Burn Testing of Polyurethane Foam Shielded with Ceramic Fiber Paper

During the design of a new fresh fuel package, testing was performed to examine and optimize the use of polyurethane foam, in combination with ceramic fiber paper, to protect a nylon neutron moderator from melting in a regulatory fire test. The characteristics tested were the polyurethane foam density and thickness of ceramic fiber paper. Burn test specimens included a typical cross section of the package lid. The test specimens were monitored with several thermocouples during the fire test and cool down period. The primary objective was to determine the lightest density polyurethane foam and minimum thickness of ceramic fiber paper capable of protecting the nylon moderator from melting. The total stack height of the foam and ceramic fiber paper was constant and a specified design constraint. The results demonstrated that six pound per cubic foot foam and one-half inch of ceramic fiber paper provided sufficient thermal protection for the nylon moderator.