Initial parametric study of the flammability of plume releases in Hanford waste tanks
This study comprised systematic analyses of waste tank headspace flammability following a plume-type of gas release from the waste. First, critical parameters affecting plume flammability were selected, evaluated, and refined. As part of the evaluation the effect of ventilation (breathing) air inflow on the convective flow field inside the tank headspace was assessed, and the magnitude of the so-called {open_quotes}numerical diffusion{close_quotes} on numerical simulation accuracy was investigated. Both issues were concluded to be negligible influences on predicted flammable gas concentrations in the tank headspace. Previous validation of the TEMPEST code against experimental data is also discussed, with calculated results in good agreements with experimental data. Twelve plume release simulations were then run, using release volumes and flow rates that were thought to cover the range of actual release volumes and rates. The results indicate that most plume-type releases remain flammable only during the actual release ends. Only for very large releases representing a significant fraction of the volume necessary to make the entire mixed headspace flammable (many thousands of cubic feet) can flammable concentrations persist for several hours after the release ends. However, as in the smaller plumes, only a fraction of the total release volume is flammable at any one time. The transient evolution of several plume sizes is illustrated in a number of color contour plots that provide insight into plume mixing behavior.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE Office of Environmental Restoration and Waste Management, Washington, DC (United States)
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 554185
- Report Number(s):
- PNNL-11639; ON: DE97054430; TRN: 98:000008
- Resource Relation:
- Other Information: PBD: Aug 1997
- Country of Publication:
- United States
- Language:
- English
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