05000346/LER-1980-030-01, /01T-0:on 800418,contrary to Tech Spec 3.4.1,decay Heat Pump 1-2 Stopped When RCS Water Level Decreased to 37 Inches Above Hot Leg Piping Centerline.Caused by Valve Operator Component Failure.Work Order Issued for Adjustment

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/01T-0:on 800418,contrary to Tech Spec 3.4.1,decay Heat Pump 1-2 Stopped When RCS Water Level Decreased to 37 Inches Above Hot Leg Piping Centerline.Caused by Valve Operator Component Failure.Work Order Issued for Adjustment
ML19309G388
Person / Time
Site: Davis Besse 
Issue date: 05/01/1980
From: David Brown
TOLEDO EDISON CO.
To:
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19309G384 List:
References
LER-80-030-01T, LER-80-30-1T, NUDOCS 8005060243
Download: ML19309G388 (3)
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LER-1980-030, /01T-0:on 800418,contrary to Tech Spec 3.4.1,decay Heat Pump 1-2 Stopped When RCS Water Level Decreased to 37 Inches Above Hot Leg Piping Centerline.Caused by Valve Operator Component Failure.Work Order Issued for Adjustment
Event date:
Report date:
3461980030R01 - NRC Website
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8 60 61 DOCAET NUMB ER 68 69 EVENT DATE 74 7b REPORT DATE 80 EVENT DESCRIPTION AND PROB ABLE CONSEQUENCES h O 2 l (NP-32-80-05) On 4/1S/80 at 1920 hours0.0222 days <br />0.533 hours <br />0.00317 weeks <br />7.3056e-4 months <br />, Decay IIcat (DH) Pump 1-2 was stopped when it l g was discovered that Reactor Coolant System (RCS) water level had decreased from 70" eq g g g 3, gl 37" above the hot leg piping centerline.

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33 J4 35 36 31 40 41 42 43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h l This occurrence is attributed to component failure of the valve operator. The remote l i o ITTT1 I valve operator (Rv0) for DH62 was found to be out of adjustment causing the valve to I yl remain one to two turns open when the RVO was on its close stop.

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TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-32-80-05 DATE OF EVENT: April 18, 1980 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: Loss of Decay Heat Flow to the Reactor Coolant System (RCS) While the Unit is in Mode 5 Conditions Prior to occurrence: The unit was in Mode 5, with Power (MWT) = 0 and Load (Gross MWE) = 0.

Description of Occurrence: On April 18, 1980 at 1915 hours0.0222 days <br />0.532 hours <br />0.00317 weeks <br />7.286575e-4 months <br />, operations personnel dis-covered that the RCS water level had decreased from 70" to 37" above the hot leg piping centerline as read at the Refueling Level Indicator LI214.

(This lower level corres,

ponds to 78" above the top of the reactor core.) This low RCS level caused an erratic decay heat flowrate due to inadequate decay heat pump suction conditions. As a result, Decay Heat Pump 1-2 was stopped at 1920 hours0.0222 days <br />0.533 hours <br />0.00317 weeks <br />7.3056e-4 months <br />. At this time, the RCS level had dropped to 35" as read on LI214. Operations began to check their isolation and drain lineup for Decay Heat Loop 1 which was out of service and found water flowing from Decay Heat Cooler 1-1 Discharge,Line Leak Test Connection Isolation Valve DH73, which had been opened to facilitate draining of Decay Heat Loop 1.

DH73 was immediately closed.

Further investigation of the loop isolation lineup revealed that Decay Heat Cooler 1-2 Discharge to Makeup and Purification System Isolation Valve DH62 was two turns open.

This valve, normally operated by a manual remote valve operator, had to be closed at the valve stem.

RCS makeup water was transferred from the Borated Water Storage Tank (BWST) to the RCS via the Decay Heat System to restore the RCS level to 75".

Decay heat flow to the RCS was restored when Decay Heat Pump 1-2 was restarted at 1949 hours0.0226 days <br />0.541 hours <br />0.00322 weeks <br />7.415945e-4 months <br /> on April 18, 1980.

Tripping Decay Heat Pump 1-2 placed the unit in violation of action statement (a) of Technical Specification 3.4.1, which states that while in Mode 5 at least one reactor coolant loop must be in operation with an associated reactor coolant pump or decay heat pump. The decay heat pump was off for 29 minutes.

Designation of Apparent Cause of Occurrence: The occurrence is attributed to component failure of the valve operator. The remote valve operator (RVO) for DH62 was found to be out of adjustment causing the valve to remain one to two turns open when the RVO was on its close stop.

Analysis of Occurrence: There was no danger to the health and safety of the public or to station personnel.

Decay heat flow was off for less than a half hour and RCS temperature remained significantly below the saturation temperature, rising from approxi-mately 93 F to 103 F.

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LER #80-030 i

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n-TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE PAGE 2 SUPPLEMENTAL INFORMATION FOR LER NP-32-80-05 S

Corrective Action

Operations checked the Decay Heat Loop 1 drain and isolation Both valves were lineups and found water flowing from DH73 and leaking by DH62.

immediately closed. RCS level was re-established at 75" by filling with water from the BUST.

Decay Heat Pump 1-2 was restarted at 1949 hours0.0226 days <br />0.541 hours <br />0.00322 weeks <br />7.415945e-4 months <br /> on April 18, 1980.

Maintenance Work Order 80-2176 has bee.n written to have the RVO on DH62 adjusted for proper valve operation.

Failure Data: No previous failures of this type.

LER #80-030 4

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