not generally used and may often be judged unsuitable for a specific
problem.) The removal of waste from tanks is the first of the process steps in
moving the material toward vitrification. Some of the considerations include
Pretreatment in the tank may allow adjustment of an undesirable physical or
chemical characteristic to make the waste material more compatible with and
amenable to future processing. Pretreatment can include pH adjustment, size
reduction, mixing, and the decant and processing of dilute waste solutions on
the surface of more concentrated waste deposits.
Based on Composition , experience at many radioactive waste storage
facilities suggests the composition of tank wastes may make extraction
techniques and extraction technology key concerns. Precipitates,
agglomerates, and foreign material such as gravel have been key
considerations in influencing the design of removal systems; subsequently,
these considerations influence the design of facilities to process the waste.
The facility design should consider the potential needs of further processing
extracted material and the potential for the waste to change significantly over
the life of the facility as different methods are employed for the extraction of
bulk waste versus residual waste.
Based on Tank Configuration , access may be difficult and may influence
removal techniques, requiring sluicers, mixing systems, etc.
Pumping techniques should consider the slurry nature of the material, both
from a pickup perspective (getting the material into the pump) and the
transport through piping to a processing facility.
Mixing/Homogeneity has influence in the process and process plant
equipment design. In cases where feed material is very consistent, less
concentration on sampling techniques and feed composition adjustment is
required. If the material is nearly all in solution, less attention to slurry
handling is necessary.