05000338/LER-1981-046-03, /03L-0:on 810527,svc Water Supply Header B to Unit 1 & 2 Charging Pumps Was Isolated to Repair Leak in Supply Line.Probably Caused by Sulfate Reducing Bacteria in Svc Water Piping.Piping Replaced.Investigation Underway

/03L-0:on 810527,svc Water Supply Header B to Unit 1 & 2 Charging Pumps Was Isolated to Repair Leak in Supply Line.Probably Caused by Sulfate Reducing Bacteria in Svc Water Piping.Piping Replaced.Investigation Underway

ML20005A015
Person / Time
Site:	North Anna
Issue date:	06/22/1981
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20005A012	List: 05000338/LER-1981-046, Forwards LER 81-046/03L-0 05000338/LER-1981-046-03, /03L-0:on 810527,svc Water Supply Header B to Unit 1 & 2 Charging Pumps Was Isolated to Repair Leak in Supply Line.Probably Caused by Sulfate Reducing Bacteria in Svc Water Piping.Piping Replaced.Investigation Underway
References
LER-81-046-03L, LER-81-46-3L, NUDOCS 8106290249
Download: ML20005A015 (2)

LER-1981-046, /03L-0:on 810527,svc Water Supply Header B to Unit 1 & 2 Charging Pumps Was Isolated to Repair Leak in Supply Line.Probably Caused by Sulfate Reducing Bacteria in Svc Water Piping.Piping Replaced.Investigation Underway

Event date:
Report date:
3381981046R03 - NRC Website

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.y U.S. NUCLEAR REGULATORY COMMISSION

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LICENSEE EVENT REPORT CONTROL BLOCK / / / / / / / (1) (PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION)

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(8) /o/6/2/2/8/1/ (9) 0 DOCKET NUMBER EVENT DATE REPORT DATE EVENT DESCRIPTION AND PROBABLE CONSEQUENCES (10)

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/ On.May 27, 1981, with both units in Mode 1 at 100 percent power, the "B" Service /

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/ Water Supply Header to the Unit 1 and 2 charging pumps was isolated to repair a /

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/ pinnole leak in a supply line (3"-WS-74-151-Q3).

Since the header was restored /

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/ to operable star g within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> as required by the Action Statement, the

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/ health and safety of the general public were not affected. This is contrary to /

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/ T.S. 3.7.4.1 and reportable pursuant to T.S. 6.9.1.9.b.

A similar event occurred /

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./ on April'21, 1981 to this pipe which was reported via LER 81-024.

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ACTION FUTURE EFFECT SHUTDOWN ATTACHMENT NPRD-4 PRIME COMP. COMPONENT TAKEN ACTION ON PLANT METHOD HOURS SUBMITTED FORM SUB. SUPPLIER MANUFACTURER

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/ The actual cause of the pinhole leak is unknown at this time. However, it is

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/ suspected that this leak may have been caused by sulfate reducing bacteria with- /

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/ in the service water piping. A study is being performed at this time to deter-____/

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/ mine the actual failure mechanism. The affected piping was removed and a new

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/ section was welded into place in the Service Water System.

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FACILITY METHOD OF STATUS

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1 NAME OF PREPARER W. R. CARTWRIGHT PHONE (703) 894-5151 I

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p Virginia Electric'and Power Company North Anna Power Station, Unit 1 Attachment: Page 1 of 1 Docket No. 50-338 Report No. LER 81-046/03L-0

Description of Event

On May 27, 1981, with both units in Mode 1 at 100 percent power, the "B" Service Water Supply Header to the Unit I and Unit 2 Charging Pumps was isolated to repair a pinhole leak in the line. The "A" Service Water Supply Header to the charging remained inservice while tne "B"

header was being repaired.

Probable Consequences of Occurrence Since service water was supplied to the charging pumps by the "A"

header and since the "B" header was restored to operable status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> as required by the Action Statement, the health and safety of the general public were not affected.

Cause of Event

The actual cause of the pin.Nole leak is unknown at this time.

However, it is suspected that this leak may have been caused by sulfate reducing bacteria within the service water piping. A study is being

. performed at this time to determine the actual failure mechanism.

Immediate Corrective Action

The affected piping was cut out and a new section was welded into place in the service water system using approved procedures. The replaced welds were liquid penetrant and hydrostatically tested prior to returning the header to service.

Scheduled Corrective Action There is no scheduled corrective action at this time. However, upon completion of a atudy being performed to determine the actual mechanism causing corrosion of the service water piping, the appropriate action will be taken.

Actions Taken to Prevent Reccurrence No action is taken to prevent recurrence at this time.

Generic Implications This failure may be generic to both units at North Anra Power Station. A study by Lehigh University conceraing the corrocion of piping and components at horth Anna subjected to service and lake water is being performed. at this time. Once this analysis is comp?. ate, plans will be formulated to arrest further !< gradation of system piping and I

restore damaged material to design specifications. Meanwhile, it is

' felt that no gross failures will occur since failures of this nature j

produce.small pinhole leaks which would be randomly located in the piping.