ML19198A340

Relief Request 64 - Unit 1 Impractical Examinations for the Third 10-Year Inservice Inspection Interval

ML19198A340
Person / Time
Site:	Palo Verde
Issue date:	07/17/2019
From:	Weber T Arizona Public Service Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
102-07950-MLL/MDD
Download: ML19198A340 (22)

Text

10 CFR 50.55a MARIA L. LACAL Oaps Senior Vice President, Nuclear Regulatory & Oversight Palo Verde Nuclear Generating Station P.O. Box 52034 102-07950-MLlVMDD Phoenix, AZ 85072 July 17, 2019 Mail Station 7605 Tei 623.393.6491 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001

Dear Sirs:

Subject; Palo Verde Nuclear Generating Station Unit 1 Docket No. STN 50-528 Renewed Operating License Number NPF-41 Relief Request 64 - Unit 1 Impractical Examinations for the Third 10-Year Inservice Inspection Interval Pursuant to 10 CFR 50.55a(g)(5)(iii), Arizona Public Service Company (APS) hereby requests NRC approval of Relief Request (RR) 64 for the third ten-year interval for the In-Service Inspection (ISI) Program for Palo Verde Nuclear Generating Station (PVNGS),

Unit 1. Certain ultrasonic examinations of welds required by Section XI of the American Society of Mechanicai Engineers Boiler and Pressure Vessel Code, sub-articles IWB-2500 and IWC-2500 have been determined to be impractical; therefore, relief is requested from those requirements to achieve essentially 100 percent weld coverage. The enclosed information supports the determinations of impracticality. The details of RR 64 are enclosed.

By letter number 102-07604 [Agency Documents Access and Management System (ADAMS) Accession number ML17318A472], dated November 10, 2017, APS submitted RR 56, which better aiigned fourth 10-year ISI intervai start dates for all three units. The RR 56 was approved by NRC ietter dated March 9, 2018 (ADAMS Accession number ML18067A073). This RR 64 is being provided within the specified one year of the close of the original third 10-year interval for PVNGS Unit 1 and does not rely on the revised interval dates described in RR 56.

No new commitments are being made in this submittal. If you have any questions about this request, please contact Michael D. DiLorenzo, Department Leader, Nuclear Regulatory Affairs, at (623) 393-3495.

Sincerely, Digitally signed by Weber, Thomas Weber, Thomas N(Z00499) DN: cn=Weber, Thomas N(Z00499)

Reason: Thomas N. Weber for Maria L. Lacal N(Z00499) Date: 2019.07.1715:18:00 -07'00' MLiyMDD A member of the STARS Alliance LLC Callaway

• Diablo Canyon

• Palo Verde

• Wolf Creek

102-07950-MLL/MDD ATTN: Document Control Desk U. S. Nuclear Regulatory Commission Reiief Request 64 - Unit 1 Impractical Examinations for the Third 10-Year ISI Interval Page 2

Enclosure:

Relief Request 64 - Unit 1 Impractical Examinations for the Third 10-Year Inservice Inspection (ISI) Interval cc: S. A. Morris NRC Region IV Regional Administrator S. P. Lingam NRC NRR Project Manager for PVNGS M. M. O'Banion NRC NRR Project Manager B. K. Singal NRC NRR Project Manager C. A. Peabody NRC Senior Resident Inspector for PVNGS

Enclosure Relief Request 64 Unit 1 Impractical Examinations for the Third 10-Year Inservice Inspection (ISI) Interval

Enclosure Relief Request 64 - Unit 1 Impracticai Examinations for the Third 10-Year ISI Interval The Palo Verde Nuclear Generating Station (PVNGS), Unit 1, Class 1 and 2 welds with limited examinations are included in Tables 1 and 2 of Attachment 1 of this enciosure. The content of this reiief request (RR) includes the insights gained from guidance provided in Reference 1.

1. ASME Code Component(s) Affected The following Code Classes, Examination Categories, and Item Numbers apply.

Code Classes: 1 and 2 Examination Categories: B-A, B-D, and C-B Item Numbers: Bl.ll, B3.110, and C2.21

2. Applicable Code Edition and Addenda

The Code of Record for the third 10-year Inservice Inspection interval is the 2001 Edition of American Society of Mechanical Engineers (ASME),Section XI, through the 2003 Addenda.

The applicable edition of the ASME Boiler and Pressure Vessel Code,Section XI, Appendix VIII program is the 2001 edition.

3. Applicable Code Requirement

The applicable code requirements for volumetric examinations are contained in the Tables and Figures of IWB-2500 and IWC-2500, ASME Section XI. The applicable Code Classes, Items, and Examination Categories for which relief is sought are included in Attachment 1 of this enclosure for each of the limited weld examinations.

4. Impracticality of Compliance Arizona Public Service Company (APS) has determined that compliance with the Code requirements of achieving essentially 100 percent (%) coverage of the welds listed in this request is impractical for Unit 1. In accordance with 10 CFR 50.55a(g)(5)(iii), this RR is based on actual demonstrated limitations when attempting to comply with the Code requirements in the performance of the examinations listed in Table 1 of Attachment 1.

The impractical examinations listed in Table 2 of Attachment 1 are not supported by field-demonstrated limitations, however discussion is provided for each of those items and the reasons for which field demonstrations are considered impractical.

The Unit 1 program for the third 10-year ISI interval utilizes ASME Code Case N-460, Alternative Examination Coverage for Class 1 and Class 2 Welds,Section XI, Division 1.

Utilization of this Code Case allows the acceptance of examinations that obtained greater than 90% coverage, (but less than 100% due to interference by another component or part geometry); therefore, such examinations are not included in this submittal.

The design of the plant has provided access for examinations; however, component design configurations with conditions resulting in examination limitations, such as

Enclosure Relief Request 64 - Unit 1 Impractical Examinations for the Third 10-Year ISI Interval geometric configurations of components or their welds, do not ailow full required examination volume and/or coverage, thus this RR addresses those conditions. Details for examination limitations in required examination coverage are provided in Attachment 1 of this enclosure.

5. Burden Caused by Compliance Components and welds associated with the items listed in this RR are constructed of standard design items meeting typical national standards that specify required configurations and dimensions including Class 1 Categories B-A and B-D, and Class 2 Category C-B.

For the Class 1 Category B-A Reactor Vessel Weld, the locations of other physical features within the vessel impede the completion of code required coverage during the ultrasonic testing (UT) examinations.

For the Class 1 Category B-D Nozzle-to-Vessel Welds of the Pressurizer, the design configurations of these welds and obstructions do not allow for the required examination coverage.

For the Class 2 Category C-B Nozzle-to-Shell Welds at the Steam Generator (SG) secondary blowdown line, the design configurations of these welds and materials do not allow for the required examination coverage. Available UT equipment could not be successfully calibrated for the configuration and materials at these nozzle locations.

For the Class 2 Category C-B Steam Generator Main Steam Nozzle Inside Radius (IR)

Section, the design configuration of these nozzles does not allow for UT of the inside radius section of these nozzles from the outside surface of the SG nozzles.

Examinations have been performed and/or attempted to the maximum extent possible.

Therefore, APS has determined that obtaining essentially 100% coverage is not feasible and is impractical without adding undue burden, increased radiation exposure, and/or potential damage to the plant or the component itself.

6. Proposed Alternative and Basis for Use Proposed Alternative

1) Periodic system pressure tests and visual examinations are performed in accordance with ASME Section XI, Examination Category B-P, for Class 1 pressure retaining welds and items each refueling outage and Examination Category C-H for Class 2 pressure retaining welds and items each inspection period in accordance with Table IWB-2500-1 and Table IWC-2500-1, respectively.

2) Conduct UT examinations to the maximum extent possible, and when required by ASME Section XI, perform a 100% surface examination.

Enclosure Relief Request 64 - Unit 1 Impractical Examinations for the Third 10-Year ISI Interval Basis for Use 10 CFR 50.55a(g){4) recognizes that throughout the service life of a nuclear power facility, components which are classified as ASME Code Class 1, Class 2, and Class 3 must meet the requirements set forth in the ASME Code to the extent practical within the limitations of design, geometry and materiais of construction of the welds and items described in Attachment 1 of this enclosure.

There is no piant-specific, or industry operating experience regarding potential degradation specific to the subject welds in this RR.

For the Class 1 and 2 welds located inside the containment of Unit 1, with limited examinations listed in Attachment 1 of this enclosure, operational leakage is monitored in accordance with the Technical Specification requirements. In addition, during outages, plant personnel perform walk-downs of systems inside the containment building. This walk-down is performed to look for evidence of leakage accumulation and boric acid as well as system abnormalities that could affect plant performance. Also, system pressure tests are performed as required by the ASME Code,Section XI.

Based on the limited UT examinations achieved, surface examinations (where applicable), applicable leakage monitoring, and required system pressure tests with VT-2 visual examinations, no reasonable action can be taken by APS at this time to improve these examinations without applying impractical options. Therefore, this RR will provide assurance of an acceptable level of quality and safety by providing reasonable assurance of structural integrity.

7. Duration of Proposed Alternative This RR is applicable to the original PVNGS Unit 1 Third 10-Year ISI Interval which began on July 18, 2008 and ended May 31, 2019 (as described in Reference 2) and covers the limited examinations that have been identified for the third interval in Unit 1.

8. Items in Corrective Action Program In addition to the examinations determined to be impractical contained within this enclosure, the following ISI inspection item was discovered and documented in the Palo Verde corrective action program at the end of the third 10-year ISI interval. This Item is applicable to all three units.

The Class 1, Category B-D Steam Generator Hot Leg Nozzle Inner Radius Section, welds 3-100-IR and 4-100-IR were examined in the first period of the third interval. As documented in the examination report, 95% of the code required coverage was achieved, and therefore, no additional attempt was made to re-perform the examinations. During the third interval close-out review performed by APS, it was discovered that the examinations were performed using the wedges, angles and skews specified for the previous steam generators, which had a slightly different design and nozzle configuration.

As part of the corrective actions, analytical modeling was performed with industry support by Electric Power Research Institute, to demonstrate actual code required volume (CRV) that could be claimed for those examinations as performed. The modeling results show that 70% of the CRV can be claimed for each of the Steam Generator Hot

Enclosure Relief Request 64 - Unit 1 Impractical Examinations for the Third 10-Year ISI Interval Leg Nozzle Inner Radius examinations. The UT examinations that were performed resuited in no rejectable indications, and system pressure tests that are performed each cycle have identified no leaks at these locations.

The procedure used previously that limited the examination volume to 70% is now canceied and no longer available for use at Palo Verde. New procedures are in place to support future exams and new equipment is available to provide for essentially 100%

coverage for these IR examinations in the future.

9. Precedents

• NRC SER, Palo Verde Nuclear Generating Station, Unit 2 - Relief Request No. 58 for the Third 10-Year Inservice Inspection Interval, Request for Relief from the American Society of Mechanical Engineers for Certain Class 1 and Class 2 Welds, dated February 19, 2019 [Agency Documents Access and Management System (ADAMS)

Accession number (No.) ML19044A641]

• NRC SER, Surry Power Station Unit No. 2 - Requests for Relief LMT-ROl, LMT-SSOl, LMT-CSOl, LMT-POl, LMT-COl, LMT-C02, LMT-C03, and LMT-C04 - For Limited Coverage Examinations Performed in the Fourth 10-Year Inservice Inspection Interval, dated February 17, 2017 (ADAMS Accession No. ML16365A118)

• NRC SER, Diablo Canyon Power Plant, Unit No. 1 - Relief Request NDE-SIF-Ul To Allow Use of Alternate American Society of Mechanical Engineers Boiler and Pressure Vessel Code Section XI Examination Requirements for the Third Inservice Inspection Interval, dated July 27, 2016 (ADAMS Accession No. ML16207A397)

• NRC SER, Millstone Power Station, Unit No. 2 - Relief Requests For Limited Coverage Examinations Performed In The Fourth 10-Year Inservice Inspection Interval, dated July 13, 2016 (ADAMS Accession No. ML16172A135)

10. References

1. NRC presentation Coverage Relief Requests, Industry/NRC NDE Technical Information Exchange Public Meeting January 13-15, 2015 (ADAMS Accession No. ML15013A266)

2. NRC letter dated March 9, 2018, Palo Verde Nuclear Generating Station, Units 1, 2, and 3- Relief Request No. 56 to Extend Third 10-Year Inservice Inspection Interval for Unit 2, and to Adopt 2013 Edition of the ASME Code,Section XI, for the Fourth 10-Year Interval for Units 1, 2, and 3 (ADAMS Accession No. ML18067A073)

3. APS letter dated January 10, 2019, Palo Verde Nuclear Generating Station Unit 3 Docket No. STN 50-530, Renewed Operating License Number NPF-74, Relief Request 63 - Unit 3 Impractical Examinations for the Third 10-Year Inservice Inspection Interval (ADAMS Accession No. ML19010A307)

4. APS letter dated June 28, 2019, Palo Verde Nuclear Generating Station Unit 3 Docket No. STN 50-530, Renewed Operating License Number NPF-74, Response to Request for Additional Information - Relief Request 63 Unit 3 Impractical Examinations for the Third 10-Year Inservice Inspection Interval (ADAMS Accession No. ML19179A331)

Enclosure Relief Request 64 - Unit 1 Impractical Examinations for the Third 10-Year ISI Interval Attachment 1 Attachment 1 Introduction This attachment contains tabies, figures and other iiiustrations that are used to depict the appiicabie iocations, iimitations, and caicuiations for obtained coverage, materiais, product forms, uitrasonic testing (UT) examination angies, wave forms used, and the examination resuits for the weids or items associated with this RR. This attachment aiso inciudes written descriptions about each iimited examination or group of simiiar examinations, and the reasons for not achieving essentiaiiy 100 percent (%).

Tabies 1 and 2 contain an inciusive iist of those weids/items for which it is determined that achieving code required voiume (CRV) is impracticai.

Table 1 - Class 1 Items / Welds

^S^ble' Category / Weld Component Weld NDE Report Required Figures Materials Item ID Description Size/Thickness No. Volume and Achieved Pictures Rx Vessel Upper Shell to Shell:

Intermediate 11.25"Tx 182" SA-533 180-9278386- Zone 1 B-A/Bl.ll 1-10 80%

Shell Diam. Grade B 000 Diagram Circumferential Class 1 Weld Vessel: Zone 5 SA-533 Diagram, Pressurizer Grade A Picture 1-1, B-D/B3.110 5-9 Surge Nozzle to 5"Tx 12" Diam. Class 1 16-UTE-1387 65% Figures Head Weld Nozzle: 1-2-1 and SA-541 1-2-2, Class 1 Table 1-2-1 Vessel:

SA-533 Zone 5 Pressurizer Grade A Diagram, B-D/B3.110 5-10 Spray Nozzle to 5"T X 4" Diam. Class 1 13-UTE-1057 81% Figure Head Weld Nozzle: 1-2-3, SA-541 Table 1-2-2 Class 1 Vessel:

SA-533 Zone 5 5-11, ll-UT-1005, Pressurizer Grade A 75% Diagram, 5-12, ll-UT-1007, B-D/B3.110 Safety Nozzle 5"T X 6" Diam. Class 1 13-UTE-1055, (for each Figure 1 5-13, Nozzle: nozzle) to Head Weld 16-UTE-1382 4, Table 5-14, 1-2-3 SA-541 Class 1

Enclosure Relief Request 64 - Unit 1 Impractical Examinations for the Third 10-Year ISI Interval Attachment 1 Table 2 - Class 2 Items / Welds Code Applicable Category Weld Component Weld NDE Report Required Figures Materials and

/ Item ID Description Size/Thickness No. Volume Achieved Pictures Zone 42 Tube SG 2 Diagram, Sheet: Figures Secondary SA-508 42-100, Blowdown 1-3-1 and C-B/C2.21 6 Diam. Class 3a No Report 0%

42-101, Nozzle 1-3-2, Nozzle:

Welded to Pictures SA-336 Tube Sheet 1-3-1 and Class F12 1-3-2 Top Head:

SG 1 Main SA-533 41-114- Grade B Steam Nozzle 4.3"T X 32" 0% Figure 1-4 C-B/C2.21 IR, 41- No Report Inside Radius Diam. Class 1 115-IR, Nozzle:

Section SA-508 Class la

Enclosure Relief Request 64 - Unit 1 Impractical Examinations for the Third 10-Year ISl Interval Attachment 1 Category B-A; Weld 1-10. Reactor Vessel Weld Location Figure 1-1 (Zone 1 Diagram)

Reactor Vessel Side View 182 1'4" OUTLET INLET SHEAR KEYS During the 1R20 refueling outage in 2017 the reactor vessel welds were examined with the following weld resulting in less than 90% volumetric coverage for weld 1-10, Reactor Vessel Upper Shell to Intermediate Shell Circumferential Weld.

The vessel design includes features that limit scanning of weld areas for the weld listed above.

Where complete coverage greater than 90% could not be obtained due to limitations, a coverage estimate worksheet was prepared and summarized in Final Report EG-26-F01, Revision 0.

Scanning was performed to the maximum extent possible for weld configurations. Where access was restricted and scanning was limited, "single-sided" scan parameters were used to improve coverage when coverage could be increased by using single sided scans. The examination procedure was qualified (Appendix VIII, Supplements 4 and 6) for single side access to address this configuration limitation.

The upper shell to intermediate shell weld 1-10 has the inlet and outlet nozzles interfering with scanning above and below the weld and limit coverage.

Enclosure Relief Request 64 - Unit 1 Impractical Examinations for the Third 10-Year ISI Interval Attachment 1 Category B-D: Welds 5-9 through 5-14. Nozzle-to-Vessel Welds of the Pressurizer Location Figure 1-2 (Zone 5 Diagram)

PRESSURIZER Pressurizer Spray Nozzle Pressurizer Safety Nozzles Pressurizer Surge Nozzle

Enclosure Relief Request 64 - Unit 1 Impractical Examinations for the Third 10-Year ISI Interval Attachment 1 Weld 5-9 This weld is in Zone 5 and was examined in the third inspection period during 1R19 outage in 2016.

The CRV was determined based on Section XI, Figure IWB-2500-7(a) and the corresponding required examination volume is shown in the Figures 1-2-1 and 1-2-2. Note that during the scan of the pressurizer surge nozzle-to-vessel weld 0°, 45°, and 60° scans were performed. The volumetric examination only credits the 45° and 60° scans as shown in Table 1-2-1. It should be noted that there is no scan from the nozzle side of the weld due to geometry of the nozzle. This weld was examined in interval 2, and no limitations were noted. The configuration of the adjacent area was changed during pressurizer heater replacement modifications. The current configuration has additional limitations in the form of obstructions from pad welds (Picture 1-1). These pads limit the scan of the required volume that prevents full coverage from being obtained.

Picture 1 Typical Pressurizer Weld Pads The measured distance from the weld pads to the Pressurizer Surge Nozzle is approximately eight inches. The weld pads extend the majority of the way around the nozzle. Two weld pads are also installed for instrumentation nozzles shown on the right side of Picture 1-1. These weld pads are just over 11.5 inches from the nozzle.

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Enclosure Relief Request 64 - Unit 1 Impractical Examinations for the Third 10-Year ISI Interval Attachment 1 Figure 1-2 Weld 5-9 Scan Coverage Diagram 0, 45 and 60 Weld Pads 8 inches from the Nozzle Figure 1-2 Weld 5-9 Scan Coverage Diagram 0, 45 and 60 Weld Pads 11.5 inches from the Nozzle Modeling in Figures 1-2-1 and 1-2-2 shows areas of the CRV that were scanned. These figures utilize the same nomenclature showing areas that were scanned and not scanned. The dotted lines with angles represent the beam paths from the different scans performed on the components. The 45° and 60° angles are drawn off of the tangent line where the 0° scans normal projection would have occurred. The scans near the nozzle were terminated where lift off would be expected for a given nozzle design. For circumferential scans, skews were not accounted for; rather the volumes of the circumferential scans were calculated by using the 0° normal projection from the scanned surface. Using the 0° scan volume to calculate the circumferential volume is considered

Enclosure Relief Request 64 - Unit 1 Impractical Examinations for the Third 10-Year ISI Interval Attachment 1 conservative as any skewing performed by examiners would have provided an increased volume than presented in caiculations of Table 1-2-1.

Table 1-2 Examination Coverage Summary Weld 5 12" Pressurizer Surge Nozzle-to-Vessel Weld CRVt^'<<>= 2624.48 Circumferential Scan 45 Volume = 60 Volume<*J =

in^ Volume = 1835.42 in 1514.30 in 921.60 in (1589.62 in)

Angle and Wave Mode Axial Scans Clockwise Counterclockwise (1) Circumferential Circumferential 45°S 57.6% 69.9% 69.9/o 60°S 35.1% (60.5%)<=> 69.9% 69.9%

Code Coverage Total 65.2%

NOTES:

(1) S = Shear Wave (2) Clockwise and counterclockwise circumferential scans use the same percentage coverage as a 0 scan. This percent calculation for the circumferential scans is considered conservative as it does not credit the skews typically used by examiners to obtain greater coverage in a nozzle to shell weld.

Code Coverage Total refers to the maximum percentage of the required examination volume that is effectively examined with the qualified examination procedures used. The total volume scanned for axial scans is credited to 50% of the code coverage total and the other 50% of the scan volume is credited towards the two circumferential directions.

Drawings used to build CAD models for the volumetric calculations are part of the Combustion Engineering Analytical Report for the Unit No. 1 Pressurizer, Document ID NOOl-0604-00073.

Note that the percent coverage of the 60° 35.1% coverage; however, the 45 and 60° scans are being credited for the total axial scan volume. The combined volume scanned for the 45° and 60° axial scans is 1589.62 in or 60.5% volume for the axial scan contribution to the Code Coverage Total.

Weld 5-10 This weld is in Zone 5 and was examined in the second inspection period during the 1R17 outage.

The CRV was determined based on Section XI, Figure IWB-2500-7(a) and the corresponding required examination volume is shown in Figure 1-2-3. Note that during the scan of the pressurizer spray nozzle-to-vessel weld 0°, 45° and 60° scans were performed. The volumetric examination only credits the 45° and 60° scans as shown in Table 1-2-2. It should be noted that no scan was performed on nozzle side of weld due to geometry.

Enclosure Relief Request 64 - Unit 1 Impractical Examinations for the Third 10-Year ISI Interval Attachment 1 Figure 1-2 Weld 5-10 Scan Coverage Diagram 0, 45 and 60 Scans Table 1-2 Examination Coverage Summary Weld 5 4" Pressurizer Spray Nozzle-to-Vessel Head Weld CRV( <<>= 1148.13 in^ Circumferential 45 Volume = 60>> Volume =

Scan Voiume = 1023.73 in 1048.60 in 807.40 in Angle and Wave Mode Axial Scans Clockwise Counterclockwise Circumferential f Circumferential 45°S 89.1% 70.3% 70.3%

91.3% 70.3% 70.3%

eo^s Code Coverage Total = 80.8%

NOTES:

(1) S = Shear Wave (2) Clockwise and counterclockwise circumferential scans use the same percentage coverage as a 0° scan.

This percent calculation for the circumferential scans is considered conservative as it does not credit the skews typically used by examiners to obtain greater coverage in a nozzle to shell weld.

(3) Code Coverage Total refers to the maximum percentage of the required examination volume that is effectively examined with the qualified examination procedures used. The total volume scanned for axial scans is credited to 50% of the code coverage total and the other 50% of the scan volume is credited towards the two circumferential directions.

(4) Drawings used to build CAD models for the volumetric calculations are part of the Combustion Engineering Analytical Report for the Unit No. 1 Pressurizer, Document ID NOOl-0604-00073.

Enclosure Relief Request 64 - Unit 1 Impractical Examinations for the Third 10-Year ISI Interval Attachment 1 Welds 5-11, 5-12. 5-13. and 5-14 Welds 5-11, 5-12, 5-13 and 5-14 are all Pressurizer Safety Nozzle-to-Vessel welds located in Zone 5.

Welds 5-11 and 5-12 were examined in the first inspection period during 1R16 outage; Weld 5-13 was examined in the second inspection period during 1R17 outage, and Weld 5-14 was examined in the third inspection period during 1R19 outage.

The CRV was determined based on Section XI, Figure IWB-2500-7(a) and the corresponding required examination volume is shown in Figure 1-2-4. Note that during the scan of the pressurizer safety nozzle-to-vessel welds 0°, 45° and 60° scans were performed. The volumetric examination only credits the 45° and 60° scans as shown in Table 1-2-3. It should be noted that there was no scan performed on nozzle side of weld due to geometry Figure 1-2 Welds 5-11, 5-12, 5-13, and 5-14 Scan Coverage Diagram

^AF_ETY VALVE NOZZLE

Enclosure Relief Request 64 - Unit 1 Impractical Examinations for the Third 10-Year ISI Interval Attachment 1 Table 1-2 Examination Coverage Summary Weld 5-11, 5-12, 5-13, 5 6" Pressurizer Safety Nozzle-to-Vessel Head Welds CRV^'<<>= 1096.43 Circumferential Scan Volume = 45 Volume = 60° Volume =

in^ 695.79 in^ 915.02 in^ 944.1 in^

Angle and Wave Mode<> Axial Scans Clockwise Counterclockwise Circumferential Circumferential 45°S 83.4% 63.4% 63.4%

60°S 86.1% 63.4% 63.4%

Code Coverage Total - 74.7 NOTES:

(1) S = Shear Wave (2) Clockwise and counterclockwise circumferential scans use the same percentage coverage as a 0° scan. This percent calculation for the circumferential scans is considered conservative as it does not credit the skews typically used by examiners to obtain greater coverage in a nozzle to shell weld.

(3) Code Coverage Total refers to the maximum percentage of the required examination volume that is effectively examined with the qualified examination procedures used. The total volume scanned for axial scans is credited to 50% of the code coverage total and the other 50% of the scan volume is credited towards the two circumferential directions.

(4) Drawings used to build CAD models for the volumetric calculations are part of the Combustion Engineering Analytical Report for the Unit No. 1 Pressurizer, Document ID NOOl-0604-00073.

(5) Due to the complex geometry of the Pressurizer Safety Nozzle-to-Vessel Head weld, the lower portion of the weld and the upper portion were both modeled and rotated about an axis for volumes. Averages of the two volumes were used for the credited examination volumes.

Category C-B: Welds42-100 and 42-101. Nozzle-to-Shell Welds at the SG Secondary Blowdown Line Location Figure 1-3 (Zone 42 Diagram)

Steam Generator - Secondary Secondary Handhole Secondary Handhole Feedwater Secondary Primary ^

{Tube Sheet)

Enclosure Relief Request 64 - Unit 1 Impractical Examinations for the Third 10-Year ISI Interval Attachment 1 The secondary blowdown nozzles on the SGs are welded directly to the outer surface of the tube sheet. The blowdown path through the tube sheet was machined vertically, then horizontally to the outer-most surface. This nozzle configuration is less common because it is not welded to a shell penetration. The 6-inch nozzle is welded to the side of a tube sheet that is approximately 25 inches thick and 202 inches in diameter. This configuration, as shown in Figures 1-3-1 and 1-3-2, would calculate the CRV based on Section XI, Figure IWC-2500-4(d).

The Unit 1 SG blowdown nozzles have the same Inconel and Inconel weld butter configuration as the Unit 3 SG blowdown nozzles. The same ultrasonic examination issues that exist on the Unit 1 SG blowdown nozzles exist on the Unit 3 SG blowdown nozzles. This issue was identified in the recent Unit 3 impractical request for relief for the third 10-year Inservice Inspection interval, see references 3 and 4.

Figure 1-3 Welds42-100 and 42-101 Configuration Detail Steam Generator Tube Sheet 0 3.50 - .00 vvao^ V l[88.9mm) wcof4a BvrrcRiwc \

• I j Tube Sheet Blowdown Nozzle IHCONELBUTTEWNC

,[292.1mm]

11.50 ,

0 3.00 i .03 - - *

[76.2mm]

0 e.875 +/- .030 (174 6mm]

>--0 3.00 4 03

- .00 ft I 5

[38.1mm]

2:3 MAX

Enclosure Relief Request 64 - Unit 1 Impractical Examinations for the Third 10-Year ISI Interval Attachment 1 Figure 1-3 Welds42-100 and 42-101 Alternate View These SGs were replaced during the second interval in Unit 1. A mock-up shown in Picture 1-3-1 was fabricated by the steam generator vendor for the Unit 1 blowdown nozzle weld configuration that utilized an Inconel attachment weld configuration. Picture 1-3-2 shows a cross section of the blowdown nozzle weld, illustrating the carbon steel tube sheet, Inconel butter, Inconel attachment weld and carbon steel blowdown nozzle. For ultrasonic preservice examinations of the replacement steam generators blowdown nozzles, efforts were made to calibrate utilizing the mock-up but examinations were documented as best effort examinations.

Picture 1-3 Blowdown Nozzle Mock-Up Block 16

Enclosure Relief Request 64 - Unit 1 Impractical Examinations for the Third 10-Year ISI Interval Attachment 1 Picture 1-3 Mock-Up Weld Cross Section During the third interval, multiple attempts were made to validate an ultrasonic technique utilizing the vendor provided weld mock-up. Ultrasonic examiners utilized a variety of shear wave transducers and longitude wave transducers and a proper validation was not achieved on the weld mock-up for welds42-100 and 42-101. The nozzle mock-up was sent to the North Carolina Electric Power Research Institute Nondestructive Evaluation Facility to evaluate inspection methods including the use of state-of-the-art phased array ultrasonic techniques. Attempts at providing an ultrasonic inspection technique for the configuration were unsuccessful. The difficulty of examination on the SG secondary blowdown nozzle weld configuration is a combination of geometric and material issues. Geometric issues exist due to the extended weld volume due to the Inconel butter on the tube sheet and blowdown nozzle as shown in Figure 1-3-2. Material issues present examination difficulties as the Inconel butter and Inconel weld complicate pulse echo ultrasonic examination techniques attempted due to the high attenuation and issues with beam redirect that occur in austenitic materials and dissimilar metal weld configurations.

Preservice volumetric examinations included both radiographic testing (RT) and UT examinations.

The RT for welds42-100 and 42-101 identified porosity but the porosity is acceptable per the ASME Section III acceptance criteria. Ultrasonic examinations were performed but examination reports specify the following with no credit for Section XI volumetric coverage: Best effort examination due to weld configuration. No best effort ultrasonic examinations were performed during the third interval for welds42-100 and 42-101 in Unit 1 as the weld configuration could not be validated for examination.

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Enclosure Relief Request 64 - Unit 1 Impractical Examinations for the Third 10-Year ISI Interval Attachment 1 Surface examinations at these locations have been performed during the third interval with no indications noted. Surface examinations were performed in 2014 during refueling outage 1R18 and noted no rejectable indications. In addition, pressure tests are performed during each refueling outage where leakage would be detected via visual examination.

Category C-B: Welds 41-114-IR and 41-115-IR. Steam Generator Main Steam Nozzle Inside Radius Section The steam nozzles on the SGs protrude into the vessel by approximately 13 inches and do not have a typical IR area as depicted on IWC-2500-4(a)-(d). Rather, the steam nozzle design is similar to the design depicted in the annulled Code Case N-311, Alternative Examination of Outlet Nozzle on Secondary Side of Steam GeneratorsSection XI, Division 1, see Figure 1-4 for the nozzle configuration. Code Case N-311 provided an alternate IR surface examination where part of the surface would only be accessible from the inside of the secondary side of a SG. Code Case N-311 was to be incorporated in ASME Section XI when annulled in 2004; however, the alternate examination provided in N-311 has not been included in any recent versions of ASME Section XI.

Scan plans were discussed within Palo Verde and with vendors to ultrasonically examine the alternate area identified in N-311. Ultrasonic methods were determined to be practical at that time so no relief was sought for an alternative ultrasonic examination volume.

Access to the inside surface of the steam nozzles is not readily available due to the internal design of the SG. Access requires removal of multiple components and removal of welds internal to the secondary side of the SG. The work would expose the SG to foreign material risks. In addition, internal access to the steam nozzles poses a potential risk to employees as egress by the examiner, and/or immediate emergency retrieval efforts by response personnel, would be delayed due to the tortuous access path.

From a design standpoint, an analysis has been performed on this nozzle as documented in ANSALDO PX-RPM-13-DNU017 Revision 0, Structural and Fatigue Analysis of the Steam Outlet Nozzle. The results of this analysis conclude that ASME Class 1 and 2 requirements for the nozzle (including its IR Section) are not exceeded. The nozzles were evaluated utilizing a 2-D axisymmetric finite element model using the ANSYS program. Revision 5.4. The loads (internal pressure, temperature transients, and external piping loads) and loading combinations were derived from the certified Design Specification, PX-SPD-OO-AESCOOl. The description, assumptions, and results of the Structural and fatigue analysis of the steam outlet nozzle for Unit 1 is the same as Unit 3, see APS Response for number 4 of reference 4.

Enclosure Relief Request 64 - Unit 1 Impractical Examinations for the Third 10-Year ISI Interval Attachment 1 Location Figure 1 Steam Generator Main Steam Nozzle Configuration see TABLE lM-4)

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