View source for PNO-V-92-010, on 920331,plant Reactor Trip Breaker Failed to Open During Routine Surveillance Test.Licensee Has Unsuccessfully Attempted to Reproduce Failure,In Breaker Cubicle & on Test Stand in Electrical Shop

{{Adams
| number = ML20203G047
| issue date = 04/02/1992
| title = PNO-V-92-010:on 920331,plant Reactor Trip Breaker Failed to Open During Routine Surveillance Test.Licensee Has Unsuccessfully Attempted to Reproduce Failure,In Breaker Cubicle & on Test Stand in Electrical Shop
| author name = Richards S
| author affiliation = NRC OFFICE OF INSPECTION &amp; ENFORCEMENT (IE REGION V)
| addressee name = 
| addressee affiliation = 
| docket = 05000530
| license number = 
| contact person = 
| document report number = PNO-V-92-010, PNO-V-92-10, NUDOCS 9712180020
| document type = PRELIMINARY NOTIFICATION OF EVENT OR OCCURRENCE (PNO,, TEXT-INSPECTION &amp; AUDIT &amp; I&amp;E CIRCULARS
| page count = 2
}}
{{#Wiki_filter:~~                                                     '' ~ ~
wy                                        .
                    . NOI!TICATION               OF EVENT OR
                                                     '                         UNUSUAL OCCURRENCE--PNO-V-9210               Date: 04/02/92                     i
                  )           .                                                     :
                 < This preliminary' notification constitutes EARLY notice of events of P0.S$1BLE safety                                             .
             ,e or public interest significance. The inforination presented is as initially received                                                   '       '
e withuut verification or evaluattun and is basically all that is known by Region V
* staff on this date.                         ,
FACILITY: ARIZONA PUBLIC SERVICE COMPANY                                        Emergency Clas'sification PALO VERDE UNIT 3                                                    Notification of Unusual Event DOCKET NO. 50 530                                                    Alert                                       ,
WINTERSBURG, AZ.                                                     Site Area Emergency General Emergency i                                     TNot Applicable

==SUBJECT:==
REACTOR TRIP BREAKER FAILURE TO OPEN
                  ;d                                   .
1jOnMarch 31,19927 at approximately 11:18 pm (MST) the Palo Ver e Unit 3The                                                'C' n          reactor trip breaker failed to open durin a routine surveillance test.
n conducting the test, operator 4 had
             ' f) breaker is ,a Westinghouse 'model t/S-206.''sttempted to trip the , breaker usin
                      *After cushing the trip button, the operators observed conflicting control room
                 > indications for the breaker. The closed indicator light went out, but the open                                                  ~
O indicator light did not illuminate. Additionally, although the alarm printer i~indicatedthatthebreakerhadopened,thw>wasindicationofcurrentstill 4 passing through the brehker. An Auiiliary Operator was dispatched to the breaker                                                   -
i and icported that the poyition flag indicated on intermediate po;ition. An                                                      '
2 . attempt tn open the breaker again both frc" the control room and locally f ailed.
                    ..The operators then tripped open'the 'A' r uctor trip brea.ker, which is in series
                    ,' w{th~the 'C' breaker. The unit remained at 100% power throughout the event with
* power to the control' element drive mechanisms provided via the parallel Dath 'B'
                     , jnd 'O' reactor trip?breakens.
1 'After discussicn with maintenance, the licensee elected to charge the breaker closing springs manually and then press the closing button. ,By breaker design, lthis resulted in'the,, breaker opening.
                  $ .TM licensee has unsNebsfully' attempted to repro' duce the,f ailure, both in the                                                ,         ,
                          .bceaker cubicle and on a test stand in the electri. cal shoo. There are .40 readily
                  ,1 visible signs of any damage to the t.reaker.                                                      _
                    . '1$e licensee has replaced the breaker with a spare breaker and has returncd the                                              -
                  ) 'r~eactor trip switchgearito a ncrmal condition. The breaker is presently
                   , ,ciuarantined. The licensee' intends to gain the assistance of Westinghouse in 1 disassembling the breaker in an attempt to determine the root cause of f ailure.
                    >         Theireaker has been previously tested month y and had no known history of                                    It
                           , failures, although thegt.icenseo was still conducting a review in this area.                                                   -
                  '        .is thought that the breaker'han been in service since initial plant                                                  -
construction.         The breaker cyqle counter indicated about 900 cycles on the f           breaker. The licensee is alsc conducting a review of industry history with this
                                                                             ~        '
model breaker.
9712180020 920402 PDR          IbE                                                                               11 s!>/-
PNO-V-92-010                     PDR (t
d                       ll
               ,                                                                              l lill. .lil! I   ll   %
        .- w m                          .
                               -               __                        m                 __                                  - --

co e ewt .
                  ;.t.-                                                                     ..
                  ',          s                             .
k       ~
                 ),                                                 -                                                                                                                                                                             .
t                                                                                                                                                                                                                              .
A conference call with the licensee was held at 1:00 pm (PST) on Aprt) 2. 1992,                                                                                                                                           '
                   . with OEDO, NRR, and Region V participating, during which the event and future actions were reviewed. 'A Region V inspector with circuit breaker experience has                                                                                                                                          ,
been dispatched to the s.ite..                                                                                                                                                         ,
This information has been discussed with the licensee and is current as of 1:30 pm (PST) on April 2,1992.
The licensee does not olen a press release.
CONTACT:                  S. Richards' FTS 448-0287
                    ]1-                                   -
r 3 (."
                  ,. ~   .                                                                        .
Se
: f.                                       -
i                                                                       ..
               +-                                       .                                                                                                                                                                                        '
i                                                                           :
                      <           c                                                  ..
P OlSTRIBUTION BY 55209-                                                                                                                       F AX 10:
Date j /.) 3 1me 4 ? $ /VT'                                                                                                                  DaTi'D/t Time 'NJi__JW)
                             .CO."un. Rogers                                            E DO .-                          .                     R1                          The Chair an g                                                             ,
O!G WJ Cemm. Curtiss                                             AE00
* R!l Co'mm. Remick                                             OPA                                                     Rlli                       ACRS k 3                                                   .
Comm. de Planque                                           St.lTP                                                 RIV                        INPO W(                                 =
                       -           #
* OP A '.                                                                                  NSAC'l V3                                                                 -
                        .      0CA                                                                                                                     '.^                 LICENSEE 3 '35' RE S ,'I OG" '.                                                    NRR                               's                                              RESIDENT INSPECTOR S'if                                                      '
                       ' DE                                                               NHSS.                                                                            HOS. OPERATIONS OFFICER 4Y
                                               .                                          IRM.                                                                              POR (702) 634-3343 41oc>                                                     ,
OCAAp:fo
                         -                                                                                                                                                  Mall.TO:
* UC3'T0riginal)                                                         '
                        *
* DOTi(Trans. Only. Applicable State)
I m.
d- c ne                                                                                    cu erm
* nue; mi .m                                      enint 7,v,ternet.n
_                      _       ___}}

{{PNO-Nav|region=V}}