Safety support for hydrogen reanalysis of Waste Tank 101-SY

Tank 101-Sy, a double-shell tank on the Hanford SY high-level waste tank farm, has periodic releases of large volumes of gas. The released gas contains hydrogen (a fuel), nitrous oxide (a strong oxidizer), and other gases. These gases are intimately mixed, and therefore, it is very difficult to reduce the potential for a hydrogen combustion event. The safety is hydrogen gas exceeding one-quarter of the Lower Flammability Limit during these periodic releases. The Department of Energy Office of Environmental Restoration and Waste Management requested Los Alamos and Brookhaven National Laboratories to perform a reanalysis of a postulated hydrogen combustion event in Tank 101-SY. This paper provide the results of this work. The results of this analysis are similar to the Westinghouse Hanford Company results with slightly higher pressures and larger releases. The results given here are believed to be conservative in that the pressures are higher and the radiological releases are larger than that would be produced by a best-estimate analysis.