05000311/LER-2004-004, Regarding Technical Specification Required Plant Shutdown Following Loss of 2B 230-Volt Vital Bus

Regarding Technical Specification Required Plant Shutdown Following Loss of 2B 230-Volt Vital Bus

ML042100397
Person / Time
Site:	Salem
Issue date:	07/20/2004
From:	Fricker C Public Service Enterprise Group
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
LR-N04-0315 LER 04-004-00
Download: ML042100397 (5)

LER-2004-004, Regarding Technical Specification Required Plant Shutdown Following Loss of 2B 230-Volt Vital Bus

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown
3112004004R00 - NRC Website

text

PSEG Nuclear LLC P.O. Box 236, Hancocks Bridge, New Jersey 08038-0236 JUL 2 0 2004 LR-N04-0315 o PSEG NuclearLLC U. S. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 LER 311/04 - 004 - 00 Salem Generating Station Unit 2 Facility Operating License DPR-75 Docket No. 50-311 This Licensee Event Report entitled 'Technical Specification Required Plant Shutdown Following Loss of 2B 230-Volt Vital Bus" is being submitted pursuant to the requirements of 10 CFR 50.73(a)(2)(i)(A). The attached LER contains no commitments.

Should there be any questions regarding this matter please contact Howard Berrick at 856-339-1862.

Sincerel er Salem Plant Manager Attachment HGB C

Distribution LER File 3.7 95-2168 REV. 7/99

Abstract

On May 21, 2004, at 1147, a fault on a Salem Unit 2 41 60/230V transformer caused a 4kV load breaker to trip open on instantaneous over-current, resulting in the loss of the 2B 460V and 230V Vital buses. A Service Water isolation valve supplying the Turbine Generator lost the ability to isolate the Turbine loads. This resulted in the entry into Salem Unit 2 Technical Specification (TS) 3.6.1.1, 'Primary Containment Integrity', Limiting Condition for Operation (LCO) to restore in 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> or be in Hot Shutdown in 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />. Operators were unable to restore the valve to operable within one hour and therefore commenced a controlled shutdown. All plant systems responded as expected to the conditions.

A failure analysis of the event indicates that the root cause of the transformer fault originated in the 2nd phase of the 3-phase transformer due to high voltage winding insulation breakdown caused during initial fabrication of the transformer. Corrective actions included replacing the 2B 41601230 Volt transformer.

This event is reportable per the requirements of 10 CFR 50.73(a)(2)(i)(A), Plant Shutdown Required by Technical Specifications.

NRC FORM 366 (7-2001)

A (If more space Is required, use additional copies of (If more space Is required, use additional copies of (if more space Is required, use additional copies of NRC Form 366A) (17)

CORRECTIVE ACTIONS

1. The 2B 4160/230 Volt transformer was replaced.

2. Preventive maintenance procedures will be reviewed and as necessary, revised/enhanced to ensure all necessary work is aligned with industry standards for the maintenance and testing of all dry-type transformers. An enhancement being considered is describing or providing examples of what indications might indicate localized heating of windings is occurring. Additionally, lessons learned from the 2B 4kV/230V transformer failure will be incorporated into Maintenance training.

3. System Engineering Performance Monitoring notebooks will be revised to record and evaluate transformer testing for transformers within the 460/230 System boundaries for megger, Doble, PF and insulation testing.

COMMITMENTS

The corrective actions cited in this LER are voluntary enhancements and do not constitute commitments.