DCL-06-099, ASME Section XI Inservice Inspection Program Relief Requests NDE-SLH U2 and NDE-LSL U2

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ASME Section XI Inservice Inspection Program Relief Requests NDE-SLH U2 and NDE-LSL U2
ML062420240
Person / Time
Site: Diablo Canyon Pacific Gas & Electric icon.png
Issue date: 08/24/2006
From: Becker J
Pacific Gas & Electric Co
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
DCL-06-099
Download: ML062420240 (15)
v • d • e


Text

Pacific Gas and Electric Company' James R. Becker Diablo Canyon Power Plant Vice President P.a. Box 56 Diablo Canyon Operations and Avila Beach, CA 93424 Station Director 805.545.3462 August 24, 2006 Fax: 805.545.4234 PG&E Letter DCL-06-099 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Docket No. 50-323, OL-DPR-82 Diablo Canyon Unit 2 ASME Section XI Inservice Inspection Program Relief Requests NDE-SLH U2 and NDE-LSL U2

Dear Commissioners and Staff:

Pursuant to 10 CFR 50.55a(g)(5)(iii), Pacific Gas and Electric Company hereby requests NRC approval for Inservice Inspection Program Relief Requests NDE-SLH U2 and NDE-LSL U2.

These requests for relief are associated with the reactor vessel lower shell-to-bottom head circumferential weld and lower shell longitudinal weld examinations performed during Diablo Canyon Power Plant (DCPP) Unit 2 Refueling Outage 13.

The bases for the requests for relief are provided in Enclosures 1 and 2.

There are no regulatory commitments in this letter.

Ifyou have any questions, please contact Mr. Stan Ketelsen at (805) 545-4720.

A member of the STARS (Strategic Callaway e Comanche Peak

  • Diablo Canyon Teaming and Resource
  • Palo Verde
  • Sharing) Alliance South Texas Project
  • Wolf Creek -Aýq

Document Control Desk PG&E Letter DCL-06-099 August 24, 2006 Page 2 Whyl/4279/A0668378 Enclosures cc: Diablo Distribution cc/enc: Edgar Bailey, DHS Terry W. Jackson, Senior Resident Inspector Bruce S. Mallett, Region IV Alan B. Wang, NRR State of California, Pressure Vessel Unit A member of the STARS (Strategic Teaming and Resource Sharing) Alliance Callaway

  • Comanche Peak
  • Diablo Canyon
  • Palo Verde
  • Wolf Creek

Enclosure I PG&E Letter DCL-06-099 INSERVICE INSPECTION (ISl) RELIEF REQUEST NDE-SLH U2 In Accordance with 10 CFR 50.55a(g)(5)(iii)

--Inservice Inspection Impracticality--

1. ASME Code Component Affected Diablo Canyon Power Plant (DCPP) Unit 2 reactor vessel lower shell-to-bottom head circumferential weld.

2. Applicable Code Edition and Addenda

ASME Section XI, 1989 Code Edition without Addenda.

3. Applicable Code Requirement

Table IWB-2500-1, Category B-A, Item B13.11, requires that the reactor vessel shell-to-bottom head weld (Unit 2 weld no.10-201) be volumetrically examined once at or near the end of the interval.

Essentially 100 percent of the weld volume is required to be examined as shown in Figure IWB-2500-1, using the acceptance standard of IWB-351 0.

Relief is requested from performing a portion of the volumetric examination where access is restricted by core support lugs and the bottom head taper. See Figure 1 for weld and lug locations.

4. Impracticality of Compliance The design of the vessel shell-to-bottom head weld precludes a portion of the required weld examination due to the presence of the six core barrel support lug locations. The support lugs and bottom head taper limit access of the vendor's reactor vessel examination tool to a portion of the required examination volume. All areas of the weld (75.36 percent) accessible for Code volumetric examination were examined as required.

See Figures 2 and 3 for illustration of limitation areas.

5. Burden Caused By Compliance Providing access at this location would require redesign of the reactor vessel internals supports, redesign of the building concrete structure or of the vessel insulation, and is impractical.

1

Enclosure 1 PG&E Letter DCL-06-099

6. Proposed Alternative and Basis for Use The inspection of DCPP Unit 2 reactor vessel lower shell to lower head circumferential weld (weld no.10-201) during Unit 2 Refueling Outage 13 (2R13) was conducted using a procedure and techniques qualified by demonstration for 1995 edition/1996 Addenda ASME Section Xl Appendix VIII examinations in accordance with Supplements 4 and 6.

The examination used a combination of 45 degree angle search units with shear and longitudinal wave propagation and 30 mm or greater focal depths. The sound beams from these transducers were directed in four orthogonal directions parallel and perpendicular to the weld in as close proximity to the six core support lugs as the inspection device and transducer sled would allow. Figures 1, 2, and 3 depict the location of this weld in the reactor vessel, the scanning limitations for parallel and perpendicular scans below the core support lugs, and the scanning access in between the lugs, respectively.

The physical size of the transducer sled limited the approach to the core support lugs without hazarding the assembly and causing damage and loose parts concerns. Calculation of the weld and volume coverage afforded by each set of transducers by the data analysts resulted in a combined coverage of 75.36 percent. Table 1 provides a breakdown of percent coverage of the required examination volume by scan direction and transducers.

Consideration was also given to examining the weld from the vessel outside diameter. The bottom head and shell insulation in this area is not designed to be removable and the close proximity of the insulated vessel to the concrete shield wall prohibits access. As stated above, providing access at these locations would require redesign of the building concrete structure and the vessel insulation, and is impractical.

7. Duration of Proposed Alternative This relief request will be implemented during the DCPP Unit 2 second ISI interval. The examinations took place during the 2R13 refueling outage in April of 2006.

This request is essentially the same as NDE-001 from the first ISI interval, which was approved in NRC letter dated December 14, 1988.

2

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U3 0"i Index Increment Size Perp Scans = 0.325! (0.5") (D Parallel scans = 0.5" 0 c"

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  • (D0 WORKING POINT 325.50" 0 2.

0 0 (78.86>) -*

0 (78.20') Top Parallel Under Lugs (77.07') Top Perp Under Lugs (76.67")

(to (75.53") Bottom Parallel (73.90") Bottom Perp §o.

R=88.16 r-3 0 -U to G)

CIOd 90 Weld 10-201 m 0 00 17-DIABLO CANYDN UNIT 2 PEG 2006 CID CDI r D CALCULATION OF Lower to Bottom Head CIr'c Weid 60 BOTTOM end TOP POSITIONS EXAMINATION PROGRAM PLAN ALL DIMENSIONS IN INCHES I -

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(0 CD

Index Increment Size (0 Perp Scans = 0.33V (0.5")

Parallel scans 0.5" 0

R=86.5 C

WORKING POINT 0 Top Perp Between Lugs 325.50" Top Parallel Between Lugs CD~

(78,86°)

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Ctad Weld 10-201 CO 0 DIABLO CANYON UNIT 2 PEG 2006 CD CD Lower to Bottom Heocd Clrc Weld l0 CALCULATION OF BOTTOM POSITIONS EXAMINATION PROGRAM PLAN ALL DIMENSIONS ININCMF 0

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DIABLO CANYON UNIT 2 DIRECTION / ORIENTATION RPV COVERAGE ESTIMATE BREAKDOWNS PARALLEL SCANS CCWICW PERP. SCANS UP / DN O (D WELD WELD NO.10-201 DESCRIPTION Lower Shell to Lower Head Circ. Weld <-

0n 0

z (n BEAM ANGLES 00C 00 BEAM 450 L Dual 450 L Single 450 Shear DIRECTION CD 0)

WELD VOLUME WELD VOLUME WELD VOLUME WELD VOLUME WELD VOLUME 0 W~

CCW 59.37 66.2 77.1 85.0 77.1 85.0 0 (D 00[2.

r C*

CW 59.37 68.2 77.1 85.0 77.1 85.0 CD0 0

  • UP 63.9 63.9 63.9 63.9 *100 *99.0 CD M -U G)

= 0. 90 DOWN 63.9 63.9 63.9 63.9 *100 *99.0

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Combined Average 75.36%

  • Area of single sided coverage below core support lugs. Limitation due to 0=

proximity of 6 core support lugs.

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Enclosure 2 PG&E Letter DCL-06-099 INSERVICE INSPECTION (ISI) RELIEF REQUEST NDE-LSL U2 In Accordance with 10 CFR 50.55a(g)(5)(iii)

--Inservice Inspection Impracticality--

1. ASME Code Component Affected Diablo Canyon Power Plant (DCPP) Unit 2 reactor vessel lower shell longitudinal welds.
2. Applicable Code Edition and Addenda ASME Section XI, 1989 Code Edition without Addenda.

3. Applicable Code Requirement

Table IWB-2500-1, Category B-A, Item B13.12, requires that the reactor vessel shell longitudinal welds (Unit 2 weld nos. 3-201A, 3-201B, and 3-201 C) be volumetrically examined once at or near the end of the interval. Essentially, 100 percent of the weld volume is required to be examined as shown in Figure IWB-2500-2, using the acceptance standard of IWB-3510.

Relief is requested from performing a portion of the volumetric examination where access is restricted by core support lugs and the bottom head taper. See Figure 1 for weld and lug locations.

4. Impracticality of Compliance The design of the vessel shell longitudinal weld precludes a portion of the required weld examination due to the presence of three of the six core barrel support lugs. The support lugs limit access of the vendor's reactor vessel examination tool to a portion of the required examination volume.

All areas of each weld (80.01 percent of each weld) accessible for Code volumetric examination were examined as required. See Figure 2 for illustration of limitation areas.

5. Burden Caused By Compliance Providing access at this location would require redesign of the reactor vessel internals supports, redesign of the building concrete structure or of the vessel insulation, and is impractical.

1

Enclosure 2 PG&E Letter DCL-06-099

6. Proposed Alternative and Basis for Use The inspection of DCPP Unit 2 reactor vessel lower shell longitudinal welds (weld no. 3-201A, 3-201B, and 3-201C) during Unit 2 Refueling Outage 13 (2R13) was conducted using a procedure and techniques qualified by demonstration for 1995 edition/1996 Addenda ASME Section XI Appendix VIII examinations in accordance with Supplements 4 and 6. The examination used a combination of 45 degree angle search units with shear and longitudinal wave propagation and 30 mm or greater focal depths. The sound beams from these transducers were directed in four orthogonal directions parallel and perpendicular to the weld in as close proximity to the six core support lugs as the inspection device and transducer sled would allow. Figures 1 and 2 depict the location of these welds in the reactor vessel and the scanning limitations for parallel and perpendicular scans above the core support lugs.

The physical size of the transducer sled limited the approach to the core support lugs without hazarding the assembly and causing damage and loose parts concerns. Calculation of the weld and volume coverage afforded by each set of transducers by the data analysts resulted in a combined coverage of 80.01 percent. Tables 1, 2, and 3 provide a breakdown of percent coverage of the required examination volume for each one of the three welds by scan direction and transducers.

Consideration was also given to examining the welds from the vessel outside diameter. The bottom head and shell insulation in this area is not designed to be removable and the close proximity of the insulated vessel to the concrete shield wall prohibits access. As stated above, providing access at these locations would require redesign of the building concrete structure and the vessel insulation, and is impractical.

7. Duration of Proposed Alternative This relief request will be implemented during the DCPP Unit 2 second ISI interval. The examinations took place during the 2R13 refueling outage in April of 2006.

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DIABLD CANYON UNIT B PEG 2006 'CD m Welds: 3-201A @ 60" I--

CD Index Increment Size 3-201B @ 180" 90 Perp Scans = 0.331" (0.5") 3-201C @ 300" Lower Shett Longltudinal. Wetds 0

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Parallel scans = 0.5" I7-EXAMINATION PROGRAM PLAN 0 m j tflu..r.3., .Jk5ualnIar. ~~.Jsr.uI 0

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Diablo Canyon #2 DIRECTION / ORIENTATION 0.

RPV COVERAGE ESTIMATE BREAKDOWNS PARALLEL SCANS IJP/DN PERP. SCANS C CW/CW ITEM / AREA Lower Long Seam Weld @ 600 WELD NO. 3-201 A BEAM ANGLES z 0

BEAM 45 Dual 45 Single 45 Shear 0 DIRECTION 0 WELD VOLUME r-WELD VOLUME WELD VOLUME WELD VOLUME WELD VOLUME 0, c" CCW 79.49 79.49 0 77.12 77.12 79.49 79.49 In CW 79.49 79.49 77.12 77.12 79.49 79.49 (D

'a 0 (D

UP 79.24 79.24 79.24 79.24 85.47 85.47 DOWN 79.24 79.24 79.24 79.24 85.47 85.47 -u (A CD -0 Ei I-CD Combined Average = 80.01% Limitation due to Core Support Lug @ 600 (D 9- c C- -1

Diablo Canyon #2 DIRECTION / ORIENTATION RPV COVERAGE ESTIMATE BREAKDOWNS PARALLEL SCANS UP/DN PERP. SCANS CCW/CW 0.

ITEM / AREA Lower Long Seam Weld @ 1800 WELD NO. 3-201 B M~.

BEAM ANGLES 0 0 BEAM 45 Dual 45 Single 45 Shear DIRECTION -AW WELD VOLUME WELD VOLUME WELD VOLUME WELD VOLUME WELD VOLUME 0)

CCW 79.49 79.49 77.12 77.12 79.49 79.49 00C 0S

-40 CW 79.49 79.49 77.12 77.12 79.49 79.49 UP 79.24 79.24 79.24 79.24 85.47 85.47 (D (D (D~ -U DOWN 79.24 79.24 79.24 79.24 85.47 85.47 0.

I-CD CD Combined Average 80.01% Limitation due to Core Support Lug @ 1800 I0 60

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01 Diablo Canyon #2 DIRECTION I ORIENTATION 0 RPV COVERAGE ESTIMATE BREAKDOWNS PARALLEL SCANS UP/DN PERP. SCANS CCW/CW 9-0 ITEM I AREA Lower Long Seam Weld @ 3000 WELD NO. 3-201C BEAM ANGLES z 0 0 BEAM 45 Dual 45 Single 45 Shear DIRECTION Cil CD WELD VOLUME WELD VOLUME WELD VOLUME WELD VOLUME WELD VOLUME -~10

-4 A)0 r-0 CCW 79.49 79.49 77.12 77.12 79.49 79.49 (r0 CW 79.49 79.49 77.12 77.12 79.49 79.49 CD MI UP 79.24 79.24 79.24 79.24 85.47 85.47 C, 8D 0

-D DOWN 79.24 79.24 79.24 79.24 85.47 85.47 CL G)

U3 M4 I-E. CD CD Combined Average = 80.01% Limitation due to Core Support Lug @ 3000 6~0

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