View source for PNO-I-88-101, on 881005,MSIV C Closed Fully During Partial Stoke Testing of Valve,Causing Water Level Decrease in Steam Generator C & Reactor Trip on lo-lo Steam Generator Level. Shutdown Extended to Perform Maint on Valve

{{Adams
| number = ML20155E320
| issue date = 10/06/1988
| title = PNO-I-88-101:on 881005,MSIV C Closed Fully During Partial Stoke Testing of Valve,Causing Water Level Decrease in Steam Generator C & Reactor Trip on lo-lo Steam Generator Level. Shutdown Extended to Perform Maint on Valve
| author name = Barber S, Bettenhausen L, Mccabe E
| author affiliation = NRC OFFICE OF INSPECTION &amp; ENFORCEMENT (IE REGION I)
| addressee name = 
| addressee affiliation = 
| docket = 05000423
| license number = 
| contact person = 
| document report number = PNO-I-88-101, NUDOCS 8810120240
| document type = PRELIMINARY NOTIFICATION OF EVENT OR OCCURRENCE (PNO,, TEXT-INSPECTION &amp; AUDIT &amp; I&amp;E CIRCULARS
| page count = 1
}}
{{#Wiki_filter:>.                                                         DCS No:   504P.388105 Date:     October 6, 1988 o                -
l           ' PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE--PNO-I-88-101 This preliminary notification constitutes EARLY notice of events of POSSIBLE safety                     ;
or public interest significance. The information is as initially received without verification or evaluation, and is basically all that is known by the Region I
,              staff on this date.
Facility:                                       Li m see Emergency Classification:
Northeast Nuclear Energy Company                 _
                                                                   , Notification of Unusual Event Millstone Nuclear Station Unit 3                       Alert Waterford, Connecticut                           ___ Site Area Emergency                                 f General Emergency X Not Applicable                                      :

==Subject:==
UNPLANNED SHUTDOWN IN EXCESS OF 48 HOURS                                                     '
On October 5, 1988, at 1:53 p.m., while at 100*. power, the "C" Main Steam Isolation i
Valve (MSIV) closed fully during partial stroke testing of the valve. The partial                        ,
;             stroke testing was part of a a routine, surveillance. The MSIV-C closure resulted in a water lever decrease (shrink) in th? "C" Steam Generator (SG) and subsequent Reactor /
turbine trip on low-low SG 1evel. The resident inspector responded to the control room and noted that the operators and plant syste'ms responded as expected except that the post-trip cooldown was greater than expected (531 degrees F vice 557 degrees F). The larger than expected coolduwn was attributed to high auxiliary feedwater (AFW) flow in combination with high post-trip steam loads. The licensee is continuing to investigate the event sequence.
 ,            The licensee is extending the shutdown for maintenance on the "B" main feedwater                         *
;             regulating valve, which was being operated in manual because it had been sticking during operation in automatic. Present plans are to perform all work with the plant
 '                                                                                                                     i in hot shutdown and to start-up on October 8, 1988.                                                      i
;            The licensee notified the news media of the shutdown.              The State of Connecticut has been informed.
This information is current as of 9:30 a.m.             (EDT), October 6, 1988.
4 CONTACT:     S. Barber                 E. McCabe             L. Bettenhausen                              l
]                         203-442-5357              215-337-5231          215-337-5233 1                                                                                                                      l DISTRIBUTION:
OWFN                   MNBB                 H-St.            NL         Mail: ADM:0MB                     :
thairman Zech          KE~dd                XM               MS                 DOT:Trans only Comm. Roberts          ARM                  p0R Comm. Carr             OGC                                              NRC Ops Ctr Comm. Rogers                                                                                              i INP0----                                     l SECY      NMS$                                               HSAC----
i                                                                                                                      '
CA        NRR OGC       OIA          Regional Offices
,            GPA       01                                                 RI Resident Office                           l PA        SLITP E00                                                          Licensee:
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[ReactorLicensees)
Region I Form 83 l
: j.           (Rev. April 1988) as1ot2024o so1006                                                             f
[l ),O ,
I                                PDR    IbE              F,DC                                               os PNO-1-sa-101
      - - -                                 _ - ---                                      -}}

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