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Information Notice No. 89-50: Inadequate Emergency Diesel Generator Fuel Supply
UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF NUCLEAR REACTOR REGULATION WASHINGTON, D.C. 20555 May 30, 1989 Information Notice No. 89-50: INADEQUATE EMERGENCY DIESEL GENERATOR FUEL SUPPLY Addressees: All holders of operating licenses or construction permits for nuclear power reactors. Purpose: This information notice is being provided to alert addressees to the potential for existence of an inadequate emergency diesel generator (EDG) fuel supply. 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 a review of the design basis for the EDGs at Palisades, it was dis- covered that the fuel oil consumption calculations, performed in 1968, had not been updated to reflect changes in equipment loading and operating times in post-accident conditions. Subsequent calculations by the licensee indicated that 23,000 gallons of diesel fuel would be required to ensure that a seven day supply would be available to support EDG operation under the current load requirements. This value exceeds the minimum 16,000 gallon limit specified in the Technical Specifications (TS). The licensee's corrective actions in-cluded prescribing a higher administrative limit of 23,000 gallons of fuel and performing additional calculations to support a TS change request. This is discussed further in licensee event report (LER) 50-255/89-005. A discrepancy between the Final Safety Analysis Report (FSAR) and the TS basis was identified at Robinson Unit 2. The TS basis specified that 25,000 gallons of fuel oil be maintained for operation of one EDG carrying "minimum safety features" load for seven days. The FSAR described the 25,000 gallons as suf- ficient for one EDG carrying "full load" for seven days. Calculations performed by the licensee indicate that 25,000 gallons is only marginally sufficient for one EDG carrying "minimum safety features" load for seven days since fuel consumption is highly dependent on selective load shedding. The licensee's 8905230215 .. IN 89-50 May 30, 1989 Page 2 of 2 calculations also indicate that one EDG carrying "full load" for seven days would require approximately 30,430 gallons. The licensee's corrective actions included redefining the basis for the seven day fuel supply to the more con- servative value (operation of the EDG at its rated capacity) and revising the TS to reflect the increased minimum fuel inventory. This is discussed further in NRC Inspection Report No. 50-261/87-06 and in LER 50-261/88-006. The McGuire FSAR indicates that the underground storage tank for each EDG is sized so that the corresponding EDG can carry the 4160 Volt Essential Auxiliary Power Systems load for seven days. The TS require that each underground storage tank contain a minimum volume of 28,000 gallons of fuel. Recently, it was discovered that 28,000 gallons is not sufficient to ensure seven days of EDG operation. The licensee has indicated that design calculations show that appro-ximately 48,533 gallons of fuel are needed to ensure seven days of operation at rated load. This is discussed further in NRC Inspection Report No. 50-369/89-02. Discussion: Regulatory Guide 1.137, "Fuel Oil Systems for Standby Diesel Generators," contains guidance for calculation of EDG fuel oil storage requirements. Two methods are provided: 1) calculations based on the assumption that the EDG operates continuously for seven days at its rated capacity and 2) calculations based on the time-dependent loads of the EDG (which should include the capacity to power the engineered safety features). 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: Jack Ramsey, NRR (301) 492-1167 Attachment: List of Recently Issued NRC Information Notices .. Attachment IN 89-50 May 30, 1989 Page 1 of 1 LIST OF RECENTLY ISSUED NRC INFORMATION NOTICES _____________________________________________________________________________ Information Date of Notice No._____Subject_______________________Issuance_______Issued to________ 89-49 Failure to Close Service 5/22/89 All holders of OLs Water Cross-Connect or CPs for nuclear Isolation Valves power reactors. 89-48 Design Deficiency in the 5/22/89 All holders of OLs Turbine-Driven Auxiliary or CPs for nuclear Feedwater Pump Cooling power reactors. Water System 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. _____________________________________________________________________________ OL = Operating License CP = Construction Permit ..
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