Valve Packing Qualification for Improved Plant Availability

Abstract

The success of using live-loaded valves in CANDU NGS is well documented; however, the specified packing material was JC-1871. The loss of asbestos-based packing products, such as JC-1871, generated a renewed effort by AECL and Ontario Hydro to review the valve packing specifications. The increased pressure to improve plant availability and the uncertainty of the new packing products being developed by the packing manufacturers required immediate action by AECL and the CANDU Owners Group (COG) to address this issue. This paper describes the successful proactive approach taken by AECL and Ontario Hydro to improve plant availability of CANDU Nuclear Generating Stations through an integrated valve packing retrofit program. The paper provides details on the packing qualification efforts for combination die-formed graphite for single- and double-packed configurations including functional performance parameters of stem friction, leakage and in-service consolidation.