IR 05000324/1993011

Insp Repts 50-324/93-11 & 50-325/93-11 on 930222-26.No Violations or Deviations Noted.Major Areas Inspected: Followup on LER 92-017 & Incomplete Closure of Ite Type K-3000 Breaker Contacts

ML20056C186
Person / Time
Site:	Brunswick
Issue date:	03/17/1993
From:	Mark Macdonald, Moore R, Shymlock M NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I), NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
To:
Shared Package
ML20056C185	List: IR 05000324/1993011 ML20056C184
References
50-324-93-11, 50-325-93-11, NUDOCS 9303300212
Download: ML20056C186 (6)

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"   UNITED STATES
[[ %'og 3- n NUCLEAR REGULATORY COMMISSION REGION 11
$ 3 y  101 MARIETTA STREET. *
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   ,,s Report Nos.: 50-325,324/93-11 Licensee: Carolina Power and Light Company P.O. Box 1551 Raleigh, NC 27602 Docket Nos.: 50-325 and 50-324  License Nos.: DPR-71 and DPR-62 Facility Name: Brunswick I and 2 Inspection Conducted February 22-26, 1993    !

Inspector: (2 (I67tB _, 3/s-/93 R. Moore ._ Date Signed

 #!    3/9/93 G. MacDonald   Date ' Signed :

Approved by: M M. Shymlock,Mhief

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3-/745 Date Signed i Plant Systems Section r Engineering Branch  ! Division of Reactor Safety i SUMMARY j Scope:  ; This routine, announced inspection was conducted in the areas of follow-up on f LER 92-017, Incomplete Closure of ITE Type K-3000 Breaker Contacts, and  ! review of deferred electrical preventative maintenance. These issues are associated with Brunswick Restart item B- . Results: The licensee's corrective actions on LER 92-017 related to ABB 480 V breakers j were on schedule for completion prior to restart and were adequate. However, j the LER corrective actions did not sufficiently resolve potential equipment-reliability problems with similar ABB type breakers used in 4160 V safety  ! related application ? l The licensee's process for PM deferral was adequat No deferred electrical

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PMs were identified which impacted plant restart capabilit !

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Restart item B-1 remains open pending appropriate resolution of equipment j reliability concerns of ABB medium voltage HK breakers used in 4160 V applica-tions. No violations or deviations were identifie PDR ADOCK 05000324' G PDR l

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REPORT DETAILS Persons Contacted f Licensee Employees

*R. Anderson, Vice President, Brunswick Nuclear Project  t
*M. Bradley, Manager, Nuclear Assessment Department
*J. Brown, Plant Manager, Unit 2   *
*K. Fennell, Manager, Balance of Plant Systems Engineering  +

M. Haynes, Preventative Maintenance Coordinator

* Kirkland, Engineer, Technical Support   !
*L. Loflin, Nuclear Assessment Department
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*P. Mazzola, Manager, Support Training   ;
*G. Miller, Manager, Technical Support   '
*D. Moore, Manager, Maintenance
*R. Morgan, Plant Manager, Unit 1   ;
*R. Schlichter, Nuclear Assessment Department T. Simonson, Technical Support Engineer S. Tabor, Regulatory Compliance   !
*G. Warriner, Manager, Control and Administration f

NRC Personnel i

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R. Prevatte, Senior Resident Inspector  !

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* Attended Exit Interview Acronyms and abbreviations are identified in paragraph ! Onsite Follow-up of Licensee Written Reports (IP 92700), LER 92-011 i

The inspectors reviewed the licensee's corrective actions for LER ! 92-017, Incomplete Closure of ITE Type K-3000 Breaker Contacts. This ! breaker failure occurred at Brunswick on April 21, 1992. This type of breaker was installed in safety related emergency bus substations E-5 : through E-8. These breakers and another ABB type breaker, medium l voltage HK breakers, were the subject of a 1989 D.C. Cook 10 CFR Part 21 ! notification. The notification identified that these two breaker types L by ABB were susceptible to lubrication age hardening and debris contami-nation. The station's applicability review in 1989 concluded there were , no concerns at Brunswick on this issue. The conclusion was based on a ! review of equipment maintenance history related to lubrication ~ problems, no breaker inspections were performe i V Breakers (ABB Low Voltage K-3000 Breakers) -l Low Voltage K-line breakers manufactured by ABB are installed as main, tie, and load breakers on emergency bus substation Approximately 58 of these breakers are installed in this safety I related application. The vendor recommended a 10 year refurbish- I ment cycle; the breakers had been installed approximately 20 years ! without refurbishment. The LER corrective actions included i refurbishment or replacement of these breakers prior to restar , f

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p Thirty-one of 38 breakers required for Unit 2 restart have been , refurbished. The remaining breakers are Unit 1 specific and were ! scheduled for refurbishment prior to Unit I restar There were nine corrective actions delineated by the LER. The , following corrective actions were specified by the LER to be ! completed prior to plant restart: i

      ! Prior to start-up, review and inspect other critical appli- l

. ' cation breakers to ensure the lubrication problem does not j exist (i.e., at a minimum this includes safety related t breakers).  ! Prior to start-up, safety related breakers that have not [ been refurbished / replaced within the last ten years will be j refurbished or replace : - The inspectors concluded the licensee had appropriately resolved safety issues associated with this LER applicable to the 480 V ,

(ABB low voltage K-line Type) breakers. Although not yet com-

plete, actions to refurbish or replace these breakers will be i , " completed prior to restart of the unit i 3 V Breakers (ABB Medium Voltage HK Type Breakers)  ! ! i . The licensee's actions to address this potential lubrication ! i related failure mechanism on other safety related breakers did not j i sufficiently resolve reliability concerns with this equipment. In ! j particular, the inspectors were concerned with the 4160 V breakers l l on the emergency buses E-1 through E-4. These breakers were ABB i medium voltage HK breakers referenced in the 1989 D.C. Cook Part 21 notification. There were approximately 56 of these breakers '

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installed in the statio !

The licensee initially provided a schedule to the inspectors which )

would refurbish the safety related and B0P breakers of this type !

in the station over the next nine years. Preventive maintenance performed on these breakers included a general statement to j lubricate accessible breaker parts. The licensee reviewed the i equipment history and verified this PM had been performed on all breakers in the previous 3 year period. This document' review of

PM accomplishment provided the licensee's basis for not refurbish-

. ing these breakers prior to restar The licensee further stated

that verification of PM performance satisfied the corrective action " review and inspect" requirement specified in LER correc-tive action statement number seve .

. The inspectors concluded the actions accomplished by the licensee i did not fully resolve reliability concerns with the ABB breakers l - installed on emergency buses E-1 through E- In LER 92-017 the !

licensee stated that a concern of their 1989 Cook Part 21 applica- ;

4 bility review was, "the reliance on operating history to j l  !

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3 , confirm no problem existed (no actual checks / inspections were done)". The recent evaluation also relied on equipment history , review + t There were several factors which indicated these breakers should be refurbished prior to restart or a more thorough evaluation performed to justify delaying refurbishment. The following 1

; factors challenge the reliability of these breakers-  '

i These breakers were addressed in the D.C. Cook Part 21 and !

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related ABB notification as susceptible to lubrication hardening over the long term and related failur [ L The breaker vendor manual recommends a 10 year refurbishment -; cycle; Brunswick breakers have been installed 20 years . without refurbishmen !

     ! Current PMs lubricate accessible pcrts only; not all of the critical friction surfaces are accessible for inspection or lubrication by this P :

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; The failure at Brunswick of an ABB low voltage breaker of !

the type referenced in the Cook Part 21 notification demon-strated that this failure mechanism was possible at Bruns- i wic j 4 i The inspectors addressed these concerns to the licensee. A [ revised refurbishment schedule was developed which projected a ; completion of safety related breaker refurbishment by December 31, ! q 1994. Six of these breakers had recently been sent to the vendor for refurbishment. The licensee contacted the vendor to pursue a justification for delaying refurbishment on these breakers until i after plant restart. The inspectors will review this issue ! further on upcoming inspections. Restart Item B-1 remains open pending resolution of this issu >

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3. Electrical Maintenance (Components & Systems) Observation of Work, and i Review of Quality Records (IP 62705)  !

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The inspectors reviewed the process for deferring preventive maintenance ; and the Unit 2 Q-List components in the PM backlog addressed by the PM exception process. Safety related low voltage and medium voltage i switchgear and circuit breaker PMs were reviewed. Selected low voltage ! and medium voltage switchgear compartments were inspecte '

     ; Deferred PMs    l
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' The inspectors reviewed Maintenance Management Manual Procedure .! OMMM-004 ," Preventive Maintenance", revision 6 (current version) : and revision 5. Revision 5 allowed the Maintenance Subunit -l Manager to approve PM exceptions without evaluation by Engineering j

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4 I or Technical support. A PM exception was required if a PM would exceed its required due date by more than 25 percen . ' The current procedure required that PM exceptions be reviewed by a Technical Support PM coordinator with assistance from other- a f engineering personnel as required. The inspectors. concluded that ' the present process contained an appropriate level- of technical i review for PM exception The licensee provided a list of deferred PMs required for Unit 2 ! restart. The inspectors reviewed the basis for the deferred PMs ! and concluded that there was no impact on Unit 2 restart. The PMs ! reviewed were dispositioned under the old PM exception proces ' The majority of the deferred PMs were non-applicable PM task For example, there were motor starter PMs designated for breaker ; compartments which did not contain motor starters. Other deferred ! PMs included tasks for plant equipment which had been deleted via l the modification process. PM activities still existed for the ! equipment. This PM program weakness had been identified by the . i licensee. The licensee was aware of problems with the current PM l process at Brunswick and had begun a three year PM upgrade pro- l gram.

- The inspectors reviewed several PM exceptions completed under the - . new PM exception process. The basis for the PM exceptions were ! acceptable and the inspectors concluded that the new PM exception , process appeared to be adequately controlle [ < B. 480 V ABB K-Line Switchgear/ Circuit Breaker PM , The vendor manual recommended maintenance was reviewed against the ! switchgear and circuit breaker PM procedure Th; vendor manual i requirement for breaker refurbishment was not contained within the i existing breaker PMs. Vendor refurbishment, a result of the LER, ; will be complete prior to restart. The licensee was in the ! process of establishing PMs for ensuring future refurbishmen i The vendor recommended maintenance based on breaker cycle inter- , val s . The 480 V breakers did not have operation couaters and the i licensee did not have any tracking mechanism on breaker opera- ! tions. The licensee breaker maintenance was scheduled on 3 year ! intervals and this was considered adequat The 480 V switchgear PMs generally implemented vendor recommenda-tions. The licensee's inspection PM interval of 3 years, although : longer than the vendor's recommendation,'was considered accept- l able. Selected compartments of all the 480 V switchgear were j observed by the inspectors. Loose cable support clamps in 480 V l tie _ breaker compartments were noted. The inspectors witnessed the ! testing cf a newly refurbished ABB 480 V K600 breaker. Mainte- ! nance was adequately controlled and personnel were familiar with ! acceptance criteri The contact pressure checks were correctly l performe !

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The vendor recommended PMs were reviewed against the switchgear l and circuit breaker PM procedures. The vendor recommended a six -t month switchgear inspection interval while the licensee had a 3 . year interval. The PM program did not incorporate vendor recom- ! mended breaker refurbishment. The licensee had begun a vendor refurbishment program in May, 1992. The licensee was in the ' process of establishing PMs for future refurbishment activitie The breaker PM procedure was considered weak in the area of j lubrication inspection and lubrication. The licensee had begun a ! revision to the procedure to expand on breaker lubricatio ! The licensee had a copy of an ABB vendor bulletin on medium voltage switchgear maintenance which identified the vendor re- : quirement for periodic breaker refurbishment. This bulletin was ; not a part of the licensee's switchgear vendor manual. It was not

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clear how this vendor information was communicated to the licens-ee. The inspectors will review this issue further on cpcoming i , inspection The inspectors accompanied operations and technical support system ! engineering personnel on a walkdown of the 4160 V emergency

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busses. Several minor items were noted by the inspectors, such as ' control circuit wiring bundle supports missing, switch covers , missing, and indicating lights needing replacement. The inspec- i tors reviewed the licensee's corrective maintenance history for , the 4160 V breakers to determine if lubrication related failures ' were common. Only four lubrication related failures _were identi- .

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fied. The most common causes of corrective maintenance on the breakers were due to spring charging motor failures, current transformer failures, and auxiliary switch failures. The PM procedures were very detailed in these areas indicating that the licensee was revising the procedures to address known maintenance problem . Westinghouse MCCB Failure Mechanisms Identified During this inspection the licensee completed their analysis of failures on Westinghouse type HMCP and HFD molded case circuit breakers. A Part - 21 notification was initiated. Several of these type breakers failed to ! open on overcurrent conditions during testing. The causes of the - breaker failures were identified to be inadequate fabrication and ! tolerances and inadequate lubrication of critical hinges during fabrica- i tion. The licensee identified 139 HMCP and 79 HFD breakers in safety i related applications. They stated their intention to replace all of the ! HMCP breakers prior to plant restart. The HFD breakers would be tested i and deficient breakers identified by the test would be replaced. Parts procurement had been initiated at the close of this inspection. The inspectors will follow this issue on upcoming inspection :

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5. Exit Meeting The inspection scope and results were summarized on February 26, 1993, with those persons indicated in paragraph I.. Proprietary information is not contained in this' report. The inspector described the areas inspected and discussed in detail the inspection results. Theie were no dissenting comments received from the license . Acronyms and Abbreviations ABB Asea Brown Boveri B0P Balance of Plant HFD letter designation (no abbreviation) HK letter designation (no abbreviation) .i HMCP letter designation (no abbreviation) IP Inspection Procedure , ITE International Telephone- and Electronics (breaker manufacturer) ; LER Licensee Event Report  ; MCCB Molded Case Circuit Breaker i PM Preventive Maintenance  ! i I

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