ML18081A861

Forwards LER 77-045/03L-0

ML18081A861
Person / Time
Site:	Salem
Issue date:	07/19/1977
From:	LIBRIZZI F P Public Service Enterprise Group
To:	OREILLY J P NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML18081A856	List: ML18081A855 ML18081A857 ML18081A858 ML18081A859 ML18081A860 ML18081A861 ML18081A862 ML18081A863 ML18081A864 ML18081A865 ML18081A867
References
NUDOCS 8001080515
Download: ML18081A861 (3)

Text

.. ' ** Public Service Electric and Gas Company 80 Park Place Newark, N.J. 07101 Phone 201 /622-7000 Mr. James P. O'Reilly Director of USNRC Off ice of Inspections and Enforcements Region 1 631 Park Avenue King of Prussia, Pennsylvania 19406

Dear Mr. O'Reilly:

LICENSE NO. DPR-70 DOCKET NO. 50-272 REPORTABLE OCCURRENCE 77-45/03L July 19, 1977 Pursuant to the requirements of Salem Gener;ting Station Vnit No. 1 Technical Specifications, Section 6.9.1, we are submitting Licensee Event Report for Reportable Occurrence 77-45/03L.

This report is required within thirty (30) days of the occurrence.

CC: Director, Office of Inspection and Enforcement (30 copies) Director, Office of Management Information and Program Control (3 copies) The Energy People Sincerely yours, .

F. P. Librizzi General Manager -Electric Production 8001 08{)

J" Report Number: Report Date: Occurrence Date: Facility:

• 77-45/03L 7/08/77 6/26/77 Salem Generating Station Public Service Electric & Gas Company Haricocks Bridge, New 08038 IDENTIFICATION OF OCCURRENCE:

Loss of 5024, 500kV Transmission Line CONDITIONS PRIOR TO OCCURRENCE:

Operational Mode 1, Reactor Power 100%, 100%

Trip Test in progress.

DESCRIPTION OF OCCURRENCE:

At 1013 am, during the conduct of the lOOi Generator Trip Test, the 5024, SOOkV transmission line became inoperable due to operation of the Bus Section 1-5 and 5-6 Breaker Flashover Relay (NCHllA) and its associated HEA Relay. Technical Specification Statement for LCO 3.8.l.l w&s implemented and Surveillance Procedures 4.8.1.1.1.a and 4.8.1.1.2.a.2 were performed.

At 1454, the 5024 transmission line was re-energized and Action 3.R.1 .J. wRs DESIGNATION OF APPARENT CAUSE OF OCCURRENCE:

Bus sections 1-5 and 5-6 flashover protection HEA relay is tripped after 13 cycles time delay by either the #1 Unit main power transformer ground relay (PJCllAV) or the bus sections 1-5 and 5-6 breaker flashover relay (NHCllA) if the auxiliary switch contacts on both bus sections 1-5 and 5-6 breakers indicate that these breakers are open. When Salem No. 1 Unit is operating at 100% load, the PJCllAV is de-energized.

It picks up at 480 amperes of main power transformer ground current. The NHCllA is energized, because it is connected to the generators output current transformers and is set to pickup at 7000 generator amps which is about 23% of rated generator load. The transient data recorder showed that after bus sections 1-5 and 5-6 breakers opened, the No. 1 Unit generator current remained for rnore than 13 cycles at or above 8000 amperes due to the transformer exciting current resulting from the momentary rise in voltage_ on the generator as a result of the load Therefore, the NHCllA relay remained energized and in 13 cycles tripped the associated HEA relay, isolating the 5024 line at the station and at the New Freedom switching station.

. . P *

• Report No. 77-45/03L

• e 7/8/77 ANALYSIS OF OCCURRENCE:

Technical Specification Action Statement 3.8.1.1.a allows 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to restore an inoperable offsite circuit to operable status. The 5024, SOOkV transmission line was restored to operable status in 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> and 41 minutes, therefore, there was no violation of the Technical cations. CORRECTIVE ACTION: The bus section 1-5 and 5-6 breaker flashover NHCllA relay has withdrawn from service for the following reasons: 1.

protection against either generator flashover is provided by the flashover relays connected to current formers located at each generator breaker. 2. Main power transformer ground relay provides redundant protection against one or two phase and/or phase to* ground flashover.

3. Due to the unpredictability of the residual current value in the generator

-main power transformer circuit; the setting for the NHCllA which would prevent false tripping may be too high to provide effective protection under *all operating conditions.

In addition, this protection is redundant.

4. A false nuclear unit trip is not offset by the questionable benefit of the redundant protection provided by the NHCllA. FAILURE DATA: This event did not involve equipment failure. Prepared by T. Spencer //{f ! ,< .' .-7 '!/ / . ff/,, / II / ' , I ./ SORC Meeting No. 75-77 Manager -Salem* Generating Station *