United States Nuclear Regulatory Commission - Protecting People and the Environment

Morning Report for January 21, 2000

                       Headquarters Daily Report

                         JANUARY 21, 2000

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                    REPORT             NEGATIVE            NO INPUT
                    ATTACHED           INPUT RECEIVED      RECEIVED

HEADQUARTERS                           X
REGION I                               X
REGION II           X
REGION III                             X
REGION IV                              X
PRIORITY ATTENTION REQUIRED  MORNING REPORT - REGION II  JANUARY 21, 2000

Licensee/Facility:                     Notification:

Tennessee Valley Authority             MR Number: 2-00-0004
Sequoyah 1 2                           Date: 01/21/00
Soddy-Daisy,Tennessee
Dockets: 50-327,50-328
PWR/W-4-LP,PWR/W-4-LP

Subject: UPDATE - UNIT 2 INADVERTENT SAFETY INJECTION AND REACTOR TRIP

Discussion:

The licensee's troubleshooting activities and corrective actions in
response to the inadvertent safety injection and reactor trip on
January 18, 2000, have been completed and Unit 2 achieved criticality on
January 20, 2000, at 4:04 a.m. (EST).

The licensee's event investigation determined that the technicians that
were working on vital inverter 2-IV modification wiring, caused a
momentary loss of power to the inverter (alternate power supply had been
previously de-energized) which generated a signal to close the main
feedwater regulating valve to steam generator number 4 (S/G NO.4). The
subsequent rapid decrease in S/G NO.4 water level generated a low-low
steam generator level trip signal (2/3 logic) and an automatic reactor
trip. The licensee also determined that the inadvertent ESF actuation
(train "A" SI signal) that occurred following the reactor trip was due to
a low steamline pressure (S/G NO.4) signal to the reactor protection
system (RPS) channels II and IV. The RPS channel IV signal was caused by
the loss of power to vital inverter 2-IV and the RPS channel II signal
was due to a malfunctioning steam generator pressure transmitter.

Reactor power level is currently at 75 percent and the unit is proceeding
to full power operations.

Contact:  PAUL FREDRICKSON           (404)562-4530
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