Flammability potential in in-tank precipitation tanks
- Westinghouse Savannah River Company, Aiken, SC (United States)
- Mason & Hanger, Amarillo, TX (United States)
The frequency of deflagration in in-tank precipitation tanks due to ventilation failures was determined. The in-tank precipitation is an addition to the tank farm operations. This facility will prepare waste tank supernate and salt for treatment by the vitrification facility and saltstone facility. As the neutralized high-level waste ages, gravity causes it to settle into a salt solution (supernate) over a layer of containing solids (sludge). In some waste tanks, some of the salt has crystallized from the solution. Salt crystallization, and thus volume reduction, is enhanced by concentrating the supernate in the waste evaporators. The salt Solution is decontaminated by in-tank precipitation using a batch process in existing waste tanks in the tank farm, which are specifically designated for that purpose. The low-activity (decontaminated) salt solution is prepared front the supernate in dedicated waste tanks by a combination of precipitation, adsorption, and filtration. The most abundant radio- isotope in the supernate, {sup 137}Cs, is precipitated with sodium tetraphenylborate (STPB). In the same step, {sup 90}Sr, uranium, and plutonium are adsorbed on monosodium titanate particles. The solution (slurry) is filtered into two separate streams: filtrate and precipitate. The filtrate from this process is treated in order to remove volatile organics and is stored for later processing in the saltstone facility. The precipitate from this process is one of two concentrate slurries fed to the vitrification facility. The precipitation and adsorption processes by which radioactive constituents are removed from the salt supernate produce flammable vapors, predominately benzene, not previously present in the tank farm. The high vapor pressure of benzene allows evaporation at the temperatures in the waste tanks and can result in flammable vapor concentrations.
- OSTI ID:
- 186289
- Report Number(s):
- CONF-950601--
- Journal Information:
- Transactions of the American Nuclear Society, Journal Name: Transactions of the American Nuclear Society Vol. 72; ISSN TANSAO; ISSN 0003-018X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ACID HYDROLYSIS
ADSORPTION
BENZENE
CESIUM 137
EVAPORATORS
FILTRATION
FLAMMABILITY
HIGH-LEVEL RADIOACTIVE WASTES
HYDROGEN
PLUTONIUM
PRECIPITATION
RADIOACTIVE WASTE PROCESSING
RADIOACTIVE WASTE STORAGE
RADIOLYSIS
SAFETY
SLURRIES
STRONTIUM 90
TANKS
THERMAL DEGRADATION
URANIUM
VAPOR PRESSURE
VENTILATION