LAST-A-FOAM® FR-3700 Series Foam: Crash & Fire Protection for Nuclear Transportation Containers

General Plastics Manufacturing Company’s LAST-A-FOAM® FR-3700 series foam has a history of successful use for radioactive material shipping containers. The LAST-A-FOAM® FR-3700 formulation is specially designed to allow predictable impact-absorption performance under dynamic loading, while also providing an intumescent char layer that insulates and protects hazardous materials, even when exposed to pool-fire conditions.In this study, General Plastics attempts to simulate a severely damaged nuclear transportation container in which the foam has been crushed and contained within the container as a single, highly compressed mass. A series of differing densities of FR-3700 series foams were subjected to crush strengths exceeding 50%, then subjected to thermal attack using an oil burner test apparatus. Thermal transfer through the foam, intumescence, burn distance, and plastics memory were monitored and will be discussed.Migration of heat through the foam was found to be extremely low, the effects of intumescence on burn length and protection of the foam beneath the intumescent char layer performed as expected, and burn distance compared to flame exposure time was minimal. For specimens that were crushed prior to thermal testing, the final solid foam length, after removing the intumescent char layer, was slightly longer than the length before thermal testing. The heat cycle relieved stresses in the crushed foam causing expansion of the foam.The information presented in this paper will help designers of radioactive material shipping containers understand the value of time that LAST-A-FOAM® FR-3700 series foam offers. The slow rate of heat transfer through the LAST-A-FOAM® FR-3700 formulation provides first responders sufficient time to respond to a radioactive material shipping container accident that includes an accidental fire.