ML032820247

Request for a License Amendment to Revise Psv Lift Settings - Byron/Braidwood Units 1 and 2

ML032820247
Person / Time
Site:	Byron, Braidwood
Issue date:	10/02/2003
From:	Mahesh Chawla NRC/NRR/DLPM/LPD3
To:	Bauer J Exelon Corp
Chawla M, NRR/.DLPM, 415-8371
References
Download: ML032820247 (2)

Text

From: Mahesh Chawla To: Joseph.bauer@exeloncorp.com Date: 10/2/03 2:03PM

Subject:

Request for a License Amendment to Revise the PSV Lift Settings -

Byron/Braidwood Units 1 and 2 With reference to your above referenced request, the NRC staff has following questions which they would like to discuss with Exelon. Please let me know your availability to have this conference call. If you have any questions, please call me at (301) 415-8371.

1. In support of the technical specification (TS) changes, reanalyses were performed for several cases to determine the DNBRs and pressurizer water levels. Discuss the methods and computers codes used in the reanalyses for each case and address acceptability of the use of the methods and computers for licensing applications. Also, identify for the reanalyzed events the values of input parameters that are different from that assumed in the analysis of record.

2. The use of PSV setpoints with inclusion of negative tolerances lowers effective PSV opening pressures, which would cause an earlier opening of the PSVs and a lower increase in the RCS pressure during overpressurization events. Lower RCS pressures result in lower departure from nucleate boiling ratios (DNBRs). As documented in the FSAR, the loss of reactor coolant and reactor coolant pump locked rotor are limiting DNBR cases. Discuss for both events whether the calculated DNBRs in the FSAR would be affected by a lower PSV opening pressure or not.

3. The information discussed on pages 11 and 12 of Reference 1 for a qualitative evaluation indicated that the spurious SI event would have similar results from the LOAC with the RCP seal injection event in terms of the change in the number of PSV water cycles and PSV discharge water temperature. The information is not sufficient for the staff to determine the accuracy of the results of the qualitative evaluation. Perform a quantitative analysis using the approved methods and provide the results to show the accuracy of the qualitative evaluation results.

4. Specify the pressure measurement uncertainties associated with the high pressure reactor trip and the PSV, and confirm that they are appropriately considered in the error analysis such that a reactor trip will occur prior to PSV actuation.

5. The information discussed on page 10 of Reference 1 for a loss of power to plant auxiliaries with RCP seal injection references an assessment by the Westinghouse Systems and Equipment Engineering Group that concluded that the PSVs will remain operable following a LOAC event with water relief through the PSVs. Please provide a copy of the Westinghouse assessment for review.

Reference 1: Attachment 1 to a letter from K. Ainger (EGC) to NRC, "Request for a License Amendment to Revise the Pressurizer Safety Valves Lift Settings, dated June 27, 2003.

CC: Kerri Kavanagh; Summer Sun; William Poertner Mail Envelope Properties (3F7C6880.AF3 : 15 : 21352)

Subject:

Request for a License Amendment to Revise the PSV Lift Settings -

Byron/Braidwood Units 1 and 2 Creation Date: 10/2/03 2:03PM From: Mahesh Chawla Created By: MLC@nrc.gov Recipients Action Date & Time owf2_po.OWFN_DO Delivered 10/02/03 02:03PM KAK CC (Kerri Kavanagh)

SBS CC (Summer Sun)

WKP CC (William Poertner) exeloncorp.com Transferred 10/02/03 02:03PM Joseph.bauer (Joseph.bauer@exeloncorp.com Post Office Delivered Route owf2_po.OWFN_DO 10/02/03 02:03PM exeloncorp.com Files Size Date & Time MESSAGE 3563 10/02/03 02:03PM Options Auto Delete: No Expiration Date: None Notify Recipients: Yes Priority: Standard Reply Requested: No Return Notification: None Concealed

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