Pretreatment

DOE-HDBK-1132-99

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

the following:

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.

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