Flammable gas generation, retention, and release in high-level waste tanks -- physical and chemical models
The most evident dangers from flammable gas release in ventilated high-level waste tanks at Hanford are those caused by periodic release of gases generated and retained in depths of the tanks. In Hanford Tank 101-SY the flammable gases and hydrogen, ammonia and methane are accumulated along with oxidizer nitrous oxide in bubbles while the ammonia and nitrous oxide are also deposited in solution. Accumulation of both the free and dissolved gases is enhanced by hydrostatic pressure. The free gases are apparently held by several mechanisms -- viscous trapping of bubbles, stabilization in three-phase foams at hydrophobic surfaces, capillary channel gas accumulation, mechanical trapping in crystal clusters, and tight engulfment in armored bubbles. Episodic release is brought about by the ascension from the bottom of large conglomerates which release gases by bubble detachment and by slower diffusion-controlled mass-transfer processes. Density of the conglomerates increases in this process, whereupon they settle to repeat the cycle again. The flammable gases are produced by a combination of radiolytic and non-radiolytic chemical processes in breakdown of water and organic and inorganic constituents. Hydrogen production is enhanced by organic destruction while radiolytic hydrogen production is depressed by nitrite ion. Most of the nitrous oxide and ammonia appear to be derived from reduction of nitrite by organics, with smaller amounts coming from amine nitrogen in chelators. Methane is produced in only small amounts. Formate, oxalate, and carbonate are refractory end-products from degradation of organic constituents such as the chelators ethylenediaminetetraacetate (EDTA) and N-(2-hydroxyethyl)ethylenediaminetriacetate (HEDTA).
- Research Organization:
- Westinghouse Hanford Co., Richland, WA (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States); Los Alamos National Lab., NM (United States); Argonne National Lab., IL (United States); Georgia Inst. of Tech., Atlanta, GA (United States); Department of the Interior, Washington, DC (United States); Texas Univ., Austin, TX (United States)
- DOE Contract Number:
- AC06-87RL10930
- OSTI ID:
- 10144122
- Report Number(s):
- WHC-SA-2129; CONF-940225-100; ON: DE94010347; BR: 35AF11201/35AF11202; TRN: AHC29410%%4
- Resource Relation:
- Conference: Waste management `94: working towards a cleaner environment,Tucson, AZ (United States),27 Feb - 3 Mar 1994; Other Information: PBD: Mar 1994
- Country of Publication:
- United States
- Language:
- English
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HANFORD RESERVATION
RADIOACTIVE WASTE STORAGE
GASES
SYNTHESIS
FLAMMABILITY
ENTRAINMENT
HIGH-LEVEL RADIOACTIVE WASTES
RADIOLYSIS
DECOMPOSITION
LIQUID WASTES
CHEMICAL COMPOSITION
GAS ANALYSIS
052002
WASTE DISPOSAL AND STORAGE