05000409/LER-1981-004, Forwards LER 81-004/03L-0.Detailed Event Analysis Also Submitted

Forwards LER 81-004/03L-0.Detailed Event Analysis Also Submitted

ML19350D108
Person / Time
Site:	La Crosse File:Dairyland Power Cooperative icon.png
Issue date:	03/27/1981
From:	Linder F DAIRYLAND POWER COOPERATIVE
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19350D109	List: 05000409/LER-1981-004, Forwards LER 81-004/03L-0.Detailed Event Analysis Also Submitted 05000409/LER-1981-004-03, /03L-0:on 810309,during Condition 3,480-volt Diesel Bldg Essential Switchgear Bus 1B Was Energized from 1B Emergency Diesel Generator for Approx 25 Minutes W/Control Power Key in on Position
References
LAC-7433, NUDOCS 8104130342
Download: ML19350D108 (3)

LER-1981-004, Forwards LER 81-004/03L-0.Detailed Event Analysis Also Submitted

Event date:
Report date:
4091981004R00 - NRC Website

text

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'D DA/RYLAND

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[k COOPERAT/W

• Po box 817

• 2615 EAST AV SOUTH * -- LA CROSSE. W1SCoNSIN S4601 (608) 788 4000 l

March 27, 1981 In reply, please refer to LAC-7433 DOCKET NO. 50-409 L

Mr. James G.

Keppler j

Regional Director U. S. Nuclear Regulatory Commission Directorate of Regulatory Operations Region III 799 Roosevelt Road Glen Ellyn, Illinois 60137

SUBJECT:

DAIRYLANDFCWERCCOPEhdTIVE I

LA CROSSE EOILING EATER REACTOR (LACBER)

D PROVISIONAL OPERATING LICENSE NO. DPR-45 g

REPORTABLE CCCURRFNCE NO. 81-04

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References:

(1) LACBWR Technical Specifications, Jb I.

Section 6.9.1.9.b LZ ah (2) LACBWR Technical Specifications, 9e S

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Section 4.2.3.2.1 9

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(3) LACBER Technical Specifications,

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Section 4.2.3.2.2

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Dear Mr. Keppler:

In accordance with Reference 1, this report is notification of operation in a degraded mode permitted by a limiting condition for operation.

Reference 2 requires that specified AC electrical buses be operable and energized from sources of power other than a diesel generator during Operating Conditions 1 and 2 and during 3, 4 and 5, when the control power key switch is not off or all control rods are not fully inserted.

On March 9, 1981, during Operating Condition 3, the 480V Diesel Building Essential Switchgear Bus 1B was energized from the 1B Emergency Diesel Generator for approximately twenty-five minutes with the control power key in the "on" position.

All rods were fully inserted.

The circumstances surrounding this event are as follows:

At 1420 on March 9, 1981, switching operations were commenced to transfer 2400V AC electrical feed from the reserve auxiliary trans-former to the main unit transformer.

2400V Bus lA was successfully transferred to the unit auxiliary transformer by closing switch 252 M1A.

Indicating lights for this switching were observed to be norral.

The next step in the procedure called for closing i

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U' JMN.EME: LAC-7433 Mr. Jamea C. K:pplcr

' :: "*C ' March-27, 1981

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Regional Director U. S. Nuclear Regulatory Commission j rr,

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switch 252 MlB to transfer 2400V Bus 1B to the unit auxiliary trans-former.

When switch 252 M1B was closed, the red-indicating light for closure did not illuminate.

After a momentary pause, the operator returned switch 252 MlB to the "open" position.

He did not check:.to determine that breaker 252 RlB had automatically tripped open when 252 MlB had been closed.

Consequently, when

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switch 252 MlB was returned to "open", 2400V Bus 1B was without any source of 2400V feed.

This condition then caused low voltage on 480V Bus la, which resulted in operation of the 480V Emergency Diesel Generator 1B, which in turn energized Diesel Building 480V Essential Switchgear Bus 1B.

Low voltage condition on Reactor Building 480V Motor Control Center IA caused a full scram of the reactor.

To restore power to 2400V Bus 1B, switch 252 RlB was closed, there-by connecting this bus to the reserve auxiliary transformer.

480V Dus 1B remained de-energized due to the fact that breaker 452 M1B did not reclose.

Breaker 452 MlB was examined.

In the breaker operating mechanism it was determined that the mechanical plunger which actuates the charging motor cut-off switch did not spring return to normal posi-tion.

This caused the spring charging motor cut-off switch to stop the motor in a " half-charged" position, which prevented the breaker from closing (refer to attached sketch).

Inspection of the breaker did not disclose why the plunger did not return to its normal position.

After one hand operation of the plunger, all sub-sequent hand operations were free of trouble.

A light silicon spray was applied to the mechanical sliding guide.

The breaker was electrically tested several times to ensure proper operation and then returned to service.

At 1534, the breaker was closed and the 1B 480V busses were energized through their normal feed.

Control power was turned off at 1445.

The applicable Technical Specification for Operating Condition 3, with the control power key switch off, is contained in Reference 3.

This specification only requires one 480V Essential Switchgear Bus lA or 1B to be operable and not energized by a diesel generator.

The 480V Essential Switch-gear Bus lA was operable throughout the event.

It was determined that switches 252 MlB and 252 RlB and operated properly at the time of initial switching and that the indicating lights for closure of 252 MlB was actually burned out.

The bulb was re-placed.

The operator involved in the switching was re-instructed about the operating characteristics of the plant's switchgear and procedural requirements.

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Mr.iJamra C. K::pplcr

!I LAC-7433 4-Regional Director Mar,ch 27, 1981 U. S. Nuclear Regulatory Commission page 3 A Licensee Event Report (Reference:

Appendix A, Regulatory Guide 1.16, Revision 4) is enclosed.

- Should you have any questions regarding this submittal, please contact ug.-

Very truly yours, DAIRYLAND POWER COOPERATIVF Frank Linder, General Manacer-FL:LSG:dh Enclosures cc - Director, Office of Inspection and Enforcement (30)

U. S. Nuclear Regulatory Commission Washington, D.

C.

20555 Director, Office of Management Information and Program Control (3)

U.

S. Nuclear Regulatory Commission Washington, D.

C.

20555 NRC Resident Inspectors