Information Notice 1988-84, Defective Motor Shaft Keys in Limitorque Motor Actuators

Defective Motor Shaft Keys in Limitorque Motor Actuators

ML031150062
Person / Time
Site:	Beaver Valley, Millstone, Hatch, Monticello, Calvert Cliffs, Dresden, Davis Besse, Peach Bottom, Browns Ferry, Salem, Oconee, Mcguire, Nine Mile Point, Palisades, Palo Verde, Perry, Indian Point, Fermi, Kewaunee, Catawba, Harris, Wolf Creek, Saint Lucie, Point Beach, Oyster Creek, Watts Bar, Hope Creek, Grand Gulf, Cooper, Sequoyah, Byron, Pilgrim, Arkansas Nuclear, Three Mile Island, Braidwood, Susquehanna, Summer, Prairie Island, Columbia, Seabrook, Brunswick, Surry, Limerick, North Anna, Turkey Point, River Bend, Vermont Yankee, Crystal River, Haddam Neck, Ginna, Diablo Canyon, Callaway, Vogtle, Waterford, Duane Arnold, Farley, Robinson, Clinton, South Texas, San Onofre, Cook, Comanche Peak, Yankee Rowe, Maine Yankee, Quad Cities, Humboldt Bay, La Crosse, Big Rock Point, Rancho Seco, Zion, Midland, Bellefonte, Fort Calhoun, FitzPatrick, McGuire, LaSalle, 05000000, Zimmer, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant
Issue date:	10/20/1988
From:	Rossi C E Office of Nuclear Reactor Regulation
To:
References
IN-88-084, NUDOCS 8810140018
Download: ML031150062 (3)

4.UNITED STATESNUCLEAR REGULATORY COMMISSIONOFFICE OF NUCLEAR REACTOR REGULATIONWASHINGTON, D.C. 20555October 20, 1988NRC INFORMATION NOTICE NO. 88-84: DEFECTIVE MOTOR SHAFT KEYS IN LIMITORQUEMOTOR ACTUATORS

Addressees

All holders of operating licenses or construction permits for nuclear powerreactors.

Purpose

This information notice is being provided to alert recipients to potentialproblems from defective motor shaft keys installed in certain Limitorqueactuators. It is expected that recipients will review the information forapplicability to their facilities and consider actions, as appropriate, toavoid similar problems. However, suggestions contained in this informationnotice do not constitute NRC requirements; therefore, no specific action orwritten response is required.

Description of Circumstances

On October 15, 1987, the NRC received a report from Houston Lighting and PowerCompany concerning sheared motor shaft-to-pinion keys found in a Limitorqueactuator at its South Texas Project, Unit 2, nuclear plant. A similar key'failure also occurred in April 1987. The sheared key from one of the valves.was sent to a metallurgical laboratory which found that the properties of the-.material were not consistent with those of American Iron and Steel Institute(AISI) type 1018 steel. AISI type 1018 steel is the material designated byLimitorque for these particular keys as specified in Limitorque design documents.In August 1987, three additional keys had been removed from similar actuatorsand sent to the laboratory for analysis. One of the removed keys was splitand the other two showed signs of deformation. Laboratory analysis of thesekeys revealed that the properties of the key material were not consistent withthose of AISI type 1018 steel. The metallurgical analysis revealed that thekeys had failed longitudinally along manganese sulfide inclusions and that thekey material was probably an AISI type 1118 or 1119 resulphurized steel. Addi-tionally, on March 16, 1983, Westinghouse had submitted a 10 CFR Part 21 reportto the NRC concerning its discovery of sheared keys on six actuators. Thesekeys were also analyzed and found to be made of other than AISI type 1018 steel.Discussion:During an NRC inspection at Limitorque in May 1988, inspectors found that atthe time of the manufacture of the South Texas actuators, keys were purchased<0 At101t40018 IN 88-84October 20, 1988 from a commercial vendor without certificates of conformance for the materialtype or properties. No checks were performed at Limitorque to verify that theproper key material was received. Keys purchased today are still bought ascommercial grade; however, certified material test reports (CMTRs) are receivedfrom the vendor. Limitorque also performs hardness and dimensional checks ofthe keys upon receipt from the vendor.In a letter to the NRC dated May 19, 1988, Limitorque provided additional in-formation on this issue. Limitorque stated that the current material controlprocedures for key procurement were fully implemented in September 1983. Atthat time, the existing key inventory was scrapped and completely replaced withkeys purchased under the new controls. It is estimated that all actuators fromserial number 362735 onward were supplied with keys procured under the upgradedmaterial controls. Additionally, Limitorque determined that only the followingactuator-motor combinations could potentially experience similar key failuresdue to improper material.Unit Size Motor SizeSMB-000 NoneSMB-OO 25-ft.lb 1800 rpmSMB-0 25-ft.lb 1800 rpm25-ft.ThY -3600 rpm--40-ft.lb 1800 rpmSMB-1 60-ft.lb 1800 rpm60-ft.lb 3600 rpmSMB-2 80-ft.lb 3600 rpmNo specific action or written response is required by this information notice.If you have any questions about this matter, please contact the technicalcontact listed below or the Regional Administrator of the appropriate regionaloffice.Division of Operational Events AssessmentOffice of Nuclear Reactor Regulation

Technical Contact:

Jeffrey B. Jacobson, NRR(301) 492-0996Attachment: List of Recently Issued NRC Information Notices

, 0 A -%IfAttachmentIN 88-84October 20, 1988 LIST OF RECENTLY ISSUEDNRC INFORMATION NOTICESInformation Date ofNotice No. Subject Issuance Issued to88-8388-8288-8188-8088-79Inadequate Testing of RelayContacts in Safety-RelatedLogic SystemsTorus Shells with Corrosionand Degraded Coatings inBWR ContainmentsFailure of Amp WindowIndent Kynar Splicesand Thomas and BettsNylon Wire Caps DuringEnvironmental Quali-fication TestingUnexpected Piping MovementAttributed to ThermalStratificationMisuse of Flashing Lightsfor High Radiation AreaControls10/19/8810/14/8810/7/8810/7/8810/7/88All holders of OLsor CPs for nuclearpower reactors.All holders of OLsor CPs for BWRs.All holders of OLsor CPs for nuclearpower, test, andresearch reactors.All holders of OLsor CPs for PWRs.All holders of OLsor CPs for nuclearpower reactors.88-69, Supp 1Movable Contact FingerBinding in HFA RelaysManufactured by GeneralElectric (GE)9/29/88All holders of OLsor CPs for nuclearpower reactors.88-7888-7788-76Implementation of RevisedNRC-Administered Requali-fication ExaminationsInadvertent ReactorVessel OverfillRecent Discovery of aPhenomenon not PreviouslyConsidered in the Designof Secondary ContainmentPressure Control9/22/889/22/889/19/88All holders of OLsor CPs for nuclearpower reactors.All holders of OLsor CPs for BWRs.All holders of OLsor CPs for nuclearpower reactors.OL = Operating LicenseCP = Construction Permit