L-2020-160, Extension of St. Lucie Unit 2 RPV Welds from 10 to 20 Years

From kanterella
Jump to navigation Jump to search

Extension of St. Lucie Unit 2 RPV Welds from 10 to 20 Years
ML20304A148
Person / Time
Site: Saint Lucie NextEra Energy icon.png
Issue date: 10/30/2020
From: Godes W
Florida Power & Light Co
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
L-2020-160 RR#15
Download: ML20304A148 (11)
v • d • e


Text

OCT 3 0 2020 L-2020-160 10 CFR 50.55a U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington D C 20555-0001 RE: St. Lucie Unit 2 Docket No. 50-389 Relief Request Number RR#15 Extension of St. Lucie Unit 2 RPV Welds from 10 to 20 Years Pursuant to 10CFR50.55a(z)(1), Florida Power & Light Company (FPL) hereby requests relief from the American Society of Mechanical Engineers Section XI Code (ASME Section XI Code) for the St. Lucie Unit 2 Fourth 10-Year ISI Interval. The attached relief request is for the deferral of the volumetric examination of the reactor pressure vessel (RPV) full penetration pressure-retaining Examination Category B-A and B-D welds for St. Lucie Unit 2 from the fourth interval in 2023 to the fifth interval in 2032. There will be an approximate 10 year deferral for volumetric examinations.

The relief request was developed from the methodology defined in WCAP-16168-NP-A, Revision 3, "Risk-Informed Extension of the Reactor Vessel In-service Inspection Interval."

The attachment to this letter provides relief request (RR) #15 for St. Lucie Unit 2. FPL requests the relief requests to be processed as a normal request on the basis that the proposed alternative would provide an acceptable level of quality and safety, with approval within one year of the submittal date.

Should you have any questions regarding this submittal, please contact Mr. Ken Frehafer, St. Lucie Licensing, at (772) 467-77 48.

Sincerely, tJ)f~

W~tt ~es St. Lucie Licensing Manager Florida Power & Light Attachment cc: USNRC Regional Administrator, Region II USNRC Project Manager, St. Lucie Nuclear Plant, Units 1 and 2 USNRC Senior Resident Inspector, St. Lucie N uclear Plant, Units 1 and 2 Florida Power & Light Company 6501 S. Ocean Drive, Jensen Beach, FL 34957

L-2020-160 Attachment 1 Page 1 of 10 Attachment 1 Relief Request Number RR#15 Proposed Alternative for the Extension of St. Lucie Unit 2 RPV Welds from 10 to 20 Years In Accordance with 10 CFR 50.55a(z)(1)

L-2020-160 Attachment 1 Page 2 of 10 Relief Request Number RR#15 Extension of St. Lucie Unit 2 RPV Welds from 10 to 20 Years Proposed Alternative In Accordance with 10 CFR 50.55a(z)(1)

-Alternative Provides Acceptable Level of Quality and Safety-

1. ASME Code Component(s) Affected The affected component is the St. Lucie Unit 2 reactor vessel (RV), specifically, the following American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (BPV)

Code, Section XI (Reference 1) examination categories and item numbers covering examinations of the RV. These examination categories and item numbers are from IWB-2500 and Table IWB-2500-1 of the ASME BPV Code, Section XI.

Category B-A welds are defined as Pressure Retaining Welds in Reactor Vessel.

Category B-D welds are defined as Full Penetration Welded Nozzles in Vessels.

Examination Category Item No. Description B-A B1.10 Shell Welds B-A B1.11 Circumferential Shell Welds B-A B1.12 Longitudinal Shell Welds B-A B1.20 Head Welds B-A B1.21 Circumferential Head Welds B-A B1.22 Meridional Head Welds B-A B1.30 Shell-to-Flange Weld B-D B3.90 Nozzle-to-Vessel Welds B-D B3.100 Nozzle Inside Radius Section (Throughout this request, the above examination categories are referred to as the subject examinations and the ASME BPV Code, Section XI, is referred to as the Code.)

2. Applicable Code Edition and Addenda

ASME Code Section XI, Rules for Inservice Inspection of Nuclear Power Plant Components, 2007 Edition through 2008 Addenda (Reference 1).

3. Applicable Code Requirement

IWB-2411, Inspection Program, requires volumetric examination of essentially 100% of reactor vessel pressure-retaining welds identified in Table IWB-2500-1 once each 10-year interval. The fourth 10-year inservice inspection (ISI) interval for St. Lucie Unit 2 is scheduled to end on August 7, 2023. The applicable Code for the fifth 10-year ISI interval will be selected in accordance with the requirements of 10 CFR 50.55a.

L-2020-160 Attachment 1 Page 3 of 10

4. Reason for Request

An alternative is requested from the requirement of the IWB-2411 Inspection Program, that volumetric examination of essentially 100% of reactor vessel pressure-retaining Examination Category B-A and B-D welds be performed once each 10-year interval. Extension of the interval between examinations of Category B-A and B-D welds from 10 years to up to 20 years will result in a reduction in man-rem exposure and examination costs.

5. Proposed Alternative and Basis for Use

FPL proposes not to perform the ASME Code required volumetric examination of the St. Lucie Unit 2 reactor vessel full penetration pressure-retaining Examination Category B-A and B-D welds for the fourth inservice inspection, currently scheduled for 2023. FPL will perform the fourth ASME Code required volumetric examination of the St. Lucie Unit 2 reactor vessel full penetration pressure-retaining Examination Category B-A and B-D welds in the fifth inservice inspection interval in 2032. The proposed inspection date is a slight deviation from the latest revised implementation plan, OG-10-238 (Reference 2), since the implementation plan reflects the next inspection being performed in 2030 for St. Lucie Unit 2. The implementation plan revised the proposed inspection date for St. Lucie Unit 2 from 2012 to 2010, but the third ISI examination was performed in 2012. The impact to the implementation plan in OG-10-238 would increase the number of inspections in 2032 (from three to four) and decrease the number of inspections in 2030 (from five to four). Based on Figure 3 and Figure 4 of OG 238, this proposed inspection schedule is considered to have a minor impact on the future inspection plan and the distribution of inspections over time.

In accordance with 10 CFR 50.55a(z)(1), an alternate inspection interval is requested on the basis that the current interval can be revised with negligible change in risk by satisfying the risk criteria specified in Regulatory Guide 1.174 (Reference 3).

The methodology used to conduct this analysis is based on that defined in the study WCAP-16168-NP-A, Revision 3, Risk-Informed Extension of the Reactor Vessel In-service Inspection Interval (Reference 4). This study focuses on risk assessments of materials within the beltline and extended beltline regions of the RV wall. The results of the calculations for St.

Lucie Unit 2 were compared to those obtained from the Combustion Engineering (CE) pilot plant evaluated in WCAP-16168-NP-A, Revision 3. Appendix A of the WCAP identifies the parameters to be compared. Demonstrating that the parameters for St. Lucie Unit 2 are bounded by the results of the CE pilot plant qualifies St. Lucie Unit 2 for an ISI interval extension.

L-2020-160 Attachment 1 Page 4 of 10 Table 1 below lists the critical parameters investigated in the WCAP and compares the results of the Westinghouse pilot plant to those of St. Lucie Unit 2. Tables 2 and 3 provide additional information that was requested by the NRC and included in Appendix A of Reference 4.

Table 1 Critical Parameters for the Application of Bounding Analysis for St. Lucie Unit 2 Additional Pilot Plant Plant-Specific Parameter Evaluation Basis Basis Required?

Dominant Pressurized Thermal Shock NRC PTS Risk Study PTS Generalization (PTS) Transients in the NRC PTS Risk No (Reference 5) Study (Reference 6)

Study are Applicable 6.75E-10 Events per Through-Wall Cracking Frequency 3.16E-07 Events per year (Calculated per No (TWCF) year (Reference 4)

Reference 4) 13 heatup/cooldown Bounded by 13 Frequency and Severity of Design Basis cycles per year heatup/cooldown No Transients (Reference 4) cycles per year Single Layer Cladding Layers (Single/Multiple) Single Layer No (Reference 4)

L-2020-160 Attachment 1 Page 5 of 10 Table 2 below provides a summary of the latest reactor vessel inspection for St. Lucie Unit 2 and an evaluation of the recorded indications. This information confirms that satisfactory examinations have been performed on the St. Lucie Unit 2 reactor vessel.

Table 2 Additional Information Pertaining to Reactor Vessel Inspection for St. Lucie Unit 2 The latest RV ISI for St. Lucie Unit 2 was conducted in accordance with the requirements of Appendix VIII of the ASME Code, Section XI, 1995 Edition with Editions and Addenda through 2000, as modified by the Performance Demonstration Initiative program and the requirements Inspection of Federal Register, Part II, Nuclear Regulatory Commission, 10 CFR Part 50, Industry Codes methodology: and Standards; Amended Requirements. Evaluation of recordable indications was performed to the acceptance standards of Section XI, 1998 Edition with Addenda through 2000. Future inservice inspections will be performed to ASME Section XI, Appendix VIII requirements.

Number of Three complete 10-year inservice inspections and a preservice inspection have been performed past (1989, 2000, and 2012).

inspections:

There were sixty total indications identified in the beltline and extended beltline regions during the most recently completed inservice inspection. These subsurface indications are located in the upper-to-intermediate shell circumferential weld seam (Item 10 in Table 3), and the longitudinal welds seams in the upper shell, intermediate shell, and lower shell (Items 14/17/18/19/20/22 of Table 3). All sixty indications are acceptable per Table IWB-3510-1 of Section XI of the ASME Code. There are five indications within the inner 1/10th or inner 1 of the reactor vessel wall thickness. The five indications are acceptable per the requirements of the Alternate PTS Rule, 10 CFR 50.61a (Reference 7).

A disposition of the five flaws against the limits of the Alternate PTS Rule is shown in the tables below. Three of the flaws were located in the weld materials and two flaws were located in the plate material. For the three flaws in the weld materials:

Scaled Maximum number of Through-Wall Extent, TWE flaws per 1,580 inches of weld (in) Number of St.

length in the inspection volume Lucie Unit 2 that are greater than or equal Flaws Evaluated to TWEMIN and less than (Axial/Circ.)

Number of TWEMIN TWEMAX TWEMAX.

indications found: 0 0.075 No Limit 0 0.075 0.475 263 3 (3/0) 0.125 0.475 143 1 (1/0) 0.175 0.475 36 0 0.225 0.475 13 0 0.275 0.475 6 0 0.325 0.475 4 0 0.375 0.475 2 0 0.425 0.475 1 0 0.475 Infinite 0 0

L-2020-160 Attachment 1 Page 6 of 10 Table 2:

Additional Information Pertaining to Reactor Vessel Inspection for St. Lucie Unit 2 For the two flaws in the plate material:

Through-Wall Scaled Maximum number of flaws per Number of St.

Extent, TWE in.) 13,889 square-inches of inside surface Lucie Unit 2 area in the inspection volume that are Flaws Evaluated greater than or equal to TWEMIN and less (Axial/Circ.)

TWEMIN TWEMAX than TWEMAX.

0 0.075 No Limit 0 0.075 0.375 111 2 (2/0) 0.125 0.375 43 0 0.175 0.375 11 0 0.225 0.375 4 0 0.275 0.375 1 0 0.325 0.375 0 0 0.375 Infinite 0 0 The plant-specific total length (1,580 inches) of reactor vessel beltline welds that were volumetrically inspected and the plant-specific total surface area (13,889 square-inches) of reactor vessel beltline plates that were volumetrically inspected are comprised of the upper-to intermediate shell circumferential weld, the intermediate-to-lower shell circumferential weld, three longitudinal welds in the intermediate shell, and three longitudinal welds in the lower shell.

While the three upper shell longitudinal welds were inspected and evaluated, the length and area associated with these welds are conservatively excluded from the total inspected length/area.

The fourth inservice inspection is scheduled for 2023. This inspection will instead be performed in 2032 plus or minus one refueling outage. The proposed inspection date is a slight deviation Proposed from the latest revised implementation plan, OG-10-238 (Reference 2), since the inspection implementation plan reflects the next inspection being performed in 2030 for St. Lucie Unit 2.

schedule for The impact to the implementation plan in OG-10-238 would increase the number of inspections balance of in 2032 (from three to four) and decrease the number of inspections in 2030 (from five to four).

plant life: Based on Figure 3 and Figure 4 of OG-10-238, this proposed inspection schedule is considered to have a minor impact on the future inspection plan and the distribution of inspections over time.

L-2020-160 Attachment 1 Page 7 of 10 Table 3 summarizes the inputs and outputs for the calculation of through-wall cracking frequency (TWCF).

Table 3 Details of TWCF Calculation for St. Lucie Unit 2 at 55 Effective Full Power Years (EFPY)

Inputs (1)

Inter. & Lower Shell Twall [inches]: 8.625 Upper Shell Twall [inches]: 10.75 Fluence Material Heat No. Copper Nickel R.G. 1.99 Chemistry RTNDT(u)

No. Region and Component Description [Neutron/cm2, Identification [weight %] [weight %] Position Factor [ºF] [ºF]

E > 1.0 MeV]

1 Upper Shell Plate 122-102-A B-3493-1 0.16 0.60 1.1 118.00 50 2 Upper Shell Plate 122-102-B C-9632-2 0.16 0.61 1.1 118.25 50 1.45E+18 3 Upper Shell Plate 122-102-C A-8524-1 0.16 0.58 1.1 116.60 10 4 Intermediate Shell Plate 124-102-A A-8490-1 0.11 0.61 2.1 103.28 0 5 Intermediate Shell Plate 124-102-B A-8490-2 0.11 0.61 2.1 103.28 30 4.49E+19 6 Intermediate Shell Plate 124-102-C B-3416-2 0.13 0.62 1.1 91.50 10 7 Lower Shell Plate 142-102-A A-3131-2 0.07 0.60 1.1 44.00 20 8 Lower Shell Plate 142-102-B A-3131-1 0.07 0.60 1.1 44.00 20 4.48E+19 9 Lower Shell Plate 142-102-C B-8307-2 0.06 0.57 1.1 37.00 20 10 Upper to Int. Shell Circ. Weld 106-121 83637 0.05 0.07 1.1 34.05 -50 1.45E+18 11 Inter. to Lower Shell Circ. Weld 101-171 83637 and 3P7317 0.07 0.07 1.1 40.05 -50 4.46E+19 12 5P5622 0.153 0.077 1.1 74.13 -40 Upper Shell Long. Weld 101-122-A 9.60E+17 13 2P5755 0.21 0.058 1.1 96.64 -50 14 Upper Shell Long. Weld 101-122-B 5P5622 0.153 0.077 1.1 74.13 -40 7.67E+17 15 5P5622 0.153 0.077 1.1 74.13 -40 Upper Shell Long. Weld 101-122-C 9.60E+17 16 2P5755 0.21 0.058 1.1 96.64 -50

L-2020-160 Attachment 1 Page 8 of 10 Table 3 Details of TWCF Calculation for St. Lucie Unit 2 at 55 Effective Full Power Years (EFPY) (cont.)

17 Int. Shell Long. Weld 101-124-A 83642 0.05 0.09 1.1 36.35 -56 2.96E+19 18 Int. Shell Long. Weld 101-124-B 83642 0.05 0.09 1.1 36.35 -56 2.36E+19 19 Int. Shell Long. Weld 101-124-C 83642 0.05 0.09 1.1 36.35 -56 2.96E+19 20 Int. Shell Long. Repair Weld 101-124-C 83637 0.05 0.07 1.1 34.05 -50 21 Lower Shell Long. Weld 101-142-A 83637 0.05 0.07 1.1 34.05 -50 2.95E+19 22 Lower Shell Long. Weld 101-142-B 83637 0.05 0.07 1.1 34.05 -50 2.36E+19 23 Lower Shell Long. Weld 101-142-C 83637 0.05 0.07 1.1 34.05 -50 2.95E+19 Outputs Methodology Used to Calculate T30: Regulatory Guide 1.99, Revision 2 (Reference 8)

Controlling Fluence RTMAX-XX FF (Fluence Material xx [Neutron/cm2, T30 [ºF] TWCF95-XX

[°R] Factor)

Region No. E >1.0 MeV]

Limiting Axial Weld - AW 5 2.500 622.64 2.69E+19 1.2875 132.97 1.09E-12 Limiting Plate - PL 5 2.456 632.26 4.49E+19 1.3807 142.59 2.74E-10 Limiting Circumferential Weld - CW 5 3.457 632.12 4.46E+19 1.3793 142.45 7.54E-17 Limiting Forging - FO n/a TWCF95-TOTAL = (AWTWCF95-AW + PLTWCF95-PL + CWTWCF95-CW + FOTWCF95-FO): 6.75E-10 (1) Material properties and fluence inputs are based on WCAP-18275-NP (Reference 9).

L-2020-160 Attachment 1 Page 9 of 10

6. Duration of Proposed Alternative

This request is applicable to the St. Lucie Unit 2 inservice inspection program for the fourth and fifth 10-year inspection intervals.

7. Precedents

  • Surry Power Station Units 1 and 2 - Relief Implementing Extended Reactor Vessel Inspection Interval (TAC Nos. ME8573 and ME8574), dated April 30, 2013, Agency wide Document Access and Management System (ADAMS) Accession Number ML13106A140.
  • Vogtle Electric Generating Plant, Units 1 and 2 - Request for Alternatives VEGP-ISI-ALT-05 and VEGP-ISI-ALT-06 (TAC Nos. MF2596 and MF2597), dated March 20, 2014, ADAMS Accession Number ML14030A570.
  • Sequoyah Nuclear Plant, Units 1 and 2 - Requests for Alternatives 13-ISI-1 and 13-ISI-2 to Extend the Reactor Vessel Weld Inservice Inspection Interval (TAC Nos. MF2900 and MF2901),

dated August 1, 2014, ADAMS Accession Number ML14188B920.

  • Byron Station, Unit No. 1 - Relief from Requirements of the ASME Code to Extend the Reactor Vessel Inservice Inspection Interval (TAC No. MF3596), dated December 10, 2014, ADAMS Accession Number ML14303A506.
  • Wolf Creek Generating Station - Request for Relief Nos. I3R-08 and I3R-09 for the Third 10-Year Inservice Inspection Program Interval (TAC Nos. MF3321 and MF3322), dated December 10, 2014, ADAMS Accession Number ML14321A864.
  • Callaway Plant, Unit 1 - Request for Relief I3R-17, Alternative to ASME Code Requirements Which Extends the Reactor Vessel Inspection Interval from 10 to 20 Years (TAC No. MF3876),

dated February 10, 2015, ADAMS Accession Number ML15035A148.

  • Braidwood Station, Units 1 and 2 - Request for Relief from the Requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code) (CAC Nos.

MF8191 and MF8192), dated March 15, 2017, ADAMS Accession Number ML17054C255.

  • South Texas Project, Units 1 and 2 - Relief from the Requirements of the ASME Code Regarding the Third 10-Year Inservice Inspection Program Interval (EPID L-2018-LLR-0010), dated July 24, 2018, ADAMS Accession Number ML18177A425.
  • R. E. Ginna Nuclear Power Plant - Issuance of Relief Request ISI-18 Regarding Fifth 10-year Inservice Inspection Program Interval (EPID L-2018-LLR-0104), dated April 22, 2019, ADAMS Accession Number ML19100A004.

L-2020-160 Attachment 1 Page 10 of 10

  • Point Beach Nuclear Plant, Units 1 and 2 - Approval of Relief Requests 1-RR-13 and 2-RR-13 Regarding Extension of Inspection Interval for Reactor Pressure Welds from 10 to 20 years (EPID L-2019-LLR-0060), dated March 4, 2020, ADAMS Accession Number ML20036F261.
8. References
1. ASME Boiler and Pressure Vessel Code, Section XI, 2007 Edition through 2008 Addenda, American Society of Mechanical Engineers, New York.
2. PWROG Letter OG-10-238, Revision to the Revised Plan for Plant Specific Implementation of Extended Inservice Inspection Interval per WCAP-16168-NP, Revision 1, Risk-Informed Extension of the Reactor Vessel In-Service Inspection Interval. PA-MSC-0120, July 12, 2010 (ADAMS Accession Number ML11153A033).
3. NRC Regulatory Guide 1.174, Revision 1, An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant-Specific Changes to the Licensing Basis, U.S. Nuclear Regulatory Commission, November 2002, (ADAMS Accession Number ML023240437).
4. Westinghouse Report, WCAP-16168-NP-A, Revision 3, Risk-Informed Extension of the Reactor Vessel In-service Inspection Interval, October 2011 (ADAMS Accession Number ML11306A084).
5. NUREG-1874, Recommended Screening Limits for Pressurized Thermal Shock (PTS), U.S.

Nuclear Regulatory Commission, March 2010, (ADAMS Accession Number ML15222A848).

6. NRC Letter Report, Generalization of Plant-Specific Pressurized Thermal Shock (PTS) Risk Results to Additional Plants, U.S. Nuclear Regulatory Commission, December 14, 2004 (ADAMS Accession Number ML042880482).
7. Code of Federal Regulations, 10 CFR Part 50.61a, Alternate Fracture Toughness Requirements for Protection Against Pressurized Thermal Shock Events, U.S. Nuclear Regulatory Commission, Washington D. C., Federal Register, Volume 75, No. 1, dated January 4, 2010 and No. 22 with corrections to part (g) dated February 3, 2010, March 8, 2010, and November 26, 2010.
8. NRC Regulatory Guide 1.99, Revision 2, Radiation Embrittlement of Reactor Vessel Materials, U.S. Nuclear Regulatory Commission, May 1988, (ADAMS Accession Number ML003740284).
9. Westinghouse Report, WCAP-18275-NP, Revision 0, St. Lucie Unit 2 Heatup and Cooldown Limit Curves for Normal Operation through End of License Extension, November 2019.
Retrieved from "https://kanterella.com/w/index.php?title=L-2020-160,_Extension_of_St._Lucie_Unit_2_RPV_Welds_from_10_to_20_Years&oldid=3570708"