Measurements of nondestructive testing (NDT) system reliability in both the nuclear and non-nuclear segments of industry have consistently produced disappointing results [1,2,3]. While the equipment and techniques appear intrinsically capable of the required performance, overall reliability is often so poor that the credibility of the entire inspection process is jeopardized. On the basis of results accumulated during the past decade, we now know that many NDT processes are not sufficiently reliable to meet the current needs of industry; but we do not know why! Furthermore, we expect NDT performance under actual field conditions to be no better, and probably worse, than the performance measured under laboratory conditions. Significantly, nondestructive testing/inservice inspection (NDT/ISI) performance under actual field conditions remains an important unknown within the nuclear industry.