RS-24-021, Response to Request for Additional Information for 10 CFR 50.55a Request No. I5R-22

Response to Request for Additional Information for 10 CFR 50.55a Request No. I5R-22

ML24093A204
Person / Time
Site:	Dresden
Issue date:	04/02/2024
From:	Humphrey M Constellation Energy Generation
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
RS-24-021, EPID L-2023-LLR-0063
Download: ML24093A204 (1)

Text

4300 Winfield Road Warrenville, IL 60555 630 657 2000 Office

RS-24-021 10 CFR 50.55a April 2, 2024

U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555- 0001

Dresden Nuclear Power Station, Units 2 and 3 Renewed Facility Operating License Nos. DPR-19 and DPR-25 NRC Docket Nos. 50-237 and 50-249

Subject:

Response to Request for Additional Information for 10 CFR 50.55a Request No. I5R-22

References:

1. Letter from M. D. Humphrey (Constellation Energy Generation, LLC (CEG)),

to U.S. NRC, "Information for Relief Request I5R-22, Inservice Inspection Program Relief Request Regarding Examination Coverage for the Fifth Inservice Inspection Interval," dated November 8, 2023

2. Email from S. Arora (U.S. NRC) to M. A. Mathews (CEG), "Request for Additional Information for Alternative I5R-22 (EPID: L-2023-LLR-0063),"

dated March 4, 2024

In Reference 1, CEG requested approval of relief requests associated with the fifth Inservice Inspection (ISI) interval at Dresden Nuclear Power Station (DNPS), Units 2 and 3.

As documented in Reference 2, the NRC found that additional information was required to support its review of Request I5R-22 as described in Reference 1. The requested information is provided in the attachment.

There are no regulatory commitments contained within this letter. CEG continues to seek approval of the Reference 1 requests by November 8, 2024.

U.S. Nuclear Regulatory Commission April 2, 2024 Page 2

Should you have any questions concerning this letter, please contact Mr. Mitchel A. Mathews at (779) 231-5765.

Respectfully,

Mark D. Humphrey Sr. Manager - Licensing Constellation Energy Generation, LLC

Attachment:

Response to NRC Request for Additional Information for 10 CFR 50.55a Request No. I5R-22 Attachment Response to NRC Request for Additional Information for 10 CFR 50.55a Request No. I5R-22 (Page 1 of 3)

REQUEST FOR ADDITIONAL INFORMATION

BY THE OFFICE OF NUCLEAR REACTOR REGULATION

RELIEF REQUEST I5R-22

FIFTH INSERVICE INSPECTION INTERVAL

CONSTELLATION ENERGY GENERATION, LLC

DRESDEN NUCLEAR POWER STATION, UNITS 2 AND 3

DOCKET NOS. 50-237 AND 50-249

EPID NO. L-2023-LLR-0063

=

Background===

By letter dated November 8, 2023 (ML23312A092), Constellation Energy Generation, LLC (Constellation, the licensee), submitted relief request I5R-22 to the U.S. Nuclear Regulatory Commission (NRC) regarding limited examination coverage of certain welds at the Dresden Nuclear Power Station, Units 2 and 3 (DNPS) for the fifth inservice inspection (ISI) interval. Specifically, pursuant to Title 10 of the Code of Federal Regulations (10 CFR) 50.55a(g)(5)(iii), the licensee requested relief due to the impracticality of satisfying the requirements of the American Society of Mechanical Engineers Boiler & Pressure Vessel Code (ASME Code),Section XI, "Rules for Inservice Inspection of Nuclear\\Power Plant Components," because of the DNPS plant design.

The NRC staff requests the response to the following request for additional information (RAI) to complete its review of relief request I5R-22.

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.

Attachment Response to NRC Request for Additional Information for 10 CFR 50.55a Request No. I5R-22 (Page 2 of 3)

RAI 1

Issue

The licensee reported recordable indications in the Examination Category B-K welds at DNPS. Table A in the Attachment to the submittal states that five recordable rounded indications in component ID " 2/1/1506-16/M-1164D-296 (IWA)"

at DNPS Unit 2 were detected. Similarly, Table B in the Attachment to the submittal states that two recordable rounded indications in component ID "3/1/RPV SHELL/M-1211D-1 (IWA)" at DNPS Unit 3 were detected. The acceptance standards for these indications are in IWB-3516 per Table IWB-2500- 1 of ASME Code,Section XI for Examination Category B-K. The associated enclosures did not provide sufficient information on the disposition of these recordable indications.

Request

Clarify how the recordable indications in component IDs "2/1/1506-16/M-1164D-296 (IWA)" and "3/1/RPV SHELL/M-1211D-1 (IWA)" were dispositioned per the acceptance standards in IWB-3516 of ASME Code,Section XI.

Constellation Energy Generation, LLC (CEG) Response to RAI 1 Request:

In 2017, during Refuel Outage D2R25, a liquid penetrant (PT) examination was performed on component 2/1/1506 -16/M-1164D-296. Five recordable indications were discovered. This component is classified as ASME XI, Class 1, Category B-K (i.e., Welded Attachments for Vessels, Piping, Pumps, and Valves), Item B10.20. The acceptance standards of the ASME Code,Section XI, IWB-3516 are applicable for these examinations. However, IWB-3516 only provides acceptance criteria for planar and laminar flaws. According to ASME Section XI, IWA-3100(b), if acceptance standards for a particular component, Examination Category, or examination method are not specified in this Division, flaws that exceed the acceptance standards for materials and welds specified in the Section III Edition applicable to the construction of the component shall be evaluated to determine disposition. The attachment welds were fabricated to USA Standard (USAS) B31.1.0- 1967, and Paragraph 136.5.3(d) provides acceptance criteria for rounded indication to be less than 3/16". The ASME Section III Code, 2007 Edition with the 2008 Addenda, NB-5352(b)(2) establishes the acceptance criteria for rounded indication to be less than 3/16 ". Component 2/1/1506-16/M-1164D-296 (IWA)

Indications Two (2), Three (3), and Four (4) did not exceed the 3/16" acceptance criteria and were acceptable by examination in accordance with IWB-3132.1. An Engineering Evaluation was performed that determined that indications One (1) and Five (5), which were both 7/32" in diameter, were located on portions of the weld that were not required by design and had no impact on the ability of the support to provide its intended design function; h owever, in accordance with IWB -3132.2, Indications One (1) and Five (5) were corrected per an ASME Section XI Repair/Replacement Activity to meet the acceptance standards of ASME Section XI and original construction code (i.e., USAS B31.1.0). The origin of the indication was determined to be resulting from the fabrication process and not from a service induced degradation mechanism. No Attachment Response to NRC Request for Additional Information for 10 CFR 50.55a Request No. I5R-22 (Page 3 of 3)

additional examinations were performed in accordance with ASME Code Case N -586-1 since the identified indications were not service related.

In 2016, during Refuel Outage D3R24, a liquid penetrant (PT) examination was performed and detected two (2) rounded indications on component 3/1/RPV SHELL/M -

1211D-1 (IWA). This component is classified as ASME XI Class 1, Category B-K (i.e.,

Welded Attachments for Vessels, Piping, Pumps, and Valves), Item B10.10. The two (2) rounded indications were both smaller than 3/16" and met the acceptance standards of the ASME Code,Section III, 2007 Edition with the 2008 Addenda, NB-5352(b)(2).

RAI 2

Issue

The staff needs clarity on the recordable indications detected in component IDs "3/1/RPV SHELL/3-SC3C-VERT" and "3/1/RPV SHELL/3-SC4B-VERT" at DNPS Unit 3, as reported in Table B in the Attachment to the submittal.

Request

Clarify whether the indications detected in component IDs " 3/1/RPV SHELL/3-SC3C-VERT" and "3/1/RPV SHELL/3-SC4B-VERT" at DNPS Unit 3 are fabrication flaws and whether they were the same indications detected in the previous (fourth) ISI interval.

CEG Response to RAI 2 Request

The indications detected during UT examination of component ID 3/1/RPV SHELL/3-SC3C-VERT and 3/1/RPV SHELL/3-SC4B-VERT in D3R27 were embedded indications that were the same indications previously identified during the Fourth ISI Interval.