Information Notice No. 91-42: Plant Outage Events Involving Poor Coordination Between Operations and Maintenance Personnel During Valve Testing and Manipulations
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C. 20555
June 27, 1991
Information Notice No. 91-42: PLANT OUTAGE EVENTS INVOLVING
POOR COORDINATION BETWEEN OPERATIONS AND
MAINTENANCE PERSONNEL DURING VALVE
TESTING AND MANIPULATIONS
Addressees:
All holders of operating licenses or construction permits for nuclear power
reactors.
Purpose:
This information notice is intended to alert addressees to potential
problems resulting from poor coordination between operations and maintenance
personnel during valve testing and manipulations. It is expected that
recipients will review the information for applicability to their facilities
and consider actions, as appropriate, to avoid similar problems. However,
suggestions contained in this information notice do not constitute NRC
requirements; therefore, no specific action or written response is required.
Description of Circumstances:
During plant outages, plant personnel may perform many testing and
maintenance activities concurrently. Valve testing and manipulation, in
particular, must be carefully coordinated so that system status is
maintained for shutdown cooling accomplishing safety-related functions, and
preventing inadvertent spills. The following events demonstrate the
importance of maintaining proper coordination between operations and
maintenance personnel.
FARLEY UNIT 1--APRIL 24, 1991
During a refueling outage at the Joseph M. Farley Nuclear Plant, Unit 1, the
licensee drained approximately 4500 gallons of water from the refueling
water storage tank (RWST) to the containment sump by performing
inappropriate valve manipulations.
A motor-operated valve testing team requested permission from the shift
supervisor to test five valves associated with the containment sump. The
shift supervisor did not specify that the valves be tested one at a time.
The valve testing team placed all five valves in midposition. This action
aligned a flow-path from the RWST to the containment sump. The control room
operators were notified of a spill in the containment sump and subsequently
shut one of the valves in the flowpath. Approximately 4500 gallons of water
had spilled into the containment sump.
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IN 91-42
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QUAD CITIES UNIT 1--JANUARY 24, 1991
During a refueling outage, plant personnel opened (for maintenance) the
shutdown cooling suction valve without appropriately notifying the
operations department as required by the test plan being used. This action
initially resulted in losing five inches of coolant from the reactor vessel
with some of the water exiting the reactor coolant system through open
shutdown cooling vent and drain valves. The vessel lost an additional nine
inches of coolant when the shutdown cooling suction header refilled as it
was restored to service. Control room personnel did not expect the two
sudden reductions in reactor vessel level.
BRAIDWOOD UNIT 1--OCTOBER 4, 1990
During a maintenance outage, 620 gallons of coolant spilled as a result of
improper valve sequencing because of poor coordination between the control
room and auxiliary building personnel. This spill contaminated three
individuals and burned one of them.
A valve testing team reported to the control room that a seat leak test was
complete on the residual heat removal (RHR) suction isolation valve from the
hot leg of the reactor coolant system (RCS). The team also reported that
they were shutting the vent valve used for this test. Without receiving
positive confirmation that the vent valve was closed, the control room
personnel opened the RHR suction isolation valve from the RCS hot leg for
stroke time testing. This action aligned the RCS to the open vent valve,
which caused a measuring tube to break loose and spray the three test
personnel. The control room personnel then shut the same valve to stop the
spill. The coolant level in the pressurizer decreased approximately five
percent during this event.
FOREIGN REACTOR EVENT--FALL 1990
During a refueling outage, RHR was lost for 46 minutes and the temperature
of the reactor coolant increased 30 degrees C. This event occurred because
a suction valve in the RHR system was unintentionally shut without valve
indication in the control room and without the operators knowing when the
work activities involved would take place.
Initially, RHR train B was aligned to transfer water from the refueling
water storage tank to the refueling cavity. When the refueling cavity
reached the desired water level, the operators attempted to restore the
normal RHR train B lineup. When the B train RHR pump was started, operators
noticed signs of cavitation and secured it. RHR train A was unavailable
because of electrical maintenance. Operators attempted to restore both RHR
trains to service. They determined that the problem with RHR train B was a
RHR pump suction isolation valve that had jammed shut. They subsequently
pried the valve open to restore the RHR flowpath. The utility investigated
the incident and found that the valve motor was incorrectly continuously
energized with temporary power. The
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IN 91-42
June 27, 1991
Page 3 of 3
temporary power was supposed to provide remote operability and indication
for the valve, but the electrical contractor mistakenly connected the
temporary power directly to the valve motor.
Discussion:
All of these events involved poor coordination and/or errors during valve
testing and manipulations. These events illustrate the importance in main-
taining proper control over the operation of valves during outages when many
testing and maintenance activities may be occurring simultaneously.
This information notice requires no specific action or written response. If
you have any questions about the information in this notice, please contact
one of the technical contacts listed below or the appropriate NRR project
manager.
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contacts: David L. Gamberoni, NRR
(301) 492-1171
Donald Kirkpatrick, NRR
(301) 492-1176
Attachment: List of Recently Issued NRC Information Notices
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