ML20085L642

Ro:On 710804,during Surveillance Testing of Msiv,Scram Relay 590-108A Failed to Drop Out When Deenergized.Possibly Caused by Wiring Clip Overlooked During Initial Installation. Relay Replaced.All 108 & 109 Relays Cleaned

ML20085L642
Person / Time
Site:	Dresden
Issue date:	08/14/1971
From:	Hoyt H COMMONWEALTH EDISON CO.
To:	Morris P US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20085L644	List: ML20085L642 ML20085L653 ML20085L798
References
NUDOCS 8311020191
Download: ML20085L642 (2)

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A ro-Mf (Q[' Commonwealth Edison Company ONE FtRST NATBoMAL PLAZA A C H I C A G O. SLLlNGlS Aeldr.se SepJr so, post optics son ter

• cuec Aco, etteNoas eoevo Q4 Dresden Nuclear Power Station YQ R. R. #1 A Y' t

Morris, Illinois 60450 .

'I August 14, 1971 '{ 4/g/g194s, q d

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\y # Y Dr. Peter A. Morris, Director Division of Reactor Licensing ' % * [~ p['-

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U. S. Atomic Energy Coasnission Washington, D. C. 20545

SUBJECT:

LICENSE DPR-25. DRESDEN NLICLEAR POWER STATION UNIT #1. SECTIO _N_

6.6.B.3 0F '1HE TECHNICAL SPECIFICATIONS e'

Dear Dr. Morris:

This is to report a condition relating to the operation of the station wherein, during surveillance testing of the Main Steam Lir e Iso-lation Valves on August 4,1971, scram relay 590-108A failed to dtop out when deenergized.

PROBLEM. INVESTIGATION AND CORRECTIVE ACTION Surveillance testing of main steam line isolation valve (MSIV) was being conducted on August 4,1971, and inboard (IA)and outboarc (2A) valves on "A" main steam line (MSL) had been closed and reopened. When the inboard valve on "B" MSL was closed a reactor protection system channel "j." trip was initiated and only control rod drive solenoid groups 2 and 3 deenc rgized.

The valve was reopened and closed again with the same results. At.ditional operations and tests failed to duplicate the malfunction. .

Investigattion revealed that two asifunctions had occurred. The first was the react'or protection system channel "A" trip. Follow.ng the reopening of the inboard and outboard valves on "A" MSL, either t'..e limit j switch oc one of the "A" MSL valves failed to pick up when the va've was .

opened, thus preventing relay 509-102A from reenergizing,. or cent. cts 1-2 or 3-4 on relay 509-102A_d Q og pick up. In either case, when the inboard d l' /

valve on "B" MSL wan[ opened,/a irip of the reactor protection system channel '

"A" was initiated. Ifermated tasting did not duplicate the as1 function, which was in the " safe" direction, since it would not have prevented the reactor h[' protection system from performing its intended function.

N The second malfunction was the failure of scram relay 590-108A

[ to deenergize. The relay was exercized satisfactorily once per shif t until it was replaced on August 6, 1971. During replacement of the relt.y a "small terminal wiring clip" fell out of the relay. Further inspection revealed no information as to where the clip came from. It is probable that the wiring clip was the cause of the as1 function and that it was overlocked Euring the initial installation, es11omoi,1 710814 A. ,e*~ , ,

cM StNT REGION

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O Dr. Peter Morris August 14, 1971 l

In addition to replacement of the malfunctioning relay, all the 108 and 109 relays were cleaned and exercised following cleaning to insure -

proper operation. No foreign materials were found during the cle ning.

Following replacement of the 108A relay, it was tested satisfactorily. - 'i

The main steam isolation valves were tested on August 8 and 11,15 71, with no repeat of the previous malfunctions.

Sincerely, 7

H. 'K. Hoyt Superinten t HFJt: do 16-t i

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4 IT*rs.. AtT 91(Rev. Stav14.1643 rasitats atesAAas T O (Name and unto Subiect: Coasnonwealth Edison Company ( 7p wA J. G. Keppler, CO:HQ E. G. Case, DRS can Unit 3 - Docket No. 50-249 4 Le h

R. S. Boyd, DRL R. C. DeYoung, DRL CO Inauiry Report No.71-012 f ~i+~#rle / /

To (Nsm saa vain w as atuanas y ' ffg D. J. Skovholt, DRL r , fh y ,

H. R. Denton, DRL t/

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A. Giambusso, CO can f

L. Kornblith, CO f R. H. Engelken, CO h

To (N3m. .ae vain l unas no.anas <A

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Rrgional Directors,CO DR Central Files ,

can FROM (Name and unit) mEndaans Attached is the revised page of my memo dated 8-11-71 D. M. Hunnicutt, DO:III transmittina subject inquiry report.

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/* UNITED STATES

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ATOMIC ENERGY COMMISSION y DIVIStoN OF COMPLIANCE l b,e REGION lil ,

p 799 ROOSEVELT ROAD l

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GLEN ELLYN. ILLINols 00137 sla)see-asse August 11, 1971 .

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J. G. Keppler, Chief, Reactor Testing and Operations Branch Division of Compliance, Headquarters .

COMMONWEALTH EDISON COMPANY -

DOCKET NO. 050-249 LICENSE NO. DPR-25 DRESDEN UNIT 3

1. FAILURE OF ONE SCRAM RELAY DURING SURVEILLANCE TESTING ON AUGUST 4, 1971

2. WIRING ERROR IN 120/240 VAC DISTRIBUTION BETWEEN REACTOR .

PROTECTION SYSTEM BUSES A AND B, DISCOVERED AUGUST 6, 1971 2

3. STEAM LEAK IN SAMPLE PROBE WELDOLET TO N0ZZLE WELD ON HAIN STEAM LINE B, DISCOVERED AUGUST 6,1971 The attached inquiry report of three occurrences is forwarded for [

information. Licensee action for each of these three itesis appears ,',

to be satisfactory. ,

We are particularly concerned with the wiring error, since it was undetected throughout construction testing, as well as preoperational '

testing. The preoperational test did not include a verification of ,

independence between the two reactor protection subeystems. A power  !-

loss test was conducted. This test demonstrated that a power loss .

to the supply bus would result in a reactor scram due to loss of some '

monitors.

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ON AUGU ST 5 1971 i'll Tli U R RON COOK RE GI ON 3 CO'.1PL A I NT CONCERNING APPARENT FAILURE OF SCRAM REL AY 590108A 2 TO DROP OU T \711E N DEE NE RG I ZE D. T11 i S IS AN ABNOR'.1AL OCCURANCE AND I S REPORTE D UNDER SECTI ON 6. 6. A.3 0F DPR-2 5 TECliN ICAL SPECIFICATIONS. AT APPROXIM ATELY 1730 If 0URS ON AUGUST 4,

- 1971 A SURVE IL ANCE CLOSURE TE ST OF TliE M AI N STE AM y

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'lSOL ATl ON VALVES (MSi V) WAS BE ING CONDUCTED 1711EN AINd S 2

203 1B 17AS CLOSED SOLON01D GROUPS 2 AND 3 iN SAFETY SYSTEMS Cli ANNEL A DEENERGIZED TliE VALVE 17AS OPENED AND TliE SOLEN 0 IDS 17ERE REENERGlZED.' VI SU AL OBSERVATI ON OF ,

TliE SCRN.1 REL AYS REVE ALED NO APPARENT ABUOR'.l ALTY. TliE '

CLOSURE OPERATION 17AS REPE ATED ONCE 171Tli TliE SN.iE RESULTS TliE OPER ATlON 17AS AG AIN RE PE ATED 17ITl1 TliE REL AYS l' UNDER OBSERVATION 'AND' TliE 'lNCIDENT DID NOT REPE AT ITSELF fT ' ALL SCR AM REL AYS 11 AVE BEEN EXCERI SED AND OPER ATE

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NORM ALLY Ti1E REL AYS 171LL BE TESTED ONCE PER SlilFT UNTil Tl1E SUSPECT REL AY CAN BE REFL ACED AND TliOROUGlilY EX AM i NE D IF FAILURE OCCURS AGA~IN BEFORE REPL ACEMENT A 1 STEM UNTIL TliE REL AY TRIP 171LL BE PL ACED iN Tli AT SUB SY,

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