ML19332F911

LER 89-021-03:on 881025,preliminary Investigations Indicated That Containment Cooling Fan B Could Not Be Relied on to Perform Intended Design Function.Motor Overcurrent Condition Existed Since installation.W/891214 Ltr

ML19332F911
Person / Time
Site:	Wolf Creek
Issue date:	12/14/1989
From:	Bailey J, Mike Williams WOLF CREEK NUCLEAR OPERATING CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-89-021, LER-89-21, NO-89-0216, NO-89-216, NUDOCS 8912190301
Download: ML19332F911 (8)

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VU$LF CREEK 1 '

NUCLEAR OPERATING CORPORATKW John A. neuer '

v=e m -December 14, 1989 i 88uesaw oseressas NO 89-0216 'l l

U. S. Nuclear Regulatory Commission ATTN Document-Control-Desk

,3E Mail Station P1-137 )

_ Washington..D. C. 20555 E

Subjects Docket No. 50-482: Licensee Event Report 88-021-03  ;

Gentlemen:

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The attached Licensee Event Report (LER). provides a supplement _ to LER 88 021-02. _This event was originally reported pursuant- to  ?

10 CFR 50.73(a)(2)(1)(B) as a condition prohibited by Wolf Creek Generating .j Station (WCGS) Technical Specifications. This . supplement provides the j results of evaluation of the potential-.cvercurrent condition on a Containment- Cooling Fan Motor. 'the evaluation identified that the motor _ ';

.would have been able to perform its' dvidgn ' function under normal'.and accident conditions. Subsequently. Wolf Creek Nuclear Operating Corporation-chas. concluded that no condition prohibited by WCGS Technical Specifications existed.

Very truly yours.

y p , d -

John A. Bailey Vice President Nuclear Operations JAB /aem

' Attachment r

cc D. L. Bartlett.(NRC), w/a E. J. Holler (NRC), w/a R. D. Martin (NRC), w/a D. V. Pickett (NRC), w/a 8*12190301 891;14 F'DR ADOCN 05000482 S p pc P.O. Box 411/ Burhngton, KS 66839 / Phone: (316) 364 9831 2 k l

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"' Supplemental Report Describing Final Evaluation Of Containment Cooling Pan Motor I Potential Overcurrent Condition tVtNT DATI 16) Lt A NUM.E m del atPORT DAf t th OTHE R P ACILifit t INVOLVE D (5)

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On October 25, 1988, at approxinately 1600 CETT, as a follow-up to canditions  !

identified during Integrated leak Rate Testing (IIRT), preliminary investigations indicated that Containment Cooling Ita 'B' could not be relied upon to perfom its intended design function under accident conditions due to a notor overcurrent condition. Containnent Cooling Fan

'B' was declared inoperable.

At the tim, it appeared that the notor overcurrent condition had existed l E

since the mtor was initially installed on July 25, 1987, (i.e. the

). condition did not appear to be due to notor degradation). Due to l

1. . inconsistencies between actual notar perfomance during the IIRT and the vendor-supplied notor test report, it was celleved the notar could not be l

t. relied upon to perfom its design function under accideat conditions. 'Ihe L

notor was replaced with a qualified notor.

'Ihis supp1 ment is being issued to detail the final results of the

evaluations conducted in conjunction with the vendor. These evaluations l-concluded that the notar would have been able to perform its design functica l

i under normal as well as under accident conditions, i.ti,'"" *"

0 IfRC ,orm s.6A U.S NUCLE A3 f.419Lt. TORY COMMthel04 UCENSEE EVENT REPORT (LER) TEXT CONTINUATION APrRoe owe no oso-m EXP RES l'8088 9 AC8ktiv hAME Of DOChli NUM88M G8 Llm NUMBER 16p PA04 (3) vlaa " RM O.*,T Wolf Creek Generating Station o l6 j o j o l 0 l 4l 8l2 81 8 0l2l1 -

0l3 Q2 oF 0 l7 rm . e o . - w , amuwnn INBGUCFICBI On October 25, 1988, at approxistely 1600 CDP, as a follow-up to conditions idetified during Integrated leak Rate Testing (IIRT), preliminary investigations indicated that Contalment Cooling Fan 'B' [BK-FAN) could not be relied upon to perfoon its intended design function under accident conditions due to a notar overcurrent condition. Containment Cooling Fan

'B' was declared inoperable. Subsequent evaluation concluded that this condition had existed since the notor [BK-)O) was initially installed on July 25,1987. Following the installation of this notor, the plant had l operated in all nodes. Technical Specification (T/S) 3.6.2.3, applicable for lede 1, Power Operations, through Mode 4, Hot Shutdown, requires two independent groups of Contalment Cooling Fans to be operable with two fan systems to each group. With one group inoperable and both Containment Spray Systems (BE) operable, T/S 3.6.2.3, action statement 'a', requires restoring the inoperable group of cooling fans to operable status within 7 days or being in at least }bde 3, Hot Standby, within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />, and in Mode 5, Cold Shutdown, within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />. In addition, T/S 3.0.4 prohibits entry into an operational node or other specified condition unless the conditicms for the Limiting Candition for Operation are net without reliance on the provisions ccntained in the action requirsents. Therefore, this event was originally reported pursuant 10CFR 50.73 (a)(2)(1)(B) as a condition prohibited by the plant's T/S.

mis su @lement is being issued to detail the final results of the evaluations conducted in conjunction with the vendor. %ese evaluations concluded that the notar would have been able to perform its design function under nomal as well as under accident conditions. Consequently, no condition prohibited by the plant's T/S ever existed.

DESCRIPTI(N OF (RIGURL BV12ffS On July 20, 1987, at approximately 1149 CDP, Containment Cooling Fan 'B' tripped. We plant was in Mode 1, with the Reactor (AB-RCT) at approxistely 100 percent power. Containment Cooling Fan 'B' was declared inoperable and T/S 3.6.2.3, action statment 'a' was entered. ,

4 On July 20, 1987, at approximately 2303 CDP, the plant experienced a Reactor Trip as discussed in Licensee Event Report (LER) 87-030-00. The Reactor Trip was neither caused by nor affected by the inoperable Containment Cooling Fan. However, T/S 3.0.4 prohibited entry into !bde 2, Startup, with Contalianent Cooling Fan 'B' inoperable.

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0] 3 0l3 OF 0l 7 f tKT (J pere spece de agpeet s#se semesist MIC Fenn JUEA W 1171 l Subsequent inspection of Containment Cooling Fan 'B' revealed that one of l the sixteen variable pitch fan blades had failed damtging several other fan blades. W e damaged fan blades were replaced. %c three runninirq Containment Cooling Fans were inspected to verify that the fan blades were firmly fastenad, at the correct pitch, and that there was no excessive notor vibration. his informatim indicated that the fan blade failure was an isolated event, not indicative of a generic design or manufacturing error that would result in the simultaneous failure of the other Containment Coolby Fans.

Examination of the fan motor identified that the notor shaft had excessive runout which indicated a possible bearing failure. mis fan notor was replaced with a new assembly on July 25, 1987. Following motor installation, notar current amperage readings were measured and recorded.

These readings were within the nameplate ratings for the notor. After Containment Cooling Fan 'B' was restored to operable status, the plant I entered Mode 2 on July 26, 1987, at approximately 0515 CDP, and Mode 1 at appmdmately 0740 CDP.

On October 17, 1988, while pressurizing Containment [NH] for the IIRr, Containment Cooling Fan 'B' was taken off line due to current values in excess of the notor's nameplate rating. % e fan was restarted when Containment was at a pressure of 50.4 psig, at which time Cmtainment Cooling Fan 'B' drew 164 anperes in slow speed. % e fan was again taken off line and a request for an engineering evaluation was initiated. % e plant was in Mode 5 in preparation for the third refueling at the time of the

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On October 25, 1988, at approximately 1600 Ctrr, preliminary investigations by Engineering indicated that Containment Cooling Fan 'B' could not be relied upon to perform its intended design function under accident conditions. No-load testing was then conducted to determine if the l described condition was the result of fan or motor problans. W e no-load ,

test results were as follows:  !

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Fast Speed (1200 rpn) Slow Speed (600 rpn)

Current Current

-Phase A 64 anperes Phase A 142 amperes Phase B 65.2 anperes Phase B 140 anperes Phase C 65.9 apperes Phase C 140 anperes l

l Based on the performance data supplied by the manufacturer with the original fan notors, the no-1 cad motor current should be approximately 41 and 104 amperes for fast and slow speed, respectively. l J

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WRC form antA U S ECUCLE A3 etttVLATOlY COMuttstot UCENSEE EVENT REPORT (LER) TEXT CONTINUATION eeaovto oMe wo mo-cine EXPlRf18'31'te t csL81Y HAM 4 Hi 00CR47 NUMet h (28 LtRNUMeth(6) PAGE (31 m- "empt' nm Wolf Creek Generating station o p;ojojol4;8;2- ej 8 _ 0;2l1 _ 0;3 0 ; 4 lo, 0;7 im <n . .- a*c ,,,,, m., m, As a result of a rwiew of all data taken during the events of July,1987, and a ocmparison with the data rw.=44 during IIRT, it agpeared that the notor overcurrent condition had existed since the notor as initially installed on July 25, 1987, (i.e. the condition did not appear to be due to notor degradation).

N nameplate values given on the notor test report supplied by the verdor with the notor met the design specifications for the notor. However, the l values for the no-load and nansplate ratings on this notcr test report '

appeared to be inconsistent with each other. h no-load value of 129.6 anperes on the test mport appeared to be too high to meet the full-load i nameplate rating of 147 anperes. Table 1 (attached) provides a ocmpilation of notor current data. In addition, the actual notor performance as naasured during the IIRT ms inconsistent with the notor test full-load value. Uhe actual fan notar current values measured during these tests exceeded the nansplate current values.

Due to these inconsistencies, it was believed the notor could not be relied upon to perfozm its design function under accident conditions. 'Ihe notor was replaced with a qualified notor. Paview of the notar test reports and field tests for other fan-notors in this application did not idantify ,

additional inconsistencies of this type. h refore, it was believed that this was an isolated case.

I ruar muarra h subject notor was returned to the supplier for testing in accordance with the original purchase specification. Wolf Creek Nuclear Operating Cwgudtion (WCNOC) engineering personnel were present to witness this testing and to discuss the identified problem with the notor nunnfacturer.

A preliminary test report documenting the ccmplete results of the above tests and an evaluation of these results has been ptwided to NOOC by the supplier, h conclusion of the preliminary test report indicates that the subject notar has passed all tests required to ensure the notor will meet the application requiranents. However, this notor has a lower power factor at 1cw speed than notom of the sane design which results in notor full-load current greater than the naneplate value.

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=ac e.. ma v s evettu motaTony commits o= I LICENSEE EVENT REPORT (LER) TEXT CONTINUATION ***aovie oMi womo-om

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Wolf Creek Generating Station o p ;o yolo; 4;8 g2 8; 8 _ 0; 2 l1 _ 0;3 05g or 0 j7 TLKT I2 mee apete h retood, see es@noner MC Fem Jn6A M 41D NWOC engineering i=.cnnel have reviewed the additional informaticn submitted by the supplier. Based upon this review, it was determined that the notor would meet the requirments for the particular application (i.e.

brake horsepower, torque, tenparature rise, etc. ). However, it was necessary to ensure that the additional full-load current would not impact the notor overcurrent protection. A calculation was performed to ensure that the notor would not trip on thermal overload when required to mitigate the consequences of an accident. In addition, it was determined by this calculation that the existing thermal overload heaters are sized properly for use with the subject notor. The locked rotor current determined by test for this notor is essentially the sane as that for the original notors at both speeds. 'Iherefore, the existing instantaneous overcurrent settings will not trip the notor during acceleration.

'Iherefore, it has been determined that the Cantainment Cooling Fan notor ruoved frun service curing October of 1988 could have been relied upon to ,

mitigate the consequences of an accident. 'Ihis motor will draw higher  !

current at full-load and no-load due to its lower power factor. However, I the existing overcurrent protection is sized am usiately for use with this

-notor. It has therefore been determined that tw.re is no technical proble associated with the subject notor.

As a result of a surveillance perfomed of the notor manufacturer and a revic.; of Wolf Creek Nuclear Operating Corporation's (NCNOC) acceptance program, deficiencies were noted. - As identified, the notor condition was the result of the subject notar having a lower power factor in slow speed than other notors of the same design. Both hCNOC and the supplier failed to identify this motor discrepancy. The supplier's quality assurance swmn did not require documentation of deviations frm naninal test values and evaluations of such deviations. Consequently, these evaluations were not available to NCNOC. Upon receipt of the notor, the routine notor test report was not reviewed by NCNOC engineering personnel as a supplier subnittal. 'Iherefore, the notor was received and installed without identification and subsequent evaluation of the discrepancy.

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'Ib prevent recurrence, the Supplier Information List and the NCNOC materials l management dauhue will be revised to invoke purchase order requirments 1 for all future safety related replacement motor purchases to ensure that routine notor test reports are subnitted to NCNOC and that any routine notor deviaticns are identified, evaluated, h-ited and subnitted for approval prior to release of the notor for shipnent. 'Ihese revisions will be ccupleted by February 28, 1990. NCN3C procedures will be reviewed and revised as necessary to ensure that supplier subnittals are forwarded to pg ppg gg 8 '$.

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ExP'nts. t'31 '88 f ACILITY hAMt (11 DOCK E T NUMtt h (U L(R NUMSIR 44) PAGE (Si visa "20!?!'.'. ' -O'J'.'O Wolf Creek Generating Station 0 l6 l0 l0 l0 l4 l 8l 2 8l 8 -

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0l3 0 l6 0F 0 l7 TtKT (2 mwe appre 4 meurest sese emmener MC form 316Caltth engineering for review and acceptance prior to release of the material for installation. 'Ihese gvcx,-lural revisions will be ocmpleted by February 28, 1990. As a remedial action, the routine motor test reports for safety related continuous-duty replacement notors received frun this manufacturer since the time of cannercial operation will be reviewed against the routine notor test reports for the original notors to ensure motor characteristics are within notor overcurrent design. 'Ihis review will be ocmpleted by - .

February 28, 1990. i The Cbntainment Cooling Fan notar is manufactured by Reliance Electric i Capany, part number 600287-43. The notor is a 460 volt two speed notor (rated at 150/75 horsepower).

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S[W SPEIO (600 rps) i (AcMrheit mda of Operation)  ;

1 NEMILRED M3KR NhMEPUEE MFKR TEST REKRT IIRP E IOhD (full-load) Ino-load) 147 129.6 164 Phase A 142 Phase B 140 .

Phase C 140

, i FASP SPEED (1200 qun)

(Routine m de of Operation) unastRio MMR NhMEPUEE M71TR TEST RERRT IIRP W IDhD (full-load) (no-load) 167 58.8

• Phase A 64 Phase B 65.2 Phase C 65.9 Not Applicable I

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