ML19308B136
| ML19308B136 | |
| Person / Time | |
|---|---|
| Site: | Oconee, Mcguire, McGuire  |
| Issue date: | 09/23/1977 |
| From: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | Parker W DUKE POWER CO. |
| References | |
| NUDOCS 7912130784 | |
| Download: ML19308B136 (1) | |
Text
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,(pS K8%q{o, UNITED STATES NUCLEAR REGULATORY COMMISSION 2
w(g REGION 11
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g 230 PEACHTREE STREET. N.W. SUITE 1217 o
ATLANTA, GEORGI A 30303
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g SEP 2 31977
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g In Reply Refer To:
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RII:JPO 50-369, 50-370
, 50-269, 50-270 50-287 Duke Power Company Attn:
Mr. William O. Parker, Jr.
Vice President, Steam Production P. O. Box 2178 422 South Church Street Charlotte, North Carolina 28242 Gentlemen:
~
The enclosed Circular 77-13 is forwarded to you for information.
If there are any questions related to your understanding of the sug-gested actions, please contact this office.
Sincerely, i
James P. O'Reilly Director
Enclosure:
J. C. Rogers, Project Manager McGuire Nuclear Station P. O. Box 2178 Charlotte, North Carolina 28242 M. D. McIntosh, Plant Manager McGuire Nuclear Etation-P. O. Box 488 1
Cornelius, North Carolina 28031 J. E. Smith, Station Manager Oconee Nuclear Station P. O. Box 1175 d
Seneca, South Carolina 29678
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79121307f y e
IE Circular 77-13 Date:
September 22, 1977 Page 1 of 3 l
1 Reactor safety signals negated during testing l
On July 12, 1977, the Commonwealth Edison Company reported that while i
conducting a surveillance test at Zion Unit 2, test signals were simul-taneously injected into several sensors which affected both protection and control systems. Injection of these test signals resulted in:
(1) the loss of instrument indications for the affected protection and control systems, (2) the loss of automatic control capability for the l
affected control systems, and (3) the loss of automatic protection capability for'the affected protection systems.
At the time of the event, the unit was in a hot shutdown condit' ion and preparations for start-up were, underway.
Station management decided to perform a surveillance' test -of the reactor protection logic circuitry.
A combination of test procedure inadequacies and the failure to follow prescribed administrative controls related to instrumentation testing led to the insertion of test signals which replaced the actual signals from three pressurizer water level sensors, three water level sensors in each of the four steam generators, four pressurizer pressure sensors and three flow sensors in each of the primary coolant loops.
The test signals had been inserted for approximately 40 minutes when, due to unexpected indications of the main coolant pump seal flow rate and other anomal ~ous indications,- the operator requested that the test signals be removed. When the test signals were removed, it was observed that the pressuriz'er water level had dropped below the range of indication.
The dro'p in pressurizer water level resulted from the pressurizer Mater level test signal being slightly higher than the automatic pressurizer' level control set point.
In response to this condition the changing pump flow was automatically reduced to the minimum pump flow rate, which was maintained until the test signals were removed.
During this forty minute period the letdown flow remained constant.
Consequently, the rate at which coolant was being removed from the primary coolant system was approximately 75 gpm greater than the rate at which coolant was being returned to the system. Approximately 5300 gallons of water was required to bring the pressurizer water level back to its original level of twenty-two percent.
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