ML22305A703

NRR E-mail Capture - Potential Audit for Hatch'S 'Rpv Head Studs' LAR

ML22305A703
Person / Time
Site:	Hatch
Issue date:	11/01/2022
From:	Dawnmathews Kalathiveettil Plant Licensing Branch II
To:	Quarles A Southern Nuclear Operating Co
References
L-2022-LLA-0120
Download: ML22305A703 (3)

Text

From: Dawnmathews Kalathiveettil Sent: Tuesday, November 1, 2022 3:28 PM To: Quarles, Adam Graham Cc: Chamberlain, Amy Christine; Michael Markley; John Lamb

Subject:

Potential Audit for Hatch's 'RPV Head Studs' LAR Importance: High Good afternoon Adam, I just wanted to give you a heads-up that the NRC staff has identified the need for a potential regulatory audit pertaining to Hatch's RPV Head Studs LAR. NRC staff would like to review the FEA runs for Load Cases A1 and A2 provided in Dominion Engineerings (DEI) calculations.

A list of potential items that NRC staff plans to review can be seen below. This list is not final and is only provided for planning purposes.

• Boundary conditions applied to the models for both Load Cases

• Stress and displacement results for both cases

• Simulation of the load transfer between head and vessel flanges

• Other aspects that will help the NRC staff understand the reason for the decrease in stud stress. For example, Section 5.2.3 in each of the two DEI calculations states that Load Case A2 represents the operating conditions with the vessel at design pressure and with intact studs. Operating conditions implies that Load Case A2 is at operating temperature and therefore includes some thermal stress. The NRC staff would like to review Load Case A2 minus the thermal stress to understand the thermal contribution.

Section 5.2.3 in each of the two DEI calculations in the enclosures describes Cases C1 and C2, which are for studs failing in service. Thus, the NRC staff will review the following aspects of the FEA run for Case C1 (and/or C2):

• The starting load state when all studs are preloaded with the specified initial strain

• The corresponding end load state when one (or two) studs are assumed to fail in service Staff hopes to have an in-person Audit at the DEI office location in Reston, Virginia (please inform if location is different). We expect the in-person Audit meetings to take about 2-3 days.

Depending on the information available/reviewed at DEIs office location, the Audit timeline could be extended to accommodate any follow-up questions/reviews that NRC staff may have.

Please provide earliest potential dates when such an Audit can be supported by both SNC and DEI. I am currently in the process of drafting the Audit Plan and Audit Agenda and will provide these as they become available.

Best Regards, Dawnmathews T. Kalathiveettil Project Manager Plant Licensing Branch (LPL 2-1)

DORL - O8 C02 Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Office Phone: 301-415-5905 Email: Dawnmathews.Kalathiveettil@nrc.gov

Hearing Identifier: NRR_DRMA Email Number: 1821 Mail Envelope Properties (BY5PR09MB56669A7468CCB7B5EAD04BBD97369)

Subject:

Potential Audit for Hatch's 'RPV Head Studs' LAR Sent Date: 11/1/2022 3:28:00 PM Received Date: 11/1/2022 3:27:00 PM From: Dawnmathews Kalathiveettil Created By: Dawnmathews.Kalathiveettil@nrc.gov Recipients:

"Chamberlain, Amy Christine" <ACCHAMBE@southernco.com>

Tracking Status: None "Michael Markley" <Michael.Markley@nrc.gov>

Tracking Status: None "John Lamb" <John.Lamb@nrc.gov>

Tracking Status: None "Quarles, Adam Graham" <AGQUARLE@southernco.com>

Tracking Status: None Post Office: BY5PR09MB5666.namprd09.prod.outlook.com Files Size Date & Time MESSAGE 2490 11/1/2022 3:27:00 PM Options Priority: High Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date: