United States Nuclear Regulatory Commission - Protecting People and the Environment

ACCESSION #: 9907080108


June 30, 1999

NCR-73-02, Revision 2

Document Control Desk
United States Nuclear Regulatory Commission
Washington, DC 20555
FAX (301) 816-5151

Subject: Interim Report of a Deviation

Nuclear Logistics presents the following additional information in accordance with 10CFR21, Section 21.21 (a)(2) concerning a deviation, which has been identified.

i) Information submitted by:
Mr. Aron Seiken
Nuclear Logistics Incorporated
7450 Whitehall Street
Fort Worth, TX 76118
Telephone: (817) 284-0077
Facsimile: (817) 590-0484
ii) The item with the deviation is a NLI DC Power Supply, P/N NLI-LGS-G-24-OV-R-8018.
iii) NLI has supplied these power supplies as Class 1E components.
iv) The deviation, which has been identified, is inadvertent over voltage protection actuation in a circuit specific application. The inadvertent over voltage protection actuation occurred during diesel generator start up. Specifically, the inadvertent voltage protection actuation occurs during diesel generator loading. The suspected premature over voltage protection actuation occurred during diesel generator startup. Based upon information provided by Public Service Electric and Gas Company, the sequence is as follows:
1) The power supply is a replacement for the original Lambda power supply. The rated output of the power supply is 50amp at 24vdc. The power supply contains a built in overvoltage protection set at approximately 27vdc, which is consistent with the Lambda specification of 26.5 to 28vdc.
2) The power supply is located in the diesel generator panel with a large number of relays which cycle during diesel generator startup. The power supply is very lightly loaded (load of about lamp from a 50amp power supply).
3) Prior to the diesel generator startup sequence, the 115 VAC input power to the power supply is stable with no voltage fluctuations or noise and the +24 VDC output is also stable with no voltage fluctuations or noise.
4) As the diesel is loaded, voltage spikes occur on the +24vdc output.
5) As the diesel continues to be loaded, the voltage spikes on the +24vdc output continue to increase and the output voltage begins to vary in what appears to be a sinusoidal manner.
6) Ultimately, the power supply over voltage protection circuit actuates and terminates the power supply output.
7) The potential source of the inadvertent over voltage protection circuit actuation is a signal being driven through the power supply or the unusually high noise level on the downstream circuit.
ii) This issue was determined to be a deviation on April 19, 1999.
iii) Power supplies models with similar over voltage protection circuitry have been supplied as safety-related components to the following facilities:
1) Public Service Electric and Gas Company
a) NLI-LGS-FA-24-OV-R-8018
b) NLI-LGS-G-24-OV-R-8018
c) NLI-LGS-G-24-OV-R-8018, Version I
d) NLI-75-PS-3111
2) Florida Power and Light
a) LI-LGS-B-28
b) NLI-LXS-C-15-R
3) Baltimore Gas and Electric
a) NLI-LJS-10-5-OV
b) NLI-LMF-28-OVMYR-3397-3
d) NLI-LXS-C-12-R
4) Omaha Public Power District
a) NLI-LJS-10-5-OV
5) Virginia Power Company
a) NLI-LUD-16-16
NOTE: None of the NLI-L series power supplies with adjustable output voltages contain over voltage protection circuitry.
ii) To date, NLI has been unable to duplicate the premature over voltage protection actuation during laboratory testing. Data collection and additional testing is being performed to resolve the deviation. If the premature over voltage protection actuation is determined to be the result of the power supply design, other NLI-L series power supplies will be tested to determine their susceptibility to similar conditions. Testing and evaluation activities will be completed on August 1, 1999.
NOTE: No NLI-L series power supply failures of a similar nature have been reported to NLI.
iii) The results of testing to date have been discussed with the cognizant personnel at Public Service Electric and Gas Company.

Should you require clarification, or additional information, please contact Mr. Archie C. Bell or me.

Very Truly Yours

Aron Seiken

cc: Public Service Electric and Gas Company
Florida Power and Light
Baltimore Gas and Electric
Omaha Public Power District
Virginia Power Company


7450 Whitehall o Fort Worth, TX 76118 o Telephone (817) 284-0077 o Fax (817) 590-0484


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