ML20113A538

Final Part 21 & Deficiency Rept Re Damaged Wires on Westinghouse Ds/Dsl Circuit Breakers.Initially Reported on 841012.Damaged Wires Will Be Replaced & Addl Wire Ties Installed

ML20113A538
Person / Time
Site:	Satsop
Issue date:	12/27/1984
From:	Rohler A WASHINGTON PUBLIC POWER SUPPLY SYSTEM
To:	Kirsch D NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
References
REF-PT21-85-121-000 (D-N#54), D-N#54, G3-84-805, GO3-84-805, PT21-85-121, PT21-85-121-000, NUDOCS 8501210140
Download: ML20113A538 (4)

Text

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Washington Public Power Supply System

' Box 1223 Elma, Washington 98541 (206)402-4428ijgj pg 3l g, December 27, 1984 G03-84-805 Docket No. 50-508 U. S. Nuclear Regulatory Commission, Region V Office of Inspection and Enforcement 1450 Maria Lane, Suite 260 Walnut Creek, California 94596-5368 Attention: Mr. D. F. Kirsch, Acting Director Division of Reactor Safety and Projects

Subject:

NUCLEAR PROJECT NO. 3 POTENTIAL 10CFR50.55(e) DEFICIENCY WESTINGHOUSE DS/DSL CIRCUIT BREAKER DEFICIENCIES (0/N/l54)

On October 12, 1984, the Supply System notified your office of a potential 10CFR50.55(e) deficiency concerning the subject condition. A subsequent Engineering / Licensing evaluation has determined that if the deficiencies remained uncorrected they could have affected adversely the safety of operations of the plant. Therefore, the subject condition is reportable in accordance with the provisions of 10CFR50.55(e).

Attached is the Supply System approved final report. The report provides a description of the deficiency, analysis of safety implications and corrective actions taken/ planned. Should you have any questions or desire further information, please contact me directly.

91/A. -

hA.D'.Kohler l

(760)

WNP-3 Program Director i

cc: J. Adams, NESCO D. Smithpeter, BPA Ebasco, Elma Ebasco, New York E. M._ Burton, Pacific Power & Light Company R. D. Hill, Puget Sould Power & Light Company ,

P. Inman, Washington Water Power Company l B. D. Withers, Portland General Electric Company i Institute of' Nuclear Power Operations A. Tuzes, Combustion Engineering Document Control Desk - U. S. NRC E501210140 841227 gDRADOCK 05000508 I 'l PDR I

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WASHINGTON NUCLEAR PROJECT N0. 3 (DOCKET N0. 50-508) 10CFR50.55(e) DEFICIENCY FINAL REPORT 4 WESTINGHOUSE DS/DSL CIRCUIT BREAKER DEFICIENCIES (D/N#54)

DESCRIPTION OF THE DEFICIENCY Ebasco was informed by Westinghouse Electric Corp. of a condition involving damage to wires on several type DS and DSL circuit breakers. ' The condition 4

involves possible damage to, the breaker. internal control wiring when the breaker is moved on the extension rails into or out of its compartment. Such damage occurs when the wire bundle is pincN.d. between the wire retainer and the steel gas shield mounted on the power center frame. Twenty-two (22)

Class IE circuit breakers of this type were' supplied by Westinghouse to WNP-3 by Contract 3240-48. Also, two (2) additional circuit breakers of this type were supplied by Westinghouse to Combustion Engineering for the Reactor Trip Switchgear under Contract 3240-02.

Subsequent to this notification, a field inspection of all Class IE circuit breakers of this type was performed at the WNP-3 site and confirmed that this condition only existed on the circuit breakers supplied by Contract 3240-48.

Two (2) of the Class IE circuit breakers exhibited insulation scrapes on the breaker control wiring. The potential for wire damage also exists on some of the remaining breakers, as evidenced by the relatively small wire bundle clearance. Tne breakers in question supply power to motors which drive safety related equipment (pumps, fans, etc.) and also power Class IE 480 Volt Motor Control Center busses. The two (2) circuit breakers supplied by Contract 3240-02 did not exhibit any potential for wire damage due to a different housing design.

4 Possible failure modes from damaged wires would be: failure of electrically operated breaker to close on demand; failure to trip by shunt trip on demand; -

spurious electrical closing in connected position (if breaker has been l levered in with closing spring charged); failure to trip on overcurrent (if l equipped with Amptector device); arcing on a sensor lead (if equipped .with l Amptector device); false overcurrent tripping (if equipped with Amptector I with residual ground fault trip); false tripping from undervoltage trip attachment (if equipped with this device); opening of auxiliary switch circuits; and shorting of auxiliary switch circuits.

The above failure modes would require a completely broken wire or wires, l simultaneous grounds on specific wires, or direct short circuits between specific wires.

It should be noted that, to date, the damage that has . occurred was not extensive enough to cause any of the above malfunctions. Damage could~only occur while the -breaker is being moved in or out of its compartment on its

-extension rails. This operation is done durir.g periodic maintenance and inspection. Also, it is likely that any such damage would be detected by ,

Maintenance personnel. l Attachment I (Page 1 of 2)

ANALYSIS OF THE SAFETY IMPLICATIONS The safety hazard which~ could exist would be the failure of a Class IE 480 volt circuit breaker (s) to supply power to its load (s) when required. This could occur by:

-1) Failure to operate upon demand, or

2) False. tripping while in service.

As indicated above, the wiring damage sustained to date has not been extensive enough to cause any malfunction. If, however, this condition were to remain uncorrected, the repeated operation of drawing out the breaker could damage the wire to the point of failure which could in turn disable the control circuit (s) and thus result in a circuit breaker malfunction (s). This problem represents a potential common mode failure that could compromise the ability to achieve safe shutdown concurrent with an accident. Therefore, the subject deviation is considered significant and reportable per 10CFR50.55(e).

CORRECTION ACTION The corrective action to be taken involves replacing the damages wires on the two (2) circuit-breakers and installing additional wire ties, where required, to ensure adequate wire bundle clearance on all breakers. A procedure detailing this has been submitted by Westinghouse (see Attachment II) and will be utilized.

A preliminary inspection of the Non-Class IE circuit breakers found that this condition did not exist. However, a more detailed inspection will be performed later. If the same problem is found, the breakers will undergo the same corrective action discussed above.

Attachment I (Page 2 of 2)

Rsv. 2 m

) V"2T!3GECUS: '"CTRIC CORPORA

• ION S4I*CZGEAT' DIVISION I

S= NUCLEAR CI..SS II DS AND DSL 3R_AICER WIRING F INSPE0! ION

~

=-i A condition involving damage to vi es on several Type DS circuit breakers has been reported and confined. "ype DS and DSL circuit breakers should be checked for possible vire dange on the left side particularly in the vicinity of the wire retainer which foms the actreme left boundary of the breaker facing the breaker front. Wires which protrude, to the left, beyond the vire retainer may be damaged ~

or be subject to damage when *he breaker is noved on the estension rails into or cut of the breaker campartment if these wires are pinched between the wire retainer -

and the steel gas shield inside the breaker campartment. Vires which protrude or are likely to protrude, to the left, beyond the wire retainer should M treated as follows.

Wires which have been damaged, havi=g ,akihned insulation, exposed copper conductor, cr immage to the conductor itself, should be replaced. Wire of at least the same A.W.G. .si:e should be used and i=sulation should be egnivalent to or better than

• that of the damaged wire. Westi=ghouse currently uses ITT Surprenant Erane II 600 volt cross linked polyolefin insulated wire for Type DS/DSL circuit breaker viring in nuclear II applications. -

. Replaced vires should be fomed back into the wire retainer along with the undamaged wires. Wires entering the vire retainer at the rear of the breaker should be famed  :

Ji~into a reasonable radius and tied with vire ties. Westinghouse currently uses ETC

=fsylon, self-locking cable ties for Type DS/DSL circuit breakers.

Note: To pemit easier access to the wires inside the wire retainer, the wire retainer may be removed. Wires can then be more readily fomed and if deemed necessary, vire ties can be added to restrain the wires. When reMa*4= the~vire retainer, estrene care must be esercised not to pinch any wires between the breaker and the wire retainer.

Additional rigidity and mechanical support for wires and vire bundles any be pro-vided by adding additional wire ties to the bundles and by tying the to the structure of the breaker.

Application of these procedures vill prevent wires fram straying, to the left, beyond the wire retainer and prevent potential wire damage in this area. However, diligent concern for wires ~ and viri:q aust always be exercised when handli=g

brsakers and good practice dictates that circuit breaker viring should be visually inspected during nomal maintenance and before a breaker is re-inserted into a breaker empa,rtment.

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L. Kalning a R. A. Roach Product Engine

• Manager, Product Engineering Switchgear sion Switchgear Division .,

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