05000245/LER-1981-031, Forwards LER 81-031/03L-0.Detailed Event Analysis Encl

Forwards LER 81-031/03L-0.Detailed Event Analysis Encl

ML20031F915
Person / Time
Site:	Millstone
Issue date:	10/09/1981
From:	Mroczka E NORTHEAST NUCLEAR ENERGY CO.
To:	Haynes R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20031F916	List: 05000245/LER-1981-031, Forwards LER 81-031/03L-0.Detailed Event Analysis Encl 05000245/LER-1981-031-03, /03L-0:on 810910,during Gas Turbine Emergency Fast Start Test,Gas Turbine Generator Output Field Breaker Failed to Close.Caused by Failure of Resistor to Open in Automatic Voltage Regulator Due to Oxide on Termination Lugs
References
MP-1-1914, NUDOCS 8110200548
Download: ML20031F915 (2)

LER-1981-031, Forwards LER 81-031/03L-0.Detailed Event Analysis Encl

Event date:
Report date:
2451981031R00 - NRC Website

text

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ue NORTHI!AST trFII.frII!S i.4 o w m, um - w. '""

P O BOX 270 N$sIU.4.U[SY.n,,

HAHTFORD. CONNECTICUT 06101 (202) 6D6911 n. w, u. + i s ms<

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October 9, 1981 MP-1-1914 4,\\'C' hop h gvf,. 'g-i Oc7j y ;gOla-i Mr. Ronald C. Haynes

- g Director, Region I

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Office of Inspection and Enforcement O

U. S. Nuclear Regulatory Commission 1/

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T' 631 Park Avenue n

King of Prussia, Pennsylvania 19406 CTi,' O "

u -

Reference:

Provisional License No. DPR-21 Docket No. 50-245 Reportable Occurrence R0-81-31/3L Dear Mr. Hayner-This letter forwards the Licensee Event Report for Reportable Occurrence R0-81-31/3L required to be submitted within 30 days pursuant to the requirements of the Millstone Unit 1 Technical Specifications, Section 6.9.1.9.a.

An additional three copies of the report are enclosed.

Yours truly, NORTHEAST NUCLEAR ENERGY COMPANY

/[N

/

E J. Mroczka Station Superintendent Millstone Nuclear Power Station EJM/TST:bjo

Attachment:

LER R0-81-31/3L cc:

Director, Office of Inspection and Enforcement, Washington, D.C. (30)

Director, Office of Management Information and Program Control, Washington, D. C. (3)

U. S. Nuclear Regulatory Commission, c/o Document Management Branch, Washington, D. C.

20555 i

8110200540 011009 PDR ADOCK 05000245 0

PDR

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ATTACHMENT TO LER 81-31/3L NORTHEAST NUCLEAR ENERGY COMPANY MILLSTONE h & LEAR POWER STATION - UNIT 1 PROVISIONAL LICENSE NUMBER OPR-21 DOCKET NUMBER 245 i

Identification of 'Jccurrence Operation in a degraded mode permitted by a limiting condition for operation occurred wh2n the Gas Turbine Generator output breaker failed to close.

Prior to Occurrence Prior to occurrence the unit was operating at a steady state power level of 100 i

percent.

Description of Occurrence

~

On September _10, 1981, at 0500 t?ars, while performing Gas Turbine Emergency Fast Start Test, the Gas Turbine generator output breaker failed to close.

Technical Specification 3.9.2 requires the Diesel Generator and Gas Turbine Generator (both emergency power sources) to be operable.

A) parent Cause of Occurrence T1e Gas Turbine Generator output breaker failed to close due to a wire wound ceramic resistor which failed open in the automatic voltage regulator circuitry.

The open drcuited resistor prevented the regulator from supplying the field excitation needed to allow the generator to reach rr.ced output voltage

)

which is required for output breaker closure.

Examination of the resistor revealed no visible signs of pm/sical damage or burn out. There were, however, formations of oxide (rust) on the resistor termination lugs where they attach to the body of the resistor. This also is usually the point of attachment for the resistive nichrome wire.

Apparently the wire being of ferric composition and exposed to the humid atmosphere at the i

this point eventually rusted through.

l Analysis of Occurrence

{

Failure of the Gas Turbine Generator output breaker to close upon receipt of a fast start signal did not create a condition which had not been analyzed.

The Gas Turbine is one out of tu emergency power sources that are utilized for I.

engineered safeguard systems.

In an actual emergency condition where emergency core cooling systems are required and a loss of off-site power accompany it, the Gas Turbine and the Diesel provide emergency power.

Each power source is independent of the other, thereby allowing the Gas Turbine or l

Diesel to solely provide emergency power if the other fails.

Corrective Action

l The failed resistor was replaced with an adjustable resistor of equal N

resistance, wattage and mounting configuration.

Additionally an exact replacement resistor was ordered and will be installed when it becomes

.available.

The subjrct resistor was manufactured by Ohmite with a resistance l

of 1800 ohms and 25 watts.

L l

I