05000269/LER-1981-001, Forwards LER 81-001/03L-0.Detailed Event Analysis Encl

Forwards LER 81-001/03L-0.Detailed Event Analysis Encl

ML20063P681
Person / Time
Site:	Oconee
Issue date:	02/04/1981
From:	Parker W DUKE POWER CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20063P682	List: 05000269/LER-1981-001, Forwards LER 81-001/03L-0.Detailed Event Analysis Encl
References
NUDOCS 8210150079
Download: ML20063P681 (3)

LER-2081-001, Forwards LER 81-001/03L-0.Detailed Event Analysis Encl

Event date:
Report date:
2692081001R00 - NRC Website

text

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7 Mr. James P. O'Reilly, Director . .

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. Re: Oconee Nuclear Station Docket ~ No. 50-269-

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Please find attached Rep'ortableOi:durre'ned Rdpji-tIR0a269781-l'. . Ihis report

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is submitted pursuant to'Oconee Nuclear Station'Techni. cal Sp'ecification F -~

. 6.6.2.1.b(2), which concerns operation in a egraded d niode permitted 'by. a f .

limiting' condition for' opera'io', t n ahd lescr'ibes"an inEident which is con-

, sidered to be of no significance with ~

• respect to its effect,on the health and safety of the public. 'c

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.Very truly yours,

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William O. Parker, Jr. - --- -

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- cc: Director Mr. Bill Lavallee Office of Management & Program Analysis Nuclear Safety Analysi's Center U. S. Nuclear Regulatory Commission P.- O. Box 10412 Washington, D. C. 20555 Palo Alto, California 94303 _

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DUKE POWER COMPANY.

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.u u n UNIT l'.'.'~

, u . uc.u i u.. . u Report Number: R0-269/81-1

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~ Rep 6rt'Dat'ei February 4, 198i " """ U-19 Occurrence Date: January 5, 1981 .

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Facility: Oconce d e.u ,: mUnit 1, Seneca,i..nrSeuth

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~ . - a c~=4 pun. - r r.~-ef t--M / Mc Identification of Occurrence: Steady State Tilt Limit Exceeded ,7 - .

, , . Conditions' Prior to' Occurrence: 90% FP _ .

Descri6 tion of Occursinch': At.0605. hours on January 5, 1981, Oconee Unit 1 tripped'from-90% FP. The actuating event was a turbine trip caused by loss of excitation on the Generator field. Personnel attempted to raise the Volt Amperes Reactive (VARs) on Oconee Units 1 and 2. In doing this, a mismatch occurred causing the Unit 1 Generator to lose excitation, and ' ~

In~ anticipatory"rchetor'tilp'Ioll'oGsf.'"Durins"Ehe'6 l nib'I'restartila large positive tilt was presetit'."Th8 valu6 'was'outsid' 'e'the ' Error"adjustid' steady ~

state. limits, and the overpower' trip, set points were reduced"by;4% pursuant

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to' Technical Specification 13.5.2.4b2.-

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PEior'to'this reactor trip Unit 1 had been operating with a Steam Generator Primary to Secondary Tube Leak of approximately .02 gpm. The release to the environment through the Safety Reliefs amounted to 8 pCi - cesium, and 112 pCi - Noble Gas Total. These values are below the allowed limits in 10,CFR2 0'. ,

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Aprat nt Cause of Occurrence: The Reactor Trip was an anticipatory reactor trip following a main turbine trip. When starting up Unit 1 after the Reactor Trip, a problem developed with Feedwater control. At approximately 12% FP. personnel attempted to open the Main Feedwater block valves A & B to allow power to be increased with the Turbine on line. . .This is,a normal .

process performed on all startups. However during this start up, a large _

feedwater swing occurred when opening the "A" feedwater block valve. The- ~~' " "

swing was due to excessive leakage through 1FDW-32, the Main Feedwater control valve in the A loop. As the block valve 1FDW-31 was opened, ex-cessive feedwater was fed into the Steam Generator through the leaking 1FDW-32. -

Since the block valve must be opened to increase power beyond 25% and due to the large swing that occurred when the block valve was electrically opened, the valve was opened manually a little at a time. This was.donc

' on the A loop followed by the B loop. During the time that the feedwater was mismatched betwe7n Steam Generators, a large ATC between loops occurred causing the large Quadrant Power Tilt. As soon as the ATC was decreased and both Feedwater loops were operating properly, the Quadrant Power Tilt decreased to within the steady state limits.

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DUKE POWER COMPANY 0 "_" ' ' " ' ' '

s OCONEE NUCLEAR STATION Report Number: R0-269/81-1

,, February 4, 1981 Page 2

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p Analysis of Occurrence: The Reactor was safely cooled down to approxi-P- mately 550"F prior to restart within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />. The RCS pressure remained

" above the ES actuation limit and below the RCS Power Operated Relief

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" Valve set point. .The RCS temperature' decrease did not exceed the 100 /hr.

limit. The pressurizer level remained on scale and the RCS was contained

, a'within its boundary with-the exception'of the .02 GPM Tube Leak. This I . .02 GPM Tube Leak resulted in a gaseous release, and, as noted in the Ydevaluation',-andivah#not Abve o any'10CFR20 Limits.

b h'All, R' P'S systems'-fhn5fionedhs ksteNked"ahd YfE TC'(nthbl OhstaYby[r'esponse

, , was as needed t.o the, changing plant gondit. ions,., " , _ _ ,} ,' ' {, { .

'The quadrant power tilt.was appYoxim'aEnly 1.81%'ab'ove thest' cad'y state linit at one time but never. approached"the Transient' Limit of 9~.44%: Due

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{  ;~ to the low power. levelf no ,','kilownt'ts phr/line'ar fuc1' assemblyf ' oo't"Ilimits

t. were exceeded and no other Technical Specification limits were exceeded.

'When Reactor power'was'-ine'rhasd to'25%7'hhe"A'TC'was'redd6cd'to 0'aEd 'the

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e quadrant power tilt in the quadrants in question was reduced below the

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steady state limit of_3.59%. Since the Steady State Tilt Limit was ex-ceeded for two hours, the overpower 'tFip 's'eE"poin't wa's reduced in 'acho~r-

' dance with Technical Specification'Y.'5.'2'.'b.'2. "Thu's, this iscident w's 4 a of no significance with respect to safe operation,'and the health and

,, safety of the public were not effected.

Corrective Action: The Startup Procedure and the Operation at Power Pro-

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cedure will be revised to contain the method, in a step-by-s,tep p,rocess, for increasing the VARs on all three Oconee Units. Specialized training Lvill be held for appropriate'1,1 censed p'ersonnel'in'the'operat' ion of',the

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Oconee G. E. Turbine - Cencrators. The training will be specific and address ~

the appropriate s'ubjects' to prevent'a future reactor trip'of thi's nat'ure.

When a control operator is performing a function in the Control Roon which he has never done before, the Unit Shift Supervisor or other appropriate supervision will give proper, concise instructions for performing that function. All Shift Operation personnel will review this report. -

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r - The same types of Feedwater control problems have occurred in previous startups on all three Units. At the next convenient outage on Unit 1, y

both Main Fecdwater valves will be pulled, c1 caned and inspected, and the g valve positions will be calibrated. Both have been done on Unit 2 and

" Feedwater control is acceptable after this maintenance.

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