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 Office of Nuclear Reactor Regulation
To:
References
IN-88-084, NUDOCS 8810140018
Download: ML031150062 (3)

4.

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555 October 20, 1988 NRC INFORMATION NOTICE NO. 88-84: DEFECTIVE MOTOR SHAFT KEYS IN LIMITORQUE

MOTOR ACTUATORS

Addressees

All holders of operating licenses or construction permits for nuclear power

reactors.

Purpose

This information notice is being provided to alert recipients to potential

problems from defective motor shaft keys installed in certain Limitorque

actuators. It is expected that recipients will review the information for

applicability to their facilities and consider actions, as appropriate, to

avoid similar problems. However, suggestions contained in this information

notice do not constitute NRC requirements; therefore, no specific action or

written response is required.

Description of Circumstances

On October 15, 1987, the NRC received a report from Houston Lighting and Power

Company concerning sheared motor shaft-to-pinion keys found in a Limitorque

actuator 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 by

Limitorque for these particular keys as specified in Limitorque design documents.

In August 1987, three additional keys had been removed from similar actuators

and sent to the laboratory for analysis. One of the removed keys was split

and the other two showed signs of deformation. Laboratory analysis of these

keys revealed that the properties of the key material were not consistent with

those of AISI type 1018 steel. The metallurgical analysis revealed that the

keys had failed longitudinally along manganese sulfide inclusions and that the

key 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 report

to the NRC concerning its discovery of sheared keys on six actuators. These

keys 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 at

the time of the manufacture of the South Texas actuators, keys were purchased

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IN 88-84 October 20, 1988 from a commercial vendor without certificates of conformance for the material

type or properties. No checks were performed at Limitorque to verify that the

proper key material was received. Keys purchased today are still bought as

commercial grade; however, certified material test reports (CMTRs) are received

from the vendor. Limitorque also performs hardness and dimensional checks of

the 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 control

procedures for key procurement were fully implemented in September 1983. At

that time, the existing key inventory was scrapped and completely replaced with

keys purchased under the new controls. It is estimated that all actuators from

serial number 362735 onward were supplied with keys procured under the upgraded

material controls. Additionally, Limitorque determined that only the following

actuator-motor combinations could potentially experience similar key failures

due to improper material.

Unit Size Motor Size

SMB-000 None

SMB-OO 25-ft.lb 1800 rpm

SMB-0 25-ft.lb 1800 rpm

25-ft.ThY -3600 rpm--

40-ft.lb 1800 rpm

SMB-1 60-ft.lb 1800 rpm

60-ft.lb 3600 rpm

SMB-2 80-ft.lb 3600 rpm

No specific action or written response is required by this information notice.

If you have any questions about this matter, please contact the technical

contact listed below or the Regional Administrator of the appropriate regional

office.

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Jeffrey B. Jacobson, NRR

(301) 492-0996 Attachment: List of Recently Issued NRC Information Notices

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Attachment

IN 88-84 October 20, 1988 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information Date of

Notice No. Subject Issuance Issued to

88-83 Inadequate Testing of Relay 10/19/88 All holders of OLs

Contacts in Safety-Related or CPs for nuclear

Logic Systems power reactors.

88-82 Torus Shells with Corrosion 10/14/88 All holders of OLs

and Degraded Coatings in or CPs for BWRs.

BWR Containments

88-81 Failure of Amp Window 10/7/88 All holders of OLs

Indent Kynar Splices or CPs for nuclear

and Thomas and Betts power, test, and

Nylon Wire Caps During research reactors.

Environmental Quali- fication Testing

88-80 Unexpected Piping Movement 10/7/88 All holders of OLs

Attributed to Thermal or CPs for PWRs.

Stratification

88-79 Misuse of Flashing Lights 10/7/88 All holders of OLs

for High Radiation Area or CPs for nuclear

Controls power reactors.

88-69, Supp 1 Movable Contact Finger 9/29/88 All holders of OLs

Binding in HFA Relays or CPs for nuclear

Manufactured by General power reactors.

Electric (GE)

88-78 Implementation of Revised 9/22/88 All holders of OLs

NRC-Administered Requali- or CPs for nuclear

fication Examinations power reactors.

88-77 Inadvertent Reactor 9/22/88 All holders of OLs

Vessel Overfill or CPs for BWRs.

88-76 Recent Discovery of a 9/19/88 All holders of OLs

Phenomenon not Previously or CPs for nuclear

Considered in the Design power reactors.

of Secondary Containment

Pressure Control

OL = Operating License

CP = Construction Permit