ML19322C374
| ML19322C374 | |
| Person / Time | |
|---|---|
| Site: | Crane, Davis Besse  |
| Issue date: | 06/12/1978 |
| From: | TOLEDO EDISON CO. |
| To: | |
| References | |
| TASK-TF, TASK-TMR NUDOCS 8001160909 | |
| Download: ML19322C374 (1) | |
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TOLEDO EDISON COMPANY j
DAVIS-BESSE UNIT ONE NUCLEAR POWER STATION SUPPLEMENTAL INFORMATION FOR LER NP-32-78-07 DATE OF EVENT: June 12, 1978 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE:
Incorrect setpoints on essential bus undervoltage relays Conditions Prior to occurrence: The unit was in Mode 6 with Power (MWT) = 0, and load (MWE) = 0.
Description of Occurrence: On June 12, 1978, during the Station Review Board review of the " Safety Features Actuation System (SFAS) 18 Month Test", ST 5031.07, it was found that the time delay setpoints of the essential bus undervoltage relays were incorrect and that the monthly channel functional test was not being performed.
The initial investigation showed the Facility Change Request (FCR)77-217 which was implemented on October 4,' 1977, called for the time delay to be set at 9a seconds. FCR 77-430 was prepared on October 28, 1977, to correct the setpoints'to 7 + 1.5 seconds, but had not yet been issued for implementation on June 12, 1978.
This occurrence is being reported in accordance with the provisions of Technical Specification 6.9.1.8f.
Designation of Apparent Cause of Occurrence: The cause of this occurrence is 7
procedure inadequacy.
Analysis of Occurrence:
There was no danger to the health and safety of the public or to unit personnel.
The intent of the 7 1 1.5 second time delay setpoint is to ensure that a bus trip will occur in 9 seconds af ter the bus voltage degrades to less than 90% of the normal voltage. The average time delay setting of the relays was found to be 8.99 seconds.
Corrective Action: FCR 77-430 was immediately implemented and at.that time it was j
also found that the voltage setpoints were incorrectly set to a maximum of 2.5%
less than the technical specification minimum. One relay was found to be defective and was replaced. The time delay and voltage setpoints were adjusted to values in compliance with Table 3.3-4 of Technical. Specification 3.3.2.1.. A modification --
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(T-2870) was prepared for a test to be performed in conjunction with ST 5031.07 to satisfy the monthly functional check. A new' surveillance test procedure will
'be written to assure the monthly functional test is completed when the unit is in the applicable modes.
This work was completed on June 15, 1978 under Maintenance e
Work' Order 78-1397.
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Failure Data: This is not a repetitive occurrence.
J U bmMD 8001160 f
LER #76-061 j
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