Information Notice 1987-40, Backseating Valves Routinely to Prevent Packing Leakage

Backseating Valves Routinely to Prevent Packing Leakage

ML031130374
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, Skagit, Marble Hill
Issue date:	08/31/1987
From:	Rossi C Office of Nuclear Reactor Regulation
To:
References
IN-87-040, NUDOCS 8708250140
Download: ML031130374 (7)

SSINS No.: 6835 IN 87-40

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555 August 31, 1987 NRC INFORMATION NOTICE NO. 87-40: BACKSEATING VALVES ROUTINELY TO

PREVENT PACKING LEAKAGE

Addressees

All nuclear power reactor facilities holding an operating license or a con- struction permit.

Purpose

-

Thislinformation notice is provided to alert recipients to potentially sig- nificant safety problems that could be caused by backseating valves routinely

to prevent packing leakage. It is expected that recipients will review the

information for appliability to their facilities and consider actions, if

appropriate, to preclude a similar problem. However, suggestions contained

in this notice do not constitute NRC requirements; therefore, no specific

action or written response is required. ...

Description of Circumstances

On-June 12, 1987, Virginia Electric and Power Company reported (Licensee Event

Report [LER] 87-011-00) that on May 16, 1987,-a low flow reactor trip occurred

at its Surry Power Station, Unit 1. The cause of the low flow was the failure

of the. stem of the A hot leg loop stop valve. The stem failure permitted the

disk to drop and partially block flow in the A loop. The licensee is performing

a detailed metallurgical examination to determine the failure mode and mechanism

of the valve stem. The preliminary report indicated that failure was due to

stress or fatigue.

Before this event, the licensee had routinely backseated the loop stop valves

as part of its Containment Checklist Procedure before startup. In accordance

with this procedure, the valves were manually torqued onto their backseats to

1/16-inch deflection while the unit was in cold shutdown. This value was

reverified when the unit reached a hot shutdown condition. To reduce the

stress on the valve stem, the licensee is revising the operating procedure

so that the valves are normally operated off the backseat.

A similar event had occurred with the B hot leg loop stop valve on December 1,

1973. This failure was evaluated by Westinghouse, and a failure report,'"Surry

Unit No. 1 Reactor Coolant Isolation Valve Stem Failure Report," was issued on

March 7, 1974. In the report, the failure mechanism was identified as a high

878250140 "lit

IN 87-40

August 31, 1987 strain, low-cycle failure with little deformation. -- The high strain was at- tributed to the licensee's practice oftroutinely electrically backseating

the valves on torque during plant startup. In this method, the valve's motor

operator is used to drive the valve open. until the forces resulting from the

disk pressing against the backseat are high enough to cause the open torque

switch to open. This practice caused the valve stem to be subjected to high

stresses each time the valve-was opened. Depending on the gearing within the

motor operator, these stresses may have remained until the valve was closed

during the next plant shutdown.

The report recommended that the valves not be electrically backseated on torque.

It further recommended that if backseating became-necessary during maintenance, it should be done manually by the use of the'handwheel with minimum' applied load

and without exceeding the compensating spring pack deflection specified in the

manufacturer's revised instruction manual. This manual, "Instruction Manual

Motor Operated Reactor Coolant 30" Loop Stop Valves for Reactor Coolant System

Westinghouse WNES 546-CAK-70497B Darling Valve S.O. E-5004," states in a cau- tion that manual backseating is permissible only if the open deflector 'indicator

reading does not exceed 1/16-inch maximum and-that manual backseating may be

used only when the packing needs replacement. As noted above, contrary -to this

recommendation, it-had been the licensee's recent poliGy to routinely manually

backseat these valves during plant startup.

Before the-1973-value-stem-failureit-hadabeen4,h4 censeei t

seszpIactace .ts:--.-

routinely electrically backseat the valves during plant startup. Although

Virginia Electric and Power Company had stopped this'practice in-1974, the- NRC staff is aware that other licensees routinely electrically backseat valves.

The most common reasonfor this is to stop valve leakage from around the stem

on valves that are not readily accessible during plant operations.

The following inspection reports reflect current practices and problems related

to electrical backseating.-

(1) NRC Inspection Report'50-321/85-34 provides the results of-an inspection

at Edwin I. Hatch Nuclear Plant, Unit 1, performed between November 10 and

December 20, 1985. In the report, the inspectors noted observing informa- tion tags that'indicated that the reactor-core isolation cooling (RCIC)

system inboard steam line isolatio'n and the' reactor water cleanup- (RWCU)

system inboard-isolation valves had been electrically backseated. The

operating personnel indicated that they were not aware that any testing

had been done to verify that the valves would close within the required

time limits. -A violation was issued when subsequent testing of the RWCU

valve demonstrated that it could -not close within the required time'limits.

Additional testing of the RWCU valve showed that it did meet the closure

time limits'when it was not starting from a backseated condition.

NRC Inspection Report 50-321/86-22 and 50-366/86-22 provides the results- of an inspection performed at Hatch Units 1 and 2 between July 28 and

August 1, 1986., In the report, the inspectors noted that the licensee

routinely electrically backseated containment isolation valves in the high

pressure coolant injection, RCIC, RWCU, and recirculating pump systems.

K)

-

IN 87-40

August 31, 1987 'Review of maintenance records Indicated that the'valves had, been electri- cilly backseated as many as 18 times during the previous 2 years. The

procedure used by the licensee to electrically'backseat the valves con- sisted of bypassing the open limit switch and then driving the valve disk

onto the backseat until the locked motor current of the motor was ap- proached.

(2) NRC Inspection Report 50-277/86-25 provides the results of an inspection

at Peach.Bottom Atomic Power Station, Unit 2, performed between December 8 and 19, 1986. In the report, the inspectors noted the licensee's practice

of electrically backseating valves suspected of having excessive packing

leakage. The procedure used by the licensee involved an operator manually

closing the motor contacts at the motor control center. The contacts were

held closed until the operator noticed an increase'in the motor current

shown on a clamp-on amp meter.

Discussion:

General Electric Company's Service Information Letter (SIL) 385 issued November

1982-discusses potential valve damage and provides recommendations for motor- operated valves that are normally backseated or are subjected to excessive

backseating torque. This describes the types of damage that could be the

result of backseating as valve stem failure, valve stem elongation, backseat

damage, .cracking of the-stem nut, and-other-re'lted compornent distress.-- It -

also notes that most damage progresses slowly to the point where valve oper- ability is uncertain or valve failure occurs, before the damage is apparent.

Among the recommendations were:

(1) identification of the valves that are normally backseated or that may have

had excessive backseating torque applied and establishment of a program

for evaluation, inspection, and repair of these valves

-(2) consultation with valve and motor operator vendors to establish any

procedures or modifications that could minimize damage, including the

use of torque switches or other vendor-recommended alternatives to

backseating motor-operated valves.

The inspectors also indicated that the licensees for the Hatch and Peach Bottom

plants are taking actions to prevent recurring packing leaks. 'Georgia Power

Company is instituting a program at the Hatch units to replace the packing on

these valves at regular intervals and also plans to live load the packing to

help prevent packing leakage. At Peach Bottom, Philadelphia Electric Company

is modifying the packing gland area, replacing the existing asbestos-based

packing with graphite packing, installing carbon bushings, and live loading

the packing.

The information herein is!being provided as an early notification of a possibly

significant matter that is still under consideration by the NRC staff. If NRC

evaluation so indicates, further licensee action may be requested.

IN 87-40

August 31, 1987 No specific action or written response is required by this information notice.

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

Administrator of the appropriate regional office or this office.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contacts: George A. Schnebli, Region II

(404) 331-5582 Larry E. Nicholson, RI, Surry Power Station

(804) 357-2102 Keith Poertner, RI, Edwin E. Hatch Nuclear Plant

(615) 842-8001 Richard J. Kiessel, NRR

=_ 301) 492-9605 Attachment: List of Recently Issued Information Notices

UNITEO STATES

-FIRST-CLASS MAIL

NUCLEAR REGULATORY COMMISSI0N IPOSTAGEIIFtESPAIOI'

WASHINGTON. D.C. 255 IUSURCI

WASW O. C.

OFFICIAL sUSINESS PERMIT No. G67 PENALTY FOR PRIVATE USE. SM

- S

IN 87-40

August 31, 1987 No specific action or written response is required by this information notice.

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

Administrator of the appropriate regional office or this office.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contacts: George A. Schnebli, Region II

(404) 331-5582 Larry E. Nicholson, RI, Surry Power Station

(804) 357-2102 Keith Poertner, RI, Edwin E. Hatch Nuclear Plant

(615) 842-8001 Richard J. Kiessel, NRR

(301) 492-9605 Attachment: List of Recently Issued Information Notices

• SEE PREVIOUS CONCURRENCES

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08/2187

• OGCB:DOEA:NRR *RII *RII *RII *RII *PPMB:ARM *C/OGCB:DOEA:NRR

RJKiessel GASchnebli FJape ARHerdt LReyes TechEd CHBerlinger

08/17/87 08/19/87 08/19/87 08/19/87 08/19/87 08/21/87 08/24/87

IN 87-XX

• August xx, 1987 No specific action or written response is required by this information notice.

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

Administrator of the appropriate regional office or this office.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contacts: George A. Schnebl1, Region II

(404) 331-5582 Larry E. Nicholson, RI, Surry Power Station

(804) 357-2102 Keith Poertner, RI, Edwin E. Hatch Nuclear Plant

(615) 842-8001 Richard J. Kiessel, NRR

(301) 492-9605 Attachment: List of Recently Issued Information Notices

• SEE PREVIOUS CONCURRENCES

D/DOEA:NRR

CERossi

08/ /87

• OGCB:DOEA:NRR *RII *RII *RII *RII *PPMB:ARM C/OGCB:DOE NRB

RJKlessel GASchnebli FJape ARHerdt LReyes TechEd CHBerlinge&4 4 -1Y

08/17/87 08/19/87 08/19/87 08/19/87 08/19/87 08/21/87 08t/q/87

- a

'bin.-

IN 87-XX

August xx, 1987 No specific action or written response is required by this information notice.

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

Administrator of the appropriate regional office or this office.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contacts: George A. Schnebli, Region II

(404)331-5582 Larry E. Nicholson, RI, Surry Power Station

(804) 357-2102 Keith Poertner, RI, Edwin E. Hatch Nuclear Plant

(615) 842-8001 Richard J. Kiessel, NRR

(301) 492-9605 Attachment: List of Recently Issued Information Notices

D/DOEA:NRR

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08/ /87 OGCB:DOEA:NRR k II' RuI RII 4 RH J PPMB:AR FC/OGCB:DOEANRR

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