Protecting People and the EnvironmentUNITED STATES NUCLEAR REGULATORY COMMISSION
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C. 20555
April 10, 1991
Information Notice No. 91-27: INCORRECT ROTATION OF POSITIVE
DISPLACEMENT PUMP
Addressees:
All holders of operating licenses or construction permits for nuclear power
reactors.
Purpose:
This information notice is intended to alert addressees to the potential
existence of positive displacement pumps with reverse rotation caused by
incorrect wiring. 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:
On February 15, 1990, one of the two positive displacement pumps in the
standby liquid control system at Brunswick Unit 2 was observed rotating in
the reverse direction. This discovery was made after maintenance; however,
nothing in the maintenance procedure could have affected the rotational
direction of the pump, and the condition had apparently existed for some
indeterminate period of time. During the resulting investigation, Brunswick
personnel discovered that two electrical leads had been interchanged in the
motor control center that fed power to the standby liquid control pump
causing the three-phase pump motor to rotate in the reverse direction.
Although Brunswick personnel routinely made rotational checks following pump
maintenance, apparently in this case the maintenance personnel mistakenly
believed that the existing direction of rotation was correct.
Discussion:
The standby liquid control system includes positive displacement
reciprocating piston pumps. The direction of rotation has no immediate
effect on the performance of these pumps. However, the pump internal drive
train lubrication system does depend upon the correct direction of pump
rotation to fill an elevated reservoir which then drains oil over the drive
pistons. Oil splash would provide some lubrication when the pump is rotated
in the reverse direction. According to the pump vendor, Union Pump, the
splash effect could supply
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IN 91-27
April 10, 1991
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sufficient lubrication for short-term operation, particularly for the slower
speed pumps used in the standby liquid control systems. Consequently, these
pumps, which are operated for approximately 15 minutes per month for
surveillance testing, might not show any adverse effects for some time. In
addition to depriving the pump of adequate lubrication, reverse operation
could cause excessive wear to the pump seals and detectable oil leakage.
Positive displacement pumps are used in the standby liquid control system at
all boiling water reactors and are also used in the charging system at some
pressurized water reactors. Both of these applications involve important
safety systems that might be required to operate for extended periods of
time in the event of an accident. In keeping with this, Brunswick personnel
have labeled the standby liquid control system pumps to indicate their
correct direction of rotation. Careful visual rotational checks, included
with the pump surveillance procedures, are important in ensuring that
positive displacement pumps will continue to operate correctly.
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: Donald C Kirkpatrick, NRR
(301) 492-1849
Ted Cintula, AEOD
(301) 492-4493
Attachment: List of Recently Issued NRC Information Notices
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