ML20246L567
| ML20246L567 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 08/30/1989 |
| From: | William Cahill TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| CP-88-33, TXX-89632, NUDOCS 8909060355 | |
| Download: ML20246L567 (2) | |
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Log. # TXX-89632 1
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908.3 Ref. # 10CFR50.55(e) 7t# ELE (37RIC August 30, 1989 Executive Vke President U. S. Nuclear Regulatory Commission Attn: focument Control Desk Washington.D.
C.
20555
SUBJECT:
COMANCHE PEAK STEAM ELECTRIC STATION (CPSES)
DOCKET NOS. 50-445 AND 50-446 EDG VOLTAGE OUTPUT SDAR: CP-88-33 (SUPPLEMENTAL REPORT)
Gentlemen:
On August 30. 1988, TU Electric verbally notified the NRC of a reportable
' deficiency under the provisions of 10CFR50'.55(e). involving the Emergency Diesel Generator (EDG) static exciter voltage regulation (SEVR) circuitry.
The last report on this issue,-logged TXX-89272, was submitted May 25, 1989.
This supplemental report is to inform you of an additional corrective, action for'this-issue.
As discussed in TXX-88656, dated August 31, 1988, the CPSES EDG's are designed to operate.at 450 rpm. Upon initiation of EDG shutdown, the SEVR is tripped and does not reset until the encine speed decreases to 425 rpm.
If an emergency start -signal is received.during the coastdown prior to reaching 425
-rpm,;the engine would accelerate to its synchronous speed of 450 rpm but there would be no generator output, since the exciter would not be energized.
As discussed in TXX-89272, to prevent occurrence of this postulated event, the Unit I system operating procedure has been revised to require that during EDG shutdown, an operator will be present at the EDG local control panel.. The operator's function is'to manually activate the exciter reset pushbutton if the EDG starting light comes on during the shutdown. The start light on the panel indicates emergency demand for an EDG start.
8909060355 890830 PDR ADOCK 05000445 S
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400 North Olive Street LB Hi Dallas, Texas 75201 Q -
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' August 30, 1989
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' Although the' above corrective action adequately = addresses the' safety' concern associated'with this issue, TU. Electric has elected to pursue a design modification to the diesel generator exciter circuitry that will ensure the energization of the exciter upon. receipt of an emergency. start signal. ("S". or manual emergency start)'and alleviate the need for a manual operator action.
This design modification will' be completed prior to commercial operation of
- Unit I and prior.'to Unit 2 fuel load for Unit 2.
Sincerely.
JhDa
'l i
William J. Ca ill, Jr.
M N
By:
Roge'r df Walker
~
Manager, Nuclear Licensing
.WJH/vid c - Mr. R. D. Martin,-Region IV Resident Inspectors CPSES (3)
,