Found Projected As-Found Projected As-Found Projected 0.1 0 0.01 1 0.02 0 0.01 0 0.03 0.2 9 0.34 8 0.47 3 0.30 7 0.55 0.3 49 2.39 21 2.70 11 1.68 9 1.76 0.4 62 8.19 29 8.93 19 4.54 20 3.35 0.5 81 17.51 71 20.08 28 8.09 18 5.71 0.6 66 27.80 71 30.84 20 12.02 18 800 0.7 41 34.87 34 35.88 16 14.23 10 9.82 0.8 24 36.28 32 35.44 10 14.84 8 9.92 0.9 21 35.23 14 32.09 8 14.30 4 8.88 1 19 31.06 15 27.60 7 12.75 1 7.41 1.1 13 24.49 11 21.71 9 11.04 3 6.21 1.2 8 18.50 5 15.85 5 9.61 1 5.08 1.3 7 13.57 3 11.65 8 8.54 1 3.96 1.4 6 9.66 9 8.97 2 7.71 1 3.16 1.5 2 6.63 3 7.07 1 6.87 0 2.57 1.6 2 4.46 3 5.54 1 5.96 0 2.09 1.7 2 3.00 0 4.21 1 5.01 1 1.70 1.8 3 2.05 2 3.11 2 4.07 2 1.38 1.9 0 1.58 1 2.23 3 3.25 0 1.12 2 1 1.40 0 1.53 3 2.56 1 0.90 2.1 0 1.26 0 1.00 0 2.01 0 0.70 2.2 0 1.04 2 0.64 0 1.55 0 0.53 2.3 1 0.80 1 0.41 0 1.17 0 0.39 2.4 1 0.61 1 0.27 1 0.86 1 0.26 2.5 0 0.47 0 0.17 0 0.62 0 0.17 2.6 0 0.37 0 0.11 0 0.44 0 0.11 2.7 1 0.31 0 0.06 0 0.31 0 0.08 2.8 0 0.27 1 0.04 0 0.22 0 0.05 2.9 0 0.24 0 0.02 0 0.15 0 0.03 3 0 0.22 0 0.01 0 0.11 0 0.02 3.1 0 0.20 0 0.00 0 0.07 0 0.02 3.2 0 0.18 0 0.00 0 0.05 0 0.01 3.3 1 0.15 0 0.00 0 0.03 0 0.01 3.4 0 0.13 0 0.00 0 0.02 0 0.01 3.5 0 0.10 0 0.00 0 0.01 0 0.00 3.6 0 0.08 0 0.00 0 0.01 0 0.00 3.7 0 0.06 0 0.00 0 0.01 0 0.00 3.8 0 0.04 0 0.00 0 0.00 0 0.00 39 0 0.03 0 0.00 0 0.00 0 0.00 4 0 0.02 0 0.00 0 0.00 0 0.00 4.1 0 0.02 0 0.00 0 0.00 0 0.00 4.2 0 0.01 0 0.00 0 0.00 0 0.00 4.3 0 0.01 0 0.00 0 0.00 0 000 4.4 0 0.01 0 0.00 0 0.00 0 0.00 4.5 0 0.01 0 0.00 0 0.00 0 0.00

>4.5 0 0.01 0 0.00 0 0.00 0 0.00 Total 420 285.67 338 278.66 1 158 155.00 106 j 86.00

86-5019218-00 Page 56 of 68 Table 5-8: EOC-11 Projected vs Actual POB & Leak Rate EOC-11 Projected EOC-11 Actual Probability of SLB Leak Probability of SLB Leak Steam Rate Rate Burst Burst Generator SG11 2.67 x 10- 0.406 1.82 x 10.5 0.325 SG12 1.57 x 10-5 0.355 1.31 x 10-5 0.278 SG13 1.94 x 10"5 0.288 1.44 x 10' 0.153 SG14 1.05 x 10s 0.109 7.75 x 10-6 0.059

86-5019218-00 Page 57 of 68 Figure 5-1 POPCD Evaluation 1A 08 06 0

0o4 0202 0 02 04 06 08 1 12 14 16 18 2 22 24 26 28 3 32 34 36 Voltage Bin

-- EPRI POPCD -A---DCPP 1Ril (Conf+ Not Insp)

86-5019218-00 Page 58 of 68 Figure 5-2 As-Found EOC-11 and Calculated BOC-12 Voltage Distributions SGI1 (POD=0.6) 140 120 100 41 0

80 r

60 E

z 40 20 0); C'ý M U1-I-O) C)

V LO r- M oD a C') . cJ N C') C. 1 C')

n m C') V., A Bobbin Voltage NEAs-Found EOC-1 1 0 Calculated BOC-12 Figure 5-3 As-Found EOC-11 and Calculated BOC-12 Voltage Distributions SG12 (POD=0.6) lAn 100 9) r 0

80 "6

z 60 -MvmU E

40 20 ý I [I I -n 0-0 All C'

0 1U 0

I'-

0-3 iilLnLmn CD

)

C n

) - C)

V' N

LO N

r._

N 0)

N

-: CO)

M LO M

i' a) V A

Bobbin Voltage ImAs-Found EOC-11 OCalculated BOC-121

86-5019218-00 Page 59 of 68 Figure 5-4 As-Found EOC-11 and Calculated BOC-12 Voltage Distributions SG13 (POD=0.6) 140 120 100 80 60 40 20 0 di on o (C) If) V- m) C m U)

LO 1 ) - C) f - 0 0 ) r.

0 0 0 0 0 Aolta Bobbin Voltage 10 As-Found EOC-11 0 Calculated BOC-121 Figure 5-5 As-Found EOC-11 and Calculated BOC-12 Voltage Distributions SG14 (POD=0.6) 140 120 100 80 60 40 20 0

U) r= m) r- 0) - n) U.) r-. m) 6m~ v~I-o 0m~ 0 0 0 -:

-~ N N' N' '

N~ N A Bobbin Voltage

[lAs-Found EOC-11 OCalculated BOC-12]

86-5019218-00 Page 60 of 68 Figure 5-6 Projected EOC-12 Distribution SG11 140 120 100 80 60 40 20 vn 0

C) 0 ~C~

0-U)

-- r-- M) 0- - -)

W) 0  ; m I 0m C') .1 Bobbin Voltage

[ Calculated BOC-12 0 Projected EOC-12 Figure 5-7 Projected EOC-12 Distribution SG12 140 120 nn-100 80 60 40 20 0

cM U) 1- 0) 1: m U) 1.. 0, M 10 r- C! V) to r- a) m U LO It o 0 0 0 - - . -' ~

-' -N CJ C ) C ) C t '

v Bobbin Voltage IN Calculated BOC-12 D Projected EOC-12 1

86-5019218-00 Page 61 of 68 Figure 5-8 Projected EOC-12 Distribution SG13 140 120 100 0,

C 0

.2 80

.0 E

z 40 20 0- n M 0n LOGc~ir, M~  ;- m~ r-. o)  ; M~ Wn t- o0 ;- 0i i o e 0 0------N IN N N N Cm C C. m Tl II V

MUT1,00ilfilit Bobbin Voltage I Calculated BOC-12 [ Projected EOC-12 I Figure 5-9 Projected EOC-12 Distribution SG14 140 120 100 E

z 40 20 0

- mi i to . 0) 7 mi n I: m) v) Ln r.- m)  ; m) i r- m) ; )

m t 0 0 0 0 0 - - - - -- N N N N V) 0m v) co It V

Bobbin Voltage INCalculated BOC-12 0 Projected EOC-12 1

86-5019218-00 Page 62 of 68 Figure 5-10 Projected EOC-12 Distribution w/ Voltage Dependent Growth SG1 I 140) -

120 __ _

,201--I 100o 80 E

60 z

40

,- o' o ý 6 0 - --- ---- N N " N C4J M'J M~BobiM Mtag Bobbin Voltage IN Calculated BOC-12 0 Projected EOC-122

86-5019218-00 Page 63 of 68 Figure 5-11 As-Found vs. Previous Projected EOC-11 Distribution SGI I (POD=0.6) 100

]

80 C

0 60

_.0 r 40 z

20 0

o LO) t- a M.

Q - So ----

0 U' t- M~

CJ cn' T 0

C4 t- T1 0 n W t ) 0 Bobbin Voltage I As-Found EOC-11 -I1RiO EOC-1 1 Projected Figure 5-12 As-Found vs. Previous Projected EOC-11 Distribution SG12 (POD=0.6) 100 80 V

0 60 __ .0U V

E 40 z

20 0 Jilln li_

C) StL I C) - "3 LO r- M* M t In I.- 0* - M In) r- 0 - t0 U 0 0 0 0 a -- - - - - N N N N 0i) M Cq M V V V Bobbin Voltage I NAs-Found EOC-11 1Rl10 EOC-11 Projected

86-5019218-00 Page 64 of 68 Figure 5-13 As-Found vs. Previous Projected EOC-11 Distribution SG13 (POD=0.6) 100 80 60 0C) 40 E

z 20 0

M L) t)- M) - C) U) r- 0)ý - M) U) C- 0) ; m U) r-. C)  ; c) Lo O0 00--- --- -N N "NNN mm) Cl)

C) m C)

Bobbin Voltage HAs-FoundcEOC-11 D1R10 EOC-11 Projected Figure 5-14 As-Found vs. Previous Projected EOC-11 Distribution SG14 (POD=0.6) 100 80 60

• 60 z

S40 E

20

~~ PC) 0) - M~ LO r- 0) - M~ U') P-

~ 0) V3-n U; 0))

CY)

CO m~

V U

a 0C - - - - - - - - -) -)

Bobbin Voltage MAs-Found EOC-11 3IR10 EOC-11 Projected

86-5019218-00 Page 65 of 68 6.0 Tube Leak Rate and Tube Burst Probabilities This section presents the results of analyses carried out to predict leak rates and tube burst probabilities for postulated SLB conditions for the projected EOC-12 voltage distributions.

6.1 Leak Rate and Tube BurstProbabilityfor EOC-12 Calculations to predict SLB leak rate and tube burst probability for each steam generator in DCPP Unit-1 at the projected EOC-12 conditions were carried out using the NRC-required constant POD value of 0.6. As described in Section 3.2, normal (non-voltage dependent) growth distributions were used for all steam generators, and additional calculations were performed for SG 1-1 using voltage dependent growth. These results are shown in Table 6-1. For SG 1-1, the results from the two voltage dependent growth analyses (_<0.50 volt, >0.50 volt) had to be combined. Conservatively, the leak rate and burst results for each analysis was simply summed together.

As shown in Table 6-1, the effect of the voltage dependent growth is minimal on the leak rate result. The leak rate for SG 1-1 increased by about 3% when using the voltage dependent growth distributions. For the probability of burst calculation, the number of bursts increased by about 75%. However, the calculated probability of burst is about two orders of magnitude below the acceptance criterion of lxl0"2 . Therefore, relative to the remaining margin, the effect of the voltage dependent growth on the probability of burst is not significant.

6.2 Summary and Conclusions The requirements for burst probabilities are met at EOC-12 with no steam generator exceeding the lxl0"2 criteria. For the leak rate, the plant-specific value of 10.5 gpm (at room temperature) for the faulted steam generator was not exceeded for any steam generator.

86-5019218-00 Page 66 of 68 Table 6-1: Leak Rate and Burst Probability Using 0.6 POD DCPP Unit 1 May 2002 Outage (1Rll)

Summary of Calculations of Tube Leak Rate and Burst Probability at EOC-12 for I million Simulations Using 0.6 POD SLB Leak NumberPOD Steam Probability of Burst Rate 0o Steam POD ofIdctosVoltage Best 95% UCL (4) Dependent Generator Applied at EOC-12o Estimate(2) (1 or More (gpm) Growth Estimate Failures)

SG11 0.6 679.01 5.50 x 10-5 6.89 x 10- 1.106 No SG11 0.6 679.01 9.60 x 10-5 1.17 x 10-4 1.143 Yes SG12 0.6 561.32 3.10 x 10-5 4.18 x 10-5 0.861 No SG13 0.6 256.34 1.90 x 10"1 2.79 x 10-5 0.436 No SG14 0.6 168.69 1.20 x 10-' 1.94 x I0-5 0.233 No Acceptance Criteria 1.0 x 10-2 10.506)

Notes:

1) Adjusted for POD.

2) Best Estimate is the number of trials with a failure divided by the number of trials.

3) Equivalent volumetric rate at room temperature.

4) The 95% Upper Confidence Limit (UCL) is based on the number of trials with one or more failures.

5) The calculated total leak rate reflects the upper 95% quantile value at an upper 95% confidence bound.

6) This limit has not been adjusted for leakage contributions from other ARCs that have been implemented during 1RL1.

86-5019218-00 Page 67 of 68 7.0 References

1. FRA-ANP Document 86-5018456-00, "DCPP IRI 1 Bobbin Coil Voltage ARC, Return-to-Power Report," May 2002.

2. NRC Generic Letter 95-05, "Voltage-Based Repair Criteria for the Repair of Westinghouse Steam Generator Tubes Affected by Outside Diameter Stress Corrosion Cracking," USNRC Office of Nuclear Reactor Regulation, August 3, 1995.

3. NRC SER for Diablo Canyon Units 1 and 2 for Voltage-Based Repair Criteria, letter to PG&E dated March 12, 1998.

4. FTI Document 51-5001160-01, "Steam Generator POB Simulation Code - POB97vb.F90", March 2000.

5. FTI Document 51-5001151-01, "Steam Generator Leak Rate Simulation Code LKR97VB2.F90",

May 2002.

6. WCAP 14277, Revision 1, SLB Leak Rate and Tube Burst Probability Analysis Methods for ODSCC at TSP Intersections, December, 1996.

7. FTI Document 86-5010437-00, "Diablo Canyon Unit 1 - IR10 Voltage-Based Repair Criteria 90 Day Report", January 2001.

8. EPRI Report NP 7480-L, Addendum 3, 1999 Database Update, "Steam Generator Tubing Outside Diameter Stress Corrosion Cracking at Tube Support Plates Database for Alternate Repair Limits",

Electric Power Research Institute, May 1999.

9. Pacific Gas and Electric, Diablo Canyon Unit 1 Refueling Outage IRI 1, "Steam Generator Tubing Degradation Assessment", Revision 0, April 23, 2002.

10. EPRI Report NP 7480-L, Addendum 4, 2001 Database Update, "Steam Generator Tube Outside Diameter Stress Corrosion Cracking at Tube Support Plates Database for Alternate Repairs Limits",

Electric Power Research Institute, March 2001.

11. Diablo Canyon Power Plant Procedure, NDE ET-7, "Eddy Current Examination of Steam Generator Tubing", Revision 1, May 2, 2002.

12. Pacific Gas and Electric Company, Diablo Canyon Power Plant, Surveillance Test Procedure, STP M-SGTI, Revision 6, "Steam Generator Tube Inspection."

13. FRA-ANP Document 51-5018527-00, "Probe Wear Monitoring for DCPP IR1 1", May 2002.

14. Not Used.

15. NRC Letter to NEI, dated February 9, 1996, "Probe Wear Criteria."

86-5019218-00 Page 68 of 68

16. EPRI Report NP 7480-L, Addendum 2 1998 Database Update, "Steam Generator Tubing Outside Diameter Stress Corrosion Cracking at Tube Support Plates Database for Alternate Repair Limits,"

Electric Power Research Instituie, April 1998.

17. FTI Document 51-5005962-00, "Bobbin Voltage Correlation for AONDB Indications at DCPP",

October 1999.

18. E-mail, John Arhar to Jeff Fleck, "Cycle Lengths", April 30, 2002.

19. FRA-ANP Document 32-5019217-00, "DCPP Unit I - IRI 1 90 Day ARC Calculations", August 2002.

20. NEI Letter to NRC, "Steam Generator Degradation Specific Management Database Update", May 8, 2002.

21. NEI Letter to NRC, March 15, 2002, "Refining the Leak Rate Sampling Methodology for ODSCC ARC Applications (GL 95-05)".