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Title: Common-mode failures. Part 1

Abstract

Nine-Mile Point-2 was operating at full power in August 1991 when at 0548 h a phase-to-ground fault occurred on phase B of the main transformer. Differential B of the main transformer. Differential relays activated to isolate the fault by disconnecting the generator from the 345-kV line. The generator tripped, and turbine stop valve and turbine control valve closure signals results in a reactor scram and a reactor recirc pump downshift to slow speed. Turbine bypass valves opened to control reactor pressure. Station loads were auto transferred from the normal station service transformer, which received power from the generator, to the reserve station transformer, which received power from the grid. The fault caused the voltage on electrical distribution phase B buses to momentarily decrease to about 50 percent of nominal value for about 200 ms, after which the electrical distribution system voltage returned to the nominal value. That momentary dip resulted in the simultaneous trip of nonsafety-related commercial grade uninterruptible power supplies (UPSs) 1A, B, C, D, and G (Exide Mark II, Model 575-60T3-120/208, 75 kVA, 60 kW). This resulted in the loss of control rod position indication, control room annuciators, radio and paging systems, cooling tower temperature monitoring, process computer,more » safety parameter display, core thermal limits computer, feedwater control system, some plant lighting, emergency response computer, transient analysis recorder, balance-of-plant instrumentation, etc.« less

Authors:
Publication Date:
OSTI Identifier:
467885
Resource Type:
Journal Article
Journal Name:
Nuclear News
Additional Journal Information:
Journal Volume: 37; Journal Issue: 3; Other Information: PBD: Mar 1994
Country of Publication:
United States
Language:
English
Subject:
22 NUCLEAR REACTOR TECHNOLOGY; 21 NUCLEAR POWER REACTORS AND ASSOCIATED PLANTS; NINE MILE POINT-2 REACTOR; ELECTRICAL FAULTS; ENGINEERED SAFETY SYSTEMS; ELECTRICAL TRANSIENTS; FAILURES

Citation Formats

Verna, B.J.. Common-mode failures. Part 1. United States: N. p., 1994. Web.
Verna, B.J.. Common-mode failures. Part 1. United States.
Verna, B.J.. Tue . "Common-mode failures. Part 1". United States.
@article{osti_467885,
title = {Common-mode failures. Part 1},
author = {Verna, B.J.},
abstractNote = {Nine-Mile Point-2 was operating at full power in August 1991 when at 0548 h a phase-to-ground fault occurred on phase B of the main transformer. Differential B of the main transformer. Differential relays activated to isolate the fault by disconnecting the generator from the 345-kV line. The generator tripped, and turbine stop valve and turbine control valve closure signals results in a reactor scram and a reactor recirc pump downshift to slow speed. Turbine bypass valves opened to control reactor pressure. Station loads were auto transferred from the normal station service transformer, which received power from the generator, to the reserve station transformer, which received power from the grid. The fault caused the voltage on electrical distribution phase B buses to momentarily decrease to about 50 percent of nominal value for about 200 ms, after which the electrical distribution system voltage returned to the nominal value. That momentary dip resulted in the simultaneous trip of nonsafety-related commercial grade uninterruptible power supplies (UPSs) 1A, B, C, D, and G (Exide Mark II, Model 575-60T3-120/208, 75 kVA, 60 kW). This resulted in the loss of control rod position indication, control room annuciators, radio and paging systems, cooling tower temperature monitoring, process computer, safety parameter display, core thermal limits computer, feedwater control system, some plant lighting, emergency response computer, transient analysis recorder, balance-of-plant instrumentation, etc.},
doi = {},
journal = {Nuclear News},
number = 3,
volume = 37,
place = {United States},
year = {1994},
month = {3}
}