RS-24-063, Response to Request for Additional Information for 10 CFR 50.55a Request No. I5R-22
| ML24166A103 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 06/14/2024 |
| From: | Humphrey M Constellation Energy Generation |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| RS-24-063 | |
| Download: ML24166A103 (1) | |
Text
4300 Winfield Road Warrenville, IL 60555 630 657 2000 Office RS-24-063 10 CFR 50.55a June 14, 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 June 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 June 14, 2024 Page 2 Should you have any questions concerning this letter, please contact Ms. Erin Whitsell at (779) 231-8262.
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
- Humphrey, Mark D.
Digitally signed by Humphrey, Mark D.
Date: 2024.06.14 10:00:28
-05'00'
Attachment Response to NRC Request for Additional Information for 10 CFR 50.55a Request No. I5R-22 (Page 1 of 2)
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 following request 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. 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 2)
NVIB RAI Issue For isolation condenser weld 3/2/1302A-12/12-8 in DNPS Unit 3, the licensee stated two subsurface flaws exceeded the allowable flaw size (Table B of the attachment to the submittal). The licensee did not state the acceptance standards for allowable flaw size that were exceeded and how the two subject subsurface flaws were evaluated and dispositioned.
Request Clarify (a) the acceptance standards for allowable flaw size that the two subject subsurface flaws exceeded; and (b) how the two subject subsurface flaws were evaluated and dispositioned.
Constellation Energy Generation, LLC (CEG) Response to NVIB RAI Request:
In 2018, during Refuel Outage D3R25, an ultrasonic (UT) examination was performed on component 3/2/1302A-12/12-8. Two recordable indications were observed. This component is classified as ASME XI, Class 2, and the examinations were performed in accordance with Table IWC-2500-1, Examination Category C-B (i.e., Pressure Retaining Nozzle Welds in Vessels), Item C2.21. The acceptance standards of the ASME Code,Section XI, IWC-3511 are applicable for these examinations. ASME Section XI, IWC-3511.1(a) requires that The size of allowable planar flaws in the nozzle and weld areas within the boundary of the examination volume specified in Fig. IWC-2500-4 shall not exceed the limits specified in Table IWC-3511-1, for ferritic steels. Indication One (1) and Two (2) exceeded the acceptance criteria established in Table IWC-3511-1, for ferritic steels. The examination results were compared with previously recorded in-service examination results in accordance with IWC-3121(a). An analytical evaluation was performed in accordance with IWC-3600, using the provisions of IWB-3610, and determined that both indications were acceptable and would remain acceptable for the service life of the component. Having satisfied the requirements of IWB-3610, the component containing these flaws was accepted by analytical evaluation in accordance with IWC-3122.3. The origin of the indications was determined to be resulting from the fabrication process during original construction and not from a service induced degradation mechanism. In comparison to previously recorded results, the indications have not changed in size, however, minor differences in measured parameters are based on variations attributed to the examiners performing the exams, equipment uncertainty, and procedural changes. The criteria in ASME Code Case N-586-1 were met, and no additional examinations were required because it was concluded that the identified indications were not service related and that no degradation mechanism exists.
The criteria in Code Case N-526 were met, and successive examinations required by IWC-2420(b) were not required because the flaws were determined to be acceptable for the remaining service life of the component.