ML19290A428
| ML19290A428 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek, Crane |
| Issue date: | 03/07/1973 |
| From: | Schwencer A US ATOMIC ENERGY COMMISSION (AEC) |
| To: | John Miller METROPOLITAN EDISON CO. |
| Shared Package | |
| ML19290A429 | List: |
| References | |
| NUDOCS 7911070608 | |
| Download: ML19290A428 (2) | |
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UNITED STATES
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ATOMIC ENERGY COMMISSION
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Docket No. 50-269 Metropolitan Edison Company ATTN:
Mr. John G. Miller Vice President P.O. Box 542 Reading, Pennsylvania 19603 Gentlemen:
' hat indicate a Two incidents have occurred at a nuclear power plant t
deficiency in the control circuit design that warrants a review of the control circuits of all facilities to assure that these types of defi-ciencies do not exis t 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 pump 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 components.
When the breaker is racked out, the control circuit e= ploying these contacts is opened and may be rendered inoperable.
Copies of the licensee's reports on these two occurrences are enclosed for your information.
The licensee's corrective measures for both of these cases included rederign 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 perform 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 interlocking or sequencing controls, render other components in-operable.
All modes of tes t, 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 control' circuits.
Also, your procedures should be reviewed to ensure they provide that,
whenever part of a redundant system is removed from service, the portion remaining in service is functionally tes ted immediately af ter c:.e dis-abling of the affected portion and, if possible, before disabling of the affected portion.
1557 282 4 2' 7911070 O
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4 Metropolitan Edison Company The results of your review are requested within sixty days.
This information should be provided with one signed original and thirty-nine additional copies.
Sincerely, Onginal Si;;ne 1 by Abert Schwencer A.
Schwencer, Chief Pressurized Water Reactors Branch No. 4 Directorate of Licensing
Enclosures:
Licensee's reports on occurrences cc:
General Public Utilities Service Corporation ATTN:
Mr. R. W. Heward, Proj ect Manager Safety and Licensing 260 Cherry Hill Road Parsippany, New Jersey 07054 General Public Utilities Service Corporation ATTN:
Mr. T. Crincins, Manager Safety and Licensing 260 Cherry Hill Road Parsippany, New Jersey 07054 Gerald Charnoff, Esquire Shaw, Pite=an, Potts, Trowb ridge,
and Madden 910. - 17th Street, N.W.
Washington, D.C.
20006 r
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