ML23318A525
| ML23318A525 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 11/09/2023 |
| From: | Thomas Wengert NRC/NRR/DORL/LPL4 |
| To: | Dewhirst L Nebraska Public Power District (NPPD) |
| Wengert T | |
| References | |
| L-2023-LLR-0035 | |
| Download: ML23318A525 (5) | |
Text
From:
Thomas Wengert Sent:
Thursday, November 9, 2023 3:27 PM To:
Dewhirst, Linda R.
Cc:
Unruh, Mark E.; Van Der Kamp, David W.; Jennifer Dixon-Herrity; Thomas Byrd
Subject:
Cooper Nuclear Station - Relief Request RC3-02 Audit Agenda and Questions (EPID L-2023-LLR-0035)
Attachments:
RC3-02 Relief Request Audit Agenda and Questions 11-9-23.pdf By letter dated June 27, 2023 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML23178A273), Nebraska Public Power District (the licensee) submitted a relief request for Cooper Nuclear Station (Cooper), seeking relief from certain containment inservice inspection (ISI) requirements concerning drywell head bolting in accordance with Title 10 of the Code of Federal Regulations (10 CFR) section 50.55a(g)(5)(iii).
The relief request pertains to the visual inspection requirements of the American Society of Mechanical Engineers (ASME) Code Rules for ISI of Nuclear Power Plant components.
On September 5, 2023 (ML23233A188), the U.S. Nuclear Regulatory Commission (NRC) staff issued an audit plan that conveyed the intent to conduct a regulatory audit to support its review of the subject relief request. In the audit plan, the NRC staff requested an electronic portal setup and provided a list of documents to be added to the portal.
The NRC staff has performed an initial review of these documents and developed a list of audit questions, as shown in the enclosure. Please post the response(s) for the questions to the online portal as the response is completed (but no later than one week before the date of the audit). The date of the audit call is set for November 27, 2023, and will be conducted via MS Teams teleconference call. The proposed agenda for the audit discussions is also contained in the enclosure.
Please contact me at any time prior if a clarification discussion is needed. We look forward to discussing these questions and Coopers responses during the virtual audit meeting. If you have any questions, please contact me at 301-415-4037 or by e-mail to Thomas.Wengert@nrc.gov.
Tom Wengert Project Manager - Cooper Nuclear Station NRR/DORL/LPL4 (301) 415-4037
Hearing Identifier:
NRR_DRMA Email Number:
2310 Mail Envelope Properties (PH0PR09MB74033F8382FC634789F309118FAFA)
Subject:
Cooper Nuclear Station - Relief Request RC3-02 Audit Agenda and Questions (EPID L-2023-LLR-0035)
Sent Date:
11/9/2023 3:27:17 PM Received Date:
11/9/2023 3:27:00 PM From:
Thomas Wengert Created By:
Thomas.Wengert@nrc.gov Recipients:
"Unruh, Mark E." <m1unruh@nppd.com>
Tracking Status: None "Van Der Kamp, David W." <dwvande@nppd.com>
Tracking Status: None "Jennifer Dixon-Herrity" <Jennifer.Dixon-Herrity@nrc.gov>
Tracking Status: None "Thomas Byrd" <Thomas.Byrd@nrc.gov>
Tracking Status: None "Dewhirst, Linda R." <lrdewhi@nppd.com>
Tracking Status: None Post Office:
PH0PR09MB7403.namprd09.prod.outlook.com Files Size Date & Time MESSAGE 1862 11/9/2023 3:27:00 PM RC3-02 Relief Request Audit Agenda and Questions 11-9-23.pdf 152843 Options Priority:
Normal Return Notification:
No Reply Requested:
No Sensitivity:
Normal Expiration Date:
AUDIT AGENDA CONTAINMENT DRYWELL HEAD BOLTING - INSERVICE INSPECTION IMPRACTICALITY PROPOSED ALTERNATIVE IN ACCORDANCE WITH 10 CFR 50.55a(g)(5)(iii)
COOPER NUCLEAR STATION DOCKET NO. 50-298 November 27, 2023 - 1:30 - 4:00 pm ET (12:30 - 3:00 pm CT)
Start of Meeting 1:30 pm ET (12:30 pm CT) o Opening Comments:
NRC Project Manager (Thomas Byrd)
DORL Branch Chief (Jennifer Dixon-Herrity) o Opening Comments by Cooper Managers o Introduction of Audit Participants (NRC Staff, and Cooper) o Introduction of topics and questions to be discussed o Questions related to audit plan and logistics Discussion of NVIB questions - John Tsao and David Dijamco Discussion of ESEB questions - George Wang Acronyms:
DORL NRR Division of Operating Reactor Licensing NVIB NRC/NRR Vessels and Internals Branch ESEB NRC/NRR Structural, Civil, Geotechnical Engineering Branch NRC U.S. Nuclear Regulatory Commission NRR Office of Nuclear Reactor Regulation
AUDIT QUESTIONS CONTAINMENT DRYWELL HEAD BOLTING - INSERVICE INSPECTION IMPRACTICALITY PROPOSED ALTERNATIVE IN ACCORDANCE WITH 10 CFR 50.55a(g)(5)(iii)
COOPER NUCLEAR STATION DOCKET NO. 50-298 By letter dated June 27, 2023 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML23178A273), Nebraska Public Power District (the licensee) submitted a relief request for Cooper Nuclear Station (Cooper), seeking relief from certain containment inservice inspection (CISI) requirements concerning drywell head bolting in accordance with Title 10 of the Code of Federal Regulations (10 CFR) section 50.55a(g)(5)(iii).
The relief request pertains to the visual inspection requirements of the American Society of Mechanical Engineers (ASME) Code Rules for ISI of Nuclear Power Plant components.
The NRC staff determined that the following information is needed to complete its review.
Vessels and Internals Branch (NVIB)
- 1. In the licensees audit portal response, the 60 pounds per square inch (psig) pressure utilized during the Local Leak Rate Test and the hold time for this pressure are not mentioned. The NRC staff would like to discuss stress calculations or qualitative analysis of the containment drywell head bolts, pertaining to the 60 psig pressurization and the length of time the 60 psig test pressure is held to determine leakage, to demonstrate that structural integrity and leak tightness of the drywell is maintained assuming the bolts that could not be examined have failed their intended function and could not be tightened.
- 2. In the audit portal response, the licensee states that the drywell head flange has two O-rings that are evaluated during the pressure test. The NRC staff would like to discuss analyses, tests, or examinations demonstrating leak tightness of the O-rings, assuming that the bolts that could not be examined have failed and could not be tightened.
- 3. Discuss analyses, tests or examinations demonstrating that structural integrity and leak tightness of the drywell containment is maintained with the existing bolting condition.
- 4. Discuss how the six lower spherical washers and 33 nuts that were able to be removed and examined by VT-1 represent a reasonable sample that would detect degradation in these components if degradation occurred. Are there any asymmetric load conditions with respect to azimuthal bolting location that could cause certain bolting locations to be at higher stress conditions? Are there any unique environmental conditions around the drywell closure circumference in the subject bolting regions that could cause general corrosion of the nuts and lower spherical washers?
Structural, Civil, and Geotechnical Engineering Branch (ESEB)
- 1. Discuss the best effort remote visual examination on the nuts and washers that are tack welded in place and provide its procedure.
- 2. Light to heavy rust, flaking, blistering, and peeling with some signs of under-deposit corrosion are observed on many photos in the ePortal (such as files: DW8F27~1.pdf, DW66CF~1.pdf, DWA4E7~1.pdf, WT-202~1.pdf, et al.). Evaluate whether these conditions will result in loose nuts or bolts that may affect the intended function of the pressure retaining bolting.
- 3. Provide VT-3 bolting examination results, pictures, and reports for the previous (i.e., second) ten-year CISI interval and discuss any nonconformances and resolutions.