05000335/LER-1982-040-03, /03L-0:on 820902,short Caused Generator Breakers to Open & Synchronizing Inhibit Timer to Start.Caused by Personnel Short Circuiting Relay During Generator Negative Sequence Relay Testing.Protection Design Reviewed

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/03L-0:on 820902,short Caused Generator Breakers to Open & Synchronizing Inhibit Timer to Start.Caused by Personnel Short Circuiting Relay During Generator Negative Sequence Relay Testing.Protection Design Reviewed
ML20027C185
Person / Time
Site: Saint Lucie NextEra Energy icon.png
Issue date: 10/04/1982
From: Pace P
FLORIDA POWER & LIGHT CO.
To:
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20027C177 List:
References
LER-82-040-03L, LER-82-40-3L, NUDOCS 8210130562
Download: ML20027C185 (5)
v • d • e


LER-1982-040, /03L-0:on 820902,short Caused Generator Breakers to Open & Synchronizing Inhibit Timer to Start.Caused by Personnel Short Circuiting Relay During Generator Negative Sequence Relay Testing.Protection Design Reviewed
Event date:
Report date:
3351982040R03 - NRC Website
v • d • e

text

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NRC f OAM 384 U.S.NUCLEAM REGULATORY COMMISSION 87 771 LICENSEE EVENT REPORT CCNTRot. SLOCK: l

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$ VENT OESCRtPTt0N ANO PRC8 ASLE CONSECUENCES h ITTTl i At 99% power, while testing a generator trip relay a brief short caused I

the generator breakers to open and started a synchronizing inhibit timer i

o 3i.i i to start. When the reactor tripped the timer had cycled so transfer of I

gl vital busses (4.16 KV) required OPERABLE by TS 3.8.2.1 to startup power 1

io g i I did not occur. Diesel generators started and loaded properly. Power was j

restored to normal. Due to the transient, iodine buildup (spiking) < ~

,o,,i; occurred. Similar bus loss was LER 79-28. Tenth Iodine spike, See LER 82-38.1 iois i ;

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34 35 36 31 ao el 42 4J 44 41 CAUSE DESCRIPTION AND CORREC.*lvt ACTIONS h 1: 1011 In testino the generator necative secuence relay, relay personnel short I

w I circuited the relay, giving a signal to open the generator breakers. By t

the time the reactor tripped the unit was out of synchronization with 1

gi i,,3i l the grid and the time delay (.17 see) inhibited automatic bus transfer.

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Generator protection design is being reviewed for possible changes.

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I REPORTABLE OCCURRENCE 335-82-40 LICENSEE EVENT REPORT PAGE 1

-. EVENT DESCRIPTION (Cont)

At approximately 10:28 AM, during normal full power operation, a negative-sequence generator trip relay was inadvertently actuated causing opening of the main generator oil circuit breakers (OCB's),

a separation from the grid, and a turbine trip on over speed. The loss of load caused the turbine and reactor to trip, however since the OCB's had already opened and the unit was out of synchronization with

'the grid, the transfer to the startup switchgear for offsite power could not occur. The diesel generators automatically loaded to provide AC power to the plant vital loads. An Unusual Event was declared at approximately 10:35 AM.

Offsite power and normal plant status was restored at approximately 10:46 AM..

During the return to power the dose equivalent iodine (DEQ) exceeded T.S. 3.4.8.a limit of 1.0 uCi/gm DEQ I-131.

The DEQ iodine was first measured above the limit at 1345 on 9-2-82 and remained above the limit for approximately 15.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />. The attached sheets contain information required by T.S.

3.4.8.d.

The health and safety of the public was not affected by this event.

CAUSE DESCRIPTION During a determination of the minimum voltage required for the negative sequence relay to actuate, Systems Protection (Relay) personnel short circuited a resistor and relay in the negative sequence relay circuitry.

The negative sequence relay was actuated for a short duration causing the main generator OCB's to open.. The subseq"ent generator lockout caused by the turbine overspeed trip would normally provide a fast transfer of onsite electrical loads from the auxiliary transformers to the startup transformers. Since the OCB's were already open for greater than 170 milli seconds (design circuitry time delay for pro-tection against electrical loading out of synchronization), the automatic transfer did not occur.

After an extended period of power operation with a nominal level of fuel leakage, a reactor scram from full power was a sufficient transient to cause iodine build-up (iodine spiking phenomenon). The DEQ I-131 level decreased to below 1.0 uC1/gm after 15.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> and to nominal levels thereafter.

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.o REPORTABLE OCCURRENCE 3'35-82-40' LICENSEE EVENT. REPORT

- 2 Page"2
- SUPPLE >tENTARY INF0PJfATION TECHNICAL SPECIFICATION REPORT DOSE EQUIVALENT IODINE 1.

Reactor power history starting 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> prior to the Eirst sample in which the limit was exceeded.

Average Reactor Average Reactor Average Reactor Time Power 8/31/82 Power 9/1/82 Power 9/2/82 0000 99.23 99.23 0100 99.18 99.15 0200 99.20 99.15 0300

- 99.23 99.15 0400 99.28 99.15 0500 99.26

'99.18 0600 99.18 99.20 0700-99.23 99.18 0800 99.20-99.20 0900 99.20 99.26 1000 99.20 99.26 1100 2 --

99.18 1200 99.28 1300 99.30 99.30 1400 99.09 99.30 1500

'99.20 99.30 1600 99.20 99.23 1700 99.18 99.20 1800 99.18 99.23 1900 99.18 99.23 2000 99.20 99.20 2100 99.23 99.23 2200 99.23 99.20 2300 99.28 99.20 2.

Fup_1 ikarniin by Core Region See Attachment "A" i

3.

Cleanup Flow History starting 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> prior to the first sample

_in which the limit was exceeded.

Tine Flow Rate (GPl!)

Flow Rate (GP}!)

Flow Rate (CP)f)

B/31/82 9/1/82 9/2/82 0000 87 86 0100 87 86 0200 87 86 0300 87 86 0400 87 86 0500 S6 86 0500 86 86 L

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. REPORTAlit.E OCCt!RRENCE 335-82-40.

I.ICENSEE EVE!.'T REPORT

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Page.3 3.-

Continued Flow Rate (GPM)

Flow Rate (GPM) _

Flow Rate (CPM)

Tim S/31/32:

9/1/82 8/2/82 0700 86 86

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87 86 1000 87 86 87 88 (Trip) 1100 87 88 1200 1300 92 87 86 1400 44 87 1500 83 87 1600 86 87 1700 86 87 1800 90 87 1900 88 87 2000 87 87 2100 87 86 2200 87 87 y

2300 87 87 p

4.

Historv of Degassing Operation, if_ anv. starting 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> prior to the first sample in which the limit was exceedM.

There vare ndlegassing operations during the 48 hour5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> period pri'ar to exceeding the dose equivalent iodine limit.

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5.

The Time _ duration when the specific _ activity of the primarv coolant f

exceeded 1.0 uci/gm dose equivalent I-131.

Data Time.

DEQ I-131 (uci/gn) 9/2/32

d500, 1.14 E-01 9/2/82 1345 1.68 E 00 9/2/82 1730 1.75 E 00 y

9/2/82 2115 1.46 E 00 9/3/82 0115.

1.24 E 00 9/3/82

.0515 8.69 E-01 The daae equivalcat I-131 exceeded the limit for a period of approxinately 15.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />.

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NUMBER OF ASSDiBLIES.

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E 3.03 40 29546.9..

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