ML20086L519

AO 74-9:on 740311,contacts of Relay 2E-K8 of Automatic Depressurization Sys Failed to Close Per Design Intent During Surveillance Testing.Caused by Sticking of Spring Loaded Finger Contact.Finger Adjusted

ML20086L519
Person / Time
Site:	Peach Bottom
Issue date:	03/21/1974
From:	Cooney M PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Giambusso A US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20086L524	List: ML20086L519 ML20086L526 ML20086L527 ML20086L536 ML20086L538 ML20086L543
References
AO-74-9, NUDOCS 8402080293
Download: ML20086L519 (2)

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PHILADELPHIA ELECTRIC COMPANY /

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.<. w March 21, 1974 50-277 Mr. A. Giambusso Deputy Director of Reactor Projects ,

United States Atomic Energy Commission Directorate of Licensing Washington, DC 20545

Subject:

Abnormal Occurrence The following occurrence was reported to Mr. R. A. Feil, A.E.C.

Region I Regulatory Operations Office on March 12, 1974. Written noti-fication was made to Mr. James P. O'Reilly, Region I Regulatory Opera-tions Office on March 12, 1974. In accordance with Section 6.7 2.A of the Technical Specifications, Appendix A of DPR-44 for Unit 2 Peach Bottom Atomic Power Station, the following report is being submitted to the Directorate of Licensing as an Abnormal Occurrence.

Reference:

License Number DPR-44, Amendment Number 1, Technical Specification Reference Table 4.2.B Report No.: 50-277-74-9 Report Date: 3-21-74 Occurrence Date: 3-11-74 Facility: Peach Bottom Atomic Power Station, Unit 2 R.D. 1, Delta, Pennsylvania 17314 Identification of Occurrence:

Contacts of relay 2E-K8, of the automatic depressurization system, failed to close per design intent during surveillance testing of the "B" automatic depressurization system logic.

Conditions Prior to Occurrence:

l Reactor operating at approximately 23% power. The high pressure ,

coolant injection system was inoperable. ,,

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.< Mr. A. Giambussor"; <s j- March 21, 1974 km) k_) Page 2 Description of Occurrence:

Af ter determining that the high pressure coolant injection system was inoperable, testing was performed on the automatic de-pressurization system in accordance with Technical Specification 4.5.C.2.

Two normally open contacts of relay 2E-K8 failed to close when called upon to do so. The coil of this relay is connected directly across the "B" 125-volt d.c. bus which supplies- the normal power to the system's "B" logic. If a power failure on the "B" bus occurs, the relay de-energi ze s, two normally open contacts close, and power is transferred to the "A" 125-volt d.c. bus. These contacts f ailed to close upon simulating a power f ailure on the "B" bus.

Designation of Apparent Cause of Occurrence:

A Spring loaded finger contact on the armature block of the HFA type relay was found to be sticking in the block. If the contact stuck in the closing direction, it would prevent another contact from closing. If the contact stuck in the opening direction, it itself would not close.

Analysis of Occurrence:

The automatic depressurization system is designed such that no single failure, such as the one just described, can render the system inoperable. Even if a power f ailure on the "B" bus occurred, and the "B" logic group was not capable of swapping over to the other power bus, a redundant logic group "A" powered from the "A" bus, would still be capable of initiating the automatic depressurization system.

Corrective Action:

The sticking relay finger contact was adjusted so that it closed properly. The entire relay armature was replaced and retested during the reactor shutdown following the loss of power test on 3/11/74.

Very truly yours, i :s lX G 7'/

J. Cooney M .#

Ass' t Gen' t Superintendent Generation Division cc: Mr. J. P. O'Reilly Director, Region i United States Atomic Energy Commission j 631 Park Avenue i

- King of Prussia, PA 19406 i

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