ML25175A182

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NRR E-mail Capture - Regarding the Farley Pre-submittal Meeting on RCS Subcooling Margin Monitor
ML25175A182
Person / Time
Site: Farley  
(NPF-2, NPF-8)
Issue date: 06/24/2025
From: Markley M
Plant Licensing Branch II
To: Joyce R
Southern Nuclear Operating Co
References
Download: ML25175A182 (11)
v • d • e


Text

From:

Michael Markley Sent:

Tuesday, June 24, 2025 7:56 AM To:

Joyce, Ryan M.

Cc:

Jamie Pelton; Coleman, Jamie Marquess; Zach Turner; John Lamb

Subject:

Regarding the Farley Pre-submittal Meeting on RCS Subcooling Margin Monitor Attachments:

Pre-Submittal Meeting for PAM-SMM-LAR.pdf

Ryan, We probably need to schedule pre-submittal meetings further in advance of the planned submittal if these meeting are to provide the intended sharing of issue likely to come up during the review. This meeting (6/23) was held only one week before the planned submittal (6/30), there is probably not much value that can be added from the NRC discussions/questions that could be incorporated meaningfully in the submittal. The attached slides for this meeting are at a high level and, at one point, you asked what the regulatory basis is for NRC questions if the RCS Subcooling Monitor is not required by 10 CFR 50.36.

NRC needs to understand the submittal and how it fits into the plant design and licensing basis. While SNC is making a case that this TS item can be removed because it is not required per 10 CFR 50.36, the NRC had questions related to defense in depth and how surveillance will be accomplished if the RCS Subcooling Margin Monitor is removed from the TS and relocated in the UFSAR. From my view, there are other regulatory requirements (e.g., GDC) and commitments (e.g., NUREG-0737 TMI Actions) that are part of the licensing basis. In my early NRC career, I recall doing inspections of the TMI Action closure, of which, RCS sampling and subcooling were included.

These are my post-meeting thoughts on how NRC and SNC can both do things better in scheduling. One week in advance of planned submittal is inadequate for a meaningful pre-submittal meeting.

Michael T. Markley, Chief Plant Licensing Branch II-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation 301-415-5723 michael.markley@nrc.gov

Hearing Identifier:

NRR_DRMA Email Number:

2775 Mail Envelope Properties (DM8PR09MB6680BBEF5BCF8421CE41093CF978A)

Subject:

Regarding the Farley Pre-submittal Meeting on RCS Subcooling Margin Monitor Sent Date:

6/24/2025 7:56:17 AM Received Date:

6/24/2025 7:56:22 AM From:

Michael Markley Created By:

Michael.Markley@nrc.gov Recipients:

"Jamie Pelton" <Jamie.Heisserer@nrc.gov>

Tracking Status: None "Coleman, Jamie Marquess" <jamiemco@southernco.com>

Tracking Status: None "Zach Turner" <Zachary.Turner@nrc.gov>

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

Tracking Status: None "Joyce, Ryan M." <rmjoyce@southernco.com>

Tracking Status: None Post Office:

DM8PR09MB6680.namprd09.prod.outlook.com Files Size Date & Time MESSAGE 1705 6/24/2025 7:56:22 AM Pre-Submittal Meeting for PAM-SMM-LAR.pdf 165153 Options Priority:

Normal Return Notification:

No Reply Requested:

No Sensitivity:

Normal Expiration Date:

Proposed Farley Nuclear Plant Units 1 & 2 License Amendment Request License Amendment Request Proposing Removal of RCS Subcooling Margin Monitor from Technical Specifications List of Post Accident Monitoring Instrumentation Presubmittal Meeting: June 23, 2025

Agenda Description

Background

Technical Evaluation Regulatory Evaluation Discussion

Remove RCS SMM Function #10 from PAM TS Table 3.3.3-1 DESCRIPTION

  • The proposed amendment would revise Technical Specifications (TS) Table 3.3.3-1, Post Accident Monitoring Instrumentation to delete Function 10, RCS Subcooling Margin Monitor.
  • The RCS Subcooling Margin Monitor indication will be retained in Farley UFSAR Table 7.5-1 (Sheet 3 of 16) as a Type B, Category 2 variable.

3

Remove RCS SMM Function #10 from PAM TS Table 3.3.3-1 BACKGROUND

  • The purpose of PAM instrumentation is to function in a post accident environment to provide indications necessary for operators to take manual actions to mitigate the consequences of an accident.
  • The RCS subcooling indication provides information to indicate whether the core cooling safety function is being accomplished.
  • The inputs to the RCS Subcooling Margin Monitor (SMM) are RCS hot leg and cold leg temperatures from loop RTDs, CET temperature, RCS wide range pressure, and pressurizer pressure. Since these indications are independently displayed in the control room, the RCS subcooling margin monitor provides redundant calculation and display functions as a backup of these input indications.

4

Remove RCS SMM Function #10 from PAM TS Table 3.3.3-1 TECHNICAL EVALUATION

  • The RCS subcooling indication provides information to indicate whether the core cooling safety function is being accomplished. Therefore, for the purpose of determining the content of Technical Specification 3.3.3, "Post Accident Monitoring (PAM) Instrumentation," this variable is considered a Type B variable.

5

Remove RCS SMM Function #10 from PAM TS Table 3.3.3-1 TECHNICAL EVALUATION (cont.)

  • The SMM is not relied upon to support any PRA-modeled system to mitigate core damage or large early release, the SMM has no contribution to the total CDF and LERF.

6

Remove RCS SMM Function #10 from PAM TS Table 3.3.3-1 REGULATORY EVALUATION

  • The evaluations performed in accordance with WCAP-15981-NP-A also support the conclusions that the affected instrumentation does not meet 10 CFR 50.36 (c)(2)(ii) Criterion 3 (i.e., it was not found to be a Type A instrument) or Criterion 4 (i.e., it was not found to be significant to risk).
  • 10 CFR 50.49 specifies design and performance requirements for safety-related instrumentation exposed to adverse environments during accident conditions. The proposed change does not impact the requirements of 10 CFR 50.49.

7

Remove RCS SMM Function #10 from PAM TS Table 3.3.3-1 Remaining Actions and Schedule

  • Submit LAR to NRC 6/30/2025

Remove RCS SMM Function #10 from PAM TS Table 3.3.3-1 Discussion / Feedback 9

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