ML19337B673

COL Docs - Vogtle LAR 19-018 Discussion

ML19337B673
Person / Time
Site:	Vogtle
Issue date:	12/03/2019
From:	NRC
To:	NRC/NRR/DNRL
References
Download: ML19337B673 (3)

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From: Rankin, Jennivine Sent: Tuesday, December 3, 2019 10:30 AM To: Kellenberger, Nicholas Cc: Vogtle PEmails

Subject:

RE: Vogtle LAR 19-018 discussion Good morning Nick -

The staff has had additional internal discussions and have narrowed our question to the following. We would like to discuss this at the public meeting on Thursday.

The NRC staff cannot confirm from the license amendment application that changing the location for measuring the wetted perimeter verifies the area wetted by the PCS water flow correlates with the wetted surface area assumed in the analysis. The NRC staff needs to evaluate measuring the percentage wetted perimeter at a different location does not change the surface area wetted by the PCS water flow. If the analysis assumes a significantly larger wetted surface area within that at proposed test location (between the test location and the application of PCS flow), it does not appear testing at a location closer to the top of the pressure containment will forecast similar wetted perimeter at the spring (or tangent) line. Surface imperfections such as welds or slightly different curve in a plate could cause channeling or redirection of the surface flow after the wetted perimeter is measured at the proposed location.

If the wetted surface is significantly less than that assumed in the analysis, than the method of evaluation described in the FSAR (as updated) used in establishing the design basis or in the safety analysis (WCAP-15846 revision 5) may not be valid.

Thanks, Jennie From: Rankin, Jennivine Sent: Wednesday, November 27, 2019 7:02 AM To: Kellenberger, Nicholas <X2NRKELL@SOUTHERNCO.COM>

Subject:

Vogtle LAR 19-018 discussion Good morning Nick -

During the review of LAR 19-018 regarding the Passive Containment Cooling System Wetted Perimeter Test modification, the NRC staff had the following question they would like to discuss.

Would it be possible to discuss it at the December 5, public meeting? Please let me know if SNC can support a discussion then. We could start it at 9 am.

The LAR proposes changes to the location where the wetted perimeter percentage is measured. The original measurement was to be at the interface between the dome and the cylindrical portion of the structure which is at 244 ft elevation. The change measures the percentage of wetted perimeter between the spring line (244 ft elevation) and 266 ft elevation.

Measuring the percentage wetted perimeter at a different location appears to change the surface area wetted by the PCS water flow. The change in wetted surface area could change the evaporation rate assumed for heat energy removal from containment. This appears to result

in a departure from a method of evaluation described in the FSAR (as updated) used in establishing the design basis or in the safety analysis (WCAP-15846 revision 5).

The LAR technical evaluation discusses percent coverage as equivalent to flow rate. There is no discussion how the change in wetted surface area affects the heat transfer rate assumed in the design basis analysis. Can SNC explain if the assumptions and methodology in the WGOTHIC analysis are affected by this change as it pertains to heat transfer rate?

Thanks, Jennie Jennie Rankin, Project Manager Vogtle Project Office Office of Nuclear Reactor Regulation

Hearing Identifier: Vogtle_COL_Docs_Public Email Number: 506 Mail Envelope Properties (BN6PR09MB129873F25FB25231763F8B2398420)

Subject:

RE: Vogtle LAR 19-018 discussion Sent Date: 12/3/2019 10:30:22 AM Received Date: 12/3/2019 10:30:24 AM From: Rankin, Jennivine Created By: Jennivine.Rankin@nrc.gov Recipients:

"Vogtle PEmails" <Vogtle.PEmails@nrc.gov>

Tracking Status: None "Kellenberger, Nicholas" <X2NRKELL@SOUTHERNCO.COM>

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