Information Notice 1986-57, Operating Problems with Solenoid Operated Valves at Nuclear Power Plants

Operating Problems with Solenoid Operated Valves at Nuclear Power Plants

ML031220718
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:	07/11/1986
From:	NRC/IE
To:
References
IN-86-057, NUDOCS 8607090425
Download: ML031220718 (4)

11$S ORIGINAL SSINS No.: 6835 IN 86-57 UNITED STATES NUCLEAR REGULATORY

COMMISSION

OFFICE OF INSPECTION

AND ENFORCEMENT

WASHINGTON, D.C. 20555 July 11, 1986 IE INFORMATION

NOTICE NO. 86-57: OPERATING

PROBLEMS WITH SOLENOID OPERATED VALVES AT NUCLEAR POWER PLANTS

Addressees

All nuclear power reactor facilities

holding an operating

license or a construction

permit.

Purpose

This notice is to advise recipients

of a series of valve failures that have occurred recently at several nuclear power plants. It is expected that recipi-ents will review the events discussed

below for applicability

to their facili-ties and consider actions, if appropriate, to preclude similar valve failures occurring

at their facilities.

However, suggestions

contained

in this notice do not constitute

NRC requirements;

therefore, no specific action or written response is required.Description

of Circumstances:

The NRC has received reports from licensees

of operating

nuclear power plants involving

failures of certain valves that are actuated by solenoid operated valves (SOVs) to operate properly.

These failures have adversely

affected the intended functions

of the main steam isolation

system, pressure relief and fluid control systems. Attachment

1 to this information

notice describes

the failure events and the corrective

actions taken.Discussion:

In most of the cases described

in Attachment

1, the cause for triggering

the event was attributed

to a malfunctioning

SOV that served as a pilot valve. This in turn resulted in the malfunction

of the associated

main valve. The failures of the SOVs can be traced to the following

different

causes: (1) potentially

high-temperature

ambient conditions

are not being continuously

monitored

in areas where SOVs are installed

and operating

in an energized

state, (2) hydrocarbon

contaminants, probably because backup air systems (e.g., plant service or shop air systems) are being used periodically

and are not designed to "oil-free" specifications

as required for Class IE service, (3) chloride contaminants

causing open circuits in coils of the SOVs, possibly as a result of questionable

handling, packaging, and storage procedures, (4) an active replacement

parts program associated

with the elastomers

and other short-lived

subcomponents

used in SOVs has not been adequately

maintained, and (5) lubricants

have been used excessively

during maintenance.

ASCO provides installation

and maintenance

8607090425 Attachment

1 IN 86-57 July 11, 1986 b. Viton has superior high-temperature

performance

when compared to EP and is impervious

to hydrocarbons.

Its major disadvantage

is that it is less resistant

to radiation

than EP by a factor of ten. ASCO recommends

Viton for applications

that are not oil-free and where radiation

levels do not exceed 20 megarads.On the basis of a licensee review of the Brunswick

Station maintenance

history, which showed the performance

of Viton to be satisfactory

in ASCO valves, and the available

literature

and industry experience, the licensee replaced all Unit 2 dual solenoid valves with valves having Viton seats and seals. Because Viton has a 20-megarad

limit, the licensee plans to replace these elastomers

every 3.3 years to meet environmental

qualifica- tion requirements

for the MSIV application.

After replacing

the faulty valves with valves having Viton disc and seal material, the licensee experienced

several SOV failures resulting

from open circuits of the dc coils on Unit 2. (Brunswick

Station employs ASCO NP8323A36V

valves that use one ac coil and one dc coil in applications

using the subject dual solenoid valve.)On October 5, 1985, the dc coils of two MSIVs failed during the perfor-mance of post-maintenance

testing of the MSIVs. Investigation

into the failures indicated

an open circuit in the dc coils. The coils were replaced and the valves subsequently

retested satisfactorily.

On October 15, 1985, an unplanned

closure of an MSIV occurred while Unit 2 was operating

at 99 percent full power. Closure of the MSIV occurred when the ac solenoid coil portion of the MSIV associated

SOV was de-energized

in accordance

with a periodic test procedure.

It was not known then that there was an open circuit in the associated

dc solenoid coil portion of the dual SOV. Consequently, when the ac coil was de-energized, closure of the MSIV resulted.

The failed dc coil was replaced and then retested satisfactorily.

Investigation

into the failures of the dc coil by the licensee determined

that the failures appeared to be separation

of the very fine coil wire at the junction point where it connects to the much larger field lead. This connection

point is a soldered connection

that is then taped and lacquered.

Further analysis of the coils (two failed dc coils plus five spares from storage) by the CP&L Research Center indicated

the separation

might be corrosion

induced by chloride contaminants.

To date, the licensee and ASCO are unable to determine

the source of the chloride.

However, followup investigation

by the NRC revealed that ASCO had previously

experienced

similar dc coil open circuit anomalies

after a surface ship-ment of SOVs overseas to Japan. At that time, ASCO believed that the salt water ambient conditions

during shipping may have been the source of the chlorine-induced

failures.

ASCO recommends

specific handling, packaging, and storage conditions

for spare parts and valves at facilities.

Attachment

1 IN 86-57 July 11, 1986 The licensee initiated

a temporary

surveillance

program to monitor opera-bility of the solenoid coils on October 16, 1985. A modification

was performed

to install a voltage dropping resistor in the individual

coil circuits so that they can be monitored

directly from cabinets in the control room. This allows continuity

of the coil circuitry

to be verified by measuring

a voltage drop across the resistor.

According

to the licensee, until the cause for failure can be determined, plans are to check the coil circuitry

for continuity

on a daily basis.2. Scram Discharge

Solenoid Valve Failure In November 1985, Carolina Power and Light's Brunswick

facility experi-enced problems with several scram discharge

SOVs. The problems were identified

during periodic surveillance

testing to determine

the single rod insertion

times and resulted in several rods with slow insertion times. Initial troubleshooting

isolated the problem to the SOVs in the scram discharge

line for two of the control rods, which were subsequently

replaced and tested satisfactorily.

The licensee disassembled

the failed SOVs, which were manufactured

by ASCO (Model HV-90-405-2A), for failure analysis.

When the valves were disas-sembled, it was noted that copious amounts of silicone lubricant

had been applied by the licensee to all gaskets, seals, and diaphragms

internal to the valves during previous routine maintenance..

The licensee believes that the excessive

amount of lubricant

may have blocked some of the valves' internal passages or caused sticking of the diaphragms, thereby contributing

to the slow insertion

times. The technical

manual for the subject valves states that body passage gaskets should be lubricated

with moderate amounts of Dow Corning's

Valve Seal Silicone Lubricant

or an equivalent

high-grade

silicone grease.The licensee conducted

successful

scram tests on all other rods. A periodic retest of 10 percent of the control rods every 120 days as required by the Technical

Specifications

provides sufficient

assurance that this problem does not exist in other SOVs. In addition, the licensee stated that maintenance

procedures

and practices

would be reviewed and modified, as required, to prevent the application

of excessive

amounts of lubricant

during repair or overhaul of components.

Haddam Neck Nuclear Power Plant On September

10, 1985, the Haddam Neck Nuclear Power Plant was operating

at 100 percent power when one of the six SOVs in the auxiliary

feedwater

system (AFW)failed to change state when de-energized.

This failure was detected during the performance

of a preventive

maintenance

procedure

developed

to periodically

cycle each of the six SOVs to prevent a sticking problem similar to SOV fail-ures previously

experienced

on November 2, 1984. In that earlier event, two feedwater

bypass valves failed to open automatically

and the cause was deter-mined to be sticking SOVs. The faulty SOV was ASCO Model NP8320A-185E

and the licensee has been unable to determine

the cause of the malfunction.

The

Attachment

2 IN 86-57 July 11, 1986 LIST OF RECENTLY ISSUED IE INFORMATION

NOTICES Information

Date of Notice No. Subject Issue Issued to 86-56 Reliability

Of Main Steam Safety Valves 7/10/86 All PWR facilities

holding an OL or CP 86-55 86-54 Delayed Access To Safety-Related Areas And Equipment During Plant Emergencies

Criminal Prosecution

Of A Former Radiation

Safety Officer Who Willfully Directed An Unqualified

Individual

To Perform Radiography

Improper Use Of Heat Shrink-able Tubing 7/10/86 6/27/86 6/26/86 86-53 86-52 Conductor

Insulation

Degrada- 6/26/86 tion On Foxboro Model E Controllers

Excessive

Pneumatic

Leakage 6/18/86 In The Automatic

Depressuriza- tion System All power reactor facilities

holding an OL or CP All holders of by-product, source, or special nuclear material All power reactor facilities

holding an OL or CP All power reactor facilities

holding an OL or CP All BWR facilities

holding an OL or CP All power reactor facilities

holding an OL or CP All power reactor facilities

holding an OL or CP All BWR facilities

holding an OL or CP 86-51 86-50 86-49 Inadequate

Testing To Detect Failures Of Safety-Related

Pneumatic

Components

Or Systems Age/Environment

Induced Electrical

Cable Failues Inadequate

Testing Of Boron Solution Concentration

In The Standby Liquid Control System 6/18/86 6/16/86 6/13/86 86-48 OL = Operating

License CP = Construction

Permit