Information Notice No. 84-48, Supplement 1: Failures of Rockwell International Globe Valves
SSINS No.: 6835 IN 84-48, Supplement 1 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C. 20555 November 16, 1984 Information Notice No. 84-48, SUPPLEMENT 1: FAILURES OF ROCKWELL INTERNATIONAL GLOBE VALVES Addressees: All nuclear power reactor facilities holding an operating license (OL) or a construction permit (CP). Purpose: This information notice supplement is provided as a notification of additional information concerning the failures of Rockwell International globe valves. It is expected that recipients will review the information for applicability to their facilities and consider actions, if appropriate, to preclude similar problems occurring at their facilities. However, suggestions contained in this information notice do not constitute NRC requirements and, therefore, no specific action or written response is required. Background: Information Notice No. 84-48 described a number of Rockwell International valve failures at Salem Generating Station Units 1 and 2. In describing these failures, it does not clearly indicate that there were two different modes of failure, each with its unique cause. Discussion: The first of these failures was identified in the reactor coolant loop resistance temperature detector (RTD) bypass line valves at Salem Generating Station Units 1 and 2 [licensee event reports (LERs) 84-010 dated May 1, 1984, and 84-001 dated February 9, 1984; respectively]. The mode of failure was the separation of the disk from the stem. The cause of the failure was stress corrosion cracking of the stem resulting from high stresses indicated as being due to excessive backseating forces. Rockwell International's recommendation for controlling this type of failure is to limit the backseating force which the valve experiences. The second failure was identified in the safety injection system flow throttling valves at Salem Generating Station Unit 1 (LER 84-012 dated June 26, 1984). This LER also addressed a similar finding at Unit 2. The mode of failure was partial unthreading of the disk from the disk nut. The cause of the failure 8411150072 . IN 84-48, Supplement 1 November 16, 1984 Page 2 of 2 was initially reported as the absence of the weld metal deposit that attaches the disk to the disk nut through a small hole in the disk. However, information received from the manufacturer indicates that the process of attaching the disk to the disk nut is not through the addition of weld metal, but rather through the use of a tungsten inert gas arc to thermally upset the threads on the disk nut opposite the small hole in the disk. Examination by the manufacturer indicated that the thermal upset had either fractured or been deformed by the disk rotating over the thermal upset area. The torque, necessary to fracture or deform the thermal upset, is attributed to the high cavitation loads that the valve disk experienced when used in severe throttling conditions. Rockwell International's recommendation for controlling this type of failure is to replace any such valve used for severe throttling with one of a smaller size so that the valve disk will be in a mid-position or a more fully open position at the required flow. No specific action or written response to this information notice supplement is required. If you have any questions about this matter, please contact the Regional Administrator of the appropriate NRC Regional Office, or this office. Edward L. Jordan Director Division of Emergency Preparedness and Engineering Response Office of Inspection and Enforcement Technical Contact: R. J. Kiessel, IE (301) 492-8119 Attachment: List of Recently Issued IE Information Notices
Page Last Reviewed/Updated Tuesday, March 09, 2021
Page Last Reviewed/Updated Tuesday, March 09, 2021