Effective and efficient in-service inspection (ISI) is crucial to maintain safety of nuclear power plants and to suppress operation costs which affect the power generation costs directly. Hence, ISI rules need to be developed rationally by considering relevant features of the reactor type and design of an individual nuclear power plant. Sodium-cooled fast reactors (SFRs) have several desirable features such as excellent compatibility between purity-controlled sodium and structural materials while traditional volumetric and surface tests are not as easily performed as in light water reactors due to the limited accessibility to components containing the sodium coolant. In this Webinar, development of ISI rules for SFRs using the System Based Code (SBC) concept is introduced. The SBC concept consists of three parts: 1) design to reliability target that must be met throughout the service life, 2) margin exchange among the various technical areas of concern such as design, inspection, fabrication, and fitness for service, and 3) expand technical options by the timely adoption of newly developed technologies that are not in current codes and standards. Such a flexible and consistent concept is suitable to develop ISI rules by taking account of individual features of SFR plants. A unique logic flow to determine ISI requirements by using reliability targets for components is discussed, and the procedure to derive the reliability targets from plant safety requirements and to evaluate corresponding structural reliability is presented.
The Generation IV International Forum