05000339/LER-1980-090-03, /03L:on 801102,pressurizer Power Operated Relief Valve Declared Inoperable.Caused by Low Nitrogen Pressure Due to Excessive Nitrogen Usage.Pressure Restored by Renewing Supply

/03L:on 801102,pressurizer Power Operated Relief Valve Declared Inoperable.Caused by Low Nitrogen Pressure Due to Excessive Nitrogen Usage.Pressure Restored by Renewing Supply

ML19345B830
Person / Time
Site:	North Anna
Issue date:	11/24/1980
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19345B828	List: 05000339/LER-1980-090, Forwards LER 80-090/03L-0 05000339/LER-1980-090-03, /03L:on 801102,pressurizer Power Operated Relief Valve Declared Inoperable.Caused by Low Nitrogen Pressure Due to Excessive Nitrogen Usage.Pressure Restored by Renewing Supply
References
LER-80-090-03L-02, LER-80-90-3L-2, NUDOCS 8012020590
Download: ML19345B830 (2)

LER-1980-090, /03L:on 801102,pressurizer Power Operated Relief Valve Declared Inoperable.Caused by Low Nitrogen Pressure Due to Excessive Nitrogen Usage.Pressure Restored by Renewing Supply

Event date:
Report date:
3391980090R03 - NRC Website

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w U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT v

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DOCKET NUMBER EVENT DATE PEPORT DATE EVENT DESCRIPTION AND PROBABLE CONSEQUENCES (10)

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During Mode 5 operation, a pressurizer power operated relief valve was declared /

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inoperable when the nitrogen gas supply dropped below 1750 psig.

The nitrogen /

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pressure was restored within seven days in accordance with T.S. 3.4.9.3. There-/

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fore, the health and safety of the public were not af fected. This item is

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reportable pursuant to T.S. 6.9.1.9.b.

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SYSTEM

CAUSE

CAUSE COMP.

VALVE CODE CODE SUBCODE COMPONENT CODE SUBCODE SUBCODE

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SEQUENTIAL OCCURRENCE REPORT REVISION LER/R0 EVENT YEAR REPORT NO.

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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 [X/ (18) [F/ (19) [C/ (20) LZ/ (21) /0/0/0/0/ (22) [Y/ (23) [N/ (24) [A/ (25) /S//42/0/ (26)

CAUSE DESCRIPTION AND CORRECTIVE ACTIONS (27)

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The PORV was made inoperable due to low nitrogen pressure. Nitrogen is re-

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quired to cycle the valve during conditions wherein overpressure protection is /

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required. The nitrogen pressure was restored in about 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> by renewing

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the supply and pressurizing the PORV nitrogen tanks.

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FACILITY METHOD OF STATUS

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ACTIVITY CONTENT RELEASED OF RELEASE AMOUNT OF ACTIVITY (35)

LOCATION OF RELEASE (36)

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PERSONNEL EXPOSURES NUMBER TYPE DESCRIPTION (39)

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LOSS OF OR DAMAGE TO FACILITY (' )

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PUBLICITY ISSUED DESCRIPTION (45)

NRC USE ONLY

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NAME OF PREPARER W. R. CARTWRIGHT PHONE (703) 894-5151 8 012020 ts9 6

i Virginia Electric and Power Company North Anna Power Station, Unit #2 Attachment: Page 1 of 1 Docket No. 50-339 Attschment to LER 80-090/03L-0

Description of Event

On October 2,- 1980, during Mode 5 operation, the pressurizer power operated relief valves (PORV's) were required to be operable for over ~

pressure protection in accordance with T.S. 3.4.9.3.

In this condition, nitrogen is used as the cycling medium for the PORV's.

The nitrogen

~

supply pressure dropped to below the pressure necessary to maintain PCV-2456 in an operable status.

Probable Consequences of Event Overpressure protection for cold shutdown condition is required to prevent pressurization in the non-ductile range of the materials used in the' reactor coolant system. Since the nitrogen pressure was restored within seven days as required by T.S. 3.4.9.3, there was no affect on the health and safety of the public.

Cause of-Event The cause of the PORV becoming inoperable was the nitrogen supply tank pressure dropping below the pressure necessary to provide this protection function. The low nitrogen supply in this system was created

.by excessive usage of nitrogen throughout the station and an inadequate method for replenishing this supply.

Immediate Corrective Action

The nitrogen supply tanks were recharged and the system returned to normal.

Scheduled Corrective Action The nitrogen supply system has been investigated and recommended corrective actions have been proposed. Yuture corrective action will be taken based on the review and acceptabil.i.ty of these proposals.

Actions Taken to Prevent Recurrence No further actions are required.

Generic Implications There are no generic implications associated with this event.