ML14316A171

2014 Report of Changes and Errors to 10CFR50.46

ML14316A171
Person / Time
Site:	Grand Gulf
Issue date:	11/12/2014
From:	Nadeau J J Entergy Operations
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
GNRO-2014/00072
Download: ML14316A171 (3)

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GNRO-2014/00072 November 12,2014 U.S.Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Entergy Operations, Inc.P.O.Box 756 Port Gibson, MS 39150 James Nadeau Manager, Regulatory Assurance Grand Gulf Nuclear Station Tel.(601)437-2103

Dear Sir or Madam:

2014 Report of Changes and Errors to 10CFR50.46 Grand Gulf Nuclear Station, Unit 1 Docket No.50-416 License No.NPF-29 j 1.Letter GNRO-2013/00093,"2013 Report of Changes and Errors to 1 OCFR50.46," dated December 6, 2013.2.Letter CEXI-2014-00002,"Entergy Plant Letters 2014-02, 2014-03, and 2014-04," dated May 23,2014.In accordance with 10CFR50.46 (a)(3)(ii)

Grand Gulf Nuclear Station, Unit 1 (GGNS)is required.to report to the Commission, at least annually, the estimated effect on the limiting Emergency Core Cooling System (ECCS)analysis caused by changes to or errors discovered in the acceptable ECCS evaluation model.Since the last 10CFR50.46 report dated December 6, 2013[see reference 1], there have been four changes or errors discovered in theGGNS ECCS evaluation model[documented in reference 2].The changes or errors are as follows: 1.2014-01: Code maintenance items were completed, and sensitivity calculations have demonstrated that these several items individually and collectively have an insignificant effect on calculated Peak Cladding Temperature (PCT).2.2014-02: A logic error that indicates the expected system mass diverges from the calculated actual system mass when the plenum liquid mass and core spray flow rate are low has been corrected.

The correction to this error manifests as a small effect on PCT for most plants, and sensitivity calculations were completed to estimate the effects at GGNS.3.2014-03: The potentially non-conservative model minimum Llp was removed and an explicit Llp calculation was applied to the model.Sensitivitycalculationswere performed to arrive at the estimated PCT effect.4.2014-04: The iteration scheme for the Counter Current Flow Limitation (CCFL)has been fixed so that, consistently, the level head is applied whenever CCFL is calculated in that location.Sensitivity studies have shown these effects to be small.

GN RO-20 14/00072 Page 2 of 3 The table below summarizes the effects of all four changes or errors to the current GGNS ECCS analysis performed by General Electric-Hitachi Nuclear Energy (GEH)for the current reporting period.Evaluation Model: SAFERIGESTR-LOCA Estimated PCT Notification Nature Of Change Effect (I1PCT)GE14 GNF2 2014-01 Code Maintenance O°F O°F 2014-02 Logic error causing system mass divergence fromO°FO°F calculated actual system mass corrected 2014-03 An explicit calculation was applied to the model to-15°F-15°F replace the model imposed minimum 2014-04 The iteration scheme for the CCFL has been fixedO°FO°F Cumulative Sum of Absolute Magnitude of Errors During this Period.-15°F-15°F The GGNS core was comprised of GE14 and GNF2 fuel types prior to Refueling Outage 19 (RF19).The post RF19 GGNS core is comprised of only GNF2 fuel.The overall impact on the licensing basis PCT as a result of the changes or errors listed above is a decrease of 15°F.As such, the licensing basis PCT of the limiting GNF2 fuel type decreased from less than 1770°F (including the impact of changes and errors reported during previous reporting periods)to less than 1755°F, which remains well below the 2200°F acceptance criterion of 10CFR50.46.

This letter contains no new commitments.

Should you have any questions or require additional information, please contact James Nadeau at (601)437-2103.Sincerely, IN/tmc cc: (see next page)

GNRO-2014/00072 Page 3 of 3 , cc: u.s.Nuclear Regulatory Commission ATTN: Mr.A.Wang, NRR/DORL (w/2)Mail Stop OWFN 8 B1 Washington, DC 20555-0001 u.s.Nuclear Regulatory Commission ATTN: Mr.Marc Dapas (w/2)Regional Administrator, Region IV 1600 East Lamar Boulevard Arlington, TX 76011-4511 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