ML20072S369

Part 21 Rept Re Failure of Substitute Relay,Mfg by Deltrol Controls,Supplied for Use in Delaval Emergency Diesel Generator.Failed Relays Replaced in Unit 1 Train B EDG W/ Original Potter & Brumfield Relay

ML20072S369
Person / Time
Site:	Comanche Peak
Issue date:	02/25/1991
From:	William Cahill TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC)
To:	Martin R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
References
REF-PT21-91 TXX-91088, NUDOCS 9104150159
Download: ML20072S369 (4)

Text

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Log # TXX 91068 I

,,,,, Fi1e # 10111 1 Ref. # 10CFR21.21 11/ ELECTRIC February 25. 1991 m ana J.Cana,  !

Mr. R. D. Martin U. S. Nuclear Regulatory Commission Region IV 611 Ryan Plaza Dr.. Suite 1000 Arlington Texas 76011

SUBJECT:

LOMANCHE PEAK STEAM ELECTRIC STATION (CPSES)

DOCKET NOS. 50 445 AND 50 446 A 10CFR21 REPORTABLE CONDITION INVOLVING FAILURE OF A SUBSTITllTE RELAY SUPPLIED FOR USE IN A DELAVAL EMERGENCY O!ESEL GENERATOR Gentlemen The attached report is being submitted pursuant to the requirea'ents of the Code of Federal Regulations. Title 10 Part 21. The report has oeen formatted in a manner that corresponds to the specific information requested by subparts (i) through (viii) of paragraph 21.21(b)(3) of the regulation. This is exclusive of that portion of subpart (vi) regarding names and locetions of other facilities which may be affected. as this-information is not known to TU Electric, and subpart (viii) in its entirety, regarding advice that has been or will be given to other facilities. Such advice would be dependent on these facilities specific use and testing of the subject relays.

Sinceroly, AML$3?sf William J. Cahill Jr. 4 JAA/ba Attachment c Resident Inspectors, CPSES (3)

Document Control Desk-Dr. T. E. Murley (3)

Cooper Enterprise Services Group l

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6ttacheent to IXX 91064 Psga 1 ef 3 1 10CFR21 REPORTABLE CONDITION INVOLVING FAILURE -

0F A SUBSTITUTE RELAY SUPPLIED FOR USE IN A DELAVAL EHERGENCY DIESEL GEkERATOR (1) Information supplied by William J. Cahill, Jr.

TV Electric P. O. Box 1002 (E22)

Glen Rose, Texas 75043 (ii) The basic component involves the neolication of a different relay (from that originally supplied) in the voltage regulator (VR) field flashing circuit of DeLaval emergency diesel generators (EDG). It should be noted that there is no known deficiency in sattrial or characteristic i of the different relay. The defect involves the specific annlication of the different relay as a VR relay in the field flashing circuitry.

The different relay is a Deltrol Controls 166 style relay which was supplied as a qualified and equivalent replacement for a Potter and Bruefield KUP 14A15 relay under DeLaval part number 76001 102 06. The l

facility is the Comanche Peak Stese Electric Station Units 1 and 2.

l (iii) The Deltrol Controls 166 style relay described in (ii) above was

' qualified and supplied to TU Electric by Energy Services Group / Division of Cooper Industries Enterprise Engine as a qualified and equivalent-relay for use as a VR relay in the EDG local control panel voltage regulator circuit. -

(iv) Description The VR relay is a 120 VAC relay that. senses EDG output voltage through i a potential transformer. The relay is energized when the generator voltage reaches approximately 601 of nominal. A contact on the VR relay opens the field flashing circuit te disconnect it when the 605 nominal voltage point is reached.

Sita Snecifie '"- ary on thy 10,1989. TU Electric issued a perchase order to Energy Services Group / Division of Cooper Industries Enterprise Engine (ESG) to procure-six (6) VR relays (DeLaval part number 76001 102 05) for use in the emergency diesel generator local control panel voltage regulator ,

i tircuit. - The VR relay originally supplied and qualified in the voltage '

regulator circuit was a Potter and Brumfield part number KUP 14A15. 1 The supplied relays were Deltrol Controls 166 style relays. A Certificate of Conformance from ESG w6s supplied with the relays -'

certifying them as a direc* replacement for the originally supplied Potter and Brumfield relays.  ;

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Attachment to TXX*91068 l Fage 2 of 3 On 12/13/90, one of the Deltrol relays was installed as the VR relay in the "B" EDG as part of a preventative maintenance activity. During a maintenance verification check following the replacement and prior to j declaring the EDG operable, a diesel start was unsuccessfully attempted. The unsuccessful attempt was traced to failure of the (Deltrol) VR relay. Subsequent to the failure. the original Potter and Brumfield relay was reinstalled and the "B" EDG was successfully started and returned to a standby ready condition.

The failure of the Deltrol relay in this application has been attributed to differences in its pickup and final sealain voltage characteristics compared to those of the Potter and Brumfield relay.

The design of the circuit is such that during diesel starts when generator voltage is increasing to nominal voltage, slight chattering of the relay occurs between initial pickup and final seal in voltage.

The duration of the chattoring is dependent on the pickup and seal in characteristics of the relay. These characteristics in the Deltrol relay extended the duration of relay chattering and resulted in the failure of the EDG to achieve proper voltage and frequency.

Based on the above, TU Electric has concluded that the use of the Deltrol Controls relay in this specific application is a defect pursuant to 10CFR21.

Site Snecific Safety Isolientions i

cT3ES Unit 1 and Unit 2 each utilize two redundant DeLaval EDG's as the essential energency AC power supply during accident conditions with-( offsite power unavailable. The problem with the use of the Deltrol relay occurred on the Train 8 EDG for Unit 1, and was discovered and corrected prior to returning the Train 3 EDG in e standby ready condition. The Train A EDG has the original style Potter and Bruefield relay. As a result, no substantial safety hazard existed at CPSES Unit

1. However, due to the nature of this deficiency. TU Elet tric is not confident that a Deltrol Controls relay utilized in this application would always fail en the first (post work test) start attempt or that if it successfully passed the first attempt, would not be subject to l failuro duriag a subsequent start. Based on this, TU Electric believes i

that a substantial safety hazard could be created by this deficiency.

(v) TU flectric completed its evaluation of this deficiency and. concluded that it represented a defect pursuant to 1DCFR21 on February 20, 1991.-

5 (vi) As discussed in (iv) above CPSES Units 1 and 2 have a total of four (4)

DeLaval EDG's. Six (6) of the subject relays were procured for use as VR relays in the voltage regulator circuit.

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i Attachment to TXX 91068 Page 3 of 3 (vii) As discussed in (iv) above. TU Electric has replaced the failed Deltrol Controls relay in the Unit 1 Train B EDG with an original Potter &

Brumfield relay. A separate TU Electric Stock Number has been assigned to Deltrol Controls 166 style relays to ensure they will not be utilized or purchased as VR relays for use in'the EDG's at CPSES Unit 1 or Unit 2. Prior to fuel load for Unit 2. TV Electric will confirm that Deltrol Controls relays were not utilized as VR relays in the voltage control circuits for the Unit 2 EDGs.

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