GNRO-2013/00043, Final Feedwater Temperature Reduction License Amendment Request - Responses to NRC Requests for Additional Information

Final Feedwater Temperature Reduction License Amendment Request - Responses to NRC Requests for Additional Information

ML13149A294
Person / Time
Site:	Grand Gulf
Issue date:	05/28/2013
From:	Ford B Entergy Operations
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
GNRO-2013/00043, TAC ME9873
Download: ML13149A294 (6)

Text

Entergy Operations, Inc.

1340 Echelon Parkway Jackson, MS 39213 Bryan S. Ford Senior Manager, Licensing Tel. (601) 368-5516 GNRO-2013/00043 May 28, 2013 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555

SUBJECT:

Final Feedwater Temperature Reduction License Amendment Request -

Responses to NRC Requests for Additional Information Grand Gulf Nuclear Station, Unit 1 Docket No. 50-416 License No. NPF-29

REFERENCES:

1. Entergy Operations, Inc. letter to the NRC, Final Feedwater Temperature Reduction License Amendment Request, October 26, 2012 (ADAMS Accession No. ML12306A519)

2. NRC e-mail to Entergy Operations, Inc., Grand Gulf Nuclear Station Request for Additional Information Regarding Final Feedwater Temperature Reduction (FFWTR) License Amendment Request (ME9873), March 28, 2013 (ADAMS Accession No. ML13087A574)

Dear Sir or Madam:

In Reference 1, Entergy Operations, Inc. (Entergy) submitted to the NRC a license amendment request (LAR) that would allow GGNS to operate with Final Feedwater Temperature Reduction (FFWTR) in effect. In Reference 2, the NRC transmitted to Entergy three (3) requests for additional information (RAIs) pertaining to the FFWTR LAR. Responses to these RAIs are provided in the attachment to this letter.

This letter contains no new commitments.

If you have any questions or require additional information, please contact Guy Davant at (601) 368-5756.

I declare under penalty of perjury that the foregoing is true and correct; executed on May 28, 2013.

Sincerely, BSF/ghd

GNRO- 2013/00043 Page 2 of 2

Attachment:

Responses to NRC Requests for Additional Information - GGNS Final Feedwater Temperature Reduction License Amendment Request cc: Mr. Arthur T. Howe Regional Administrator, Region IV U. S. Nuclear Regulatory Commission 612 East Lamar Blvd., Suite 400 Arlington, TX 76011-4005 U. S. Nuclear Regulatory Commission ATTN: Mr. A. B. Wang, NRR/DORL (w/2)

ATTN: ADDRESSEE ONLY ATTN: Courier Delivery Only Mail Stop OWFN/8 B1 11555 Rockville Pike Rockville, MD 20852-2378 NRC Senior Resident Inspector Grand Gulf Nuclear Station Port Gibson, MS 39150 State Health Officer Mississippi Department of Health P. O. Box 1700 Jackson, MS 39215-1700

ATTACHMENT GRAND GULF NUCLEAR STATION GNRO-2013/00043 RESPONSES TO NRC REQUESTS FOR ADDITIONAL INFORMATION -

GGNS FINAL FEEDWATER TEMPERATURE REDUCTION LICENSE AMENDMENT REQUEST

Attachment to GNRO-2013/00043 Page 1 of 3 RESPONSES TO NRC REQUESTS FOR ADDITIONAL INFORMATION -

GGNS FINAL FEEDWATER TEMPERATURE REDUCTION LICENSE AMENDMENT REQUEST In a letter to the NRC1, Entergy Operations, Inc. (Entergy) submitted a license amendment request (LAR) that would allow GGNS to operate with Final Feedwater Temperature Reduction (FFWTR) in effect. In an e-mail to Entergy2, the NRC staff transmitted three (3) requests for additional information (RAIs) pertaining to the FFWTR LAR. Responses to these RAIs are provided below.

RAI 1

In the first paragraph of Section 2.1 (page 9) of Attachment 2 (Reference 1) to the FFWTR LAR, it was stated that the effect of the 100°F Feedwater Heaters Out of Service (FWHOOS) condition on the Emergency Core Cooling System (ECCS) performance for the limiting break failure combination was previously evaluated for the GGNS Extended Power Uprate (EPU) using the NRC-approved SAFER/GESTR-LOCA methodology, and that the results of this evaluation are also applicable to a 100°F FFWTR.

Please provide the following additional information:

a) Clarify, whether the only difference between the analyses for 100°F FWHOOS and 100°F FFWTR cases are the core exposure levels assumed in the two cases, because FWHOOS event is expected to occur before End-of-Cycle (EOC) and FFWTR after EOC. And if so, b) Provide the core exposure levels assumed in the 100°F FWHOOS and the FFWTR analyses, and corresponding values for Maximum Average Planar Linear Heat Generation Rate (MAPLHGR) and peak clad temperature (PCT) for the two cases.

c) If the difference between the two cases involves more than just the core exposure level, then discuss those differences and their effects on the safety analysis results.

Response to 1.a) and 1.b)

A single analysis is performed to encompass both operational conditions of 100°F FWHOOS and FFWTR. The primary operational difference is the core average exposure for the conditions of 100°F FWHOOS for feedwater temperature reduction during the cycle up to EOC (defined as 100% power and maximum core flow with all control blades withdrawn) and operation with 100 F FFWTR after EOC.

1 Entergy Operations, Inc. letter to the NRC, Final Feedwater Temperature Reduction License Amendment Request, October 26, 2012 (ADAMS Accession No. ML12306A519) 2 NRC e-mail to Entergy Operations, Inc., Grand Gulf Nuclear Station Request for Additional Information Regarding Final Feedwater Temperature Reduction (FFWTR) License Amendment Request (ME9873), March 28, 2013 (ADAMS Accession No. ML13087A574)

Attachment to GNRO-2013/00043 Page 2 of 3 The 100°F FWHOOS and 100°F FFWTR use the same feedwater temperature reduction and were, thus, analyzed as one event at the same single limiting LOCA core exposure occurring near the knee exposure of the fuel-dependent linear heat generation rate (LHGR) curve.

FFWTR occurs at exposures well beyond the limiting LOCA core exposure. The PCT results of this 100°F feedwater temperature reduction analysis at the single limiting LOCA core exposure were provided in Table 2-2 of Reference 1 and correspond to 100°F FWHOOS since the single limiting LOCA core exposure is less than EOC core exposure. The impact of a small increase in core exposure after EOC associated with FFWTR results a decrease in PCT since the EOC core exposure is well beyond the single limiting LOCA core exposure. The LHGR and fuel stored energy are decreasing after the single limiting LOCA core exposure; any increase in core exposure due to FFWTR results in a decrease in PCT. Therefore, the feedwater temperature reduction analysis performed for the power and core flow points listed in Table 2-2 of Reference 1 corresponding to 100°F FWHOOS is applicable to 100°F FFWTR.

Response to 1.c)

As discussed above, the primary operational difference is the core exposure at which 100°F FWHOOS or 100°F FFWTR operation occurs. However, the LOCA analysis for these conditions is performed at the single limiting LOCA core exposure.

RAI 2

Provide the exposure-dependent MAPLHGR limit curve showing in the curve the higher exposure level that will be achieved for FFWTR operation and the exposure at which the limiting PCT (i.e., the current licensing-basis PCT of 1,690°F) occurs.

Response

The exposure-dependent MAPLHGR limit curve used in the analysis is listed in Table 1. The core exposure achieved with FFWTR operation is approximately 34,000 MWd/MTU. The core exposure used as the basis to determine the licensing basis PCT of 1690°F is the single limiting LOCA core exposure, which occurs near the beginning of the cycle.

Although higher core average exposures are possible with FFWTR, the LOCA results are driven by the peak bundle, which is conservatively assumed to be operating on the limit listed in Table 1 at the single limiting LOCA core exposure. The limits listed in Table 1 are developed on a bundle basis and extension of these limits is unnecessary with the implementation of FFWTR.

Attachment to GNRO-2013/00043 Page 3 of 3 Table 1: GNF2 Thermal Limits Exposure MAPLGHR Limit (MWd/MTU) (kW/ft) 0 13.78 19,309 13.78 67,000 7.50 70,000 6.69

RAI 3

In Section 6.1 of Attachment 2 (page 24) of the FFWTR LAR, it was stated:

Any effects of a slightly higher core exposure with FFWTR on the AOO performance is (sic) addressed as part of the cycle-specific reload analysis.

Clarify, for which operating cycles (the current cycle and/or the future cycles) the licensee is planning to operate with FFWTR. If it includes the current operating cycle, then provide the cycle-specific reload analysis report that should have been specifically performed for the current cycle with FFWTR, and discuss any effects of a slightly higher core exposure on the plant safety analyses, including thermal-hydraulic stability analysis.

Response

Entergy has no plans to operate GGNS with FFWTR during Cycle 19, the current operating cycle. FFWTR is under consideration for extending Cycle 20 operation, which is currently scheduled to conclude Spring 2016.

REFERENCE

1. Attachment 2 to Entergy letter GNRO-2012/00125: GEH Report NEDC-33671P, Safety Analysis Report for Operation with Final Feedwater Temperature Reduction at Grand Gulf Nuclear Station, Rev. 0, October 2012