ML20010E811

Forwards LER 81-124/03L-0.Detailed Event Analysis Encl

ML20010E811
Person / Time
Site:	McGuire
Issue date:	08/24/1981
From:	Parker W DUKE POWER CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20010E812	List: ML20010E811 ML20010E814
References
NUDOCS 8109080280
Download: ML20010E811 (2)

Text

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DUKE PdWER COMPANY -

Powen Ilcu.nixo 422 Sourn Cut:ncis SrnesT, CHAHLOTTE, N. C. ana.sa

• I,I 4 WILLIAM O. PA R K E R, , R.

Vice PRE 5iDFNT YE L{ PMo% t:Anta 704 src. e wuc%.. 7 -'

• August 24, 1981 Mr. James P. O'Reilly, Director _

U. S. Nuclear Regulatory Commission @r I fg/

Region II 101 Marietta Street, Suite 3100 'g%

Atlanta, Georgia 30303 (h@]f1\ { {i

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Re: McGuire Nuclear Station Unit 1 \ "g.aon"#

Docket No. 50-369 '\

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Dear Mr. O'Reilly:

J- [\ p Please find attached Reportable Occurrence Report R0-369/81-124. This report concerns 1.S. 3.6.3, "The containment isolation valves specified in Table 3.6-2 shall be operable with isolation times as shown in Table 3.6-2." This incident was considered to be of no significance with respect to the health and safety of the public.

VerytrulyyYrs,

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! William O. Parker, Jr.

PBN/php Attachment cc: Director Mr. Bill Lavallee Office of Management and Program Analysis Nuclear Safety Analysis Center U. S. Nuclear Regulatory Commission P. O. Box 10412 Washington, D. C. 20555 Palo Alto, California 94303 Ms. M. J. Graham Resident Inspector-NRC h McGuire Nuclear Station S

//

8109080280 810824 PDR ADOCK 05000369 S PDR

McGUIRE NUCLEAR STATION >

REPORTABLE OCCURRENCE REPORT NUMBER: 81-124 REPORT DATE: August 24, 1981 OCCURRENCE DATE: July 25 and July 26, 1981 FACILITY: McGuire Unit 1, Cornelius, NC ,

I IDENTIFICATION OF OCCURRENCE: Two containment isolation valves were declared inoperable due to nitrogen leaks in their pneumatic operators.

CONDITION PRIOR TO OCCURRENCE: Mode 3, Hot Standby DESCRIPTION OF OCCURRENCE: On 7/25/81, a Steam Generator 1B Feedwcter ContainmentIsolationValvewasdeclaredinoperablesothat[N2 leaks from fittings between the tank and valve could be repaired and the Nitrogen Accumulator could be recharged." The accumulator was charged to 2100 psig, and three N leaks were found and repaired.

2 On 7/26/81, a Steam Generator 1C Feedwater Containment Isolation Valve was declared inoperable for the same reason. The Accumulator was charged and the leaks repaired.

APPARENT CAUSE OF OCCURRlNCE: The 2 N Accumulators of both valves were losing pressure due to(small N2 leaks around the fittings.

I ANALYSIS OF OCCURRENCE: This problem has happened with these valves in the past, and the valve fittings had been checked and retightened such that they no longer leaked at that time. However, they later have to be tightened further when they leak again. Therefore, it appears that these fittings leak as a result of being tightened too many times. The need for higher grade fittings was apparent.

SAFETY ANALYSIS: The N2 Accumulators close the containment isolation valves during a safety injection signal. Since the valves were closed before work began, containment integrity was maintained while the valve was being worked on. This incident had no effect on the health and safety of the public.

h feedwater system CORRECTIVE ACTION: As a result of valves, four' valves were modified) Thispast experience modification with involved te relocating the Marrotta Pressure Regulator, associated gauges, and tubing of each

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valve downstream of the external filter mounted on the valve operator base plate. Also, Parker fittings were removed from the nitrogen accumulator lines to the feedwater isolation valves (up to the external filters), and socket weld fittings installed. The connection into the N2 bottle and to the external filter remained screwed fittings. These valves were declared operable on 08/06/81.

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