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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 9104040062 . IN 91-27 April 10, 1991 Page 2 of 2 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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