IE Circular 77-15, Degradation of Fuel Oil Flow to the Emergency Diesel Generator
CR77015 November 28, 1977 MEMORANDUM FOR: B. H. Grier, Director, Region I J. P. O'Reilly, Director, Region II J. G. Keppler, Director, Region III E. M. Howard, Director, Region IV R. H. Engelken, Director, Region V FROM: H. D. Thornburg, Director, Division of Reactor Operations Inspection, Office of Inspection and Enforcement SUBJECT: IE CIRCULAR 77-15, DEGRADATION OF FUEL OIL FLOW TO THE EMERGENCY DIESEL GENERATOR The subject circular is transmitted for issuance by close of business within three days after date of this letter. The Circular should be issued to all holders of Reactor Operating Licenses or Construction Permits. Also enclosed is a draft copy of the transmittal letter. Harold D. Thornburg, Director Division of Reactor Operations Inspection Office of Inspection and Enforcement Enclosures: 1. Draft Transmittal Letter 2. IE Circular 77-15 CONTACT: C. J. DeBevec 49-28180 . IE Circular No. 77--15 (Date) (Transmittal letter for IE Circular 77-15 to each holder of an NRC Operating License or Construction Permit.) Addressee: The enclosed IE Circular No. 77-15 is forwarded to you for information. No written response is required. Should you have any questions related to your understanding of this matter, please contact this office. Sincerely, Signature (Regional Director) Enclosures: 1. IE Circular No. 77-15 2. List of IE Circulars Issued in 1977 . UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON D.C. 20555 November 23, 1977 IE Circular No. 77-15 DEGRADATION OF FUEL OIL FLOW TO THE EMERGENCY DIESEL GENERATOR During surveillance testing on July 14, 1977, personnel at the Cooper Nuclear Station noted a degradation of fuel oil flow to the day tank for the emergency diesel generator. Although the fuel oil transfer pump capacity is 13.8 gpm for each of the two redundant pumps, flow to the day tank for number one diesel generator was only 3 gpm. At full load, engine consumption is 4.5 gpm. Investigation of this occurrence revealed a clogged strainer in a float operated shutoff valve on the day tank inlet. This valve operates as a backup to level switches which start and stop the fuel oil transfer pumps to maintain normal day tank level. The strainer is an integral part of the float valve assembly and is not shown on the as-built system drawings. This valve was manufactured by McDonnell-Millen Company. Station personnel were thus unaware of the presence of this strainer and did not schedule it for routine strainer cleaning under the preventive maintenance program. Normal testing of the system under the Technical Specification surveillance requirements does not verify system flow rates. This occurrence represents an example where the as-built system configuration was not accurately indicated on the system drawings, and that adequate system description was apparently not available to Station personnel. All holders of construction permits or operating licenses should be aware of the potential for variance between as-built configurations and system drawings. This is especially true for support systems to the engineered safeguards features where all required system conditions such as pressure and flows may not receive routine testing under the surveillance testing program. It is recommended that the following be considered in your review of this matter: 1. A field verification of the drawing against the as-built system configuration should be made for the entire diesel generator fuel oil delivery system from the storage tanks to the engines. Appropriate changes should be made to the drawings and preventive maintenance program to account for any components or configurations not previously covered. 1 of 2 . IE Circular No. 77-15 November 23, 1977 2. Consideration should be given to revising surveillance test procedures to include a flow test on the fuel oil system to ensure the system continues to meet design specifications. In addition, the following information relating to the maintenance of fuel oil cleanliness should be considered in your review: 1. During long-time storage, degradation of fuel oil is a common occurrence. The rate of degradation is not easily predicted since it is a function of the source of the crude oil, the process utilized in making the fuel (e.g., straight distillation or the method of catalytic cracking), and the conditions under which the fuel oil is stored. 2. It is known that certain detrimental processes are accelerated in fuel oils when they are in contact with certain metals. The presence of zinc, such as from galvanizing, has a tendency to form soluble soaps in the fuel oil which are deposited on the diesel engine's injection nozzles. A buildup of this deposit will eventually degrade the engine's performance. The presence of copper promotes the formation of gums which degrade the stored fuel oil and tends to clog filters. 3. The presence of water in the fuel oil promotes the growth of fungi or slime that also degrades the fuel and has the potential for clogging filters. No written response to this Circular is required. If you require additional information regarding this matter, contact the Director of the appropriate NRC Regional Office. 2 of 2
Page Last Reviewed/Updated Tuesday, March 09, 2021
Page Last Reviewed/Updated Tuesday, March 09, 2021