Heat load limits for TRU drums on pads

Some of the Trans-Uranic (TRU) waste generated at SRS is packaged in 55 gallon, galvanized steel drums and stored on concrete pads that are exposed to the weather. It was necessary to compute how much heat can be generated by the waste in these drums without exceeding the temperature limits of the contents of the drum. This report documents the calculation of heat load limits for the drum, which depend on the temperature limits of the contents of the drum. The applicable temperature limits for the contents of the drum are the melting temperature of the polyethylene liner, 284 ± 8 F, the combustion temperature of paper, 450 F and the decomposition temperature of anionic resin, 190 F. One part of the analysis leading to the heat load limits was the collection of weather records on solar flux, wind speed and air temperature. Another part of the task was an experimental measurement of two important properties of the drum lid, the emittance and the absorptance. As used here, emittance is the rate at which an object emits infrared thermal radiation divided by the rate at which a perfect black body at the same temperature emits thermal radiation. Absorptance is the rate at which an object absorbs solar radiation divided by the rate at which a perfect black body absorbs radiation. For nine locations on each of eight typical weathered drum lids the measured emittance ranged from 0.73 ± 0.05 to 1.00 ± 0.07 (95% confidence level) and the average emittance for the eight lids was 0.85. For the eight drum lids the measured absorptance ranged from 0.64 ± 0.07 to 0.79 ± 0.07 with an average absorptance for the eight lids of 0.739