View source for PNO-IV-88-075, on 880906,reactor Scrammed from 100% Power. Caused by Main Generator Trip Due to Loss of Normal Station Transformer,Probably Caused by Cat Crawling Into Transformer.Noue Declared Because HPCS & RCIC Sys Initiated

{{Adams
| number = ML20154B712
| issue date = 09/06/1988
| title = PNO-IV-88-075:on 880906,reactor Scrammed from 100% Power. Caused by Main Generator Trip Due to Loss of Normal Station Transformer,Probably Caused by Cat Crawling Into Transformer.Noue Declared Because HPCS & RCIC Sys Initiated
| author name = Madsen G
| author affiliation = NRC OFFICE OF INSPECTION &amp; ENFORCEMENT (IE REGION IV)
| addressee name = 
| addressee affiliation = 
| docket = 05000458
| license number = 
| contact person = 
| document report number = PNO-IV-88-075, PNO-IV-88-75, NUDOCS 8809140089
| document type = PRELIMINARY NOTIFICATION OF EVENT OR OCCURRENCE (PNO,, TEXT-INSPECTION &amp; AUDIT &amp; I&amp;E CIRCULARS
| page count = 1
}}
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PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE -- PN0-IV-88-75 This preliminary notification constitutes EARLY notice of events of POSSIBLE
* safety or public interest significance. The infonnation is as initially received without verification or evaluation, and is basically all that is known by the Region IV staff on this date.
FACILITY: Gulf States Utilities                    Licensee Emergency Classification:
River Bend Station                        X Notification of Unusual Event DN:   50-458                                 Alert 1
Site Area Emergency General Emergency Not Applicable i

==SUBJECT:==
OUTAGE GREATER THAN 2 DAYS On September 6,1988, at 6:06 a.m. (CDT) the reactor scramed from 100 percent power. The main generator tripped because of a loss of a normal station transformer (believed to have been caused by a cat crawling into the transformer).
This resulted in a turbine' trip and reactor scram. Although the vessel water           '.
level does not appear to 5 ave dropped to the HPCS and RCIC initiation setpoint (Level 2), the HPCS and RCIC pumps started and injected briefly. as occurred
 ;    during the reactor trip of August 25, 1988 (PN0-IV-88-70). Howe a r, unlike the August 25 trip, there was no indication of backleakage into the HPCS injection
: l. line. The licensee declared a NOUE because of the HPCS and RCIC system initiation.
The licensee secured from the NOUE at 7:30 a.m. All station transformer transfers, from normal to preferred, occurred as expected. Reactor pressure is being controlled by the bypass valves and level maintained utilizing one reactor feed pump and the startup regulating valve. Reactor shutdown is expected to exceed 72 hours.
Neither the licensee nor the NRC plans to issue a press release.
!     The state of Louisiana has been informed.
Region IV received notification of this occurrence by telephone from the headquarters duty officer.
l This information has been confirmed with a licensee representative.
l CONTACT:   G. L. Madsen, FTS 728-8134                                                   ;
DISTRIBUTION:
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NRC Ops Ctr Licensee (Reactor)
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9/6/88                          9)6/88                                            h g 91 {0 p 800906 PNO-IV-88-075            PNV I}}

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