ML20084H030

AO 50-244/74-04:on 740406,during Surveillance Test PT 2.1, Safety Injection Pump 1C Failed to Start Manually When Connected to Bus 16.Caused by Trip Bar Switch Prematurely Closing.Lockout Coil Assembly & Trip Bar Switch Adjusted

ML20084H030
Person / Time
Site:	Ginna
Issue date:	04/16/1974
From:	Amish K ROCHESTER GAS & ELECTRIC CORP.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20084H033	List: ML20084H030 ML20084H034
References
AO-50-244-74-04, AO-50-244-74-4, NUDOCS 8304270430
Download: ML20084H030 (4)

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ROCitESTER CAS AllD ELECTRIC CORPORATI0tt e 89 EAST AVEttUE, ROCHESTER, ti.Y.14549 u .. e. w,m m e...~,

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Mr. James P. O'Reilly, Director / ,/d Directorate of Regulatory Operations \ 9, Cg- ,.

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Subject:

Abnormal Occurrence 74-4: Failure of 1C Safety Injection Pump to start manually from Bus 16 /

R. E. Ginna Nuclear Power Plant,' Unit No.1 Docket, No. 50-244

Dear Mr. O'Reilly:

In accordance with Technical Specifications, Article 6.6.2a, the attached report of Abnormal Occurrence 74-4 is hereby submitted.

Ver ruly yours,

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ll Cb},f'19f /ML Keith W. Amish Attachment xc: Mr. John F. O' Leary

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1. Report No. : 50-244/74-4 2a. Report Date: April 16,1974 2b. _ Occurrence Date: April 6,1974

3. Facility: R. E. Ginna Nuclear Power Plant, Unit No.1

4. Identification of Occurrence:

This abnormal occurrence is defined by Technical Specifications Article 1.9d: Pallure of one or more components of an engineered safety feature or plant protection system that causes or threatens to cause the feature or system to be incapable of performing its intended function.

5. Conditions Prior to Occurrence:

At the time of the occurrence, the plant was in a hot shutdown condition.

6. Descrintion of Occurrence:

On April 6,1974, during the monthly performance of periodic test (PT 2.1), which verifies satisfactory Safety Injection pump head development, the IC Safety Injection pump failed to start manually 2 of the 4 times tried when connected to Bus 16. It had been tested successfully when connected to Bus 14.

7. Deci; nation cf Anparent Cause of Occurcence, The 1C Safety Injection pump can be operated from either Bus 14 or Bus 16. During a safeguard operating sequence, Bus 14 is the pre-ferential Bus and Bus 16 is considered the alternate Bus. A lockout scheme exists between the two supply breakers to insure that only one breaker can be closed at a time. When the system is functioning '

properly, the lockout relay will energize when a breaker closure is  !

called for, providing that all interlocks are satisfied. The sequence for proper operation is as follows: ,

(a) The lockout relay's plunger will force the trip bar downward and properly latch the breaker's mechanical closing mechanism.

(b) The movement of the trip bar closes a trip bar switch which f then permits the breaker control relay to operate ("X" coil). ~

(c) Operation of the control relay reflects a closed "X" contact i' in the circuit for the breaker closing coll.

(d) The closing coil is then energized and the coil's armature will travel upward resulting in actuation of the breaker closing mechanism.

The cause of the intermittent failures was that the trip bar switch was closing prematur aly. This allowed the breaker control relay to energize which in turn energized the breaker closing coil. However, L

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,. Abnormal Occur 'nce 74-4 cont'd. A 2, V

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because the breaker's mechanical latch had not yet properly positioned the breaker's mechanical closing mechanism, the breaker would not close.

Although it did not contribute to the occurrence, another condition was noted during the investigation. A IMFD capacitor in the control circuit was found to fall intermittently. This capacitor is connectea in series with a 5 ohm resistor and they are in parallel with a normally open contact for the white breaker trip light and the 74BFD alarm relay.

This intermittent failure caused a white light and alarm.

8. Analysis of Occurrence:

There were no safety implications because the pump did start from Bus 14, and also both the 1A and IB Safety Injection pumps started satisfactorily. There were no consequences or potential consequences from the standpoint of public health and safety.

9. Corrective Action:

! The lockout coil assembly and the tripper bar switch were adjusted i so that the breaker's mechanical closing mechanism will latch into position before the trip bar switch closure is established. The IMFD 1

capacitor in the control circuit was replaced. The IC Safety Injection

pump was started successfully 6 times immediately after the adjustments 4 were made and the pump was restored to normal service at 1600 hours0.0185 days <br />0.444 hours <br />0.00265 weeks <br />6.088e-4 months <br /> on j Sunday, April 7,1974. The pump was also started successfully from

! hc 15 cn April 10 and April 11, 1074.

[ The Plant Operations Review Committee reviewed the abnormal 4

occurrence and the Committee concurred that the adjustments that were

, made should prevent a repetition of the occurrence and that the continued monthly surveillance should verify that the Safety Injection system will i

I respond promptly and perform its intended function.

10. Failure Data:

(a) Previous failure of the IC Safety Injection pump to start from Bus 16 was reported to the AEC in a letter dated June 21, 1973 and listed as Abnormal Occurrences 73-3 and 73-4. After the L June 1973 letter, Periodic Test (PT 2.1) was revised to require that the IC Safety Injection pump be started from both-Bus 14 and Bus 16. Since that time the pump has been manually started successfully from .either Bus supply until this latest incident.

l- Also, correct automatic starting of the IC Safety Injection pump was verified during the recently performed Refueling Shutdown l Surveillance Procedure RSSP 2.2. This is a test of the diesel generator automatic starting and carrying safeguards load. .

The cause of this abnormal occurrence is different from abnormal ~

occurrences 73-3 and 73-4 which were experienced on June 11 and 12, 1973 respectively. At first it was believed that the over-current trip.

device in the pump breaker was misaligned, however, the next day -

the breaker was removed and further inspaction showed the operator-

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Abnormal Occurronce 74-4 cont'd. ,c 3.

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arm on the cell switch to be slightly bent. Investigation has been conducted by Westinghouse and Rochester Gas and Electric to install a cell monitor indication light to verify the continuity of lock-out relay logic of the breaker and this installation is under review by on-site and off-site review committees for installation in the near future.

(b) Equipment identification:

Westinghouse DB-50 Air Circuit Breaker 500 amp Rating.

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