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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 local steel sheet temperatures measured 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.
The presentation gives an overview over three current fire testing activities for testing transport packages for the transport of high-level radioactive material. Packages for the transport of high-level radioactive material must withstand severe hypothetical accidents. Regulatory test conditions shall cover these severe accident conditions and consist of mechanical tests and a following thermal test. To withstand the mechanical tests heavy weight packages are often designed with impact limiters consisting of wood encapsulated in steel sheets. The thermal test is defined precisely in the IAEA-regulations as a 30 minute fully engulfing 800 °C fire. After the fire phase a pre-damaged impact limiter might continue burning or smoldering and influence the cask thermal behavior with its energy release. The energy transferred from the impact limiter to the cask is of importance for the safety of transport packages. A full-scale fire test with an impact limiter of 2.3 m in diameter and filled with spruce wood was designed and performed. The impact limiter continued burning for 3 days. Energy transfer and temperature measurements were performed. A new test is designed to examine pressure build up and possible mechanical failures in an undamaged impact limiter with a diameter of 1.9 m. The test is designed to measure heat flux from the impact limiter in case of its ignition and burning. To furthermore examine the burning behavior of steel encapsulated wood piles, tests are prepared with wood fire containers and an infrared ignition source. A fire reference package for calorimetric tests was designed. The fire reference package design consists of a closed steel sheet cylinder with a length of 1,500 mm, an exterior diameter of 1,050 mm, and a wall thickness of 10 mm. 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 overall integral heat fluxes versus time and versus surface temperature. Currently, tests are planned with a new and relatively small fire reference package design. The new design will have a steel sheet cylinder with a length of 182 mm, an exterior diameter of 120 mm. Additionally heat flux sensors will be used in the new fire reference package test design. The propane gas fire will be adjusted with respect to the outcome of the fire tests to meet the requirements of the IAEA-fire.