ML19331C758

Forwards LER 80-012/01T-0

ML19331C758
Person / Time
Site:	Peach Bottom
Issue date:	08/04/1980
From:	Cooney M PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19331C759	List: ML19331C758 ML19331C767
References
NUDOCS 8008190496
Download: ML19331C758 (3)

Text

9 PHILADELPHIA ELECTRIC COMPANY 2301 MARKET STREET P.O. BOX 8699 PHILADELPHI A. PA.19101 (215)841 4000 August 4, l'980 4;. .l o y c e II . Grier, Director O f f '. c c of laspection and Enf orcement 3 c ;; '. o n i Unt'.ed States Muclear Regulatory Commission

$31 Park Avenue sin; of P ru s s ia , Pennsylvania 19406 Deat Mr. Grier:

SUBJECT:

Licensee Event Report Narrative Description The following occurrence was reported to Mr. Cowgill, Region I, Office of Inspection and Enforcement on July 21, 1980.

leference: Docket Number 50-277/278 Report No.: LER 2-80-12/lT-0 Report Date: August 4, 1980 Occurrence Date: July 21, 1980 l Facility: Peach Bottom Atomic Power Station RD 1, Delta, PA 17314 T_cch l i e n i, S.2ccification

Reference:

Technical Specification 6.9.2.a(9) states that

performance of structures, systems, or components that requires r e ne d ist l 2ction or corrective measures to provent operation in a

.ta n n e r less conservative chan assumed in the accident analysis...

of an unsafe condition.

Description of, tie, l Event:

During the Unit 2 operational hydro performed on July 16, 1930, the Unit 2 scram discharge volume vent and drain valves failed to operate. An analysis of this failure indicated that at least one of the vent and drain valve solencias (SV 2-3-31A & 3) and both tae scram backup valves (SV 2-3-140A & 3) failed to l operate. Investigation indicated that the backup scram solenoids l were rated for 250 vde while the control circuit was powered f rom a 123 vde aource. Dismantling of the scram discharge volume vent qs g,

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. Grier P ar;e 2

, est 4, 19aa Ldu 2-30-12/lT-0 nd drain valve solenoid valves determined that an improper r2 built hit uas installed during the previous maintenance period.

Probable Consequences of the Occurrence:

During normal operation, the scram valves on each

draulic control module for each control rod are maintained in ha closed nosition by an air supply which ma'intains pressure on

• S2 valve diaphragm. When scram is initiated via the RPS logic,

aC solenoid valves in the supply piping to the scram valves n aach hydraulic control module are de-energized, which vents

.2 air from the diaphragm and permits the scram valve to open, IraSy initiating rod insertion. As designed, the backup air

c :2 :s valves should be energized via the RPS logic when scram is

'nitiated. Energizing of these solenoid valves removes the air

.ui?ly from the entire scram valve pilot air header and exhausts ha air in this header to the atmosphere. In the unlikely event h2t the air pilot valves on a hydraulic control module failed to

>roperly port when de-energized, it would result in a delayed

' cram of that particular control rod. Inoperability of the

'a:wa scram valves would result in the pilot air header not bainn depressurized and requiring manual insertion of the affected rod.

Inoperability of the scram discharge volume cent and drain valve solenoids would result'in inhibiting closure of the scr2m discharge volume vent and drain valves following scram.

later flowing through the scram valves to the scram discharge v o lu,n e would therefore immediately be drained to radwaste. This ficw would continue as long as scram was not reset. Flow, however, would be limited by the leakage flow across the control roe seals following rod insertion. During the previous operation period, Unit 2 did experience several scrams. These were not act,apanied by significant inputs to radwaste or release of nateous or particulate activity. It has not been determined whether these valves were inoperable during the previous operating cycle.

Cause of the Svent:

Inoperability of the scram backup valves was caused by an initial design error.

Inoperability of the scram discharge volume vent and drain solenoid valves was caused by an improper maintenance operation.

c ce . Crier Page 3

,;t 's , 1930 LER 2-30-12/1T-0 Corrective Action:

Corrective action following the identification of this nroblem was as follows:

A review of the nameplate data on the scram backup vtive solenoids and the system Jrawings indicated that both Unit 2 nnd Unit 3 valves were identical. The inoperability of the

,ait 3 s c r a .a backup valves was immediately reported to the NRC.

'a operator was also stationed in the area of the air piping and ocevided with a procedure to manually vent the scram pilot air 1 i c. d e r follouing a scram. Engineering was requested to design a tt por2ry modification which would connect a 250 VDC source to t.e sceau backup solenoids. Simultaneously, General Electric C,ipany and the valve manufacturer were asked to identify.and

? o vi *e new coils with a 125 VDC rating. By July 27, new 125 VDC c .f is :t a d been obtained and a procedure developed to replace t :.c s c coils on Unit 3 without causing a scram. Following rarlacement, the scram backap valves were functionally tested s u ts f act orily. A similar replacement of the 250 VDC coils with 1.5 VGC coils has been completed on Unit 2.

The scram discharge volume vent and drain solenoid valves on Unit 2 were rebuilt with the p rop er rebuild kits.

llowinn repair, these valves were also functionally tested satisfactorily. In order to verify operability, the Unit 3 scram discharge volume vent and drain solenoid valves were also functionally tested on July 27, 1980.

Pre'ious L Similar Occurrences:

None.

l Very truly yours,

/

b M./J.

Cooney

. Superintendent Generation Division / Nuclear Attachment ec: Director, NRC - Office of Inspection and 2nforcement Mr. Norman M. It a lle r , NRC - Office of Management &

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Program Analysis I

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