Preservice and inservice requirements for containment structures in the United States - A status report

Abstract

Assuring the lifetime integrity of containment structures for nuclear power plants is becoming increasingly important as existing design criteria are reexamined, as new requirements for containment inspection and testing are formulated, and as today's operating nuclear plants are growing older. The American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code contains requirements for the design and construction and for the preservice and inservice requirements for nuclear power plant systems and components in the United States. Section III of the ASME Code contains the rules for design and construction of nuclear systems and components. Rules for the preservice examination, inservice inspection, system pressure testing, repair, modification and replacement of nuclear systems and components are contained in Section XI, Rules for Inservice Inspection of Nuclear Power Plant Components. Compliance with the rules of the ASME Code in the United States is mandated by the federal government in Title 10, Part 50 of the Code of Federal Regulations (10CFR50). Section XI of the ASME Code contains separate rules for metal (Class MC) and concrete (Class CC) containments. Requirements for Class MC containments have been published in Subsection IWE, Requirements for Class MC Components of Light-Water Cooled Power Plants, of Section XI. Rules for Class CC containments are currently being developed and will be published in Subsection IWL, Requirements for Class CC Components of Light-Water Cooled Power Plants, of Section XI. First published in 1981, Subsection IWE has been adopted by a number of state jurisdictions in the United States and is presently being reviewed by the United States Nuclear Regulatory Commission. Federal regulations that will require mandatory compliance by nuclear plant owners are forthcoming. When implemented, the requirements in Subsection IWE and Subsection IWL will provide a reasonable and systematic basis for assuring the integrity of metal and concrete containment structures during their service lifetime. This paper presents an overview of the preservice and inservice requirements for containment structures in Section XI of the ASME Code with consideration of the practical factors that should accompany user compliance.