Accelerated Design and Certification of a Small Plutonium Air Transport Package

Abstract Sandia National Laboratories (SNL) is in the process of developing a plutonium air transportation (PAT) package with a 2-liter capacity containment vessel. The package is being designed to satisfy requirements defined in both Title 10 of the United States (U.S.) Code of Federal Regulation Part 71 (10 CFR 71) and in the Specific Safety Requirements 6 (SSR-6) of the International Atomic Energy Agency (IAEA). The regulations define hypothetical accident condition (HAC) test sequences, which include a 129 m/s impact of the package into an essentially unyielding target and a post-impact exposure of the package to a 60-minute fully engulfing jet fuel pool fire in 10 CFR 71. These conditions are exceptionally challenging to design for and have historically necessitated prolonged development and certification times. To achieve an accelerated design and certification schedule, an initial design iteration of the energy absorbing elements of this small PAT package have been largely based on a simple volumetric scaling of the geometry and features of a previously developed PAT package with a 33-liter capacity containment vessel, called the Large PAT package. Since the physical processes governing the response of the package to the mechanical and thermal HAC test environments do not scale equally, a direct geometric scaling of the Large PAT package is unlikely to produce a package that meets the containment, shielding, and criticality performance requirements. Preliminary scoping analyses investigating the performance of a notional Small PAT package have been completed. These analyses leveraged a significant amount of design and performance data acquired during the design and certification of the Large PAT, including models and modeling and simulation processes. This paper presents some of the challenges associated with developing a smaller PAT package based on a larger existing PAT package. It discusses the primary design features of both the existing Large PAT package and a notional Small PAT package, describes details of the finite element models (thermal and mechanical) used in the initial scoping analyses, and summarizes results and conclusions drawn from those analyses.