NUREG/CP-0146 Proceedings of the <ss orkshop on Gate Valve Pressure Locking and Thermal Binding Held at Marriott Hotel New Orleans, LA February 4, 1994 Prepared by Earl J. Brown Sponsored by Office for Analysis and Evaluation of Operational Data Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 Prepared by U.S. Nuclear Regulatory Commission c,v^REG%, AVAILABILITY NOTICE Availability of Reference Materials Cited in NRC Publications Most documents cited in NRC publications will be available from one of the following sources: 1. The NRC Public Document Room, 2120 L Street. NW., Lower Level, Washington, DC 20555-0001 2. The Superintendent of Documents, U.S. Government Printing Office, P. O. Box 37082, Washington, DC 20402-9328 3. The National Technical Information Service, Springfield, VA 22161-0002 Although the listing that follows represents the majority of documents cited in NRC publications, it is not In• tended to be exhaustive. 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DISCLAIMER Portions of this document may be illegible in electronic image products. Images are produced from the best available original document. NUREG/CP-0146 Proceedings of the Workshop on Gate Valve Pressure Locking and Thermal Binding Held at Marriott Hotel New Orleans, LA February 4, 1994 Manuscript Completed: July 1995 Date Published: July 1995 Prepared by Earl J. Brown Sponsored by Office for Analysis and Evaluation of Operational Data Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 Prepared by U.S. Nuclear Regulatory Commission Washington, DC 20555-001 DISTRIBUTION OF THIS DOCUMENT IS UNLIMITED*^ ABSTRACT The purpose of the Workshop on Gate Valve Pressure Locking and Thermal Binding was to discuss pressure locking and thermal binding issues that could lead to inoperable gate valves in both boiling water and pressurized water reactors. The goal was to foster exchange of information to develop the technical bases to understand the phenomena, identify the components that are susceptible, discuss actual events, discuss the safety significance, and illustrate known corrective actions that can prevent or limit the occurrence of pressure locking or thermal binding. The presentations were structured to cover U.S. Nuclear Regulatory Commission staff evaluation of operating experience and planned regulatory activity; industry discussions of specific events, including foreign experience, and efforts to determine causes and alleviate the affects; and valve vendor experience and recommended corrective action. The discussions indicated that identifying valves susceptible to pressure locking and thermal binding was a complex process involving knowledge of components, systems, and plant operations. The corrective action options are varied and straightforward. iii NUREG/CP-0146 CONTENTS ABSTRACT iii FOREWORD vii INTRODUCTORY LETTER 1 Public Workshop Meeting Agenda 9 List of Meeting Participants 13 Questions Received From Public in Response to Federal Register Notice 25 Pressure Locking and Thermal Binding Issues — U.S. Nuclear Regulatory Commission Earl J. Brown and Chuck Hsu, Office for Analysis and Evaluation of Operational Data 33 Industry Experience and Efforts 57 Licensee Experience Dana Smith, Entergy Operations Inc 59 International Experience Nabil Schauki, Siemens Power Corporation 75 Licensee Experience Mark Dowd, LaSalle County Station 93 Licensee Experience Dick Kadlec, American Electric Power Service Corporation 181 Licensee Experience William R. Rowlett, Jr. P.E., Arkansas Nuclear One James M. Warren, P.E., Gilbert/Commonwealth 191 Vendor Actions Ike Ezekoye, Westinghouse Electric Corporation 235 Vendor Actions Drew W. Wright, Anchor/Darling Valve Co 261 Vendor Actions John M. Farrell, Velan Valve Corporation 275 Draft Generic Communication — U.S. Nuclear Regulatory Commission Thomas G. Scarbrough, Office of Nuclear Reactor Regulation 295 NUREG/CP-0146 FOREWORD The U.S. Nuclear Regulatory Commission staff and the nuclear industry have been aware of gate valve disc binding problems for many years. The industry has issued several event reports describing safety-related gate valve failures to operate due to pressure locking or thermal binding of the valve discs. Several generic industry communications have given guidance for both identifying susceptible valves and performing appropriate preventive and corrective measures. Despite industry awareness of the problems, pressure locking and thermal binding events continue to occur. The purpose of the Workshop was to have licensees, manufacturers, consultants, and regulators exchange technical information about the phenomena. In March 1993, the NRC issued NUREG-1275, Volume 9, "Pressure Locking and Thermal Binding of Gate Valves." This NUREG gives the history of pressure locking and thermal binding events, describes the phenomena, discusses the consequences of locking or binding on valve functionality, summarizes preventive measures, and assesses the safety significance of the phenomena. Pressure locking or thermal binding can cause a power-operated valve to fail to open, resulting in an inability of the associated safety train or system to perform its safety function. Pressure locking and thermal binding represent potential common-cause failure mechanisms that can render redundant trains of certain safety-related systems or multiple safety systems incapable of performing their safety function. Such failures may not be self- revealing through existing surveillance tests or normal operating cycles. After issuing the NUREG, the NRC staff discussed pressure locking and thermal binding with several licensees to: (1) gather information on the technical issues related to generic and plant-specific valve and system characteristics, and (2) determine the implementation status