ML19269D166

LER 79-003/03L-0 on 790123:main Steam Safety Valve Nitrogen Setpoint of 1220 Psi Found During Surveillance Testing,In Excess of Tech Spec Max.Caused by Setpoint Drift

ML19269D166
Person / Time
Site:	Vermont Yankee
Issue date:	02/22/1979
From:	Conway W VERMONT YANKEE NUCLEAR POWER CORP.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19269D163	List: ML19269D162 ML19269D166
References
LER-79-003-03L, LER-79-3-3L, NUDOCS 7902270409
Download: ML19269D166 (2)

Text

NRC FORM 366 U. S. NUCLEAR REGULATORY COMMISSION (7 77)

LICENSEE EVENT REPORT LER 79-3/3L CONTROL BLOCK: [l l l l l l (PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION) f 6 o i IV IT IV ly IS 11 l@l- 10 l- 10 10 10 10 10 14 15 LICENSE NUMBER 4 0 0 25

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TYPE JO 7 8 9 LICENSE E CODE CON'T 7

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DATE EVENT DESCRlPTION AND PROBABLE CONSEQUENCES h O 2 l See attached sheet i o !a O 4 l I

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18 19 X l@ W @ 20 7 8 11 SEQUENTI AL OCCURRENCE REPORT REVISION REPORT NO. CODE TYPE NO.

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CAUSE DESCRIPTION AND CORRECTIVE ACTIONS I

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lil4 li 80 7 8 9 ST S  % POWER OTHER ST ATUS ISCO Y DISCOVERY DESCRIPTION Surveillance Test l li I5 l W@ l 0l 9l 9l@l NA l lB l@l ACTIVITY CO TENT RELEASED OF RELE ASE AMOUNT OF ACTIVITY LOCATION OF RELEASE NA l l NA l 7

1 G 8 9 W @ lZ l@l 10 11 44 45 80 PERSONNEL F XPOSURES NUMBER TYPE DESCRIPTION NA l l i l 71 1010101@l Z l@l *

' PEnSONNd'iN;URiES NUMBER DESCRIPTICN l

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VTVYS1 05000271 LER 79-3/3L EVENT DESCRIPTION AND PROBABLE CONSEQUENCES Tech. Spec. Secti-on 4.6.D requires that one of the two main stem n safety valves _be removed for testing and replaced with a successfully tested spare each refueling outage. Surveillance testing of the safety valve removed during the 1978 refueling outage revealed that it had an as-found nitrogen setpoint of 1220 psi (1207 psi nitrogen maximum allow-able). This could be correlated to a steam pressure setpoint approxi-mately 1% higher than the 1240 psi required by Tech. Spec. Section 2.2.B.

There were no consequences to the health and safety of the public as a result of this event and there have been no similar events reported to the Commission.

CAUSE DESCRIPTION AND CORRECTIVE ACTION The cause of this occurrence is attributed to an apparent setpoint drift. The valve was overhauled, adjusted to the proper setpoint range and returned to stock. The valve is a Dresser Industries Model 3700 Maxiflow Safety Valve.