ML24100A440
| ML24100A440 | |
| Person / Time | |
|---|---|
| Site: | Hatch  |
| Issue date: | 04/09/2024 |
| From: | Quarles A Southern Nuclear Operating Co |
| To: | Dawnmathews Kalathiveettil Plant Licensing Branch II |
| References | |
| L-2023-LLA-0169 | |
| Download: ML24100A440 (3) | |
Text
From:
Quarles, Adam Graham <AGQUARLE@southernco.com>
Sent:
Tuesday, April 9, 2024 11:28 AM To:
Dawnmathews Kalathiveettil Cc:
Joyce, Ryan M.; Michael Markley; John Lamb; Zach Turner
Subject:
[External_Sender] Re: RAI - Hatch, Units 1 and 2, 'Revise Technical Specifications to Adopt Extended RICTs for RHRSW and PSW Systems' LAR (EPID: L-2023-LLA-0169)
Thanks, Dawnmathews. RAI received - well respond within 30 days.
Get Outlook for iOS From: Dawnmathews Kalathiveettil <Dawnmathews.Kalathiveettil@nrc.gov>
Sent: Tuesday, April 9, 2024 10:24:52 AM To: Quarles, Adam Graham <AGQUARLE@southernco.com>
Cc: Joyce, Ryan M. <RMJOYCE@southernco.com>; Michael Markley <Michael.Markley@nrc.gov>; John Lamb <John.Lamb@nrc.gov>; Zach Turner <Zachary.Turner@nrc.gov>
Subject:
RAI - Hatch, Units 1 and 2, 'Revise Technical Specifications to Adopt Extended RICTs for RHRSW and PSW Systems' LAR (EPID: L-2023-LLA-0169)
- Adam, By letter dated December 6, 2023 (Agencywide Documents and Access Management System (ADAMS) Accession No. ML23340A223), Southern Nuclear Operating Company (SNC, the licensee) submitted a license amendment request (LAR) for Edwin I. Hatch Nuclear Plant (Hatch), Units 1 and 2. The proposed amendments would modify Technical Specification (TS) requirements to permit the use of Risk-Informed Completion Times (RICTs), not exceeding 45 days, for the condition of one pump inoperable for both TS 3.7.1, Residual Heat Removal Service Water (RHRSW) System, and for TS 3.7.2, Plant Service Water (PSW) System and Ultimate Heat Sink (UHS).
To complete its review, the NRC staff requests additional information (RAI) as shown below. On April 4, 2024, NRC staff provided SNC the draft RAI to ensure that it is understandable, the regulatory basis is clear, to ensure there is no proprietary information, and to determine if the information was docketed previously.
This request is now released formally with a 30-day calendar response period from the date of this e-mail. If you have any questions, you may contact me at 301-415-5905.
REQUEST FOR ADDITIONAL INFORMATION Title 10 of the Code of Federal Regulations (10 CFR) Part 50.36, Technical Specifications, specifies the content required to be included in TSs.
The methodology for implementing a RICT Program is described in Nuclear Energy Institute (NEI) Topical Report NEI 06-09, Risk-Informed Technical Specifications Initiative 4b, Risk-Managed Technical Specifications (RMTS) Guidelines, Revision 0-A (ADAMS Accession No. ML12286A322) (hereafter referred to as NEI 06-09-A). Adherence to NEI 06-09-A is required by the RICT Program as specified in Hatch TS 5.5.16. The RICT program also requires that risk management actions (RMAs) be considered and implemented in accordance with NEI 06-09-A.
RAI-01
NRC staff notes that the role of RMAs (also known as compensatory measures) in managing risk may be more important for extended completion times (CTs). As this is a first-of-a-kind request to extend the backstop for select CTs to 45 days, the NRC is requesting additional details with respect to RMA examples, particularly for cases where incremental conditional core damage probability / incremental conditional large early release probability (ICCDP/ICLERP)
thresholds could be exceeded if common cause failure (CCF) adjustment was accounted for in the RICT estimate.
Previous emergency LARs for one-time CT extensions for Hatch have provided more detailed discussion of compensatory measures. For examples, see (1) Enclosure 5 to the LAR supplement dated September 23, 2021 (ADAMS Accession No. ML21266A004), to support a CT extension to restore operability to Unit 1 PSW Pump C, and (2) the RAI response dated April 22, 2021 (ADAMS Accession No. ML21112A067), to support a CT extension to restore operability to Unit 2 Residual Heat Removal Pump 2D. The NRC staff recognize that the discussion of RMAs (or compensatory measures) may be more detailed in requests for one-time CT extensions because the planned configuration to restore specific equipment is known in advance. Furthermore, RG 1.174, Rev. 3 Section 2.6 further states, NRC management would give increased attention to the application if the calculated values of the changes in the risk metrics and their base values, when appropriate, approach the acceptance guidelines.
Please address the following:
a) Provide additional discussion as to what RMAs would be considered to help ensure mitigation of high-risk scenarios, such as maintaining containment venting capability (e.g., protecting equipment required for containment venting, briefings on hardened containment vent procedures). The NRC notes that use of the hardened containment vent system may be more risk significant for scenarios in which the normal means of suppression pool cooling is lost.
b) Provide additional details as to what RMAs may be considered for specific high-risk fire zones (e.g., limiting hot work or transient combustible permits) when either a PSW or RHRSW pump is out of service.
Best Regards, Dawnmathews T. Kalathiveettil Hatch Project Manager Plant Licensing Branch (LPL 2-1)
DORL - O9 E07 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:
2460 Mail Envelope Properties (MWHPR04MB08798D7E0B1AE517F400AD3FAD072)
Subject:
[External_Sender] Re RAI - Hatch, Units 1 and 2, 'Revise Technical Specifications to Adopt Extended RICTs for RHRSW and PSW Systems' LAR (EPID L-2023-LLA-0169)
Sent Date:
4/9/2024 11:28:17 AM Received Date:
4/9/2024 11:28:32 AM From:
Quarles, Adam Graham Created By:
AGQUARLE@southernco.com Recipients:
"Joyce, Ryan M." <RMJOYCE@southernco.com>
Tracking Status: None "Michael Markley" <Michael.Markley@nrc.gov>
Tracking Status: None "John Lamb" <John.Lamb@nrc.gov>
Tracking Status: None "Zach Turner" <Zachary.Turner@nrc.gov>
Tracking Status: None "Dawnmathews Kalathiveettil" <Dawnmathews.Kalathiveettil@nrc.gov>
Tracking Status: None Post Office:
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