ML20140E323
| ML20140E323 | |
| Person / Time | |
|---|---|
| Site: | Hope Creek  |
| Issue date: | 12/14/1984 |
| From: | Martin J Public Service Enterprise Group |
| To: | Murley T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| REF-PT21-85-033-000 PT21-85-033-000, PT21-85-33, NUDOCS 8501100775 | |
| Download: ML20140E323 (3) | |
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Public Service Electric and Gas Company Thomas J. Martin 80 Park Plaza, Newark, NJ 07101 201430-8316 Mailing Address: P.O. Box 570, Newark, NJ 07101 trica President Engineering and Construction December 14, 1984 Dr. Thomas E. Murley, Administrator U.
S. Nuclear Regulatory Commission Office of Inspection and Enforcement Region I 631 Park Avenue King of Prussia, Pennsylvania 19406
Dear Dr. Murley:
POTENTIAL CONSTRUCTION DEFICIENCY GE SUPPLIED TOPAZ INVERTERS HOPE CREEK GENERATING STATION On October 9, 1984, a verbal report was made to Region I, Office of Inepection and Enforcement representative, Mr. E.
Kelly, advising of a potentially significant construction deficiency concerning the low voltage cut off setting on Topaz inverters supplied by General Electric.
On November 8, 1984, an interim report was submitted to your office.
The following final report is provided in accordance with 10CFR50. 55 (e).
Description of the Deficiency Our Architect / Engineer and Constructor, Bechtel, has advised us that the low voltage cut off and turn-on adjustment for GE Class lE inverters was set too high by.the original manufac-turer, Power Mark, a division of Topaz.
The GE dedication process was checking for an operable range of 105 to 140 volts DC, instead of 100 to 140 volts DC.
Topaz had been routinely setting the low voltage cut off at 105 volts DC. _ General Electric has specified typical DC bus voltages to range from 108 to 132 volts with momentary volta 3e dips to 105 valts DC
~during the startup of large DC loads.
This results in a condition where the inverter may not start or restart until the voltage is increased, not just to 105 volts DC, but to above 118 volts (13 volt fixed offset).
Since the allowable momentary dip of the input bus voltage is equal to the 8501100775 841214 PDR ADOCK 05000354 S
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Dr. T. E. Murley 2
12/14/84 factory preset inverter low voltage cut off (105VDC), the concern was that this dip could result in an inverter trip and a failure to restart during a design base accident.
Safety Analysis Bechtel has investigated the problem and determined that Topaz inverters have only been supplied to Hope Creek by GE, for use in panels Hil-P617, P-618, P-620, P-621, P-640 and P-641.
The safety systems affected by these panels are RHR, Core Spray, HPCI and RCIC.
Bechtel Project Engineering has performed an analysis of safety implications and determined that the Hope Creek DC system design is such that the battery capacity is sufficient to maintain the system voltage above 105 volts during the design basis accident (DBA) upon loss of the battery charger for four hours.
The DBA loading includes starting and operating
. required loads during this period, and the only time in which the system voltage may be at 105 volts is at the end of the battery duty cycle.
At the end of the battery duty cycle, all safety functions will have been accomplished.
Since the batteries of the affected systems are independent and are connected to Class lE battery chargers served by Class lE AC power sources, it is unlikely that more than one battery system channel will be without its battery charger (in conformance with the single failure criterion).. When a battery is connected to a battery charger, the system voltage is always above 105 volts for all conditions of loading.
Even when assuming a single failure of a battery' charger, safe operation of the plant is not affected by the existing low voltage setpoint of the Topaz inverters.
Therefore, this item related to the Topaz inverter would not impact the safe shutdown of the plant.
Based upon the above analysis, we conclude-that the. subject deficiency is not reportable in accordance with 10CFR50.55 (e).
Corrective Action
-General Electric will issue a Field Disposition Instruction providing for testing and adjusting as necessary the Topaz J
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Dr. T. E. Murley 3
12/14/84 inverters.
The Instruction will specify that the inverter shall not trip at voltages between 100 and.140 VDC, and after an inverter trip, it shall resume operation when input voltage increases to 108 VDC.
Very traly yours,
/
C Office of Inspection and Enforcement Division of Reactor Construction Inspection Washington, D. C.
20555 NRC Resident Inspector - Hope Creek P. O. Box 241 Hancocks Bridge, NJ 08038 Records Center Institute of Nuclear Power Operations 1100 Circle 75 Parkway, Suite 1500 Atlanta, GA 30339
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