The process involves raising the temperature of the contaminated equipment or material to 260 °C (500 °F) for a specified period of time. The gas effluent from the material is treated in an afterburner system to destroy all volatilized contaminants. The method eliminates a waste that currently is stockpiled and requires disposal as a hazardous material. This method will permit reuse or disposal of scrap as nonhazardous material.
Hot gas decontamination can also be used for decontamination of explosives-contaminated masonry or metallic structures. The method involves sealing and insulating the structures, heating with hot gas stream to 260 °C (500 °F) for a prescribed period of time, volatilizing the explosive contaminants, and destroying them in an afterburner. Operating conditions are site-specific. Contaminants are completely destroyed.
The method is applicable for process equipment requiring decontamination for reuse. It is also applicable for explosive items, such as mines and shells, being demilitarized (after removal of explosives) or scrap material contaminated with explosives.
The method can also be used for buildings or structures associated with ammunition plants, arsenals, and depots involved in the manufacture, processing, loading, and storage of pyrotechnics, explosives, and propellants.
The following factors may limit the applicability and effectiveness of the process:
- The costs of this method are higher than open burning.
- Flash chamber design must take into consideration possible explosions from improperly demilitarized mines or shells.
- The rate at which equipment or material can be decontaminated is slower than that for open burning.
Specific data required to evaluate the potential use of hot gas decontamination include:
- Types of explosives present.
- Weight of the explosives present.
Items decontaminated for 6 hours at a minimum temperature of 260 °C(500 °F) were found to be safe for public release as scrap. TNT destruction rates of 99.99% can be achieved.
The cost of the decontamination will vary with the application, depending upon the size and geometry of the equipment or material to be decontaminated and the temperature and holding time required for the decontamination. No specific cost analysis has been completed.