On-line maintenance of valve bolted body-to-bonnet joints

摘要

The majority of maintenance activities on valves in Nuclear Power Plants are performed during outages. A large portion of these maintenance activities involves either seat leakage or body-to-bonnet leakage. While it is recognized as difficult for plants to perform seat repairs on-line, there is an increasing interest in on-line maintenance of valve body-to-bonnet conections. This interest is driven by the desire of plants for longer operating cycle times and for shorter and shorter refueling outages. This paper discusses the various technologies available for on-line maintenance and the technical issues that need to be resolved to make each technology viable.