ML24327A007
| ML24327A007 | |
| Person / Time | |
|---|---|
| Site: | Watts Bar  |
| Issue date: | 11/21/2024 |
| From: | Kimberly Green Plant Licensing Branch II |
| To: | Hughes S Tennessee Valley Authority |
| References | |
| L-2024-LLA-0041 | |
| Download: ML24327A007 (3) | |
Text
From:
Kimberly Green Sent:
Thursday, November 21, 2024 10:15 AM To:
Hughes, Shawna Marie Cc:
Wells, Russell Douglas
Subject:
Additional RAI for Watts Bar MCR Chiller LAR (EPID L-2024-LLA-0041)
Dear Shawna Hughes:
After the call on November 19, the NRC staff added part c to RAI SCPB-2. See highlighted portion below.
RAI SCPB-2 The May 19, 2020, LAR indicated that the non-safety related chiller in conjunction with the existing CREATCS air handling units would be capable of providing adequate cooling to maintain the MCR conservatively below 80 °F. In its letter, dated May 5, 2021, the NRC approved this LAR as a one-time amendment that allowed the use of a temporary, non-safety related chiller to support MCR cooling during the replacement of the CREATCS chillers.
The current LAR describes plans to use a non-safety related chiller to provide backup cooling in the event both CREATCS trains become inoperable. Section 3.2 of the current LAR provides a description of the non-safety related chiller and refers to the May 19, 2020, LAR, the December 16, 2020, RAI response (ML20351A424), the May 5, 2021, safety evaluation, and the NRC regulatory audit summary (ML21012A084).
- a. Describe any differences between the temporary non-safety related chiller system from the previously reviewed configuration, and the proposed non-safety related chiller equipment and configuration to support the mitigating measures proposed in the current LAR.
- b. Confirm that the sizing of the non-safety related chiller and related heatup calculation referenced in the May 19, 2020, LAR are bounding for the proposed non-safety related chiller configuration referred to in the current LAR.
- c. The NRC staff notes that in TVA letter CNL-23-015, dated February 27, 2023 (ML23058A447), TVA identified several changes from the May 19, 2020, LAR (Table 2) and the NRC regulatory audit summary (Table 3), and what TVA has currently planned (as of February 27, 2023). One such change is going from a 2.5-inch diameter supply and return hose to either 3-, 4-, and 6-inch hoses. However, TVA did not include any information on potential flooding impacts and line breaks due to the larger size hoses.
Describe any potential impacts due to the change in hose sizes. Additionally, describe any changes to the control room envelope penetrations, piping connections, and locations due to the larger hose sizes or other reasons that differ from what have been previously described and included on the docket.
TVA may request a clarification, if needed; however, the NRC staff believes that the request is straightforward. Please let me know if a clarification call is needed.
Respectfully, Kimberly Green Senior Project Manager Division of Operating Reactor Licensing
U.S. Nuclear Regulatory Commission 301-415-1627
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2648 Mail Envelope Properties (MW4PR09MB9156F832E9BD27EF6F8D46E08F222)
Subject:
Additional RAI for Watts Bar MCR Chiller LAR (EPID L-2024-LLA-0041)
Sent Date:
11/21/2024 10:14:41 AM Received Date:
11/21/2024 10:14:00 AM From:
Kimberly Green Created By:
Kimberly.Green@nrc.gov Recipients:
"Wells, Russell Douglas" <rdwells0@tva.gov>
Tracking Status: None "Hughes, Shawna Marie" <smhughes@tva.gov>
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