ML17252B498

LER 78-042/03L-0 for Dresden, Unit 2 Re During Weekly Turbine Control Vlv Exercising #3 Control Vlv Failed to Fast Close at the 10% Vlv Position

ML17252B498
Person / Time
Site:	Dresden
Issue date:	08/07/1978
From:	Stephenson B Commonwealth Edison Co
To:	James Keppler NRC/RGN-III
References
BBS LTR 78-1148 LER 78-042/03L-0
Download: ML17252B498 (3)

Text

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'* f<) Commonwe:A Edison Dresden Nuclea~er Station

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....,, R.R. #1 Morris, Illinois 60450' Telephone 815/942-2920 August 7, 1978 r

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BBS Ltr, #78~1148 ~~~~1~!

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.::.:,.1 <::: ::>J James G, *Keppler, Regional Director -< ,2::;3 C:-) -j.._*.:,:.

D_irectorate of Regulatory Operations .,.. Region I I I t"t*1" --i.

.U, s*. Nuclear Regulatory Connnission.

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7qq Roosev~lt Road Glen ElJyn, IL 60137 Reportable Occurrence Report #78-042/031~0, Docket #050-237 is hereoy suomitted to your office in accordance witq Dresden Nuclear Power Statfon Tedi.rtical~'.s:.pecification 6, 6, :S, 2 ! (o), conditions leading to opet?atfon ::tn a deg'raded mode permitted f>y a limiting condition for opera~::ton or plant _.shutdown required f>y a limiting condition for opeTation; phe Station Superlntende.nt Dresden Nuclear Power Station BBSjdeD.

Enclostire cc! D:l;:r:ectoT of Inspection & Enforcement I)i'irector.of Man_?gement Information & Program Control File/NRC AUG 91!J78

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e NRC J;ORM U.S. NUCLEAR REGULATORY COMMISSION 17-771  :*

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• LICE~SEE EVENT REPORT -

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(PLEASE PRINT OR TYPE ALL REQUIRED INFORMATIONI

[D::!J I I I L I D I R Is I 2 101 0 I 0 I - I 0 I0 I 0 I 0 I0 I_; I0 I0 101 4 I 1 I 1 I 11 1101 I I © 7 8 9 LICENSEE CODE 14 15 LICENSE NUMBER _ 25 26 LICENSE TYPE JO 57 CAT_ 58 CON'T CW]

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60 61 DOCKET NUMBER 68 69 EVENT DATE i'- 75. REPORT DATE 80 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES@

EE:IIJ I On 8-78 at 2330 hrs during weekly turbine control vlv exercising 113 control vlv failed to fast close at the 10% vlv position, This event is contrary to Technical Specifications which require two channels be operable per trip system in case of a generator load reject, The fast acting solenoids are utilized to close the control valves, A load reduction began immediately, The reactor scram was automatically

[£J2J I by~passed at less than 45%, . This has not happened before at Dresden,

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47' CAUSE DESCRIPTION AND CORRECTIVE ACTIONS @

[JJ]J l Investigation of the f/3 control vlv revealed that an electrical terminal lug on the fast acting solenoid had become deteriorated and had finally broken off, The termina]J

-_ ITJ)) lug was replaced and the vlv tested satisfactorily, Unit returned to higher power DJ)) I operation, No further corrective action necessary, rr:m 7 8 9 80 FACILITY METHOD OF t:;::;\

STATUS  % POWER OTHER STATUS DISCOVERY DISCOVERY DESCRIPTION ~

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'IUrJ'qER TV~E DESCRIPTION 82] L 01 01 ol@~J@.____ _ _ _ _N_A_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ ____,

7 8 9 11 12 13 80 PERSONNEL INJURIES Q NU~!.llER DESCRIPTION6 ITIE] 1*01 OI OJ@)L--_______N_A_ _ _ _ __;____~----_;___---~-~

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ATTACHMENT TO LICENSEE EVENT REPORT 78-042/031-0 COMMONWEALTH EDISON COMPANY (CWE)

DRESDEN UNI'P-2 (ILDRS-2)

DOCKET If 050-237 During weekly turbine control valve exercising per DOS 5600-2, 113 control valve failed to fast close from 10% valve position. Valve was exercised four times t.f:ttnout fast closure operation. Tech Spec 3 .1 requires two trip channels operable in case of a generator load reject. The fast acting solenoids are utilized to close the control valves following a generator load reject condition, Since the 113 control valve would not fast close at the 10% position load reduction was begun immediately w:l:th .the unit at 700 MWe, The reactor scram was by-passed when the reactor was less than 45% power. This event has. not occurred previously at Dresd~n.

Investigation of the #3 control valve revealed that an electricial terminal lug ori the fast acting solenoid had become deteriorated and had finally oroken'off,

• The terminal lug was re'placed and the valve tested satisfactorily. Unit returned to higher power operation. No further corrective action necessary,

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