IR 05000413/1999003

Discusses Insp Repts 50-413/99-03 & 50-414/99-03 Completed on 990605 & Transmitted by Ltr .Results of Delibrations for Violation Re Discovery of Potentially More Limiting Single Failure Affecting SGTS Analysis Provided

ML20209E323
Person / Time
Site:	Catawba
Issue date:	07/01/1999
From:	Reyes L NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
To:	Gordon Peterson DUKE POWER CO.
References
50-413-99-03, 50-413-99-3, 50-414-99-03, 50-414-99-3, EA-99-132, NUDOCS 9907140203
Download: ML20209E323 (4)

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t July 1,1999 EA 99-132 l

Duke Energy Corporation )

ATTN: Mr. G. j Site Vice President Catawba Nuclear Station 4800 Concord Road York, SC 29745 l

SUBJECT: EXERCISE OF ENFORCEMENT DISCRETION l (NRC INSPECTION REPORT 50-413/99-03,50-414/99-03)  ;

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Dear Mr. Peterson:

l On June 5,1999, the Nuclear Regulatory Commission (NRC) completed an inspection at Duke I Energy Corporation's (DEC) Catawba Nuclear Station. The results of the inspection were discussed with your staff at an exit conducted on June 15,1999, and were formally transmitted l to you by letter date July 1,1999. This letter provides you with the results of our deliberations regarding a violation documented in this inspection report.

During the inspection, the NRC examined the details of the DEC's discovery of a potentially '

more limiting single failure than previously analyzed, affecting the steam generator tube rupture (SGTR) analysis. Specifically, Licensee Event Report (LER) 50-413/97-01, dated March 12,1997, described that a single failure of a 125 Volt Direct Current (VDC) vital instrumentation and control (l&C) distribution panel would result in the loss of control power to two steam generator power operated relief valves (PORV). The SGTR accident analysis assumed the use of two PORVs for rapid depressurization and cool down during a postulated SGTR accident. Because Technical Specification (TS) 3.7.1.6 required three of four PORVs to be operable per unit in Mode 1, a condition could exist in which a single failure of the l&C distribution panel could result in the availability of only one PORV to cool down and depressurize the plant, which is outside the current analyzed conditions of the Updated Final Safety Analysis Report (UFSAR). Likewise, LER 50-413/97-09-01, dated January 19,1998, identified that this single failure would not only result in the loss of control power to two steam generator PORVs, but would also result in the inability to remotely isolate auxiliary feedwater flow to two steam generators. The inability to isolate auxiliary feedwater flow could result in a steam generator overfill condition, absent operator manual action, and is also more limiting than previously analyzed in the UFSAR. Although the Catawba units were operated at times in the past with three of four PORVs operable in accordance with TS, neither a failure of the 125 VDC I&C distribution panel nor a SGTR event actually occurred. DEC identified that the root cause of these two deficiencies was a less than adequate single failure analysis when implementing the generic Westinghouse SGTR analysis methodology in 1987.

I 9907140203 PDR 990701

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" ADOCK 05000413 PDR

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Duke Energy Corporation 3 In accordince with 10 CFR 2.790 of the NRC's " Rules of Practice," a copy of this letter will be i placed in the NRC Public Document Room.

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Sincerely, Original Signed by Luis A. Reyes  :

Luis A. Reyes Regional Administrator Docket Nos.: 50-413 and 50-414 License Nos.: NPF-35 and NPF-52 cc: see Page 4

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Duke Energy Corporation 4 i

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Distribution-WTravers, EDO FMiraglia, DEDR MKnapp, DEDE 4 DDambly, OGC l

EJulian, SECY l BKeeling, CA Enforcement Coordinators Rl, Rlli, RIV JLieberman, OE GCaputo, Ol WBeecher, OPA HBell, OlG CEvans, Ril ABoland, Ril f

MSatorius, OEDO LPlisco, Ril BMallett, Ril COgle, Rll

. ABoland, Ril SSparks, Ril HBerkow, NRR PTam, NRR DNelson, OE RCarroll, Ril OE:EA File (BSummers, OE)(2 letterhead)

PUBLIC NRC Resident inspector U.S. Nuclear Regulatory Commission 4830 Concord Road York, SC 29745 SEND TO PUBLIC DOCUMENT R00M7 YES OFFICE RII:EICS RII:D4P A RII:DRS RII:0RA

Signature NAME ABOLAND LP SO BMALLETT JJOHNSON DATE /' /99 h / 7 /99 / /97 / /99 / /99 / /99-COPY? YES No YES M YES NO YES No YES NO YES NO OFFICIAL RECORD COPY DOCUME Y NAME:M:\ ENFORCE \99 CASES \99132 CAT.DIR\CATSGTR.WPD

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Duke Energy Corporation 5 )

i Distribution: )

WTravers, EDO )

FMiraglia, DEDR '

MKnapp, DEDE DDambly, OGC EJulian, SECY

- BKeeling, CA 4 Enforcement Coordinators RI, Rlli, RIV

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JLieberman, OE J GCaputo, Ol WBeecher, OPA HBell, OlG CEvans, Rll ABoland, Ril MSatorius, OEDO LPlisco, Ril BMallett, Ril COgle, Rll l

- ABoland, Ril l SSparks, Rll HBerkow, NRR PTam, NRR {

DNelson, OE RCarroll, Ril OE:EA File (BSummers, OE)(2 letterhead)

PUBLIC

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NRC Resident Inspector U.S. Nuclear Regulatory Commission 4830 Concord Road York, SC 29745 )

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SEND TO PUBLIC DOCUMENT R00M7 YES / j OFFICE .At1JLEs RII:DRP RI!:DRS Rll:QBA / / l Signat d $ pf [f8 NAME ' AB0 RAND LPLISCO BMALWTT k '

DATE d Lt /99 / /99 / 2 99 W ' /99 [#/ 8 [ /99 / /99

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