ML19260C375

LER 79-112/03L-0:on 791119,valve MS106 Failed to Open During Surveillance Testing.Caused by Improper Installation of Worm Gear Spacer.Drive Sleeve Machined & Worm Gear Spacer Reinstalled

ML19260C375
Person / Time
Site:	Davis Besse
Issue date:	12/18/1979
From:	Oneill J TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19260C372	List: ML19260C371 ML19260C375
References
LER-79-112-03L, LER-79-112-3L, NUDOCS 7912260258
Download: ML19260C375 (2)

Text

U.S. NUCLEAR REGULATORY COMMISSION NRC FORM 366

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• LICENSEE EVENT REPORT CONTROL BLOCK: l l

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ERCE60 lLl@l0 5 l 0 l - l 0 l 3 l 4 l 6 gl 1l l j 1 l 9 l 7 l 9 l@l1 l2REPORT 74 76 l1 l8DATEl7 980l@

6d 63 EVENT OATE 7 8 61 DOCKET NUMB ER EVEN1 DESCRIPTION AND PROBABLE CONSEQUENCES h o 2 l At 2030 hours0.0235 days <br />0.564 hours <br />0.00336 weeks <br />7.72415e-4 months <br /> on November 19, 1979 while performing surveillance testing, valve MS106 l o 3 l failed to open. This placed the unit in the action statement of Technical Specifica- l the inoperable pump be re-l lo ;4 j l tion 3.7.1.2 which requires that with one pump inoperable, Thercq g g l paired within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or the pnit be in hot shutdown within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

o lc I was no danger to the health and safety of the public or station personnel. Auxiliary l l

l o l 7 ] l Feed Pump (AFP) 1-2 was operable during the inoperability of AFP l-1.

l o a (NP-33-79-130) 80 7 8 9 COMP. VALVE SYSTEV CAUSE CAUSE COMPONENT CODE SUBCODE SU8 CODE CODE CODE SUSCODE

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43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h i o l The motor operator torque switches were adjusted and surveillance testing successfull 3

[i li j l performed on 11/20/79, removing the unit from the action statement. However, disas- [

g,,7; l sembly of the motor operator revealed that the cause was actually the worm gear spacey l 113 l l was installed upside down. The drive sleeve was machined and the worm gear spacer l l

li14l l was reinstalled correctly. 80 7 8 9 OTHER STATUS IS O RY DISCOVERY DESCRIPTION ST S  % POWER l

i s W @ l0l0l0l@l NA l lBl@l Surveillance Test ST 5071.01 ACTIVITY CONTENT LoCATroN oF RELEASE RELEASED OF RELE ASE AMOUNT OF ACTIVITY NA l i c l 7 8 9 LzJ @ Lz_J@l to 11 NA 44 45 80 PERSONNEL FXPOSURES NUMBER TYPE DESCRIPTION

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TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-33-79-130 DATE OF EVENT: November 19, 1979 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: Auxiliary Feed Pump 1-1 inoperable Conditions Prior to Occurrence: The unit was in Mode 3, with Power (MNT) = 0, and Load (Gross MWE) = 0.

Description of Occurrence: At 2030 hours0.0235 days <br />0.564 hours <br />0.00336 weeks <br />7.72415e-4 months <br /> on November 19, 1979 while performing Sur-veillance Test ST 5071.01, " Auxiliary Feedwater System Monthly Test", valve main steam (MS) 106 failed to open.

This placed the unit in the action statement of Technical Specification 3.7.1.2 which requires that with one pump inoperable, the inoperable pump be repaired with-in 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or the unit be in hot shutdown within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. The technical specification requires operability of both Auxiliary Feed Pumps (AFPs) while in Modes 1, 2, and 3.

Designation of Apparent Cause of Occurrence: The cause of this occurrence was ini-tially thraught to be the torque switch being set too light. However, after taking the limitorque apart, it was found that the worm gear spacer was installed upside down causing a mushrooming ef f ect on the drive sleeve. This mushroomed area was dragging on the worm gear causing it to turn harder, requiring more torque. This caused the limitorque to torque out prior to opening the valve.

Analysis of Occurrence: There was no danger to the health and safety of the public or to station personnel. Auxiliary Feed Pump 1-2 was operable during the inoperabi-lity of AFP l-1.

Corrective Action: Under Maintenance Work Order (MWO) 79-3546, . the torque settings were adjusted. Surveillance Test ST 5071.01 was successfully performed on November 20, 1979, and the AFP l-1 was declared operable. The unit was then removed from the action statement of Technical Specification 3.7.1.2.

Under MWO 79-3704, which was completed on December 12, 1979, the mushroomed drive sleeve was machined for proper tolerance and the worm gear spacer was reinstalled correctly. Surveillance Test ST 5071.01 will be performed to ensure operability of AFP l-1 as soon as the plant is in Mode 3.

A modification will be made to maintenance procedure MP 1410.32, " Removal and Repair of Limitorque Valve Controls", to ensure the worm gear spacer on all similar limitor-ques will be installed correctly.

Failure Data: There has been one other similar occurrence reported under Licensee Event Raport NP-33-79-85.

LER #79-112 lfl[ }}[