RS-24-001, Response to Request for Additional Information Regarding Relief Request I5R-26, Inservice Inspection Program Relief Request Regarding Examination Coverage for the Fifth Inservice Inspection Interval

Response to Request for Additional Information Regarding Relief Request I5R-26, Inservice Inspection Program Relief Request Regarding Examination Coverage for the Fifth Inservice Inspection Interval

ML24003A690
Person / Time
Site:	Quad Cities
Issue date:	01/03/2024
From:	Humphrey M Constellation Energy Generation
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
RS-24-001, EPID L-2023-LLR-0047
Download: ML24003A690 (5)

Text

4300 Winfield Road Warrenville, IL 60555 630 657 2000 Office January 3, 2024 10 CFR50.55a RS-24-001 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001 Quad Cities Nuclear Power Station, Units 1 and 2 Renewed Facility Operating License Nos. DPR-29 and DPR-30 NRC Docket Nos. 50-254 and 50-265

Subject:

Response to Request for Additional Information Regarding Relief Request I5R-26, Inservice Inspection Program Relief Request Regarding Examination Coverage for the Fifth Inservice Inspection Interval

References:

1. Letter from K. Lueshen (Constellation Energy Generation, LLC (CEG)) to U.S. Nuclear Regulatory Commission (U.S. NRC), "Relief Request I5R-26, Inservice Inspection Program Relief Request Regarding Examination Coverage for the Fifth Inservice Inspection Interval," dated August 28, 2023 (ADAMS Accession Number ML23240A390)

2. Email from R. Kuntz (U.S. NRC) to R.L. Steinman (CEG),

Subject:

DRAFT Request for Additional Information RE: Quad Cities Relief Request I5R-26 (EPID L-2023-LLR-0047), dated November 21, 2023 (ADAMS Accession Number ML23338A119)

3. Email from R. Kuntz (U.S. NRC) to R.L Steinman (CEG),

Subject:

DRAFT Request for Additional Information RE: Quad Cities Relief Request I5R-26 (EPID L-2023-LLR-0047), dated December 6, 2023 In Reference 1, Constellation Energy Generation, LLC (CEG) submitted a relief request related to design configuration limitations that precluded completion of full American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code,Section XI, "Rules for Inservice Inspection of Nuclear Power Plant Components," Examination Requirements of Class 1 and 2 components during the Quad Cities Nuclear Power Station (QCNPS), Units 1 and 2 Fifth Inservice Inspection interval (ISI).

The QCNPS Fifth Ten-year ISI Program Plan was developed in accordance with ASME Code,Section XI, 2007 Edition through 2008 Addenda. The Fifth ISI Interval for QCNPS ended May 17, 2023.

As documented in References 2 and 3, the NRC found that additional information was required to support its review of Reference 1. The requested information is provided in the attachment.

U.S. Nuclear Regulatory Commission January 3, 2024 Page 2 There are no regulatory commitments included in this letter.

Should you have any questions concerning this letter, please contact Ms. Rebecca L. Steinman at 779-231-6162.

Respectfully, Humphrey, Mark Digitally signed by Humphrey, Mark D.

D. Date: 2024.01.03 08:23:27 -06'00' Mark Humphrey Sr. Manager Licensing Constellation Energy Generation, LLC

Attachment:

Response to NRC Request for Information cc: Regional Administrator - NRC Region III NRC Senior Resident Inspector - Quad Cities Nuclear Power Station

ATTACHMENT Response to NRC Request for Information REQUEST FOR ADDITIONAL INFORMATION RELIEF REQUEST I5R-26 CONSTELLATION ENERGY GENERATION, LLC QUAD CITIES NUCLEAR POWER STATION, UNITS 1 AND 2 DOCKET NOS. 50-254 AND 50-265 EPID L-2023-LLR-0047 Regulatory Basis Adherence to Section XI of the ASME Code is mandated by 10 CFR 50.55a(g)(4), which states, in part, that ASME Code Class 1, 2, and 3 components will meet the requirements, except the design and access provisions and the pre-service examination requirements, set forth in the ASME Code,Section XI.

Inservice Inspection (ISI) of ASME Code Class 1, 2, and 3 components is to be performed in accordance with Section XI of the ASME Code and applicable edition and addenda as required by 10 CFR Section 50.55a(g), except where specific relief has been granted by the U.S. Nuclear Regulatory Commission (NRC or the Commission) pursuant to 10 CFR 50.55a(g)(6)(i).

10 CFR 50.55a(g)(5)(iii) states in part that licensees may determine that conformance with certain code requirements is impractical and that the licensee shall notify the Commission and submit information in support of the determination.

Issue 1 (11/21/23)

Table B of Attachment 1 to the submittal stated that five recordable indications were detected in the QCNPS, Unit 2, Top Head-to-Flange weld (Component ID RPV-THHF) during the Q2R24 outage. This table stated that the flaw sizes showed no evidence of growth from previous examinations, that the indications are bounded by the existing analytical evaluation, and that these five recordable indications were evaluated as acceptable. However, the description of the examination of the subject weld on page 37 of Attachment 3 to submittal described the five recordable indications as unacceptable to the requirements of IWB-3000. Therefore, the disposition of the five recordable indications is not clear. It is not clear whether the existing analytical evaluation that bounds the indications is a flaw evaluation performed per IWB-3600 of the ASME Code,Section XI, as required by the code.

Request 1 (11/21/23) a) Clarify the disposition of the five recordable indications detected in the QCNPS, Unit 2, Top Head-to-Flange weld (Component ID RPV-THHF) during the Q2R24 outage.

b) Clarify the basis for the disposition in Part a, including how the five indications are bounded by the existing analytical evaluation, as stated in Table B of Attachment 1 to the submittal, Page 1 of 3

ATTACHMENT Response to NRC Request for Information and whether this analytical evaluation was performed per IWB-3600 of the ASME Code,Section XI.

Constellation Energy Generation, LLC (CEG) Response to Request 1 (11/21/23)

During the Unit 2 spring 2018 outage, five recordable indications were detected in the Top Head-to-Flange weld. Initial evaluation of these five indications was using ASME B&PV Section XI code, 2007 edition, 2008 Addenda IWB-3000 criteria. According to this criterion the indications would have been evaluated as unacceptable. However, these indications correlated to previously observed indications during the 1989 refueling outage and no new growth was detected.

General Electric (GE) report "Structural Evaluation of Cracks in the Top Head at Quad Cities Nuclear Power Station Unit 2," dated April 1990 (Reference 1) determined the indications were from Intergranular Stress Corrosion Cracking (IGSCC). GE performed a crack growth analysis using SCC crack growth rate data for similarly welded stainless steel and found good agreement between their model and actual flaw size. This predictive model was then used to estimate future crack growth in the next cycle. Reference 1 concludes a flaw evaluation using ASME B&PV Section XI, 1989 edition, IWB-3600 was completed and the indications were evaluated to be acceptable. As a result, continued operation of Quad Cities Nuclear Power Station (QCNPs) was justified for the next cycle with subsequent exams showing no new growth.

In conclusion, the five indications mentioned in Table B of Attachment 1 of QCNPS Relief Request I5R-26 (Reference 2) were evaluated as unacceptable per ASME Section XI Code, 2007 edition, 2008 addenda. However, upon comparison to previous inspection reports it was determined that no new indication growth had occurred. Since the five indications remained bounded by the 1990 flaw evaluation in Reference 1 the indications were deemed acceptable.

Issue 2 (12/6/23)

In Table A of Attachment 1 to the submittal, the licensee stated that two recordable indications were detected in the QCNPS, Unit 1, Pipe-to-Valve and Valve-to-Pipe welds (Component ID 1016C-2R and 1016C-3R respectively) during the Q2R24 outage. In this table, the licensee stated that the two recordable indications met the acceptance standards.

Request 2 (12/6/23) a) Describe the recordable indications that were detected in QCNPS, Unit 1 Pipe-to-Valve and Valve-to-Pipe welds for Component ID 1016C-2R and 1016C-3R during the Q2R24 outage.

b) Clarify the acceptance standards that were used to verify that the detected indications were acceptable.

Page 2 of 3

ATTACHMENT Response to NRC Request for Information Constellation Energy Generation, LLC (CEG) Response to Request 2 (12/6/23)

Table A of Attachment 1 of QCNPS Relief Request I5R-26 (Reference 2) mistakenly states Pipe-to-Valve and Valve-to-Pipe (component ID 1016C-2R and 1016C-3R) had two indications each. Neither of the components had indications. The inclusion of these two components in Table A was only to state the pre-service UT inspection had <90% coverage due to valve geometry.

The Torus suction valve MO-1-1001-7C was replaced during the Unit 1 spring 2019 outage. A repair/replacement (R&R) plan was written (18-062) for this work according to ASME B&PV Section XI code, 2007 edition, 2008 addenda IWA-4000. That R&R plan identified the construction code as B31.1 1967 edition and the pre-service inspection requirements were PT or MT (surface) and RT (volumetric) exam on all completed welds. In lieu of the RT (volumetric) requirements of B31.1, QCNPS implemented Relief Request I5R-02 Risk-Informed Inservice Inspection requirements and acceptance criteria of Code Case N-578-1 and TR 112657 B-A by requiring Encoded UT. Additionally, QCNPS utilized Relief Request I5R-16 which allows encoded PAUT in lieu of RT for pre-service inspection requirements of welds. The Encoded PAUT was performed on welds 1016C-2R and 1016C-3R during the 2019 outage as pre-service inspection. Both welds had acceptable results for both surface and volumetric pre-service inspections and satisfied the VT-2 system leakage test. Satisfactory pre-service inspection results are reported as Acceptable whereas existing component welds satisfactory results are reported as NRI - No Recordable Indication.

Upon review of GE-Hitachi Inservice Inspection reports, no indications were observed during inspection of the new welds. The reports show calculation of limited coverage of UT of 1016C-R2 and 1016C-3R due to geometry of the valve location. No customer notification report (CNR) or issue reports (IR) were found in relation to these two welds. The inclusion of 1016C-2R and 1016C-3R in Table A of Attachment 1 was only for <90% coverage, not because any indications were found. This was a mistake in Reference 2 due to verbiage of the vendor reports.

References

1. Enclosure to letter from R. Stols (Commonwealth Edison) to T.E. Murley (U.S. NRC), "Quad Cities Nuclear Power Station Units 1 and 2, Dresden Power Station Units 2 and 3, LaSalle Nuclear Power Station Units 1 and 2, Reactor Head Inspection," dated May 4, 1990 (ADAMS Accession No. ML17202L231 or 9005140114)

2. Letter from K. Lueshen (Constellation Energy Generation, LLC (CEG)) to U.S. Nuclear Regulatory Commission (U.S. NRC), "Relief Request I5R-26, Inservice Inspection Program Relief Request Regarding Examination Coverage for the Fifth Inservice Inspection Interval,"

dated August 28, 2023 (ADAMS Accession Number ML23240A390)

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