DCL-01-138, Special Report 00-01, Revision 1-90 Day Report, Results of Steam Generator Alternate Repair Criteria for Diablo Canyon Power Plant Unit 2 Ninth Refueling Outage

Special Report 00-01, Revision 1-90 Day Report, Results of Steam Generator Alternate Repair Criteria for Diablo Canyon Power Plant Unit 2 Ninth Refueling Outage

ML020240233
Person / Time
Site:	Diablo Canyon
Issue date:	01/03/2002
From:	Womack L Pacific Gas & Electric Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
DCL-01-138
Download: ML020240233 (9)

Text

SPacificGas and Electric Company Lawrence F. Womack Diablo Canyon Power Plant Vice President PO.Box 56 Nuclear Services Avila Beach, CA 93424 805. 545.4600 January 3, 2002 Fax: 805.545.4234 PG&E Letter DCL-01 -138 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Docket No. 50-323, OL-DPR-82 Diablo Canyon Unit 2 Special Report 00-01, Revision 1 - 90 Day Report, Results of Steam Generator Alternate Repair Criteria for Diablo Canyon Power Plant Unit 2 Ninth Refueling Outage

Dear Commissioners and Staff:

Special Report (SR) 00-01, Revision 1, is enclosed to transmit a revised 90 day report for WStar (W*) alternate repair criteria implemented during the Unit 2 ninth refueling (2R9)- SR 00-01 Revision 0 was submitted via DCL-00-008, dated February 20, 2000.

Revision bars in the right hand margin identify revision 1 changes.

Revision 1 corrects a flaw location in steam generator (SG) 22, row 28, column 15.

The flaw is located -11.48 to -11.35 inches relative to the top of tubesheet, and the upper tip of the flaw is located -11.13 inches relative to the top of tubesheet, including NDE uncertainty. The minus signs were inadvertently truncated in revision 0. Revision 1 also clarifies that the W* performance criteria to limit free span cracking is not applicable to 2R9 because 2R9 was the first implementation of the W* ARC.

Sincerely, Lawrence F. Womack cc: Ellis W. Merschoff David L. Proulx Girija S. Shukla State of California Diablo Distribution Enclosures DDMW469

Enclosure 1 PG&E Letter DCL-01-138 SPECIAL REPORT 00-01 90 DAY REPORT W* ALTERNATE REPAIR CRITERIA DIABLO CANYON POWER PLANT UNIT 2 NINTH REFUELING OUTAGE NRC Reportingq Requirements Diablo Canyon Power Plant (DCPP) Technical Specification (TS) 4.4.5.5.e requires that the results of the inspection of W* tubes be reported to the Commission pursuant to TS 6.9.2 (i.e., as a Special Report) within 90 days following return to service of the steam generators (SGs). The report shall include:

1. Identification of W* tubes.

2. W* inspection distance measured with respect to the bottom of the W* 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 steam generator per WCAP-14797.

DCPP TS 4.4.5.5.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 TS 6.9.2 (i.e., Special Report) 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 first time in DCPP Unit 2 during the ninth refueling outage (2R9). Following inspections and maintenance, the SGs were returned to service on October 23, 1999, upon entry into Mode 4.

100 percent of the SG tubes were inspected by bobbin from tube end to tube end.

100 percent of the hot leg top of tube sheet (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 2R9 Plus Point inspections. The following TS-required reporting information is extracted from the table:

1. Identification of W* tubes. See "W* Tube" column in Table 1. Fifty-seven tubes are categorized as W* tubes: 10 in SG 21, 6 in SG 22, 20 in SG 23, and 21 in SG 24.

1

Enclosure 1 PG&E Letter DCL-01-138 An additional 5 tubes with axial PWSCC were plugged because they did not meet W* ARC (upper crack tip was located above BWT, including uncertainty). One circumferential PWSCC indication (not listed) was also detected and plugged because circumferential indications in the W* region are excluded from W* ARC.

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

For the 100 percent Plus Point hot leg TTS exam, the inspection extent relative to the TTS was specified as +2/-8 in. Assuming no degradation in the W* length, 8 in.

below the TTS constitutes the W* inspection distance. This distance bounds W*

lengths for Zone A and Zone B (5.2 in. and 7.0 in., respectively, relative to BWT),

and includes margin for a nominal distance from BWT to TTS plus non-destructive 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*Insp 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.

4. Angle of inclination of clearly skewed axial cracks (if applicable). None of the axial indications were skewed, so the angle of inclination was reported as 0 degrees for all axial indications.

5. The total steam line break leakage for the limiting steam generatorper WCAP-14797. Steam Line Break (SLB) leakage attributed to each W* indication at end of cycle (EOC) 9 (condition monitoring) and EOC 10 (operational assessment) are listed in "CM LR" and "OA LR" columns in Table 1. The limiting W* SLB leak rates for condition monitoring and operational assessment are 0.1468 gpm and 0.6330 gpm, respectively (see Table 2).

Table 2 reports the following SLB leak rates, pursuant to TS 4.4.5.5.e.4 and 4.4.5.5.f:

1. Total W* ARC SLB leakage for each SG at EOC 9.

2. Total W* ARC SLB leakage for each SG at EOC 10.

3. Total Generic Letter (GL) 95-05 voltage based ARC SLB leakage for each SG at EOC 9 and EOC 10.

4. The aggregate calculated SLB leakage from application of both ARC at EOC 9.

5. The aggregate calculated SLB leakage from application of both ARC at EOC 10.

Table 3 provides the updated cumulative probability distribution for growth of W* region axial PWSCC indications. The updated 95 percent cumulative probability DCPP Units 2

Enclosure 1 PG&E Letter DCL-01-138 1 and 2 growth rate is 0.18 in./effective full power year (EFPY), and the distribution includes 28 data points (19 of which are Plus Point to Plus Point). The updated 95 percent cumulative probability combined industry data growth rate is 0.24 in./EFPY (which is lower than the prior 0.25 in./EFPY growth rate documented in WCAP-14797, Rev 1), and the distribution includes the 28 DCPP data points plus 31 data points from plants W1 and W2 documented in WCAP -14797, Rev 1. The W* operational assessment documented herein applies the 0.24 in./EFPY growth rate.

In-situ Leak Testing In an effort to validate the leak rate model in WCAP-14797, Rev 1, three W* indications were in-situ leak tested in 2R9: SG 21 R3C59, SG 21 R7C62, and SG 22 R31C25. All three indications were in deplugged tubes. The in-situ guidelines for selecting indications for leak testing were established in PG&E letter DCL-98-148, "Response To NRC Request For Additional Information, Dated August 6, 1998, Regarding Proposed W* Steam Generator Tube Repair Criteria," dated October 22, 1998. The peak voltage for R3C59 and R31 C25 exceeded the 4.0 volt critical voltage and the peak voltage for R31 C35 was 3.99 volts (approximately 4 volts), requiring that all three indications be leak tested. The indications were locally tested to normal operating pressure differential. Because they did not leak, the test was terminated at that pressure. Plus Point inspections were performed again and verified that the indications satisfy the W*

repair criteria. The indications were returned to service.

Tube Integrity Performance Monitoring Performance Criteria to Limit Free Span Cracking: The upper crack tip of W*

indications returned to service under W* ARC shall remain below the TTS by at least the NDE uncertainty on locating the crack tip relative to the TTS. Since 2R9 was the first time implementation of W* ARC on DCPP Unit 2, this performance criteria is not applicable to 2R9 condition monitoring. This performance criteria is applicable to subsequent inspections following 2R9.

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, shall not exceed 12.8 gpm (at room temperature) in the faulted SG for condition monitoring and operational assessment. Based on Table 2, the aggregate calculated SLB leakage from application of both ARC at EOC 9 is 0.4683 gpm for limiting SG 24, and 1.7247 gpm at EOC 10 for limiting SG 24. In both assessments, SLB leakage is less than the allowable limit of 12.8 gpm for a faulted SG.

Therefore, the performance criteria has been satisfied for condition monitoring at EOC 9 and operational assessment at EOC 10.

3

Enclosure 1 PG&E Letter DCL-01-138 Table 1 DCPP Unit 2 - 2R9 Axial PWSCC Indications in Hot Leg WEXTEX Region SG R C IND +Pt From To L UCT W* W* L BWT UCT UCT UCT EOC UCT W* Insp W* Flex CMLR EOCl00ALR Deplug Plug volt to Zone to Below Below 10 Below Tube Ext Insp W* L UCT TSH BWT W* BWT UCT TSH at Dist BWT

[7 IEOC1O 21 7 24 SAI 0.23 -1.92 -1.78 0.14 -1.56 B3 7.121-0.26 1.24 No Yes -1.20 Yes Yes -21.4 21.05 7.48 -0.95 0.019 Yes 21 8 32 SAI 0.48 -1.88 -1.79 0.09 -1.57 B2 7.12 -0.24 1.27 No Yes -1.21 Yes Yes -9.2 8.87 7.43 0.015 -0.98 0.019 21 11 37 SAI 0.5 -7.49 -7.4 0.09 -7.18 B2 7.12 -0.32 6.8 No Yes -6.82 Yes Yes -9.31 8.9 7.63 0.0005 -6.51 0.0005 21 SAI 0.68 -6.61 -6.48 0.13 -6.26 B2 7.12 -0.32 5.88 No Yes -5.90 Yes Yes -9.31 8.9 7.63 0.0005 -5.59 0.0008 21 SAI 0.28 -2.02 -1.95 0.07 -1.73 B2 7.12 -0.32 1.35 No Yes -1.37 Yes Yes -9.31 8.9 7.63 0.015 -1.06 0.019 21 11 39 SAI 1.27 -1.7 -1.56 0.14 -1.34 81 7.12 -0.33 0.95 No Yes -0.98 Yes Yes -21.08 20.66 7.48 -0.66 0.023 Yes 21 11 40 SAI 0.45 -0.98 -0.81 0.17 -0.59 B1 7.12 -0.34 0.19 No Yes -0.23 Yes Yes -9.46 9.03 7.51 0.038 0.10 0.045 21 11 48 SAI 1.21 -4.86 -4.47 0.39 -4.25 B1 7.12 -0.31 3.88 No Yes -3.89 Yes Yes -9.36 8.96 7.73 0.005 -3.59 0.0055 21 3 59 SAI 5.58 -1.39 -0.9 0.49 -0.68 B1 7.12 -0.39 0.23 No Yes -0.32 Yes Yes -21.4 20.92 7.83 0.06 0.045 Yes 21 7 62 SAI 4.17 -2.13 -1.66 0.47 -1.44 B2 7.12 -1.07 0.31 No Yes -1.08 Yes Yes -21.4 20.24 7.81 -0.02 0.045 Yes 21 28 62 SAI 0.31 -0.55 -0.46 0.09 -0.24 A 5.32 -0.27 -0.09 No No 0.12 No No -9.96 9.6 5.63 0.043 Yes 21 .23 70 SAI 0.9 -1.57 -1.24 0.33 -1.02 A 5.32 -0.12 0.84 No Yes -0.66 Yes Yes -21.4 21.19 5.87 -0.55 0.025 Yes 21 6 77 SAI 1.31 -1.33 -1.2 0.13 -0.98 B4 7.12 -0.5 0.42 No Yes -0.62 Yes Yes -21.4 20.81 7.47 -0.13 0.041 Yes 22 28 15 SAI 0.76 -11.48 -11.35 0.13 -11.13 A 5.32 -0.49 10.58 Yes Yes 10.77 Yes Yes -21.4 20.82 N/A -10.29 Yes 22 SAI 0.68 -2.53 -2.4 0.13 -2.18 A 5.32 -0.49 1.63 No Yes -1.82 Yes Yes -21.4 20.82 5.98 -1.34 0.007 Yes 22 SAI 0.66 -2.04 -1.86 0.18 -1.64 A 5.32 -0.49 1.09 No Yes -1.28 Yes Yes -21.4 20.82 5.98 -0.80 0.013 Yes 22 5 18 SAI 0.46 -1.14 -0.97 0.17 -0.75 B4 7.12 -0.3 0.39 No Yes -0.39 Yes Yes -11.04 10.65 7.51 0.03 -0.10 0.043 22 31 25 SAI 3.99 -2.06 -1.59 0.47 -1.37 A 5.32 -0.61 0.70 No Yes -1.01 Yes Yes -21.4 20.7 6.01 -0.41 0.03 Yes 22 13 43 SAI 1.03 -1.57 -1.36 0.21 -1.14 B1 7.12 -0.45 0.63 No Yes -0.78 Yes Yes -21.4 20.86 7.55 -0.34 0.031 Yes 22 10 48 SAI 0.51 -3.17 -3.05 0.12 -2.83 81 7.12 -0.31 2.46 No Yes -2.47 Yes Yes -9.04 8.64 7.46 0.0083 -2.17 0.0095 22 10 56 SAI 0.96 -1.05 -0.90 0.15 -0.68 B1 7.12 -0.35 0.27 No Yes -0.32 Yes Yes -21.4 20.96 7.49 0.02 0.045 Yes 23 28 12 SAI 0.72 -1.86 -1.7 0.16 -1.48 A 5.32 -0.59 0.83 No Yes -1.12 Yes Yes -8.88 8.2 5.70 0.012 -0.54 0.028 23 9 22 SAI 0.26 -0.15 -0.01 0.14 0.21 B4 7.12 -0.45 -0.72 No No 0.57 No No -8.19 7.65 7.48 0.043 Yes 23 14 24 SAI 0.59 -1.87 -1.64 0.23 -1.42 B4 7.12 -0.14 1.22 No Yes -1.06 Yes Yes -21.4 21.17 7.57 -0.93 0.015 Yes 23 16 24 SAI 0.35 -1.39 -1.28 0.11 -1.06 B4 7.12 -0.24 0.76 No Yes -0.70 Yes Yes -21.4 21.07 7.45 -0.47 0.028 Yes 23 25 37 SAI 2.41 -1.44 -0.96 0.48 -0.74 B4 7.12 -0.59 0.09 No Yes -0.38 Yes Yes -21.4 20.72 7.82 0.20 0.043 Yes 23 45 37 SAI 1.65 -1.76 -1.27 0.49 -1.05 A 5.32 -0.36 0.63 No Yes -0.69 Yes Yes -21.4 20.95 6.03 -0.34 0.028 Yes 23 21 38 SAI 1.17 -1.68 -1.09 0.59 -0.87 B3 7.12 -0.43 0.38 No Yes -0.51 Yes Yes -21.4 20.88 7.93 -0.09 0.04 Yes 23 12 48 SAI 0.35 -2.09 -1.97 0.12 -1.75 B1 7.12 -0.35 1.34 No Yes -1.39 Yes Yes -21.4 20.96 7.46 -1.05 0.018 Yes 23 5 51 SAI 0.3 -2.04 -1.94 0.1 -1.72 B1 7.12 -0.32 1.34 No Yes -1.36 Yes Yes -21.4 20.99 7.44 -1.05 0.018 Yes 23 7 52 SAI 3.44 -1.61 -1.11 0.5 -0.89 81 7.12 -0.15 0.68 No Yes -0.53 Yes Yes -21.4 21.16 7.84 -0.39 0.03 Yes 23 5 55 SAI 0.51 -1.82 -1.72 0.1 -1.5 B1 7.12 -0.22 1.22 No Yes -1.14 Yes Yes -9.66 9.35 7.44 0.015 -0.93 0.015 23 32 55 SAI 0.94 -1.22 -1.02 0.2 -0.8 A 5.32 -0.46 0.28 No Yes -0.44 Yes Yes -21.4 20.85 5.74 0.01 0.043 Yes 23 7 59 SAI 0.98 -1.49 -1.17 0.32 -0.95 B1 7.12 -0.24 0.65 No Yes -0.59 Yes Yes -21.4 21.07 7.66 -0.36 0.031 Yes 23 3 69 SAI 0.31 -1.16 -0.98 0.18 -0.76 B2 7.12 -0.29 0.41 No Yes -0.40 Yes Yes -9.71 9.33 7.52 0.03 -0.12 0.04 23 19 71 SAI 1.22 -1.99 -1.59 0.4 -1.37 A 5.32 -0.32 0.99 No Yes -1.01 Yes Yes -21.4 20.99 5.94 -0.70 0.02 Yes 23 17 72 SAI 1.75 -1.01 -0.60 0.41 -0.38 A 5.32 -0.25 0.07 No Yes -0.02 Yes Yes -21.4 21.06 5.95 0.22 0.043 Yes 23 6 77 SAI 0.39 -1.6 -1.50 0.1 -1.28 B4 7.12 -0.34 0.88 No Yes -0.92 Yes Yes -21.4 20.97 7.44 -0.59 0.021 Yes 4

Enclosure 1 PG&E Letter DCL-01-138 SG R C IND +Pt From To L UCT W* W*L BWT UCT UCT UCT EOC UCT W* Insp W* Flex CMLR EOC11 OALR Deplug Plug volt to Zone to Below Below 10 Below Tube Ext Insp W* L UCT TSH BWT W* BWT UCT TSH at Dist BWT EOC10 23 21 83 SAI 1.39 -1.23 -0.90 0.33 -0.68 A 5.32 -0.31 0.31 No Yes -0.32 Yes Yes -21.4 21 5.87 -0.02 0.043 Yes 23 2 91 SAI 0.61 -0.94 -0.59 0.35 -0.37 A 5.32 -0.12 0.19 No Yes -0.01 Yes Yes -21.4 21.19 5.89 0.10 0.043 Yes 23 7 92 SAI 0.68 -1.22 -1.00 0.22 -0.78 A 5.32 -0.38 0.34 No Yes -0.42 Yes Yes -21.4 20.93 5.76 -0.05 0.043 Yes 23 8 93 SAI 1.54 -0.95 -0.59 0.36 -0.37 A 5.32 -0.12 0.19 No Yes -0.01 Yes Yes -21.4 21.19 5.90 0.10 0.043 Yes 24 7 4 SAI 1.02 -1.36 -1.15 0.21 -0.93 A 5.32 -0.26 0.61 No Yes -0.57 Yes Yes -21.4 21.05 5.75 -0.32 0.031 Yes 24 13 4 SAI 0.44 -1.4 -1.27 0.13 -1.05 A 5.32 -0.41 0.58 No Yes -0.69 Yes Yes -9.21 8.71 5.67 0.023 -0.29 0.031 24 3 5 SAI 1.1 -2 -0.97 1.03 -0.75 A 5.32 -0.34 0.35 No Yes -0.39 Yes Yes -21.4 20.97 6.57 -0.06 0.043 Yes 24 2 10 SAI 0.61 -1.61 -1.5 0.11 -1.28 A 5.32 -0.1 1.12 No Yes -0.92 Yes Yes -21.4 21.21 5.65 -0.83 0.013 Yes 24 15 10 SAI 0.47 -1.07 -0.8 0.27 -0.58 A 5.32 -0.36 0.16 No Yes -0.22 Yes Yes -21.4 20.95 5.81 0.13 0.043 Yes 24 16 10 SAI 1.17 -2.57 -2.15 0.42 -1.93 A 5.32 -0.48 1.39 No Yes -1.57 Yes Yes -21.4 20.83 5.96 -1.10 0.009 Yes 24 3 12 SAI 0.57 -2.98 -2.85 0.13 -2.63 A 5.32 -0.3 2.27 No Yes -2.27 Yes Yes -21.4 21.01 5.86 -1.98 0.004 Yes 24 SAI 1.2 -2.61 -2.42 0.19 -2.2 A 5.32 -0.3 1.84 No Yes -1.84 Yes Yes -21.4 21.01 5.86 -1.55 0.006 Yes 24 26 24 SAI 3.94 -2.42 -1.77 0.65 -1.55 A 5.32 -0.39 1.1 No Yes -1.19 No No -21.4 20.92 6.3 Yes Yes 24 SAI 0.57 -0.49 -0.38 0.11 -0.16 A 5.32 -0.39 -0.29 No No 0.20 No No -21.4 20.92 6.3 Yes Yes 24 24 26 SAI 0.55 -1.93 -1.77 0.16 -1.55 A 5.32 -0.43 1.06 No Yes -1.19 Yes Yes -9.69 9.17 5.7 0.0083 -0.77 0.022 24 2 29 SAI 1.7 -4.77 -3.85 0.92 -3.63 B2 7.12 -0.58 2.99 No Yes -3.27 Yes Yes -21.4 20.73 8.94 -2.70 0.007 Yes 24 SAI 0.39 -3.56 -3.38 0.18 -3.16 B2 7.12 -0.58 2.52 No Yes -2.80 Yes Yes -21.4 20.73 8.94 -2.23 0.0082 Yes 24 SAI 0.49 -2.46 -2.14 0.32 -1.92 B2 7.12 -0.58 1.28 No Yes -1.56 Yes Yes -21.4 20.73 8.94 -0.99 0.019 Yes 24 SAI 0.23 -2.08 -2.03 0.05 -1.81 B2 7.12 -0.58 1.17 No Yes -1.45 Yes Yes -21.4 20.73 8.94 -0.88 0.02 Yes 24 SAI 0.32 -2 -1.87 0.13 -1.65 B2 7.12 -0.58 1.01 No Yes -1.29 Yes Yes -21.4 20.73 8.94 -0.72 0.022 Yes 24 6 33 SAI 0.4 -2.87 -2.75 0.12 -2.53 B2 7.12 -0.14 2.33 No Yes -2.17 Yes Yes -10.82 10.59 7.46 0.008 -2.04 0.009 24 13 34 SAI 0.4 -0.14 -0.01 0.13 0.21 B2 7.12 -0.34 -0.61 No No 0.57 No No -9.42 8.99 7.47 0.043 Yes 24 4 35 SAI 1.15 -1.79 -1.34 0.45 -1.12 B1 7.12 -0.24 0.82 No Yes -0.76 Yes Yes -21.4 21.07 7.79 -0.53 0.025 Yes 24 6 35 SAI 0.91 -2.3 -2.14 0.16 -1.92 B1 7.12 -0.31 1.55 No Yes -1.56 Yes Yes -21.4 21 7.5 -1.26 0.015 Yes 24 5 36 SAI 0.22 -1.53 -1.44 0.09 -1.22 B1 7.12 -0.17 0.99 No Yes -0.86 Yes Yes -8.45 8.19 7.43 0.019 -0.70 0.022 24 5 37 SAI 0.36 -4.58 -4.43 0.15 -4.21 B1 7.12 -0.43 3.72 No Yes -3.85 Yes Yes -21.4 20.88 8.02 -3.43 0.006 Yes 24 SAI 1.06 -4.4 -3.87 0.53 -3.65 B1 7.12 -0.43 3.16 No Yes -3.29 Yes Yes -21.4 20.88 8.02 -2.87 0.0075 Yes 24 7 38 SAI 3.04 -7.16 -6.65 0.51 -6.43 Bi 7.12 -0.35 6.02 No Yes -6.07 Yes Yes -21.4 20.96 8.58 -5.73 0.0009 Yes 24 SAI 2.16 -4.73 -4 0.73 -3.78 81 7.12 -0.35 3.37 No Yes -3.42 Yes Yes -21.4 20.96 8.58 -3.08 0.007 Yes 24 13 40 SAI 1.35 -1.91 -1.48 0.43 -1.26 B2 7.12 -0.28 0.92 No Yes -0.90 Yes Yes -21.4 21.03 7.77 -0.63 0.023 Yes 24 29 42 SAI 0.52 -0.23 -0.11 0.12 0.11 B4 7.12 -0.38 -0.55 No No 0.47 No No -10.56 10.09 7.46 0.043 Yes 24 26 45 SAI 0.52 -3.76 -3.61 0.15 -3.39 B4 7.12 -0.36 2.97 No Yes -3.03 Yes Yes -10.52 10.07 7.49 0.0025 -2.68 0.0033 24 31 45 SAI 1.59 -2.09 -1.57 0.52 -1.35 A 5.32 -0.34 0.95 No Yes -0.99 Yes Yes -21.4 20.97 6.06 -0.66 0.021 Yes 24 20 47 SAI 0.55 -1.7 -1.54 0.16 -1.32 B2 7.12 -0.24 1.02 No Yes -0.96 Yes Yes -21.4 21.07 7.5 -0.73 0.021 Yes 24 5 53 SAI 1.22 -2.03 -1.62 0.41 -1.4 81 7.12 -0.32 1.02 No Yes -1.04 Yes Yes -20.86 20.45 7.75 -0.73 0.021 Yes 24 25 64 SAI 1.54 -1.62 -1.16 0.46 -0.94 B4 7.12 -0.31 0.57 No Yes -0.58 Yes Yes -21.4 21 7.8 -0.28 0.02 Yes 5

Enclosure 1 PG&E Letter DCL-01-138 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. Some tubes have multiple non-parallel SAL.

+P Volt Peak voltage from Plus Point coil.

From - To Elevation (in.) of lower crack tip (from) to upper crack tip (to), relative to the hot leg top of tubesheet (TSH).

L Length of crack (in.)

UCT to TSH Elevation (in.) of the upper crack tip (UCT) relative to TSH, including ANDECT-TTS (Plus Point NDE uncertainty on locating the crack tip relative to the TTS).

W* Zone W* tubesheet zone based on crack location.

W* L W* length based on W'* Zone, plus ANDEw (NDE uncertainty in measuring the W* depth).

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

UCT to BWT Distance (in.) from the upper crack tip (UCT) to BWT, minus ANDECT-BWT (Plus Point NDE uncertainty on locating the crack tip relative to the BWT).

UCT below W* If the 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 If the UCT is located below BWT, then the tube is a W* candidate.

EOC 10 UCT UCT location (in.) relative to TSH at the end of the next operating cycle, EOC 10, based on growing the UCT at 0.25 in./EFPY. Unit 2 Cycle 10 is projected to be 1.44 EFPY.

UCT below TSH at Ifthe UCT is below TSH at EOC 10, a free span indication is precluded and the tube is a W* candidate.

EOC 10 W* Tube If the UCT is below BWT and the UCT is below TSH at EOC 10, then the tube is a W* tube. If the UCT is located below the W* length, then the tube is a W* tube.

Insp Ext Inspection extent of Plus Point relative to TSH (in.).

W* Insp Dist W* inspection distance (in.). 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 BVVT (in.), equal to W* Length + 7-CIj (total axial crack length) + NcL*ANDEcL(number of indications times Plus Point NDE uncertainty with measuring length of axial cracks) + NCL*ACG (number of indications times crack growth allowance from prior cycle tube integrity assessment, 0.25 in./EFPY)

CM LR Condition monitoring SLB leak rate at EOC 9 conditions, gpm at room temperature, based on distance of UCT to BWT using Figure 6.4-3 of WCAP-14797 Rev 1. No accident leakage is assigned to an indication with an UCT below the W* length. No accident leakage is assigned to an indication in a tube deplugged and returned to service.

EOC 10 UCT to Distance of UCT to BWT (in.) at EOC 10 for operational assessment, based on growing the UCT at the latest updated industry combined 95%

BWT growth rate (0.24 in./EFPY).

OA LR Operational assessment leak rate at EOC 10 conditions, gpm at room temperature, based on distance of UCT (at EOC 10) to BWT using Figure 6.4-3 of WCAP-14797 Rev 1.

Deplug Tube was deplugged in 2R9.

Plug Tube was plugged in 2R9.

6

Enclosure 1 PG&E Letter DCL-01-138 Table 2 DCPP Unit 2 Steam Line Break Leak Rates for Alternate Repair Criteria EOC 9 Condition Monitoring Leak Rate SG 2-1 SG 2-2 SG 2-3 SG 2-4 (gpm at room temperature) _

W*ARC 0.1170 0.0383 0.1000 0.1468 Voltage-Based ARC 0.0627 0.0244 0.0312 0.3215 Aggregate ARC 1.1797 0.0627 -

0.8688 1.5317 EOC 10 Operational Assessment Leak SG 2-1 SG 2-2 SG 2-3 SG 2-4 Rate (gpm at room temperature)

VV*ARC 0.2818 0.1765 0.6330 0.4799 Voltage-Based ARC 0.2349 0.1267 0.1500 1.2448 Aggregate ARC 1.5167 0.3032 -0.217 0.2753 7

Enclosure 1 PG&E Letter DCL-01-138 Table 3 DCPP Unit 2 Cycle 10 Growth Rate for Axial PWSCC in W* Region Cumulative Probability Distribution for Growth of Axial PWSCC Indications in W* Region 1

0.9 0.8 0.7 0

..- , 0.6 a) 0.5 0.4 E 0.3 0 0.2 0.1 0

-0.30 -0.20 -0.10 0.00 0.10 0.20 0.30 0.40 0.50 WEXTEX Axial Crack Growth per EFPY (inches) 8