ML19318C607
| ML19318C607 | |
| Person / Time | |
|---|---|
| Site: | Shoreham File:Long Island Lighting Company icon.png |
| Issue date: | 08/22/1978 |
| From: | Burke T LONG ISLAND LIGHTING CO. |
| To: | |
| Shared Package | |
| ML19318C601 | List: |
| References | |
| SNRC-317, NUDOCS 8007020073 | |
| Download: ML19318C607 (3) | |
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O.. acc LONG lSLAN O LiG HTIN G COM PABN SHOREHAM NUCLEAR POWER STATION m s,w e g P.C. SCX sia. NORTM COUNTRY RO AD e WACING RIVER. N.Y.11792 Augusc 22, 1978 SNRC-317 Mr. Boyce Grier, Director' Office of Inspection and Enforcecent, Region 1 U.S. Nuclear Regulatory Commission 631 Park Avenue King of Prussia, PA 19401 LONG ISLAND LIGHTING COMPANY Shoreham Nuclear Power Station - Unit 1 Docket No. 50-322
Dear Mr. Grier:
'>n April 22, 1978, in accordance with 10CFR50.55 (e), we reported verbally to Region 1 a deficiency with the closing latch driving pawl associated with General Electric 4160 volt circuit breakers. ' This letter serves as our 90 day written report of this deficiency.
Descriotion of Deficiency The 4160 vole circuit breakers are General Electric type 1200 and 2000 ampere magne-blast breakers with ML-13 mechanisms, as manufactured by GE in their Philadelphia facilities.,
During field checkout of the subj ect breakers, i. was noted that an attempt to electrically close one of the breakers failed.
A subsecuent investigation revealed that the breaker closing latch had jammed and would not disengage from the breaker closing roller.
This resulted in a failure to release the breaker closing springer and, therefore, the breaker would not close upon receiving a close signal.
This deficiency was noted on safety related circuit breakers.
Failure of a breaker to close will prevent safety related equip-mant from being energized.
Corrective Action General Electric has-determined that the failure to close was caused by wearing of the driving pawl sleeve bearing.
This l
8007020073
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August 22, 1978 Mr. Boyce Grier Pega 2 bosring was a General Electric type Tuf-loc sleeve bearing, I
with a teflon coated fiberglass construction.
In accordance l
with instructions from General Electric, all breaker mechan-ics Tuf-loc sleeve. bearings shall be replaced with aluminum-bronze sleeve bearings.
Final adjustments to the mechanism I.'
shall be cade as required in accordance with reconstended GE
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Corrective Action to Prevent Recurrence Gansral Electric factory engineering and Quality Assurance groups have been fully apprised of this problem.
t Data of Full Comoliance t
Ja estimate that all adjustments to correct the driving pawls and the Tuf-loc sleeve bearings will be complete by February 28, 1979.
Very truly yours, i
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T Burke Proj eet Manager E
i-Shoreham Nuclear Power Station i
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A T T A C F2 2 :: T The breaker operating =achanism is of a spring-stored energy type, designed to give high speed opening and closing.
The spring charging mechanism compresses.the set of breaker closing springs through a high speed gear motor, eccentric, ratchet and driving pawl assembly.
The rotary motion of the motor is converted to a,'.
straight stroke through the eccentric and a lever.
The driving pawl is attached to the lever via a ein, and the oawl advances a ratchet wheel a few degreas with e'ach stroke, kotating the ratchet wheel approximately 130 degrees will fully compress the breaker closing springs.
After a few more degrees of rotation, the closing roller will engage the closing latch and the compress ed springs will be held by this latch until a closing operation is required.
During the last few degrees of ratchet wheel rotation, power to the spring charging motor will be interrupted and the motor and driving pawl assembly will coast to a natural stop, expending all residual energy.
During this coast-down period, the driving pawl rides over the ratchet wheel (i.e.) it is disengaged from the ratchet wheel teeth by riding on a metal bar which bridges the ratchet wheel teeth.
The breaker is closed electrically by energizing the close coil (spring release solenoid).
Energizing the coil will cause the closing latch to disengage This will release the closing springs,from the closing roller., whose energy will rotate a cam and p
close the. breaker.through the operating mechanism linkage.
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