Performance Characteristics of 0-Ring Seals for Radioactive Material Packages When Subjected to Extreme Temperatures*

Performance requirements for radioactive material (RAM) packages are specified in Title 10, Code of Federal Regulations, Part 71 (NRC 1993). Package components that form the containment boundary must function in both high- and low-temperature environments characteristic of the hypothetical fire accident and the -40°F (-40°C) normal transport condition, respectively. Seals that provide the containment system interface between the packaging body and closure(s) are routinely a source of special consideration when designing, testing, and licensing a RAM package. Seals are most often elastomeric 0-rings and can be considered delicate by cask component standards. A research and testing program has been conducted at Sandia National Laboratories to examine the performance of elastomeric seal materials commonly used in RAM packages during temperature extremes. Performance characteristics examined included leakage rate versus temperature, physical property inspections, and tracer gas permeation. This paper presents the results and findings of the test program (Bronowski 1994). Of particular interest are the use of modified 0-ring groove widths and the high temperature testing in excess of manufacturers' standard ratings.