PNO-I-86-033, on 860423,during Restart from Steam Generator Tube Insp Outage,Reactor Tripped from 8% Power on High RCS Pressure.Caused by Main Feedwater Transient in Which turbine-driven Pump Decreased Speed

PNO-I-86-033:on 860423,during Restart from Steam Generator Tube Insp Outage,Reactor Tripped from 8% Power on High RCS Pressure.Caused by Main Feedwater Transient in Which turbine-driven Pump Decreased Speed

ML20155F995
Person / Time
Site:	Three Mile Island
Issue date:	04/23/1986
From:	Blough R, Kister H NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
To:
References
PNO-I-86-033, PNO-I-86-33, NUDOCS 8604300028
Download: ML20155F995 (1)

-. 4 DCS No: 50289860423 Date: April 23, 1986 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE--PNO-I-86-33 This pieliminary 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: Licensee Emergency Classification:

GPU Nuclear Corp. Notification of Unusual Event Three Mile Island Unit 1 Alert Middletown, PA Site Area Emergency (DN50-289) General Emergency X Not Applicable 1

Subject:

UNPLANNED TRIP DURING PLANT STARTUP About 5:10 a.m. April 23, during restart from the steam generator tube inspection '

outage, the reactor tripped from 8 percent power on a high reactor coolant (RCS) system p essure. The high pressure resulted from a main feedwater transient in which a turbine driven pump decreased speed ouring the transfer of steam supply from the auxiliary system to the main steam system. The RCS relief and safety valves were not challenged. Emergency feedwater was not needed. Plant response was normal; licensee post trip review concluded that increased attention to feed pump control could have prevented the trip. Corrective actions include increased shif t manning for selected portions of the startup process. The licensee made a 10 CFR 50.72 report. The NRC resident staff has been in 24-hour coverage of startup activities since 4/20/86, and the SRI was in the control room at the time of the trip. Tne plant has restarted and is at about 10 percent power as of 1 p.m., April 23.

This PN is issued for information only. The Commonwealth of Pennsylvania has been informed. -

CONTACT: R. Blough H. Kister 488-1146 488-1233 DISTRIBUTION:

H. St.

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SECY CA SP NSACD PDR Regional Offices TMI Resident Section 7 31 i

RI Resident Offico _p D q Licensee: ~~

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Region I Form 83 i

(Rev. July, 1984) 1 8604300028 860423 PDR ILE PNO-I-86-033 PDR q gD 0 1