Abstract
The American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (BPVC) Committee has recently developed a new Section XI (Nuclear Components Inspection) Division 2 Code named “Reliability and Integrity Management (RIM).” RIM incorporates a new concept known as “System-Based Code (SBC)” originally due to Asada and his colleagues, where an integrated approach from design to service inspection is introduced using three new types of statistical quantities: (1) ”system reliability index,” or “system failure probability,” for any system consisting of structures and components, (2) “structural failure probability”. or “structural co-reliability,” for any structure, and (3) “component failure probability,” or “component co-reliability” for any component. In a recent paper published in the International Journal of Pressure Vessels and Piping (Vol. 173 (2019), pp. 79-93). Fong, Heckert, Filliben, and Freiman developed a new theory of fatigue and creep rupture life modeling for metal alloys at room and elevated temperatures such that the upper bound of failure probability (FPUB) of an uncracked component can be rigorously estimated from fatigue or creep rupture test data with simple loading histories. This led to the publication of a second paper, ASME PVP2021-62169 (Fong, Marcal, Rainsberger, Heckert, Filliben, Doctor, and Finney, Jr.), where the methodology was applied to the inspection results of both uncracked and cracked components by NDE inspectors with probability of detection (POD) qualification at certain statistical level of confidence.(e.g., 95 %). In a numerical example presented in that ASME PVP-2021-62169 paper, a quantitative relationship was shown between the POD qualification at certain statistical level of confidence of an NDE inspector and the estimated FPUB curve of an uncracked component when the inspector reports a result of either a crack or “no crack.” This result is significant to the NDE industry, and we discuss it in this paper and propose to use the result as a basis for revising the Article 14 (Examination System Qualification) of the ASME Section V (2015) Code.
