ML21063A319

Request for Additional Information Regarding Relief Request RR 15 - Extension of RPV Welds from 10 to 20 Years

ML21063A319
Person / Time
Site:	Saint Lucie
Issue date:	03/04/2021
From:	Natreon Jordan Plant Licensing Branch II
To:	Godes W Florida Power & Light Co
Jordan N, NRR/DORL/LPL2-2, 415-7410
References
EPID L-2020-LLR-0157
Download: ML21063A319 (4)

Text

From: Jordan, Natreon To: Godes, Wyatt Cc: Shoop, Undine; Frehafer, Ken; Mack, Jarrett

Subject:

Relief Request RR#15 - Extension of St. Lucie Unit 2 RPV Welds from 10 to 20 Years - Request For Additional Information (L-2020-LLR-0157)

Date: Thursday, March 04, 2021 11:34:00 AM

Dear Mr. Godes,

By letter dated October 30, 2020 (Agencywide Documents Access and Management System Accession No. ML20304A148), Florida Power and Light Company (FPL or the licensee) requested U.S. Nuclear Regulatory Commission (NRC) approval for use of an alternative from the requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel, Division 1,Section XI for the St. Lucie Plant, Unit 2 facility. If approved, the NRC staff's authorization of this ISI alternative will result in an alternate, 20-Year ISI Interval for performance of these RPV component-specific ISI examinations, with the alternate interval commencing on August 8, 2013 and ending on August 7, 2033. To complete its review, the NRC staff generated requests for additional information (RAIs) that are provided below. The NRC staff then held a meeting with the licensee, on March 4, 2021, to ensure that the licensee clearly understood the nature of the RAIs. As discussed during the call, the NRC staff request your response to the RAIs within 30 days of the date of this email. If you do not believe that you can meet the response date, please provide an acceptable alternate date and justification for extending the response date.

If you have any questions, please contact me at (301) 415-7410 or Natreon.Jordan@nrc.gov.

Thanks,

-Nate Natreon (Nate) Jordan Nuclear Engineer (Project Manager)

Plant Licensing Branch II-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Mail Stop O-8B1A Washington, DC 20555 301-415-7410 natreon.jordan@nrc.gov REQUESTS FOR ADDITIONAL INFORMATION RELIEF REQUEST EXTENSION OF REACTOR PRESSURE VESSEL WELDS FROM 10 TO 20 YEARS

ST. LUCIE PLANT, UNIT 2 DOCKET NUMBER 50-389 By letter dated October 30, 2020 (Agencywide Documents Access and Management System (ADAMS) Accession Number ML20304A148), Florida Power and Light Company (FPL or the licensee) requested U.S. Nuclear Regulatory Commission (NRC) approval for use of an alternative from the requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel, Division 1,Section XI (ASME Section XI) for the St. Lucie Plant, Unit 2 Facility (St. Lucie Unit 2). The licensee's Code alternative proposed in Relief Request No. RR#15 requests NRC staff authorization to eliminate the performance of the inservice inspection (ISI) volumetric examinations that are required to be performed on pressure retaining welds in the heads, flanges, and shells of the reactor pressure vessel (RPV) and on associated RPV-to-nozzle welds and nozzle inside radius locations (i.e., ASME Code Section XI Category B-A and B-D required examinations) during the ASME-defined Fourth (4th) 10-Year ISI interval for St. Lucie Unit 2. Instead, FPL now requests staff authorization to defer performance of these volumetric inspections until the Fifth (5th) 10-Year ISI interval for the unit. If approved, the staff's authorization of this ISI alternative will result in an alternate, 20-Year ISI Interval for performance of these RPV component-specific ISI examinations, with the alternate interval commencing on August 8, 2013 and ending on August 7, 2033.

Regulatory Requirements/Background Title 10 of the Code of Federal Regulations (10 CFR) Part 50.55a(z) establishes a process for licensees to propose alternatives to codes and standard requirements. Specifically, for alternatives requested under the criteria in 10 CFR 50.55a(z)(1), FPL must demonstrate that the proposed alternative would provide an acceptable level of quality and safety. The following requests for additional information (RAIs) are needed to reach a conclusion that FPL's proposed alternative achieves an acceptable level of quality and safety in lieu of following the applicable ASME Section XI requirements referenced in the October 30, 2020 letter.

RAI 1

In FPL's proposed alternative, the licensee requests staff authorization to defer the following until the 5th 10-Year ISI interval for the unit:

1) the inspections of the RPV pressure retaining welds required to be inspected in accordance with ASME Section XI, Table IWB-2500-1, Examination Category B-A, Inspection Items B1.11, B1.12, B1.21, B1.22, and B1.30, and

2) the inspections of RPV nozzle-to-shell welds and inside radius sections required to be inspected in accordance with ASME Section XI, Table IWB-2500-1, Examination Category B-D, Inspection Items B3.90 and B3.100.

FPL makes the following statement in Section 5 of the RR#15 enclosure: "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)."

Tables 4-2, 6-1, and 6-2 in WCAP-18275-NP, Revision 0, as referenced in Reference No. 9 of the RR#15 enclosure, indicate that there are many more RPV weld seam and inside radius section locations that would need to be inspected during the 4th interval (i.e., if the Code rules were followed) than just eight RPV pressure retaining components. Thus, the staff is unable to determine whether the "number of inspections" terminology included in the referenced RR#15 statement is being made in reference to a specific set of eight RPV weld or nozzle inside radius section locations, or rather to a specific population of RPV components for each RPV component type that is required to be inspected in accordance with the specific ASME Section XI Inspection Items referenced in RR#15.

Request Please clarify whether the term "number of inspections" in Section 5 of the RR#15 enclosure is being made in relation to inspection of specific RPV weld or nozzle inside radius section locations or in reference to a specific population of RPV components for each of RPV component type that is required to be inspected in accordance with the specific ASME Section XI Inspection Items referenced in RR#15

RAI 2

Issue The criteria in ASME Section XI Paragraph IWB-2411 require the licensee to perform a volumetric inspection of essentially 100% of the population of components in the specified ASME Section XI Inspection Items for the reference B-A and B-D Examination Categories.However, the relief request does not specifically state that the licensee will inspect essentially 100% of the population of RPV components for the specified component type in each of the ASME Section XI Inspection Items referenced in RR#15.

Request For each of the ASME Section XI, Table IWB-2500-1, Examination Category B-A and B-D inspection items referenced in RR#15, identify the percent (%) population of components that will be inspected during the alternate 20-Year ISI interval (i.e., the interval duration for the 4th and 5th 10-Year ISI Intervals combined) proposed in RR#15.

RAI 3

Issue Table 2 in RR#15 identifies that FPL performed volumetric ISI examinations of the RPV pressure retaining welds in 1989, 2000, and 2012.

FPL identifies that there were five (5) indications that were detected within the inner 1/10th or inner 1 inch of the RPV wall thickness, with three (3) of the indications referenced as weld indications and two (2) of the indications referenced as plate indications. It is not evident whether the Year 2012 inspections of the welds containing these indications were the first inspections that revealed evidence of flaw indications or re-inspections of the welds containing the flaw indications (meaning the flaw indications were first detected during inspections prior to Year 2012). The staff seeks additional information relative to the risk-based assessments of these flaw indications to confirm that any potential growth of the flaws is bounded by fatigue flaw growth assumptions and values used in the WCAP-16168-NP-A, Rev. 3 methodology.

Request

a. Clarify whether the five (5) flaw indications are a subset or the 60 flaw indications that were identified as being acceptable per ASME Section XI Table IWB-3510-1 or in addition to the 60 indications that were found to be acceptable per Table IWB-3510-1.

b. Confirm whether the Year 2012 inspections were the first ISI inspections that detected the flaw indications and whether there is any site-specific flaw growth data for the flaw indications evaluated in Table 2 of RR#15. If there is applicable site-specific flaw growth data for the flaw indications, identify the limiting site-specific flaw growth value that was calculated for the flaws evaluated in Table 2.