Analysis of US Regulatory Status to Buried and Underground Piping and Tanks of Nuclear Power Plant

Damage to buried piping is one of the important issues facing the nuclear power industry. Unlike an above-ground pipe, buried piping is exposed to a corrosion environment because of the water chemistry condition inside the pipe, and to mechanical damage, chemical damage, and heavy-load fatigue caused by the soil outside the pipe. If leakage occurs in buried piping, it is very difficult to find its cause and to repair it in a timely manner. In Korea, after the leakage has been identified, follow-up measures are implemented, such as temporary repair or maintenance. Therefore, the identification of potential damage, which is part of the integrity management of buried piping in soil and concrete, is fairly limited. Therefore, an effective buried-pipe aging management program that is applicable to Korean nuclear power plants and that includes the preventive management of damage is necessary. In this study, US regulation trends were identified through the regulatory requirements and the management documents of licensees to develop regulatory guidelines. Using these results, regulatory guidelines for buried and underground piping/tanks can be developed for the future in-service inspection and license renewal of Korean nuclear power plants.