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UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF NUCLEAR REACTOR REGULATION WASHINGTON, D.C. 20555 March 15, 1989 Information Notice No. 89-29: POTENTIAL FAILURE OF ASEA BROWN BOVERI CIRCUIT BREAKERS DURING SEISMIC EVENT Addressees: All holders of operating licenses or construction permits for nuclear power reactors. Purpose: This information notice is being provided to alert addressees to potential failures of ASEA Brown Boveri (ABB) K-Line circuit breakers (CBs) during a seismic event. 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: ABB submitted two letters, dated January 13 and February 16, 1989, to the NRC in accordance with the requirements of 10 CFR Part 21 regarding a deficiency in K-Line CBs, model numbers K-225 through K-2000, that were delivered to cus- tomers before July 1974. These CBs have a slow-close lever that could move during a seismic event and prevent the CBs from closing upon an electrical demand. The slow-close lever is used to perform diagnostic checks on the CB internals during initial installation. The lever is located in the rear portion of the CB and is only accessible while the CB is out of its cubicle. Discussion: In late 1988, Rancho Seco personnel asked ABB why some K-Line CBs used at the Rancho Seco plant had springs on the slow-close lever and others did not. ABB investigated the matter and determined that rebound springs were added to CBs manufactured after July 1974 as a response to CB failures that occurred during seismic testing of K-Line CBs. The seismic testing was conducted on several sample K-Line CBs at Wyle Labora- tories in 1974 and consisted of 123 test runs under varying seismic conditions. During test run number 100 (which consisted of side-to-side sine dwell at 23 hertz, amplitude 0.5 g, duration greater than 20 seconds), one K-1600 CB jammed and failed to close on demand. During test run number 101 (which consisted of 8903090021 .. IN 89-29 March 15, 1989 Page 2 of 2 side-to-side sine dwell at 30 hertz, amplitude 0.36 g, duration greater than 20 seconds), a second K-1600 CB failed to close on demand. The causes of the breaker malfunctions were not immediately recognized. ABB later determined that the CBs had failed to close because of vibration-induced movement of the slow-close lever to a position where it interfered with the closing mechanism of the CB. As a result, a rebound spring that prevents any undesired movement of the slow close lever was added to the CB design and installed in all CBs manufactured after mid-1974. ABB sent the letters of January 13 and February 16, 1989, to all nuclear power plants that have purchased safety-related electrically operated K-Line CBs, model numbers K-225 through K-2000, and requested that all users of these CBs add rebound springs to the slow-close levers. The letters are included as Attachment 1 and Attachment 2 respectively. Attachment 1 also includes a sketch of the location of the slow-close lever with the rebound spring in place and the field installation procedures for adding the rebound spring to the slow-close lever. Additional information on this subject may be obtained by contacting the appropriate ABB representative. It is important for addressees to determine whether any of the subject CBs, regardless of their delivery or installation date, are installed at their facilities and to verify that the CBs are seismically qualified. In addition, addressees are reminded that component manufacturers do not typically notify customers who have procured commercial grade items of design changes and deficiencies identified in their components. Therefore, it is important that this fact be considered when purchasing components that were procured as commercial grade and dedicated for safety-related applications by entities other than the component manufacturer. No specific action or written response is required by this information notice. If you have any questions regarding 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: Jaime Guillen, NRR (301) 492-1170 Attachments: 1. ASEA Brown Boveri Letter dated January 13, 1989 2. ASEA Brown Boveri Letter dated February 16, 1989 3. List of Recently Issued NRC Information Notices .. Attachment 3 IN 89-29 March 15, 1989 Page 1 of 1 LIST OF RECENTLY ISSUED NRC INFORMATION NOTICES _____________________________________________________________________________ Information Date of Notice No._____Subject_______________________Issuance_______Issued to________ 89-28 Weight and Center of 3/14/89 All holders of OLs Gravity Discrepancies or CPs for nuclear for Copes-Vulcan power reactors. Air-Operated Valves 89-27 Limitations on the Use 3/8/89 All holders of OLs of Waste Forms and High or CPs for nuclear Integrity Containers for power reactors, the Disposal of Low-Level fuel cycle Radioactive Waste licenses and certain by-product materials licenses. 89-26 Instrument Air Supply to 3/7/89 All holders of OLs Safety-Related Equipment or CPs for nuclear power reactors. 89-25 Unauthorized Transfer of 3/7/89 All U.S. NRC source, Ownership or Control of byproduct, and Licensed Activities special nuclear material licensees. 89-24 Nuclear Criticality Safety 3/6/89 All fuel cycle licensees and other licensees possessing more than critical mass quantities of special nuclear material. 89-23 Environmental Qualification 3/3/89 All holders of OLs of Litton-Veam CIR Series or CPs for nuclear Electrical Connectors power reactors. 89-22 Questionable Certification 3/3/89 All holders of OLs of Fasteners or CPs for nuclear power reactors. 89-21 Changes in Performance 2/27/89 All holders of OLs Characteristics of Molded- or CPs for nuclear Case Circuit Breakers power reactors. __________________________________________________________________________________ OL = Operating License CP = Construction Permit ..
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