This chapter provides a chronological overview of the development of Section XI, “The Rules for Inservice Inspection of Nuclear Power Plant Components,” from its 1968 inception to the 1998 edition. It traces the development, edition-by-edition, of important Code elements including the philosophy behind many of the revisions. Emphasis is placed on the 1989 through 1998 editions because they apply to a majority of nuclear plants in the United States and in other countries. Through an extensive tabulation of Code Interpretations, this chapter also attempts to give the Code user some insights into clarification of many Section XI requirements. Further insight into the philosophy and technical basis behind Section XI may be gained from review of papers cited in the Bibliography of this chapter.

Subsequent chapters of this book address the major areas of Section XI, including inservice inspection (ISI) examination and test programs, repairs and replacements, acceptance and evaluation criteria, containment programs, and fatigue crack growth. Reference to specific chapters is included as changes to their topics are introduced. Their specific discussions may be easier to follow and will be more complete than the brief chronological development in this chapter. Nondestructive examination is addressed in this chapter as its requirements evolve.

The 2010 Edition of the Code including the 2011a Addenda provides the basis for canges and additions to this Chapter.