Information Notice 1986-13, Standby Liquid Control Squib Valves Failure to Fire

Standby Liquid Control Squib Valves Failure to Fire

ML070180057
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:	08/05/1986
From:	Jordan E NRC/IE
To:
References
IN-86-013, Suppl 1, NUDOCS 8608010284
Download: ML070180057 (3)

SSINS No.: 6835 IN 86=13.W

., Supploement I

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF INSPECTION AND ENFORCEMENT

WASHINGTON, DC 20555 August 5, 1986 IE INFORMATION NOTICE NO. 86-13, SUPPLEMENT 1: STANDBY LIQUID CONTROL SQUIB

VALVES FAILURE TO FIRE

Addressees

All boiling water reactor facilities holding an operating license or a

construction permit.

Purpose

This notice is to alert addressees to additional information regarding the

causes of a generic problem with squib valves used in the standby liquid

control system. Recipients are expected to review the information for

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

preclude similar problems occurring at their facilities. However, suggestions

contained in this information notice do not constitute NRC requirements;

therefore, no specific action or written response is required.

Description of Circumstances

Information Notice 86-13 stated that failure of the squibs to fire at Vermont

Yankee was caused by two problems: a plant wiring change in the terminal box

and incorrect wiring of the connector supplied with the squib valve primer

charge. However the latest information regarding the event shows that the

principal cause for the squib valve failures and the loss of the standby liquid

control (SLC) system. function was the incorrect wiring in the primer chamber

supplied by the vendor in 1983 and initially installed in July 1984.

A secondary cause for the event was the failure to detect the manufacturing

defect before using the parts in the plant. Although a squib valve from the

vendor's same manufacturing lot was "bench" tested in the plant maintenance

shop before installation, the bench test only verified the adequacy of the

explosive material, but did not test the electrical wiring configuration. If a

test had been conducted for a representative sample of the chambers installed

in the SLC system in 1984, the loss of SLC system function could have been

prevented. The error was identified by the licensee's staff in February 1986 while testing the installed valves at the end of the operating cycle.

The electrical wiring configuration in the plant gave an indication of circuit

continuity in the control room but was incapable of firing the squib valves.

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IN 86-13, Supplement 1 August 5, 1986 NRC inspection also found irregularities in the plant wiring in that the

as-found firing circuit wiring differed from the design e-awings. The

differences occurred following a design change to the firing circuits in 1977 when difficulties encountered during the installation resulted in a needed

field modification for the firing circuit. The adequacy of the modified

circuit was demonstrated by the successful completion of the annual surveil- lance tests from 1977 to 1984 with primer chambers of the type supplied in

1977. The field modification did not go through the normal review process and

therefore was not reflected in a change to the as-built drawing of the firing

circuit. However, if the field modification had been reviewed in 1977 it would

have been approved. Thus the primary cause for the SLC system failure remains

the primer manufacturing error and the secondary cause is the failure to detect

the error.

Discussion:

According to the NRC staff's understanding, there are two important lessons

from the experience gained as a result of this event.

Bench testing of squib valves is not an absolute indication that the valves

will function in the plant circuit. Testing in the plant circuit provides an

added confidence that the plant circuit is capable of firing the valves.

Control room indication of circuit continuity may be achieved by an electrical

pathway that is not the pathway of the firing circuit. Therefore, control room

indication of SLC system continuity is not an absolute indication of the

circuit's ability to fire the squib charge and activate the SLC system.

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

If you have questions about this matter, please contact the Regional Adminis- trator of the appropriate NRC regional office or this office.

Divisi in of Emergency Preparedness

and Engineering Response

Office of Inspection and Enforcement

Eric Weiss, IE

(301) 492-9005 Attachment: List of Recently Issued IE Information Notices

Attachment I

IN 86-13, Supplement 1 August 5, 1986 LIST OF RECENTLY ISSUED

IE INFORMATION NOTICES

Information Date of

Notice No. Subject Issue Issued to

86-63 Loss Of Safety Injection 8/5/86 All PWR facilities

Capability holding an OL or CP

86-62 Potential Problems In West- 7/31/86 All power reactor

inghouse Molded Case Circuit facilities holding

.Breakers.Equipped With A an OL or CP

Shunt Trip

86-61 Failure Of Auxiliary Feed- 7/28/86 All power reactor

water Manual Isolated Valve facilities holding

a CP

86-60 Unanalyzed Post-LOCA Release 7/28/86 All power reactor

Paths facilities holding

an OL or CP

86-31 Unauthorized Transfer And 7/14/86 All NRC general

Sup. 1 Loss Of Control Of Industrial licensees that possess

Nuclear Gauges and use industrial

nuclear gauges

86-59 Increased Monitoring Of 7/14/86 All NRC licensees

Certain Patients With authorized to use

Implanted Coratomic, Inc. nuclear-powered

Model C-100 and C-101 cardiac pacemakers

Nuclear-Powered Cardiac

Pacemakers

86-58 Dropped Fuel Assembly 7/11/86 All power reactor

facilities holding

an OL or CP

86-57 Operating Problems With 7/11/86 All power reactor

Solenoid Operated Valves At facilities holding

Nuclear Power Plants an OL or CP

86-56 Reliability Of Main Steam 7/10/86 All PWR facilities

Safety Valves holding an OL or CP

OL - Operating Lice-,,;

CP - Construction Permit