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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