THE S300 SPECIAL FORM SOURCE OVERPACK

To transport certain plutonium-beryllium neutron sources, a Type AF fissile material packaging was needed. Since the sources were destined for final disposal, they were first packaged in strong, leak tight special form capsules. The demands on the packaging were thereby reduced such that a simple shielded drum would suffice. The packaging chosen was based on the pipe overpack, designed as a container for use within the TRUPACT-II shipping package. Type AF packages are required to maintain criticality control of the fissile material while subjected to the full hypothetical accident sequence of tests. In this case, it was also required to maintain the leak tight integrity of the special form capsule. The novel licensing approach taken in the case of the S300 was to propose that the packaging was progressively expendable, and that each accident event could permanently eliminate a portion of the packaging structure. The key assertion, as demonstrated by the Safety Analysis Report, was that, regardless of what happened to the packaging overpack, the special form capsule would never experience an accident condition which was more severe than that experienced during qualification testing of the special form capsule. This was accomplished without any additional physical testing. This paper will discuss the details of the licensing demonstration.