scope:

General

Nuclear power plants have traditionally been designed to minimize the overall site footprint and associated lengths of buried piping. Construction began with excavating to a stable geological foundation, then the strategic assembly of layered components, installation of engineered backfill, and associated soil compaction to achieve a seismically stable environment. At the time of these designs, circa 1950 to 1960, neither cathodic protection (CP) nor the need for the ability to perform inspection on these components was envisioned at many sites.

As a consequence of the design strategies at nuclear power plants, pipe networks are much more complex than those found in transmission pipelines (e.g., close proximity to other pipe, crossing pipe, mixed metals, vertically layered, deep) and are generally grounded for personnel safety. This affects both the design of the CP systems and the ability to evaluate CP system performance. These complex configurations also create a challenging situation for pipe inspection.

Nuclear power plants have unique processes and procedures for planning and implementing site activities. Among these include issues with security, operational train availability, missile impact contingencies, and contingency planning in the event that significant degradation that could lead to a plant outage is discovered.

More significant than the technical configuration/installation challenges is the overarching concern for the continued protection of the line from degradation that could jeopardize the ability of buried piping to support the intended functions of a given system or isolate its contents from the environment.

This standard practice provides guidance on preparing for an inspection, identifying issues influencing the selection of viable NDE technologies suitable for the anticipated buried pipe threat, and the post-examination activities appropriate for a comprehensive inspection process.

This standard provides introductory information on some NDE technologies. This information is intended to be basic in nature about select NDE technologies. The user is referred to more detailed resources that provide enhanced information regarding the detection capabilities and limitations of NDE methods. Other reference documents should be consulted before use if the user is unfamiliar with a technology.

This standard is intended for use on piping that is buried, submerged, embedded, or otherwise inaccessible piping.

This standard is intended for those managing, planning, selecting, implementing, or evaluating buried pipe inspections using NDE at nuclear power plants.

Working in nuclear plants involves special practices not common to other industries. It includes requirements, terminology, and processes that may be unique to the industry. Some of these are included in this standard to provide insight. If the reader is unfamiliar with a concept, plant personnel shall be consulted for more details on the specific procedure(s) to be followed.