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Information Notice No. 89-48: Design Deficiency in the Turbine-Driven Auxiliary Feedwater Pump Cooling Water System
UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF NUCLEAR REACTOR REGULATION WASHINGTON, D.C. 20555 May 22, 1989 Information Notice No. 89-48: DESIGN DEFICIENCY IN THE TURBINE- DRIVEN AUXILIARY FEEDWATER PUMP COOLING WATER SYSTEM Addressees: All holders of operating licenses or construction permits for nuclear power reactors. Purpose: This information notice is being provided to alert addressees to a design deficiency in a turbine-driven auxiliary feedwater pump cooling water system. 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 April 13, 1989, the licensee for the Zion Station identified a design de- ficiency in the turbine-driven auxiliary feedwater (AFW) pump cooling water system. The deficiency was created when a modification was made to the turbine-driven AFW pump in order to satisfy the AC power independence criteri- on. This modification changed the pump's cooling water supply from the service water system to the auxiliary feedwater system. The cooling water now comes from the fifth stage leakoff of the AFW pump and is supplied to the pump's lube oil cooler, the AFW turbine governor, and the AFW turbine bearings at 75 psig by a pressure-regulating valve. The cooling water is then returned to the AFW pump suction line. The deficiency would have occurred when the AFW pump suction was aligned to its emergency supply (service water) rather than its normal supply (the condensate storage tank). In this emergency lineup, the suction pressure will increase to approximately 90 psig. Because the AFW pump cooling water pressure would be below the AFW pump suction pressure, AFW pump cooling water flow would be lost. This loss of cooling water flow could eventually lead to overheating of the AFW pump turbine bearings and failure of the AFW pump turbine. 8905160199 .. IN 89-48 May 22, 1989 Page 2 of 2 Discussion: The licensee made a temporary modification in the AFW pump cooling water return line configuration to correct this design deficiency. A permanent modification is under development for future installation. No specific action or written response is required by this information notice. If you have any questions about this matter, please contact the technical contact listed below or the Regional Administrator of the appropriate regional office. Charles E. Rossi, Director Division of Operational Events Assessment Office of Nuclear Reactor Regulation Technical Contact: Jared Wermiel, NRR (301) 492-0870 Attachment: List of Recently Issued NRC Information Notices .. Attachment IN 89-48 May 22, 1989 Page 1 of 1 LIST OF RECENTLY ISSUED NRC INFORMATION NOTICES _____________________________________________________________________________ Information Date of Notice No._____Subject_______________________Issuance_______Issued to________ 89-47 Potential Problems With 5/18/89 All holders of OLs Worn or Distorted Hose or CPs for nuclear Clamps on Self-Contained power reactors and Breathing Apparatus fuel facilities. 89-46 Confidentiality of 5/11/89 All holders of Exercise Scenarios licenses for fuel cycle facilities and byproduct material licensees having an approved emergency response plan. 89-45 Metalclad, Low-Voltage 5/8/89 All holders of OLs Power Circuit Breakers or CPs for nuclear Refurbished with Sub- power reactors. standard Parts 89-44 Hydrogen Storage on the 4/27/89 All holders of OLs Roof of the Control Room or CPs for nuclear power reactors. 88-82, Torus Shells with Corrosion 5/2/89 All holders of OLs Supp. 1 and Degraded Coatings in or CPs for BWRs. BWR Containments 89-43 Permanent Deformation of 5/1/89 All holders of OLs Torque Switch Helical or CPs for nuclear Springs in Limitorque power reactors. SMA-Type Motor Operators 88-97, Potentially Substandard 4/28/89 All holders of OLs Supp. 1 Valve Replacement Parts or CPs for nuclear power reactors. 89-42 Failure of Rosemount 4/21/89 All holders of OLs Models 1153 and 1154 or CPs for nuclear Transmitters power reactors. 89-41 Operator Response to 4/20/89 All holders of OLs Pressurization of Low- or CPs for nuclear Pressure Interfacing power reactors. Systems _____________________________________________________________________________ OL = Operating License CP = Construction Permit ..
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