DCL-17-017, ASME Section XI Inservice Inspection Relief Requests NDE-RPV 10 Year 2R19
| ML17068A082 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 03/08/2017 |
| From: | Welsch J Pacific Gas & Electric Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| DCL-17-017 | |
| Download: ML17068A082 (37) | |
Text
lrl Pacific Gas and
~ ~
- Electric Company James M. Welsch Diablo Canyon Power Plant Vice President, Nuclear Generation Mail Code 104/6 P. 0. Box 56 Avila Beach, CA 93424 805.545.3242 Internal: 691.3242 March 8, 2017 Fax: 805.545.4884 PG&E Letter DCL-17-017 U.S. Nuclear Regulatory Commission 10 CFR 50.55a ATTN: Document Control Desk Washington, DC 20555-0001 Docket No. 50-323, OL-DPR-82 Diablo Canyon Power Plant (DCPP) Unit 2 ASME Section Xllnservice Inspection Relief Requests NDE-RPV 10 Year 2R19
Dear Commissioners and Staff:
Pursuant to 10 CFR 50.55a(g)(5)(ii.i}, Pacific Gas and Electric Company (PG&E) hereby requests NRC approval of five inservice inspection (lSI) relief requests (RRs) for the Diablo Canyon Power Plant (DCPP) Unit 2 third lSI interval. The details of these requests are enclosed.
These five RRs are associated with impracticalities encountered when attempting to implement the requirements of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code,Section XI, for examination of the subject DCPP Unit 2 reactor vessel welds during the Unit 2 Nineteenth Refueling Outage (2R19) in May of 2016. 2R19 was the last refueling outage in the third lSI interval.
PG&E makes no new or revised regulatory commitments (as defined by NEI 99-04) in this letter. If you have any questions or require additional information, please contact Mr. Hossein Hamzehee at (805) 545-4720.
SiniL/~C~
James M. Welsch ~
rntt/4231/SAPN 509034 74 Enclosures cc: Diablo Distribution cc/encl: Kriss M. Kennedy, NRC Region IV Administrator Christopher W. Newport, NRC Senior Resident Inspector Balwant K. Singal, NRC Senior Project Manager State of California, Pressure Vessel Unit A member of the STARS Alliance Callaway
- Diablo Canyon
- Palo Verde
- Wolf Creek
Enclosure 1 PG&E Letter DCL-17-017 INSERVICE INSPECTION (lSI) RELIEF REQUEST NDE-SLH U2 In Accordance with 10 CFR 50.55a(g)(5)(iii)
--lnservice 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, 2001 Edition through 2003 Addenda.
3. Applicable Code Requirement
Table IW8-2500-1, Category 8-A, Item 81.11, requires that the reactor vessel lower 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 IW8-2500-1, using the acceptance standard IW8-351 0.
Relief is requested from performing a portion of the volumetric examination where access is restricted by.six core barrel support lugs. See Figure 1 of this enclosure for weld and lug locations.
- 4. Impracticality of Compliance The design of the vessel lower shell-to-bottom head weld precludes a portion of the required weld examination due to the presence 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 the weld examination volume accessible for Code volumetric examination (78.32 percent) were examined as required. See Figures 2 and 3 of this enclosure for illustration of limitation areas.
- 5. Burden Caused By Compliance Providing access at this location would require redesign of the reactor vessel core barrel supports and is impractical.
Consideration was also given to examining the weld from the vessel outside surface. The bottom head and shell insulation in this area are not designed to be removable and the close proximity of the insulated vessel to the concrete shield wall prohibits access. Providing external access to these weld locations would require redesign of the building concrete structure and the vessel insulation, and is impractical.
1
Enclosure 1 PG&E Letter DCL-17-017
- 6. Proposed Alternative and Basis for Use The inspection of the DCPP Unit 2 reactor vessel lower shell-to-bottom head circumferential weld (weld No.10-201) was conducted during the Unit 2 Nineteenth Refueling Outage (2R19) using a procedure and techniques qualified by demonstration to Supplements 4 and 6 of ASME Section XI, Appendix VIII, 2001 Edition without Addenda. The examination used a combination of 45 degree angle search units with shear and longitudinal wave propagation. 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 barrel support lugs as the inspection device and transducer sled would allow.
Scanning was conducted between and below the obstructing lugs with scan boundaries maximized by visually assisted positioning of the exam head.
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 barrel support lugs, and the scanning access in between the lugs, respectively.
The physical size of the transducer sled limited the approach to the core barrel support lugs without damaging the assembly and causing loose parts concerns.
Calculation of the weld and volume coverage afforded by each set of transducers by the data analysts resulted in a combined average of 78.32 percent. Table 1of this enclosure provides a breakdown of percent coverage of the required examination volume by scan direction and transducers.
- 7. Duration of Proposed Alternative This relief request (RR) will be applied for the DCPP Unit 2 third lSI interval which ran from March 13, 2006, through June 2, 2016. The examinations took place during 2R19 in May of 2016.
- 8. Precedents This RR is similar to the DCPP second interval RR NDE-SLH U2 approved in NRC Letter, "Diablo Canyon Power Plant, Unit 2 - Relief Requests NDE-SLH U2 and NDE-LSL U2 for Reactor Vessel Shell Weld Inspections (TAC No.
MD2921 ),"dated June 25, 2007 (ADAMS Accession No. ML071620072).
Increased examination coverage from the previous interval was achieved due to improved design of the examination robot and control systems .
. This RR is also similar to the Tennessee Valley Authority Watts Bar Unit 1 RR 1-ISI-17 approved in NRC Letter, "Watts Bar Nuclear Plant, Unit 1 - Relief Request Nos. 1-ISI-16, 1-ISI-17, 1-ISI-18, and 1-ISI-19 Requesting Relief from the lnservice Inspection Program (TAC Nos. MC9638, MC9639, MC9640, and MC9641)," dated October 27, 2006 (ADAMS Accession No. ML062480232).
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Enclosure 2 PG&E Letter DCL-17-017 INSERVICE INSPECTION (lSI) RELIEF REQUEST NDE-LSL U2 In Accordance with 10 CFR 50.55a(g)(5)(iii)
--lnservice 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, 2001 Edition through 2003 Addenda.
3. Applicable Code Requirement
Table IW8-2500-1, Category 8-A, Item 81.12, requires that the reactor vessel shell longitudinal welds (Unit 2 weld Nos. 3-201A, 3-2018, 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 IW8-2500-2, using the acceptance standard IW8-351 0.
Relief is requested from performing a portion of the volumetric examination where access is restricted by core barrel support lugs. See Figure 1 of this enclosure for weld and lug locations.
- 4. Impracticality of Compliance The design of the vessel shell longitudinal welds precludes a portion of the required weld examination due to the proximity of three core barrel support lugs
- located at 60, 180, and 300 degrees. 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 examination volume accessible for Code volumetric examination (80.10 percent of each weld) were examined as required.
See Figure 2 of this enclosure for illustration of lirpitation areas.
- 5. Burden Caused By Compliance Providing access at this location would require redesign of the reactor vessel internals supports and is impractical.
Consideration was also given to examining the welds from the vessel outside diameter. The bottom head and shell insulation in this area are not designed to be removable and the close proximity of the insulated vessel to the concrete shield wall prohibits access. Providing external access to these weld locatio~s would require redesign of the building concrete structure and the vessel insulation, and is impractical.
1
Enclosure 2 PG&E Letter DCL-17-017
- 6. Proposed Alternative and Basis for Use The inspection of the DCPP Unit 2 reactor vessel lower shell longitudinal welds (weld Nos. 3-201A, 3-201 B, and 3-201C) was conducted during the Unit 2 Nineteenth Refueling Outage (2R19) using a procedure and techniques qualified by demonstration to Supplements 4 and 6 of ASME Section XI, Appendix VIII, 2001 Edition without Addenda. The examination used a combination of 45 degree angle search units with shear and longitudinal wave propagation. 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 barrel support lugs as the inspection device and transducer sled would allow. Figure 1 of this enclosure depicts the location of these welds in the reactor vessel.
Figure 2 of this enclosure depicts the scanning limitations for parallel and perpendicular scans above the core barrel support lugs.
The physical size of the transducer sled limited the approach to the core barrel support lugs without damaging the assembly and causing loose parts concerns.
Scan boundaries were maximized by visually assisted positioning of the exam head. Calculation of the weld and volume coverage afforded by each set of transducers by the data analysts resulted in a combined average of 80.10 percent for each weld. Tables 1, 2, and 3 of this enclosure provide a breakdown of percent coverage of the required examination volume for each one of the three welds by scan direction and transducer type.
- 7. Duration of Proposed Alternative This relief request (RR) will be applied for the DCPP Unit 2 third lSI interval which ran from March 13, 2006, through June 2, 2016. The examinations took place during 2R19 in May of 2016.
- 8. Precedents This RR is similar to the DCPP second interval relief request NDE-LSL U2, approved in NRC Letter, "Diablo Canyon Power Plant, Unit 2- Relief Requests NDE-SLH U2 and NDE-LSL U2 for Reactor Vessel Shell Weld Inspections (TAC No. MD2921)," dated June 25, 2007 (ADAMS Accession No. ML071620072).
Slightly increased examination coverage from the previous interval was achieved due to improved design of the examination robot and control systems.
This RR is also similar to the Three Mile Island Unit 1 RR-02-19 Part C, approved in NRC Letter, "Three Mile Island Nuclear Station, Unit 1 (TMI-1) Re:
Second and Third 10-Year lntervallnservice Inspection (lSI) Program Requests for Relief, RR-02-19, Parts A through N, and RR-02-20 (TAC No. MB4482),"
dated June 6, 2003 (ADAMS Accession No. ML031570114).
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Enclosure 3 PG&E Letter DCL-17-017 INSERVICE INSPECTION (lSI) RELIEF REQUEST NDE-LHC U2 In Accordance with 10 CFR 50.55a(g)(5)(iii)
--lnservice Inspection Impracticality--
- 1. ASME Code Component Affected Diablo Canyon Power Plant (DCPP) Unit 2 reactor vessel bottom head circumferential weld
2. Applicable Code Edition and Addenda
ASME Section XI, 2001 Edition through 2003 Addenda.
3. Applicable Code Requirement
Table IW8-2500-1, Category 8-A, Item 81.21, requires that the reactor bottom head circumferential weld (Unit 2 weld No. 4-202 *) 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 IW8-2500-3, using the acceptance standard IW8-351 0.
Relief is requested from performing a portion of the volumetric examination where access is restricted by bottom mounted instrumentation (8MI) penetration tubes. Figure 1 of this enclosure depicts the weld location and vessel layout.
Figure 2 or this enclosure depicts the bottom mounted instrumentation tube locations. *
- Note: A typographical error by the examination vendor shows this weld 4-202 labeled as "4-402" on the original Figures and Table included in this relief request (RR), which are extr~cted from the original examination report. The vendor issued a global correction statement to change this incorrect typographical reference throughout the examination report.
- 4. Impracticality of Compliance The design of the bottom head circumferential weld precludes a portion of the required weld examination due to the presence of multiple 8MI tubes. The required scans were conducted as close as possible to the obstructing 8MI's.
Scan boundaries were maximized by visually assisted positioning of the exam head. The 8MI tubes limit access of the vendor's reactor vessel examination tool to a portion of the required examination volume. All areas of weld 4-202
- accessible for Code volumetric examination (68. 77 percent of examination volume) were examined as required. Refer to Figure 1, 2, and 3 for illustration of weld location and limitation areas.
1
Enclosure 3 PG&E Letter DCL-17-017
- 5. Burden Caused By Compliance Providing weld access at this location would require redesign of the reactor vessel internals bottom mounted instrumentation tube locations, and is impractical.
Consideration was also given to examining the weld from the vessel outside surface. The bottom mounted penetration tubes which penetrate the bottom head would equally limit access for external examination of the weld. As stated above, providing access at these locations would require redesign of the bottom vessel head, internals, and instrumentation, and is impractical.
- 6. Proposed Alternative and Basis for Use The inspection of the DCPP Unit 2 reactor vessel bottom head circumferential weld (weld No. 4-202 *) was conducted during the Unit 2 Nineteenth Refueling Outage (2R19) using a procedure and techniques qualified by demonstration to Supplements 4 and 6 of ASME Section XI, Appendix VIII, 2001 Edition without Addenda. The examination used a combination of 45 degree angle search units with shear and longitudinal wave propagation. The sound beams from these transducers were directed in four orthogonal directions parallel and perpendicular to the weld in as close proximity to the BMI tubes as the inspection device and transducer sled would allow. Figure 2 of this enclosure depicts the location of the weld in the reactor vessel bottom head and the limiting BMI tubes that intersect or are adjacent to the weld.
The physical size of the transducer sled limited the approach to the BMI tubes without damaging the assembly and causing loose parts concerns. Calculation of the weld and volume coverage afforded by each transducer by the data analysts resulted in a combined average of 68.77 percent. Table 1 of this enclosure provides a breakdown of percent coverage of the required examination volume by scan direction and transducer type.
- 7. Duration of Proposed Alternative This RR will be applied for the DCPP Unit 2 third lSI interval which ran from March 13, 2006, through June 2, 2016. The examinations took place during 2R19 in May of 2016.
- 8. Precedents This request is similar to the DCPP second interval relief request NDE-2 in PG&E Letter DCL-96-031, "lnservice Inspection Program Plan- Second Ten Year Inspection Interval lnservice Inspection (lSI) Relief Requests)," dated March 11, 1996, and approved October 15, 1998, with additional transmittal June 21, 2
Enclosure 3 PG&E Letter DCL-17-017 1999. Increased examination coverage from the previous interval was achieved due to improved design of the examination robot and control systems.
This RR is also similar to the Tennessee Valley Authority Watts Bar Unit 1 RR 1-ISI-17 approved in NRC letter, "Watts Bar Nuclear Plant, Unit 1- Relief Request Nos. 1-ISI-16, 1-ISI-17, 1-ISI-18, and 1-ISI-19 Requesting Relief from the lnservice Inspection Program (TAC Nos. MC9638, MC9639, MC9640, and MC9641)," October 27, 2006 (ADAMS Accession No. ML062480232).
3
Enclosure 3 PG&E Letter DCL-17-017 Figure 1 Diagram of DCPP Unit 2 Reactor Pressure Vessel Showing the Location of the Bottom Head Circumferential Weld No. 4-202
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Enclosure 4 PG&E Letter DCL-17-017 INSERVICE INSPECTION (lSI) RELIEF REQUEST NDE-LHM U2 In Accordance with 10 CFR 50.55a(g)(5)(iii)
--lnservice Inspection Impracticality--
- 1. ASME Code Component Affected Diablo Canyon Power Plant (DCPP) Unit 2 reactor vessel bottom head meridional welds.
2. Applicable Code Edition and Addenda
ASME Section XI, 2001 Edition through 2003 Addenda.
3. Applicable Code Requirement
Table IW8-2500-1, Category 8-A, Item 81.22, requires that the reactor vessel bottom head meridional welds (Unit 2 weld Nos. 1-2028 and 1-202F) 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 IW8-2500-3, using the acceptance standard IW8-3510.
Relief is requested from performing a portion of the volumetric examination where access is restricted by bottom mounted instrumentation (8MI) penetration tubes. See Figure 1 of this enclosure for weld locations and vessel layout. See Figure 2 of this enclosure for weld and bottom mounted instrument locations.
- 4. Impracticality of Compliance The design of the bottom head meridional welds precludes a portion of the required weld examination for two of the six welds, Unit 2 weld Nos. 1-2028 and 1-202F, due to the presence of multiple 8MI tubes penetrating the bottom head.
Required scanning was conducted as close as possible to the obstructing 8MI's with scan boundaries maximized by visually assisted positioning of the exam head. 8MI tubes limit access of the vendor's reactor vessel examination tool to a portion of the required examination volume. All areas of each weld accessible for Code volumetric examination for the bottom head meridional weld Nos. 1-2028 (70 percent) and 1-202F (79.5 percent) were examined as required. See Figure 1 of this enclosure for weld locations and Figure 2 for illustration of limitation areas.
Note: The remaining four bottom head meridional welds met the examination coverage requirement and are not subject to this relief request (RR).
1
Enclosure 4 PG&E Letter DCL-17-017
- 5. Burden Caused By Compliance Providing access at this location would require redesign of the reactor vessel bottom head BMI positions, and is impractical.
- Consideration was also given to examining the welds from the vessel outside surface. The bottom mounted penetration tubes which penetrate the bottom head would limit access for external examination. As stated above, providing access at these locations would require redesign of the bottom vessel head, internals, and instrumentation, and is impractical.
- 6. Proposed Alternative and Basis for Use The inspection of the DCPP Unit 2 reactor vessel bottom head meridional welds (weld Nos. 1-2028 and 1-202F) was conducted during the Unit 2 Nineteenth Refueling Outage (2R 19) using a procedure and techniques qualified by demonstration to Supplements 4 and 6 of ASME Section XI, Appendix VIII, 2001 Edition without Addenda. The examination used a combination of 45 degree angle search units with shear and longitudinal wave propagation. The sound beams from these transducers were directed in four orthogonal directions parallel and perpendicular to the welds in as close proximity to the bottom mounted instrumentation tubes as the inspection device and transducer sled would allow. Figure 1 of this enclosure depicts the location of these welds in the reactor vessel. Figure 2 of this enclosure shows the scanning limitations for parallel and perpendicular scans in proximity to the bottom mounted instrumentation tubes.
The physical size of the transducer sled limited the approach to the bottom mounted instrumentation tubes without damaging the assembly and causing loose parts concerns. Calculation of the weld and volume coverage afforded by each set of transducers by the data analysts resulted in a combined average of 70 percent for weld 1-2028 and 79.5 percent for weld 1-202F. Tables 1 and 2 of this enclosure provide a breakdown of perc.ent coverage of the required examination volume for each weld by scan direction and transducer type.
- 7. Duration of Proposed Alternative This RR will be applied for the DCPP Unit 2 third lSI interval which ran from March 13, 2006, through June 2, 2016. The examinations took place during 2R19 in May of 2016.
- 8. Precedents This RR is similar to Diablo Canyon second interval relief request NDE-3 R 1, PG&E Letter DCL-96-031, "lnservice Inspection Program Plan- Second Ten Year Inspection lntervallnservice Inspection (lSI) Relief Requests)," dated 2
Enclosure 4 PG&E Letter DC L-17 -017 March 11, 1996, and approved October 15, 1998, with additional transmittal June 21, 1999 (TAC Nos M95068 and M95069). Increased coverage from the previous interval was achieved due to improved design of the examination robot and control systems.
This RR is also similar to Tennessee Valley Authority Watts Bar Unit 1 RR 1-ISI-18 approved in NRC Letter, "Watts Bar Nuclear Plant, Unit 1 - Relief Request Nos. 1-ISI-16, 1-ISI-17, 1-ISI-18, and 1-ISI-19 Requesting Relief from the lnservice Inspection Program (TAC Nos. MC9638, MC9639, MC9640, MC9641) dated October 27, 2006 (ADAMS Accession No ..ML062480232).
3
Enclosure 4 PG&E Letter DCL-17-017 Figure 1 Diagram of DCPP Unit 2 Reactor Pressure Vessel Showing the Location of the Bottom Head Meridional Welds (Weld Nos. 1-2028 and 1-202F) a;. ~:r
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Enclosure 5 PG&E Letter DCL-17-017 INSERVICE INSPECTION (lSI) RELIEF REQUEST NDE-ONV U2 In Accordance with 10 CFR 50.55a(g)(5)(iii)
--lnservice Inspection Impracticality--
- 1. ASME Code Component Affected Diablo Canyon Power Plant (DCPP) Unit 2 reactor vessel outlet nozzle-to-vessel welds.
2. Applicable Code Edition and Addenda
ASME Section XI, 2001 Edition through 2003 Addenda.
3. Applicable Code Requirement
Table IW8-2500-1, Category 8-D, Item 83.90, requires that the outlet nozzle-to-vessel welds (Unit 2 weld Nos. WN22, WN158, WN202 and WN338) 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 IW8-2500-7(a), using the acceptance standard IW8-3512.
Relief is requested from performing a portion of the volumetric examination where access is restricted by nozzle configuration. See Figure 1 of this enclosure for outlet nozzle configuration and Figure 2 for weld limitations.
- 4. Impracticality of Compliance The design of the vessel outlet nozzle precludes a portion of the required weld examination due to the presence of the outlet nozzle boss protrusion. The proximity of the nozzle boss protrusion limits the parallel scans from the vessel inner diameter (I D) (tangential or "Tan" scans) and portions of the perpendicular scans from the vesseiiD (radial or "Star" scans). Access of the vendor's reactor vessel examination tool to a portion of the required examination volume is restricted by the outlet nozzle boss protrusion. All areas of each weld (84.5 percent for weld No. WN22, 84.5 percent for weld No. WN158, 84.5 percent for weld No. WN202 and 84.5 percent for weld WN338) accessible for Code volumetric examination were examined as required. See Figure 1 of this enclosure for illustration of limitation areas.
- 5. Burden Caused By Compliance Providing access at this location would require redesign of the reactor vessel outlet nozzle configuration and is impractical.
1
Enclosure 5 PG&E Letter DCL-17-017 Consideration was also given to examining the welds from the vessel outside surface. The vessel 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. Providing access at these locations would require redesign of the building concrete structure and the vessel insulation, and is impractical.
- 6. Proposed Alternative and Basis for Use The inspection of the DCPP Unit 2 reactor vessel outlet nozzle-to-shell weld Nos.
WN22, WN158, WN202, and WN338, was conducted during the Unit 2 Nineteenth Refueling Outage (2R 19) using a procedure and techniques qualified by demonstration to Supplements 4 and 6 of ASME Section XI, Appendix VIII 2001 Edition without Addenda. The examination used 45 degree angle search units directed perpendicular (radial "Star" scans) and parallel (tangential "Tan")
scans to the weld examination volume as close as the inspection device and transducer sled would allow to the outlet nozzle boss protrusion. Figure 1 of this enclosure depicts the location of the nozzle-to-shell welds. Figure 2 of this enclosure depicts the scanning limitations for parallel and perpendicular scans.
Additionally, scans were made from the nozzle bore (axially into and out of the bore) without limitation. These bore scans are combined with the star scans as noted in Tables 1 through 4 of thi~ enclosure. As a result bore scans and star scans are considered together as a single scan (to avoid double counting) in combined average calculations).
The physical size of the transducer sled limited the approach to the outlet nozzle protrusion without damaging th-e assembly and causing loose parts concerns.
Calculation of the weld and volume coverage afforded by each set of transducers by the data analysts resulted in a combined average of 84.5 percent for weld No. WN22, 84.5 percent for weld No. WN 158, 84.5 percent for weld No. WN202 and 84.5 percent for weld No. WN338. Tables 1 through 4 of this enclosure provide a breakdown of percent coverage of the required examination volume for each of the four welds by scan direction.
- 7. Duration of Proposed Alternative This relief request (RR) will be applied for the DCPP Unit 2 third lSI interval which ran from March 13, 2006, through June 2, 2016. The examinations took place during 2R19 in May of 2016.
- 8. Precedents This RR is similar to Diablo Canyon second interval relief request NDE-68, PG&E Letter DCL-96-031, "lnservice Inspection Program Plan- Second Ten Year Inspection lntervallnservice Inspection (lSI) Relief Requests)," dated March 11, 1996, and approved October 15, 1998, with additional transmittal June 21, 1999. (TAC NOS M95068 and M95069). Increased examination 2
Enclosure 5 PG&E Letter DCL-17-017 coverage from the previous interval was achieved due to improved design of the examination robot and control systems.
This RR is also similar to Tennessee Valley Authority Watts Bar Unit 1 RR 1-ISI-19 approved in NRC Letter "Watts Bar Nuclear Plant, Unit 1 - Relief Request Nos. 1-ISI-16, 1-ISI-17, 1-ISI-18, and 1-ISI-19 Requesting Relief from the lnservice Inspection Program (TAC Nos. MC9638, MC9639, MC9640, and MC9641)," dated October 27, 2006 (ADAMS Accession No. ML062480232).
3
Enclosure 5 PG&E Letter DCL-17-017 Figure 1 Diagram of DCPP Unit 2 Reactor Pressure Vessel Showing the Locations of the Outlet Nozzles
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DIABLO, CANYO~ N UNIT 2 DIRECTION I ORIENTATION 0
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