In general, the design process involves envisioning and developing concepts for a component or system, combining these fractions into an integrated whole and evaluating the final design against functional requirements. A major challenge is developing components or systems to a level of maturity that permits feasibility evaluation of the integrated whole while optimizing opposing performance functions (e.g., thick for strength, but thin for heat transfer). Economic pressure often drives design concepts to conservative bases early in the process. The approach presented in this paper is a highly costeffective means of developing alternative design solutions for given set of design requirements -in this case a radioactive materials (RAM) transportation package.

Polyurethane foam has been employed in impact limiters for large radioactive materials packagings since the early 1980's. Its consistent crush response, controllable structural properties and excellent thermal insulating characteristics have made it attractive as replacement for the widely used cane fiberboard for smaller, drum size packagings. Accordingly, polyurethane foam was chosen for the overpack material for the 9977 and 9978 packagings. The study reported here was undertaken to provide data to support the analyses performed as part of the development of the 9977 and 9978, and compared property values reported in the literature with published property values and test results for foam specimens taken from a prototype 9977 packaging. The study confirmed that, polyurethane foam behaves in a predictable and consistent manner and fully satisfies the functional requirements for impact absorption and thermal insulation.