Information Notice 1995-31, Motor-Operated Valve Failure Caused by Stem Protector Pipe Interference

Motor-Operated Valve Failure Caused by Stem Protector Pipe Interference

ML031060323
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, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant
Issue date:	08/09/1995
From:	Crutchfield D Office of Nuclear Reactor Regulation
To:
References
IN-95-031, NUDOCS 9508030253
Download: ML031060323 (11)

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555-0001 August 9, 1995 NRC INFORMATION NOTICE 95-31: MOTOR-OPERATED VALVE FAILURE CAUSED

BY STEM PROTECTOR PIPE INTERFERENCE

Addressees

All holders of operating licenses or construction permits for nuclear power

reactors.

Purpose

The U.S. Nuclear Regulatory Commission (NRC) is issuing this information

notice to alert addressees of motor-operated valve (MOV) failures caused by

the stem protector pipe interfering with stem nut rotation. 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 are not NRC

requirements; therefore, no specific action or written response is required.

Background

A stem protector pipe may be attached to an MOY through the housing cover to

prevent debris from entering the stem/actuator interface area (see Figure 1).

To keep the stem protector pipe from interfering with actuator operation

(specifically rotation of the stem nut and its locknut), the threads on the

pipe may be restricted to a certain length. Another option is to stake the

threads on the stem protector pipe at a specific location. If neither of

these precautions is taken, the stem protector pipe may thread sufficiently

into the actuator housing to interfere with the rotation of the stem nut may

locknut. Additional torque may be required to operate the valve, which

cause the torque switch to trip prematurely, motor thermal overload devices to

activate, or the motor to be damaged on high torque demand.

Description of Circumstances

On February 11, 1995, a residual heat removal (RHR) MOV at Cooper Nuclear

Station failed to close on demand while RHR trains were being switched.

Licensee reviews showed that the stem protector pipe on the valve actuator had

threaded into the MOV housing and interfered with the stem nut rotation.stemThe

motor was damaged during an attempted opening stroke. The replacement

protector pipe was manufactured by the licensee. The root cause apparently

was that a replacement stem protector pipe was not constructed to the same

tolerance levels as the original. Specifically, the length of threaded

portion of the protector pipe was too long when manufactured. The extended

threads allowed the pipe to be threaded to the point where it interfered with

PD1K 03 Crict q95- 031 S 0

9508030253

'II

K..-) IN 95-31 August 9, 1995 the stem nut locknut. Also, actions (such as staking) were not takenhousing. to

prevent threading of the stem protector pipe into the valve actuator

Three other valves were found to have stem protector pipes with extended

threads that might have interfered with actuator operation. The licensee

long-term solution was to stake the extended threads in all of the stem

protector pipes of safety-related MOVs.

In addition to the Cooper event, similar failures have occurred atThese four other

plants as reported in the Nuclear Plant Reliability Data System.

failures are discussed below.

On May 24, 1992, an RHR pump discharge valve failed to close on demand. The

pipe had been threaded too far into

licensee review showed the stem protector also caused a

the operator and had interfered with actuator operation. This

gear to crack.

On August 14, 1991, an RHR suppression pool full flow discharge isolation the

valve failed to fully close on demand. The cause of the failure was that earlier

stem protector pipe had interfered with the stem locknut. Two years

on January 23, 1989, the plant had experienced the same failure ofwas the RHR

suppression pool full flow discharge isolation valve; the problem

corrected by removing approximately one inch of threads from the was stem

protector pipe. After the second failure, the licensee solution to stake

the threads of the stem protector pipe.

On March 18, 1988, a low-pressure core spray pump suction valve would not

stroke manually or electrically. The licensee analysis indicated that the

stem protector pipe had been threaded too far into the actuator.

On March 6, 1987, an RHR outboard containment isolation valve tripped on

stroked open. The valve was still operable by

thermal overload while being

hand. The licensee review showed that the stem protector pipe had been

inserted too far and had interfered with the actuator.

Discussion

The NRC staff noted that the failure occurred at Cooper Nuclear Station thread

because the stem protector pipe was manufactured with an extensive pipe

length. The licensee constructed and installed its own stem protector

without taking adequate precautions to prevent the protector pipe from

interfering with stem nut rotation. This incident and the earlier problems

indicate that such MOV failures are a recurring problem. The in trend toward win

house manufacture of components could result in an increase this type of

failure. The licensee could have prevented this type of failure by as those

manufacturing the stem pipe protector with the same tolerance pipe levels

made at the factory or adequately staking the stem protector during the

installation process.

IN 95-31 August 9, 1995 response. If

This information notice requires no specific action or writtenplease

notice, contact

you have any questions about the information in this Office of

one of the technical contacts listed below or the appropriate

Nuclear Reactor Regulation (NRR) project manager.

enns Crutcrector

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contacts: Thomas G. Scarbrough, NRR Glenn T. Dentel, NRR

(301) 415-2794 (301) 415-1321 Thomas Greene, NRR

(301) 414-1175 Attachments:

1. Figure 1: Valve Actuator and Protector Pipe

2. List of Recently Issued NRC Information Notices

are IP (e{ s ~'

Attachment 1 IN 95-31 August 9, 1995 Copyright e 1993. Electric Power Research Institute, EPRI NP-7214. Technical RepairGuidelinesfor the

Limitorque Models SMB 0 Through 4 Valve Actuators. PIPE CAP

Reprinted with Permission.

-.0..

Figure 1 Valve Actuator with Protector Pipe

ir-tachment 2 IN95-31 August 9, 1995 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information Date of

Notice No. Subject Issuance Issued to

95-30 Susceptibility of Low- 08/03/95 All holders of OLs or CPs

Pressure Coolant Injection for nuclear power reactors.

and Core Spray Injection

Valves to Pressure Locking

94-66, Overspeed of Turbine- 06/16/95 All holders of OLs or CPs

Supp. 1 Driven Pumps Caused by for nuclear power reactors.

Binding in Stems of

Governor Valves

95-29 Oversight of Design and 06/07/95 All holders of OLs or CPs

Fabrication Activities for nuclear power reactors.

for Metal Components Used

in Spent Fuel Dry Storage

Systems

95-28 Emplacement of Support 06/05/95 All holders of OLs or CPs

Pads for Spent Fuel Dry for nuclear power reactors.

Storage Installations at

Reactor Sites

95-27 NRC Review of Nuclear 05/31/95 All holders of OLs or CPs

Energy Institute, for nuclear power plants.

UThermo-Lag 330-1 Combustibility Evaluation

Methodology Plant Screening

Guide"

95-26 Defect in Safety- 05/31/95 All holders of OLs or CPs

Related Pump Parts due for nuclear power reactors.

to Inadequate Heat

Treatment

94-61, Corrosion of William 05/25/95 All holders of OLs or CPs

Supp. 1 Power Gate Valve Disc for nuclear power reactors.

Holders

95-25 Valve Failure during 05/11/95 All U.S. Nuclear Regulatory

Patient Treatment with Commission Medical

Gamma Stereotactic Licensees.

Radiosurgery Unit

OL - Operating License

CP - Construction Permit

IN 95-31 August 9, 1995 This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact

one of the technical contacts listed below or the appropriate Office of

Nuclear Reactor Regulation (NRR) project manager.

orig /s/'d by DMCrutchfield

Dennis M. Crutchfield, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contacts: Thomas G. Scarbrough, NRR Glenn T. Dentel, NRR

(301) 415-2794 (301) 415-1321 Thomas Greene, NRR

(301) 415-1175 Attachments:

1. Figure 1: Valve Actuator and Protector Pipe

2. List of Recently Issued NRC Information Notices

• See previous concurrence 'E" - Copy with attachmentlenclosure

To receve a copy of this document, Indcate In the box: 'C

• Copy without attachment/enclosure

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lOFFICE OECB/DOPS [TechED S:OECB/DOPS I EMEB/DE I E.

NAME GDentel* 1MMejac* IBDennig* TScarbrough*

DATE 03/15/95 02/27/95 03/30/95 04/03/95 OFFICE C:EMEB/DEDOPS I OECB/DPSS I C:OECB/DPS E O .

NAME RWessman* RKiessel* jAChaffee* DC§ ithfi eld

DATE 04/03/95 05/08/L95 05/15/95 08/ j /95

[OFFICIAL RECORD COPY]

DOCUMENT NAME: 95-31.IN .7 1 '

IN 95-XX

July XX, 1995 This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact

one of the technical contacts listed below or the appropriate Office of

Nuclear Reactor Regulation (NRR) project manager.

Dennis M. Crutchfield, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contacts: Thomas G. Scarbrough, NRR Glenn T. Dentel, NRR

(301) 415-2794 (301) 415-1321 Thomas Greene, NRR

(301) 415-1175 Attachments:

1. Figure 1: Valve Actuator and Protector Pipe

2. List of Recently Issued NRC Information Notices

• See previous concurrence

To receive a copy of this document. Indicate in the box: C' = Copy without attachmentlenclosure 'E' - Copy with attachment/enclosure

IN' No copy

OFFICE TOECB/DOPS T ED JchI S:OECB/DOPS EMEB/DE I E

NAME IGDentel* MMeJac* BDennig* TScarbrough*

DATE 103/15/95 02/27/95 03/30/95 04/03/95 OFFICE C:EMEB/DEDOPS I XOECB/DPSS I C:OECB/DPS I E D:DRPM

NAME IRWessman* RKiessel* AChaffee* DCrutchfield

DATE 104/03/95 05/08/95 05/15/95 / /95 u

LU[FILIAL KLLUKU LUrYJ -,0- S, " 1, g- DOCUMENT NAME: G:\TAG\C0950211.IN

IN 95-XX

May xx, 1995 This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact

one of the technical contacts listed below or the appropriate Office of

Nuclear Reactor Regulation (NRR) project manager.

Brian K. Grimes, Director

Division of Project Support

Office of Nuclear Reactor Regulation

Technical contacts: Thomas G. Scarbrough, NRR Thomas A. Greene, NRR

(301) 415-2794 (301) 415-1175 Attachments:

1. Figure 1: Valve Actuator and Protector Pipe

2. List of Recently Issued NRC Information Notices

DOCUMENT NAME: G:\GTD\C0950211.IN

• See previous concurrence

'E' = Copy with attachment/enclosurs

To receive a copy of this document, Indicate In the box: IC, = Copy without attachment/enclosure

n-N INOCopy

OFFICE OECB/DOPS IE Tech ED l E S:OECB/DOPS N EMEB/DE

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April XX, 1995 This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact

one of the technical contacts listed below or the appropriate Office of

Nuclear Reactor Regulation (NRR) project manager.

Brian K. Grimes, Director

Division of Project Support

Office of Nuclear Reactor Regulation

Technical contacts: Thomas G. Scarbrough, NRR Glenn T. Dentel, NRR

(301) 415-2794 (301) 415-1321 Attachments:

1. Figure 1: Valve Actuator and Protector Pipe

2. List of Recently Issued NRC Information Notices

• See previous concurrence 'E'

• Copy with attachmentlenclosure

To receive a copy of this document, Indicate In the box: 'C' - Copy without attachment/enclosure

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OFFICE *OECB/DOPS *Tech ED l *S:OECB/DOPS I E

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DATE 3/15/95 2/27/95 3/30/95 4/3/95 OFFICE C:OECB/DOPS *C: MEB/DE i

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DOCUMENT NAME: G:\GTD\C0950211.IN

IN 95-XX

. J KJsarcXX, 1995 G~ This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact

one of the technical contacts listed below or the appropriate Office of

Nuclear Reactor Regulation (NRR) project manager.

Brian K. Grimes, Director

Division of OperatiifglRcactor Support

Office of Nuclear Reactor Regulation

Technical X ntacts: Thomas G. Scarbrough, NRR Glenn T. Dentel, NRR

(301) 415-2794 (301) 415-1321 Attachments:

1. Figure 1: Valve Actuator and Protector Pipe

2. List of Recently Issued NRC Information Notices

• See previous concurrence 'E' Copy with attochment/enclosure

document, Indicate In the box: 'C

To receive a copy of this = Copy without attachment/enclosure

'N'

• No copy

OFFICE OECB/DOPS -Tech ED SC:OEP D)PS E

NAME GDentel 4 4 BDenv&Kv ITSe'aAWugh

DATE 03/1,'/95 02/27/95 03/ - /95 0 3 /95 OFFICE C:OECB/DOPS C:EMEB RD

NAME IAEChaffee WesskN4.'v BGrimes

DATE 03/ /95 Q3/3 1/95 03/ /95

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NAME RWessman BGrimes

DATE / /95 / /95 / /95 (OFFICIAL RECORD COPY]

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