ML20211P702
| ML20211P702 | |
| Person / Time | |
|---|---|
| Site: | Fermi  |
| Issue date: | 12/12/1986 |
| From: | Lenart R DETROIT EDISON CO. |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| NP860650, NUDOCS 8612190123 | |
| Download: ML20211P702 (4) | |
Text
1 P7a na Fermi-2 6400 North Dixie Hi Ed.ison me=
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December 12, 1986 NP860650 PRIORITY FOUTIf.G Mr. James G. Keppler
_h Regional Administrator g ; kj; ?L_
pt Region III U. S. Nuclear Regulatory Commission 6-h pj!.
799 Roosevelt Road y
Glen Ellyn, Illinois 60137 nt4/
Dear Mr. Keppler:
References:
(1) Fermi 2 NRC Docket No. 50-341 Facility Operating License No. NPF-43 (2) Emergency Diesel Generator Start Failure Report, NP 86034 4, Dated July 11, 1986
Subject:
Emeroency Diesel Generator Start Failure Please find attached our report on one start f ailure of Emergency Diesel Generator (EDG) 12 which occurred on November 14, 1986.
This report is submitted to you in accordance with Fermi 2 Technical Specificaitons 4.8.1.1.3 and 6.9.2.
If you have any questions regarding this report, please contact Mr. Lewis Bregni at (313) 586-5313.
Sincerely, w
R.
S. Lenart Plant Manager cc:
W. G. Rogers J.J. Stefano G. C. Wright Xgl f
USNRC Document Control Desk Washington, D.C. 20555 gatg@R $$hgi O
9G S
r Mr. James G. Keppler December 12, 1986' NP860650-Page 2 ENCLOSURE 1 Emergency Diesel Generator Start Failure I
1.
Emeroency Diesel Generator Involved:
Emergency Diesel Generator EDG 12 2.
Identification of Failure Failure Date: November 14, 1986, 0933 hours0.0108 days <br />0.259 hours <br />0.00154 weeks <br />3.550065e-4 months <br /> Description of Event:
This :- the second start failure of EDG 12 since the issuance of the Ft ti 2 operating license.
At the time of this start failure, there had been 27 previous valid test starts since the operating license was issued.
The November 14, 1986 start f ailure is considered a f ailure in an invalid test under section C.2.e(2) of NRC Regulatory Guide 1.108 because the failure involved, a " low jacket water pressure" trip, which is bypassed during emergency starts.
The cumulative number of start failures incurred during valid tests for EDG 12 sine issuance of the operating license remains unchanged at one.
3.
Cause of Failure:
On November 14,1986, EDG 12 was being started to perform a
" fast" start surveillance test, which is required on a six month basis.
About 8 seconds af ter receiving a start signal, the engine unexpectantly tripped due to lov jacket water pressure.
A jacket coolant pressure low alarm was received.
The low jacket water pressure trip signal and the jacket coolant pressure low alarm are both initiated by the CPLA pressure switch.
The following trouble shooting activities were performed to determine the cause of the engine trip:
a)
The CPLA pressure switch calibration was verified to be acceptable.
b)
A functional check of the CPLA pressure switch scheme was performed and all terminations in the scheme were checked.
No problems were found.
c)
A troubleshooting " slow" star t was made on EDG 12 and the jacket water system pressure was checked at 575, 775, 900 &
945 RPM.
No variation was noted between pressures recorded and pressures that were taken during testing in 1985.
l
4 Mr. James G. Keppler December 12, 1986 NP860650 Page 3 d)
A " fast" start was performed on EDG 12.
During the start,
- actual pressure at the CPLA pressure switch was compared to the engine rpm.
It was found that the pressure at 810 rpm only marginally exceeded the setpoint required to close the switch.
At 810 rpm a relay closes activating the CPLA Pressure switch.
After reviewing the above information with the engine vendor (Colt Industries, Fairbanks-Morse Engine Division), it was determined that (for this start) the jacket water coolant pressure was insufficient to close the CPLA pressure switch before the engine reached 810 rpm.
The cause of this problem could not be resolved.
Because the jacket water pressure barely exceeds the CPLA setpoint threshold, it appears that enough time was not permitted for the engine to develop sufficient jacket water pressure.
Prior to 1985, the CPLA pressure switch was bypassed for 10.5 seconds after the engine reached 810 rpm.
In 1985 the EDG trip logic was modified to bypass the CPLA pressure switch until the engine reaches 810 rpm.
This logic change allows " slow" start capability during testing.
It should be noted that the EDGs were started using "f ast" starts in excess of 35' times without jacket water low pressure trip or alarm af ter the " slow" start modification was inctalled.
At the completion of troubleshooting, EDG 12 was restarted
("f ast" start) and surveillance testing was successfully completed on November 15, 1986.
4.
Corrective Measures Taken:
Af ter evaluating the data obtained during troubleshooting, Detroit Edison has decided to revise the CPLA pressure switch setpoint on all four Emergency Diesel Generators.
This will ensure that the switch will be closed prior to the engine reaching 810 rpm, and should preclude recurrence of a similar event.
The new setpoint still assures sufficient jacket water pressure is maintained while the engine is running.
5.
Lenoth of Time EDG Unit Unavailable:
EDG 12 was out of service less than 28 hours3.240741e-4 days <br />0.00778 hours <br />4.62963e-5 weeks <br />1.0654e-5 months <br /> to troubleshoot the EDG and determine the cause of the start failure.
. ~o Mr. James'G. Keppler December 12, 1986 NP860650 Page 4 6.
Current survelliance Test Intervair The current surveillance. test interval is once per 31 days.
7.
Verification of Conformance of Test Intervair Because this start failure is considered an " invalid test" start failure as defined by Regulatory Guide 1.108, the EDG surveillance test interval is not affected.
As reported in Reference 2, the number of valid test start failures of EDG 12 is equal to one, and the required test frequency stated in Fermi 2 Technical Specification Table 4.8.1.1.2-1 is at least once per 31 days.
Therefore, the current surveillance test interval is in conformance with Regulatory Position C.2.d of Regulatory Guide 1.108 and with Fermi 2 Technical Specifications.
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