Introduction: This report describes a program to develop a nondestructive (ultrasonic) tester and testing procedure to perform integrity tests on isotope heat source containers. The increased application of isotope heat sources has brought more attention to the engineering problems encountered during fabrication. One of the most important of these problems is insuring the isotope containment during the long unattended periods of use. To determine the integrity of the heat source container, a nondestructive testing procedure must be adopted to test each heat source after fabrication.