Response of Conventional Ring Closures of Drum Type Packages to Regulatory Drop Tests With Application to the 9974/9975 Package

Abstract

DOT, DOE and NRC Type A and Type B radioactive material (RAM) transport packages routinely use industrial or military specification drums with conventional clamp ring closures as an overpack. Considerable testing has been performed on these type packages over the past 30 years. Observations from test data have resulted in various design changes and recommendations to the standard drum specification and use, enhancing the reliability of the overpack. Recently, performance of the 9975 conventional clamp ring closure design was questioned by the DOE Regulatory Authority. This paper highlights the observations of recent 9974 and 9975 package testing that led to redesign of the 9975, replacing the standard clamp ring closure with a bolted flange closure. In the course of this review and redesign effort, 18 package designs and approximately 100 Hypothetical Accident Condition (HAC) drops of various size and weight drum packages were evaluated. A trend was observed with respect to overpack lid failures for packages utilizing conventional ring closure. Based on this trend, a limit on the ratio of the internal weight to total package weight was identified, beyond which clamp ring closure failure may be expected.