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- MORR!STOWN, N.J.07950
- 201539 6111
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Puelic utihties Corporation o.n.rai 4
March 15, 1974 y
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Mr. A. Giambusso
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Deputy Director for P.eactor Projects N'.
Directorate of Licensing
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United States Atomic Energy Commission Washington, D. C. 20545
Dear Mr. Giambusso:
Subject:
Oyster Creek Station Docket No. 50-219 Abnormal Occurrence Report No. 50-219/74/17 The purpose of this Ictter is to fomard to you the attached Abnormal Occurrence Report in Compliance with paragraph 6.6.2.a of the Technical Specifications.
Enclosed are forty copies of this submittal.
Very truly yours, l
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Ivan R. Fin'froc1P, Jr.
Vice President
cs Enclosures cc:
Mr. J. P. O'Reilly, Director Directorate of Regulatory Operations, Region I I0' 1
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4 OYSTER CREEK NUCLEAR GENERATING STATION FORKED RIVER, NEW JERSEY 08731 Abnormal Occurrence Report No. 50-219/74/17
- Report Date March 15, 1974 Occurrence Date, March 7,1974 Identification of Occurrence Violation of the Technical Specifications, paragraph 3.7.B. when power operation of the reactor continued with the SB transformer unavailable for service for a time period greater than the Technical Specification limit of 7 days out of any 30 day period. This event is considered to be an abnormal occurrence as defined in the Technical Specifications, paragraph 1.15B.
Conditions Prior to Occurrence
'A routine plant shutdown was in progre'ss.
The major plant parameters at the time of the event were as follows:
Power:
Electric, "100 MWe j
Reactor, 5300 MWt 1
4 Flow:
Recirculation, 7.5 x 10 gpm Feedwater, 1.2 x 106 lb/hr Stack Gas:
=10,000 pCi/sec Description of Occurrence On Thursday, March 7,.1974, at 1700, as part of the routine plant shut-down procedure, it was required to transfer plant power from the IB auxiliary transformer to the SB startup transformer. The control room
. opera or:on duty operated the closing switch for the SIB breaker with t
no results. The reactor shutdown was teminated,: holding the generetor electric power at 'approxim,ately 100 MWe'in order to maintain a power supply path _ through the IB auxiliary transformer.
Inspection of the SIB breaker revealed that the closing spring was not in the charged position;
- hence,_ breaker closure was not possible in either the manual or automatic mode. The failure of the spring to wind has been traced to a failed spring cam switch which closes when the spring unwinds.* The cam switch closure normally causes a relay,_52Y, to energize which in turn deenergizes-
- Sec' attached reproduction of pertinent portion of General Electric
. Drawing No.' 0223K0173, Sheet 14.
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Abnormal Occurrence No. 50-219/74/17 Page 2 the SIB breaker closing coil 52X.
Contacts from 52X in turn cause the spring winding motor to start and rewind the spring.
Since the cam
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switch contacts failed to cause.52Y to energize, a continuous current, was applied to 52X causing it to burn which resulted in freezing the coil auxiliary contacts in their energized position.
It is thought 'at this time that the failure of the spring to rewind occurred following the January 12, 1974 reactor shutdown operation, since this was the last successful operation of -the breaker.
After replacing the 52X coil and the failed cam switch, successful transfer of load from IB auxiliary transformer to the SB startup transformer was achieved.
Apparent Cause of Occurrence Component failure was the cause of this occurrence.
The failure of the cam switch is presently under investigation.
Analysis of Occurrence
.The SIB breaker is intended to close automatically when the IB auxiliary transformer breaker trips.
Had the breaker been required to perform this function, it would have resulted in a loss of power to.the IB and.
ID 4160 volt switchgear.
The 1-2 emergency diesel generator would have initiated in the fast start mode and assumed load on the ID en.ergency b us.
Corrective Action At this time, it is thought that this occurrence is an isolated incident.
However, all 4160 volt safeguard and 460 volt safeguard switchgear will be checked to see that the closing springs have been properly charged.
In addition, the feasibility of installing a closing circuit monitoring system will be explored with the Generation Engineering Departncnt.
Failure Data Manufacturer data pertinent to the failed switch are as follows:
General Electric Company switch Part No. 456-A8668-5 4160V Switchgear
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c.obt %s 52 Limit switch for spring 52X Spring releases coil 52 Closing latch SMILS - charging motor contacts operates latch which
. CLMS - monitoring switch (1-2) (3-4) open and release closing springs is closed when contact (5-6) closed when to close 52 latch is capable springs are fully charged.
5215 Interlock switch closed charged closing springs.
of blocking fully when 52 is in fully raised or fuITy lowered position.
12R = Relay Panel Limit SW shown with PCB -
0223R0173 8F/DF = Gen. and Aux. Power Panel in raised position.
Sheet 14 of 15
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