Waste Treatments - STD-1128-98master0236

DOE-STD-1128-98

Guide of Good Practices for Occupational Radiological Protection in Plutonium Facilities

to minimize mixed waste (and hazardous waste) problems: procurement of

hazardous chemicals, actions of subcontractors and vendors, and training of

workers. In some cases, decontamination processes have been used that result in

mixed waste, such as Freon cleaning, electropolishing, and chemical

decontamination. These should be used only after due consideration of the waste-

management consequences. In some cases, these mixed wastes can be readily

treated; in other cases, their use needs to be avoided. Some new techniques are

designed specifically for waste minimization and waste classification control. For

example, one method involves abrasive blasting with solid carbon dioxide (dry

ice), which sublimes after use and can be exhausted through a HEPA filter, leaving

no added material to the waste. Decontamination with high-pressure water has

some similar advantages, but care must be taken to ensure that used

decontamination solutions do not spread contamination.

8.3.3 Waste Treatments

Available treatments for solid waste include compaction and incineration. In specific cases,

there may be decontamination options available, as well.

Compaction, with pressures in the range of 40,000 to 60,000 psi, is most often used

on paper, fabric, and plastic although it is effective on glass, sheet metal, and some other

materials. With such ordinary materials, one commercial reactor has approached up to

800 pounds of waste per 55-gallon drum, although an average of 500 pounds per drum is

considered very good. Compaction is done by drum compactor or box compactor.

Compacting into a drum or a 4- by 4- by 8-ft box is normally a labor-intensive operation

and often involves some risk of personnel exposure, even though the better compactors are

equipped with HEPA-filtered ventilation systems. Supercompaction uses considerably

higher pressures than compaction, normally 200,000 psi or greater. Supercompaction

usually involves compacting filled waste drums into a box or overpack. Supercompaction

has been success-fully used on piping and other materials that are normally considered

noncompactable.

It is really a choice of words whether incineration is considered a disposal technique or a

volume-reduction technique. All carbon, oxygen (except for any that becomes bound in

oxide ash), nitrogen, hydrogen, and sulfur present in the incinerator feed will be converted to

gasses and disposed to the atmosphere. Plutonium and most metals will remain as a solid

material. As a volume-reduction technique, incineration is very successful, with volume-

reduction factors up to 200:1 or greater achieved on some waste streams. There have been

licensing delays for some incinerators, and often there are limitations brought about by air-

quality restrictions. There is also the possibility that incinerator ash may be a mixed waste

due to the concentration of other impurities such as heavy metals in the waste. If a facility

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