Information Notice 1989-43, Permanent Deformation of Torque Switch Helical Springs in Limitorque SMA-Type Motor Operators

Permanent Deformation of Torque Switch Helical Springs in Limitorque SMA-Type Motor Operators

ML031190353
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:	05/01/1989
From:	Rossi C Office of Nuclear Reactor Regulation
To:
References
IN-89-043, NUDOCS 8904250410
Download: ML031190353 (5)

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555 May 1, 1989 NRC INFORMATION NOTICE NO. 89-43: PERMANENT DEFORMATION OF TORQUE SWITCH

HELICAL SPRINGS IN LIMITORQUE SMA-TYPE

MOTOR OPERATORS

Addressees

All holders of operating licenses or construction permits for nuclear power

reactors.

Purpose

This information notice is being provided to alert addressees to potential

problems resulting from permanent deformation of the torque switch helical

springs in Limitorque SMA-type motor operators. It is expected that re- cipients 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

Problems with the helical springs were discovered during a series of dynamic

tests that were conducted with a motor-operated wedge-gate valve from the

decommissioned Shippingport Atomic Power Station (Shippingport). The valve

was installed in a portion of the piping system that had been modified to

simulate the stiffness of a typical United States piping system. The valve

was 30 years old and had its original Limitorque SMA-type motor operator.

One of the main objectives of these tests was to determine the operating

capability of the valve when subjected to simultaneous internal hydraulic

and seismic loadings. This was typically accomplished by operating the

valve to achieve maximum hydraulic loading during maximum seismic loading.

During testing, an operability problem with the valve motor operator occurred.

Disassembly and inspection of the motor operator revealed that the torque

switch helical spring had a free length of 3.99 inches. Review of the

Shippingport records for the valve indicated that the torque switch spring

had not been changed while the valve had been in service at Shippingport.

Limitorque's records indicated that the original free length of the spring

was 4.46 inches. Thus, the spring had developed a permanent deformation

of 0.47 inches during the motor operator's 30-year life. Since the spring

Thee, dIIC

IN 89-43 May 1, 1989 had been installed in a space 4.06 inches in length, a gap of approximately

0.07 inch had existed during the tests. This gap appears to indicate that

there was no preload on the helical spring during the tests.

The torque switch helical spring from a second Shippingport valve with a

Limitorque SMA-type motor operator was also found to have a permanent defor- mation. For this second spring, the original free length was 3.84 inches;

the current'free length was 3.74 inches; and it was Installed in a space 3.37 inches in length. However, even though this spring was subjected to a preload

and there was no gap, the amount of preload was less than expected because of

the permanent deformation.

Discussion:

Permanent deformation of the torque spring without compensating for it will

reduce the torque required to open the torque switch. The switch setting

that is selected corresponds to the closing torque that the motor operator

is to deliver. If the permanent deformation of the spring sufficiently

reduces this closing torque, it may cause the motor operator to stop before

the valve is fully seated. In an extreme case, the motor operator may stop

with the valve partially open.

The design of the SMA-type motor operator is such that the torque switch helical

spring is in its most compressed condition when the valve is closed. Thus, a

normalTy cto ed-val-Ve-Is mord-Ti-keTy-tod e~xefrence O ieiitdfeBorimatifon of theF'

helical torque spring. A review of the Shippingport records indicated that both

of these valves had been used as normally closed valves at'Shippingport. Thus, normally closed, safety-related valves with Limitorque SMA-type motor operators

may not accomplish their intended safety-related function bqcause the original

torque switch setting may result in lower output torque caused by the permanent

deformation of their torque switch helical springs.

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

If you have any questions about this matter, please contact one of the techni- cal contacts listed below or the Regional Administrator of the appropriate

regional office.

Charles E.Ross , rcr

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contacts: Gerald H. Weidenhamer, RES

(301) 492-3839 Richard J. Kiessel, NRR

(301) 492-1154 Attachment: List of Recently Issued NRC Information Notices

Attachment

IN 89-43 May 1, 1989 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information I Date of

Notice No. Subject Issuance Issued to

88-97, Potentially Substandard 4/28/89 All holders of OLs

Supp. 1 Valve Replacement Parts or CPs for nuclear

power reactors.

89-42 Failure of Rosemount 4/21/89 All holders of'OLs

Models 1153 and 1154 or CPs for nuclear

Transmitters power reactors.

89-41 Operator Response to 4/20/89 All holders of OLs

Pressurization of Low- or CPs for nuclear

Pressure Interfacing power reactors.

Systems

88-75, Disabling of Diesel 4/17/89 All holders of OLs

Supplement 1 Generator Output Circuit or CPs for nuclear

Breakers by Anti-Pump power reactors.

Circuitry

89-40 Unsatisfactory Operator Test 4/14/89 All holders of OLs--

Results and Their Effect on or CPs for nuclear

the Requalification Program power reactors.

89-39 List of Parties Excluded 4/5/89 All holders of OLs

from Federal Procurement or CPs for nuclear

or Non-Procurement Programs power reactors.

89-38 Atmospheric Dump Valve 4/5/89 All holders of OLs

Failures at Palo Verde or CPs for nuclear

Units 1, 2, and 3 power reactors.

89-37 Proposed Amendments to. 4/4/89 All U.S. NRC licensees.

40 CFR Part 61, Air

Emission Standards

for Radionuclides

89-36 Excessive Temperatures 4/4/89 All holders of OLs

in Emergency Core Cooling or CPs for nuclear

System Piping Located power reactors.

Outside Containment

OL = Operating License

CP = Construction Permit

IN 89-43 May 1, 1989 had been installed in a space 4.06 inches in length, a gap of approximately

0.07 Inch had existed during the tests. This gap appears to Indicate that

there was no preload on the helical spring during the tests.

The torque switch helical spring from a second Shippingport valve with a

Limitorque SMA-type motor operator was also found to have a permanent defor- mation. For this second spring, the original free length was 3.84 inches;

the current free length was 3.74 inches; and it was installed in a space 3.37 inches in length. However, even though this spring was subjected to a preload

and there was no gap, the amount of preload was less than expected because of

the permanent deformation.

Discussion:

Permanent deformation of the torque spring without compensating for it will

reduce the torque required to open the torque switch. The switch setting

that is selected corresponds to the closing torque that the motor operator

is to deliver. If the permanent deformation of the spring sufficiently

reduces this closing torque, it may cause the motor operator to stop before

the valve is fully seated. In an extreme case, the motor operator may stop

with the valve partially open.

The design of the SMA-type motor operator is such that the torque switch helical

spring is in its most compressed condition when the valve is closed. Thus, a

normally closed valve is more likely to experience permanent deformation of the

helical torque spring. A review of the Shippingport records indicated that both

of these valves had been used as normally closed valves at Shlppingport. Thus, normally closed, safety-related valves with Limitorque SMA-type motor operators

may not accomplish their intended safety-related function because the original

torque switch setting may result In lower output torque caused by the permanent

deformation of their torque switch helical springs.

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

If you have any questions about this matter, please contact one of the techni- cal contacts listed below or the Regional Administrator of the appropriate

regional office.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contacts: Gerald H. Weidenhamer, RES

(301) 492-3839 Richard J. Kiessel, NRR

(301) 492-1154 Attachment: List of Recently Issued NRC Information Notices

The draft of this information notice was transmitted to DOEA by RES in a

memorandum from MVagins dated March 2, 1989.

• Concurrence with issuance of this information notice was transmitted to OGCB

by EMEB in a note from LBMarsh dated April 11, 1989.

• C/OGCB:DOEA:NRR *RPB:ARM

'NCERefsfj CHBerlinger TechEd

R 9E R \

O4D&B 04/20/89 04/18/89

• OGCB:DOEA:NRR *EME:DE:RES *C/EME:DE:ES *EMEB:DEST:NRR *C/EMEB:DEST:NRR

RJKiessel GHWeidenhamer MVagins EJSullivan LBMarsh

04/13/89 03/02/89 03/02/89 04/11/89 04/11/89

IN 89-XX

April xx, 1989 No specific action or written response is required by this information notice.

If you have any questions about this matter, please contact one of the techni- cal contacts listed below or the Regional Administrator of the appropriate

regional office.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contacts: Gerald H. Weidenhamer, RES

(301) 492-3839 Richard J. Kiessel, NRR

(301) 492-1154 Attachment: List of Recently Issued NRC Information Notices

The draft of this information notice was transmitted to DOEA by RES in a

memorandum from MVagins dated March 2, 1989.

• Concurrence with issuance of this information notice was transmitted to OGCB

by EMEB in a note from LBMarsh dated April 11, 1989.

D/DOEA:NRR C/OG9:DWEA:NRR RPB:ARM o

CERossi CHBerlinger TechEd

do

OGCB:DOEA:NRR *EME:DE:RES

04/ /89

• C/EME:DE:RES

04k 6/89

• EMEB:DEST:NRR

04//5/89

• C/EMEB:DEST:NRR

RJKiessel GHWeidenhamer MVagins EJSullivan LBMarsh

04/*/089 03/02/89 03/02/89 04/11/89 04/11/89