ML19326A045
| ML19326A045 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek, Davis Besse |
| Issue date: | 04/20/1973 |
| From: | Schwencer A US ATOMIC ENERGY COMMISSION (AEC) |
| To: | Sampson G TOLEDO EDISON CO. |
| Shared Package | |
| ML19326A046 | List: |
| References | |
| NUDOCS 8001310621 | |
| Download: ML19326A045 (2) | |
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Docket No. 50-346 The Toledo Edison Company ATDit Mr. Glenn J. Sampeen i
Vice President, Fower i
300 Edison Plaza Toledo, Ohio 43652 Gentlanen:
Two incidents have occurred at a nuclea power plant that indicate a i
deficiency in the control circuit design that warrants a review of the r
control circuits of all facilitics to assure that these types of defi-ciencies do not exist or are corrected if they do exist. Both incidents involved the inadvertent disabling of a component by racking out the circuit breaker for a different component. In one case, this caused the loss of capability to isolate secondary containment when this capability was required. In the second case, the racking out of a breaker for one punp disabled not only the pump being removed from service but also its redundant counterpart. Both of these occurrences resulted from the use of auxiliary contacts on the movable portion of the circuit breakers in the control circuits of other couponents. When the breaker is racked out, the control circuit employing these contacts is opened and may be l
rendered inoperable. Copies of the licensee's reports on these two occurrences are enciesed for your information. The licensee's corrective measures for both of these cases included redesign of the control circuits so that racking out the breakers would not render the control circuits of other equipment inoperable.
As a result of these occurrences, we request that you perforn a review of the control circuits of all safety related equipment at the plant to assure that disabling of one component does not, through incorporation in other intericching or sequancing controls, render other components in-operable. All modes of test, operation, and failure must be considered.
It appears that in the cases cited above, the racked out position of breakers had not been included in the failure mode analysis of these l
control circuits.
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Also, your procedures should be reviewed to ensure they provide that, whenever part of a reduarh=e system is removed from service, the portion j
remmising in service is functionally tested immediately after the dis-abling of the affected portion and, if possible, before disablir.g of the affected porties.
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'~ Form AEc-$ls (Rev.,9-53) ABCM 0240
- u s coven.namt marww. once i,72-4es-c s
l The Toledo Edison Cacapany q s
The results of your review are requested within sixty days. This l
information should be provided with one signed original and thirty-nine additional copies.
Sincerely, Uridnal Signed gy
& Schwencer A. Schwencer, Chief Pressurized '7ater Reactors Branch No. 4 Directorata of Licensing Enclosures I.icensee's reports on occurrences ect Leslie Henry, Esquire DISTRIBUTION Pullar, Seney. Henry & Hodge AEC POR 800 Owens-Illinois Building Local POR 405 Madison Avenue RCDeYoung i
Toledo, Ottio 43604 J Hendrie AKenneke Gerald Charnoff, Esquire RWKlecker Shaw, Pittman, Potts, Trowbridze OGC and Madden R0 (3) l 910 - 17th Street, N.W.
I APel tier Washington, D.C.
20006 EGoulbourne ASchwencer Donald H. Esuser, Esquire The Claveland Electric Illuminating Company P.O. Boa 5000, Roca 610 Cleveland, Ottio 44101 DISTRIBUTION:
I Docket PWR-4 R/F EIGoulbourne (2)
Project Manager l
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