'Mind the Gap' between old and new nuclear qualified cable: Lessons learned from aging, historical adverse events and other nuclear cable issues

摘要

Nuclear-qualified cable designs have been available since the 1970s. Though their polymeric formulations may still be considered as sophisticated today, compounds are presently being formulated to meet more rigorous requirements or due to restrictions in compound ingredient use. The Technical and Quality requirements of Environmental Qualification have also evolved as improvements to reduce risk, sometimes initiated in response to adverse events involving cables or perhaps to meet the rigors of new advanced reactor designs. Legacy plants have qualified, aged cable near retirement or life extension and may require condition monitoring. Some of the new cable designs have improved materials, construction and advancements. Regulations have been developed and improved upon for various reasons to better assure public safety. There have been examples of gaps - but still in compliance - in considering the Technical or the Quality requirements of the Environmental Qualification to which the cable is qualified, how well the Environment was defined, how it the cable was installed. Examples discussed include risks from shipping, storage or installation of cable, cable submergence as an unforeseen environment and the post LOCA severe accident condition. This paper will review the history of US nuclear cable use and issues. The author suggests mindfulness in gaps and cable-specific recommendations for use at the new, advanced reactor designs.