05000302/LER-1979-057-03, /03L-1 on 790606:emergency Diesel Generator Output Breakers a & B Tripped During Separate Tests. Caused by Procedural Deficiencies.Revisions Have Been Implemented

/03L-1 on 790606:emergency Diesel Generator Output Breakers a & B Tripped During Separate Tests. Caused by Procedural Deficiencies.Revisions Have Been Implemented

ML19274F824
Person / Time
Site:	Crystal River
Issue date:	07/30/1979
From:	Cooper J FLORIDA POWER CORP.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19274F823	List: 05000302/LER-1979-057, Forwards LER 79-057/03L-1 05000302/LER-1979-057-03, /03L-1 on 790606:emergency Diesel Generator Output Breakers a & B Tripped During Separate Tests. Caused by Procedural Deficiencies.Revisions Have Been Implemented
References
FOIA-81-159 LER-79-057-03L, LER-79-57-3L, NUDOCS 7908060514
Download: ML19274F824 (3)

LER-1979-057, /03L-1 on 790606:emergency Diesel Generator Output Breakers a & B Tripped During Separate Tests. Caused by Procedural Deficiencies.Revisions Have Been Implemented

Event date:
Report date:
3021979057R03 - NRC Website

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,, ; it was reported at 1600 that. A' nd "B" Emergency Diesel Generator output breakers tripped during separate tests conducted through the performance of gg SP-354.

This created an event contrary to Technical Specification 3.8.1.2.

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ois l There was no effect upon the plant or general public as offsite power was [TTTl i available. This is the eichth occurrencJ reported.

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SUPPLEMENTARY INFORMATION Report No.:

50-302/79-057/03L-1 Facility:

Crystal River Unit #3 Report Date:

30 July 1979 Occurrence Date:

6 June 1979 Identification of Occurrence:

Both Emergency Diesel Generators inoperable contrary to Technical Specification 3.8.1.2.

Conditions Prior to Occurrence:

Mode 6 refueling.

Description of Occurrence:

At 1600 it was reported that "A" and "B" Diesel Generators were declared inoperable.

Investigation revealed that both Diesel Generators were started, on separate occasions, as a function of Engineered Safeguards Response Time Test SP-135.

After each Diesel Generator was started, it was synchronized and loaded in accordance with the fast start verification section of SP-354 During the respective tests, each Diesel Generator developed excessive noise and the corresponding output breaker tripped.

Immediate restarts of both Diesel Generators did not produce pre-vious aymptoms.

"A" Diesel Generator was returned to service at 2100 and "B" Diesel Generator was returned to service at 2230 fol-lowing satisfactory completion of SP-354.

Designation of Apparent Cause:

A review of this event has resulted in a series of apparent causes stemming from procedural deficiencies. The Diesel Genera-tor output breakers tripped on reverse power as a function of power directional relay (GGP). This could have resulted from any one, or a ccmbination, of the following series of events.

1) The =p.ed droop setting on the Diesel Generator governor remained on zero (0) when the Diesel Generator was synchronized with the grid. The fast start verification section of SP-354 did not address governor speed droop setting requirements. With the Diesel Generator in this Mode, it is felt that the load on the machine drifted down to the point where the reverse power relay actuated tripping the output breakers.

2) The unit / parallel switch remained in the " unit" position.

SP-354 did not address the operation or position of this switch.

The unit / parallel switch inserts an automatic reactive load compensation net-work that controls the reactive load, during transients when the Diesel Generator is in parallel with the grid.

Supplementary Information 50-302/79-057/03L-1 Page 2 Designation of Apparent Cause: (Cont'd) 2)

It is felt that this contriauted to the gradual loss of load on the Diesel Generator and subsequently tripped the output breakers on reverse power.

3) An overadjustment of the automatic voltage adjust theostat by the on-shift operator could also have contributed to reverse power trip on the Diesel Generator output breakers.

With the speed droop on zero (0) and the unit / parallel switch on " unit", overadjustiag the machine voltage would increase the reactive load on the machine. This, in turn, would contribute in reducing true power output of the machine until the output breakers trip on reverse power.

Investigation did reveal that thete were no equipment failures and that the reverse power relay was within cali-bration limits.

Analysis of Occurrence:

No effect upon the plant or gene al public as offsite power was available. The Diesel Generator speed droop setting was in the position required for engineered safeguards actuation.

Proper operation of Diesel Generator during ESS would not have been deterred.

Corrective Action

Procedure revisions have been implemented to the applicable sections of SP-354 to include the operation of the unit / parallel switch.

Proper governor speed droop settings have also been impleinented into the fast start verification portion of SP-354.

Failure Data:

This is the eighth (8th) occurrence reported. Reference LER's 77-55, 94, 128, 146, 158, and 78-01.

This is the first reported occurrence for output breakers tripping.

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