ML19329A713
| ML19329A713 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 04/21/1977 |
| From: | DUKE POWER CO. |
| To: | |
| Shared Package | |
| ML19329A708 | List: |
| References | |
| RO-287-77-05, RO-287-77-5, NUDOCS 8001090689 | |
| Download: ML19329A713 (1) | |
Text
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[q,I; DUKE POWER COMPANY s
OCONEE UNIT 3 Report No.: R0-287/77-5 Report Date: April 21, 1977 Occurrence Date: March 25, 1977 Facility:
Oconee Unit 3, Seneca, South Carolina Identification of Occurrence: Reactor Protective System flux / flow /
imbalance function generator out of calibration Conditions Prior to Occurrence: Unit at 100 percent full power Description of Oc'urrence:
c On March 25, 1977, while performing the monthly Reactor Protective System Channel B On-Line Test, RPS Channel B tripped at a lower than required simulated reactor coolant flow. The flux / flow / imbalance function generator on NI-6 Power Range Channel was recalibrated and RPS Channel B was placed back in service approximately four hours after the on-line test.
Apparent Cause of Occurrence:
The cause of this incident has not been determined.
Three examinations of the NI-6 Power Range Channel were made during the next three weeks to determine if the channel was experiencing drift, but no indications of setpoint drift were found.
Analysis of Occurrence:
Although Reactor Protective System Channel B failed to trip during an on-line test at the required low flow setpoint, the other three redundant RPS channels assured that the required input 3 to the RPS would have been supplied. The RPS utilizes a two-out-of-four logic system, and would have been disabled only if two channels were inoperable.
It is concluded that this occurrence did not impair the operability of the Reactor Protective System, and therefore, the health and safety of the public was not affected.
Corrective Action:
The flux / flow / imbalance function generator on the NI-6 Power Range Channel was recalibrated. Checks for setpoint drift on the channel were made each week during the three weeks following the incident.
No evidence of setpoint drift-was discovered.
No similar problems with the flux / flow / imbalance function generator have been experienced in the past and no further correction action is considered i^ *"
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necessary.
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