05000296/LER-2002-004, Loss of High Pressure Coolant Injection (HPCI) Flow Controller Power Supply
| ML030060408 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 12/20/2002 |
| From: | Bhatnagar A Tennessee Valley Authority |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LER 02-004-00 | |
| Download: ML030060408 (11) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(v), Loss of Safety Function |
| 2962002004R00 - NRC Website | |
text
December 20, 2002 U.S. Nuclear Regulatory Commission 10 CFR 50.73 ATTN: Document Control Desk Mail Stop OWFN, P1-35 Washington, D. C. 20555-0001
Dear Sir:
TENNESSEE VALLEY AUTHORITY - BROWNS FERRY NUCLEAR PLANT (BFN) -
UNIT 3 - DOCKET 50-296 - FACILITY OPERATING LICENSE DPR LICENSEE EVENT REPORT (LER) 50-296/2002-004-00 The enclosed report provides details of an unplanned inoperability condition of the Unit 3 high pressure coolant injection (HPCI) system which resulted from a loss of the systems flow controller power supply. The power supply was lost as a result of a battery charger failure during a maintenance activity.
In accordance with 10 CFR 50.73(a)(2)(v), TVA is reporting this event as a condition that could have prevented the fulfillment of the HPCI system safety functions of removing residual heat and mitigating the consequences of an accident.
There are no commitments contained in this letter.
Sincerely, original signed by R.G. Jones for:
Ashok S. Bhatnagar cc: See page 2
U.S. Nuclear Regulatory Commission Page 2 December 20, 2002 Enclosure cc (Enclosure):
(Via NRC Electronic Distribution)
Mr. Kahtan N. Jabbour, Project Manager U.S. Nuclear Regulatory Commission (MS 08G9)
One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852-2739 Mr. Stephen J. Cahill Branch Chief U.S. Nuclear Regulatory Commission Region II Sam Nunn Atlanta Federal Center 61 Forsyth Street, SW, Suite 23T85 Atlanta, Georgia 30303-8931 NRC Resident Inspector Browns Ferry Nuclear Plant 10833 Shaw Road Athens, Alabama 35611-6970
U.S. Nuclear Regulatory Commission Page 3 December 20, 2002 TEA:DTL:PSH:BAB Enclosure cc (Enclosure):
A. S. Bhatnagar, PAB 1B-BFN M. J. Burzynski, BR 4X-C R. G. Jones, POB 2C-BFN J. Scott Martin, PMB 1A-BFN F. C. Mashburn, BR 4X-C D. C. Olcsvary, LP 6A-C C. L. Root, PAB 1G-BFN J. R. Rupert, CFC 17B-BFN K. W. Singer, LP 6A-C E. J. Vigluicci, ET 11A-K R. E. Wiggall, PEC 2A-BFN LEREvents@inpo.org NSRB Support, LP 5M-C EDMS-K s:lic/submit/Lers/296 2002-04.doc
Abstract
On 10/22/02, Electrical Maintenance personnel were engaged in a maintenance activity on 250 VDC Battery Charger 4. To aid in the repair of out-of-service Battery Charger 4, a supporting work activity was being performed to obtain comparison waveform data from in-service Battery Charger 3. While connecting an oscilloscope to the Battery Charger 3 circuitry as part of this supporting work, a malfunction was inadvertently induced which resulted in the charger output going to its maximum value. This abnormally high output voltage was briefly applied to Battery Board 3 and its associated loads before the charger was automatically tripped by electrical protective devices. As a result of the application of this abnormally high voltage, fuses of two Emergency Core Cooling System Analog Trip Unit (ECCS ATU) Inverters cleared. One of these ECCS ATU inverters supplied Unit 2 loads. With Unit 2 shutdown in a mid-cycle outage, the loss of this inverter had no operational impact. The other inverter supplied Unit 3 loads. These loads included the flow controller for the high pressure coolant injection (HPCI) system. The capability to control HPCI flow was lost as a consequence.
The root causes of this event were: 1) the failures of personnel to identify all possible failure modes of the charger, 2) the work authorization process did not require a reassessment of the work activity following a change in the original work scope to include additional equipment. Operations, Maintenance, and Engineering personnel will be trained on the possibilities of introducing grounds into circuits via M&TE use. The work authorization process will be revised.
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Safety System Functional Failure Consideration:
This event involves a safety system functional failure as referenced in 10CFR 50.73(a)(2)(v),
and it will be included in Performance Indicator reporting in accordance with NEI 99-02.
E.
Loss of Normal Heat Removal Consideration:
N/A This event did not involve a reactor scram.
VIII. COMMITMENTS
None