ML20085D062

Ao:On 730628-0705 & 09-10,changes Performed on Safeguards Equipment W/O Demonstrating Operability of Redundant Equipment Before Removal.Safety Injection Pumps B & C Tripped & Circuit Breaker Tripped,Respectively

ML20085D062
Person / Time
Site:	Robinson
Issue date:	07/17/1973
From:	Bessac N CAROLINA POWER & LIGHT CO.
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20085D064	List: ML20085D062 ML20085D066 ML20085D072 ML20085D077 ML20085D084
References
NG-73-199, NUDOCS 8307200103
Download: ML20085D062 (3)

Text

f - -- - - . . . . ..

4

- - i

)

mW">f dun Carolina Power & Light Company July 17, 1973 File: NG 5211.1 NG-73-199 g Q~ *

[

• l Mr. John F. O' Leary, Director Q%.,%,'.,[b:

.' ' < 4 s, k Directorate of Licensing 2-< # ,gj \p's

,2 p.t U. S. Atomic Energy Commission Q(

Washington, D. C. 20545 ' '

],

;s y l4!

N

/

50-261 \ v "

s M

Dear Mr. O' Leary:

.c H. B. ROBINSON UNIT NO. 2

. m LICENSE DPR-23 FAILURE OF SAFEGUARDS EQUIPMENT TO START ON MANUAL INITIATION e

In accordance with Section 6.6.2.A, Technical Specifications and Bases, it is reported that the following abnormal occurrences involving violations of procedural controls and failure of engineering safeguards equipment took place between June 28 and July 10, 1973.

During the period from June 28 to July 5, 1973, the breaker over-current trip devices on the safeguards equipment (except MCC-5 and 6) served from emergency busses E-1 and E-2 were replaced. This was done based on a vendor notification that these breakers (Type DB-50) contained .

potentially defective time delay dashpots which could neutralize the time delay feature. The new overcurrent trip' devices were identical to the originals except for the material of manufacture of a portion of the dashpot.

Subsequent review of plant operations and records by the staff revealed that these changes were performed on safeguards equipment without demonstrating the operability of redundant equipment before removal from service, a violation of Technical Specifications, and without demonstration of operability immediately after return to service, a violation of Administrative Procedures.

On July 9, 1973, while operating at 94% power, "B" Safety Injection Pump tripped upon initiatica of a manual start for a routine periodic test.

Subsequent checks of "A" and "C" pumps resulted in the tripping of "C" pump upon starting. This condition was discovered at approximately 0900 hours0.0104 days <br />0.25 hours <br />0.00149 weeks <br />3.4245e-4 months <br /> while attempting to supply makeup water to the Safety Injection System accumulators using "B" Safety Injection Pump. An investigation of the incident revealed that the pump trips were the result of the instantaneous overcurrent trips on the pump breakers being set at their minimum value. Further investigation by Westinghouse service personnel verified that the actual setting on the trip devices for "B" and "C" pumps was approximately 100 amperes below the intended setting. The instantaneous trip settings on these breakers were increased to approximately 750% of name plate rating, and the pumps were satisfactorily tested and returned to service.

j COPY SENT REGION ~ M r3072OO103 730717 PDR ADDCK 0500026 .m_m

/[6. li .

e n= ~

..u .

55 %

7 b

.m o m, . .n

- m.,.

O 0 v

Mr. John F. O' Leary . July 17, 1973 Also on July 9, 1973, "B" Auxiliary Feedwater Pump tripped upon initiation of a manual start during a routine periodic test. Investigation showed that the cause was a disconnected spring on the setpoint adjustment

~

for the instantaneous overcurrent trip. This spring supplies the tension which resists a breaker trip at any current less than the trip setting. If disconnected or misaligned, it has the effect of lowering the trip setting to a small percentage of the intended setting. The spring was replaced, and the pump was tested satisfactorily and returned to service.

At 0830 on July 10, 1973, while placing containment recirculation unit (HVH) No. 2 in service, the circuit breaker tripped. Investigation

• revealed that the cause of the trip was identical to that of "B" Auxiliary Feedwater Pump, discussed above. The disconnected spring was realigned, and the HVH Unit was returned to service at 1007 on July 10, 1973.

Immediate corrective action included resetting the instantaneous overcurrent trip setting on all safeguards equipment from 500% to 750% of breaker name plate rating. This change was recommended by the manufacturer and approved by the Plant Nuclear Safety Committee in special session. Following these adjustments, each piece of safeguards equipment was satisfactorily test operated a minimum of two times. The proper alignment of the instantaneous and time delay adjustment springs was verified by visual observation on all safeguards equipment breakers.

Calibration checks on the instantaneous and time delay trip devices were performed by Westinghouse service personnel on July 10-12, 1973. "Each breaker was trip tested a minimum of five times on the test bench, and the equipment was test run to ensure proper operation.

The personnel involved in the violation of procedural controls were thoroughly counseled and made aware of the potential consequences of their actions. They were instructed in the conditions which constitute equipment being inoperable and in their responsibility as licensed operators. It was made clear that this type of occurrence will not be permitted and cannot be defended.

A review of these incidents was conducted by the Plant Nuclear Safety Committee in two special sessions. The Committee approved the corrective actions taken and concluded that continued operation of the plant did not  ;

endanger the health and safety of the public.

I S

G

o es

. l Mr. John F. O' Leary -

3- July 17, 1973

• Notification of the incident was made'to Mr. Herb Whitener of DRO in person and to the Director of Licensing and the Director of Regional Regulatory Operations Office by telegraph on July 9 and 10,1973.

~

Yours very truly, .

}[ a_14 C N. B. Bessac

• Manager Nuclear Generation ACT:DBW:mvp

, cc: Messrs. C. D. Barham B. J. Turr D. V. Menscer N. C. Moscicy E. E. Utley D. B. Waters O

e I

4 i

. l

, ,