Fire reference test for IAEA package thermal testing in a propane gas fire test facility

Packages for the transport of radioactive materials shall withstand severe accidents. Therefore, the IAEA regulations define different test scenarios with severe hypothetical accident conditions. One of these tests defined in detail is the thermal test, mainly consisting of a 30 minute fully engulfing 800°C pool fire or an equally severe fire test. The heat fluxes into the package are of significant importance and depend substantially on the fire characteristics and the surface temperature of the package.In order to investigate the heat fluxes over a wide range of surface temperatures during a propane gas fire test and to get information about local fire impact a fire reference package, representing the outer geometry of a specific type of transport cask for radioactive waste, was designed. A closed steel sheet cylinder with a wall thickness of 10 mm was chosen as fire reference package. The cylinder was filled with refractory insulation material and instrumented with thermocouples distributed all over the cylinder. The measured local steel sheet temperatures allow the determination of local as well as global heat fluxes as a function of time and surface temperature.With this fire reference package three open-air propane gas fire tests were performed at BAM’s open air fire test stand. The flame exposure time period was changed for the different fire tests. Furthermore, the wind conditions changed between and during the tests. Test stand parameters like wind shield location and propane gas volume flow were chosen constant for the three tests. The test results were used to determine the changes of heat flux into the fire reference package in relation to the package surface temperature. This data also allows the calculation of local characteristics of the propane gas fire as there are the flame temperature, the fire convection coefficient and the radiation exchange coefficient in a first approach. The recently conducted tests provide an initial picture of local fire characteristics of the propane gas fire test facility. The test shows that the propane gas fire covers the IAEA-fire over a wide range of surface temperatures with the chosen test stand parameters.