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4-22 TYPICAL PROCESS FLOW DIAGRAM FOR HOT GAS DECONTAMINATION OFEXPLOSIVES-CONTAMINATED EQUIPMENT

4.22 HOT GAS DECONTAMINATION

Description: The process involves raising the temperature of the contaminated equipment ormaterial 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. Consideration is being given toapplying the hot gases to explosives-contaminated underground piping in situ.

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.

Applicability: 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.

Limitations: The following factors may limit the applicability and effectiveness of theprocess:

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.

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The rate at which equipment or material can be decontaminated is slower

than that for open burning.

Data Needs: A detailed discussion of these data elements is provided in Subsection 2.2.1

(Data Requirements for Soil, Sediment, and Sludge). Specific data required toevaluate the potential use of hot gas decontamination include:

Types of explosives present.

Weight of the explosives present.

PerformanceData: 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.

Cost: The cost of the decontamination will vary with the application, depending upon

the size and geometry of the equipment or material to be decontaminated andthe temperature and holding time required for the decontamination. No specific

cost analysis has been completed.

References: Maumee Research and Engineering, April 1986. Design Support for a Hot GasDecontamination System for Explosives-Contaminated Buildings.

McNeill, W., et al., October 1987. Pilot Plant Testing of Hot Gas Building

Decontamination Process - Final Report, USATHAMA Report AMXTH-TE-

CR-87130.

USATHAMA, July 1990. Pilot Test of Hot Gas Decontamination of Explosives-

Contaminated Equipment at Hawthorne Army Ammunition Plant (HWAAP),Hawthorne, NV, Final Technical Report, USATHAMA Report CETHA-TE-CR-

90036.

Woodland, L.R., et al., August 1987. Pilot Testing of Caustic Spray/Hot Gas

Building Decontamination Process, USATHAMA Report AMHTH-TE-CR-

87112.

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Site Information:

Site Name Contact Summary Levels Attained Costs

Beginning Levels

HWAAP Erik B. Hangeland Successful pilot-scale 99.99%

Hawthorne, NV USAEC ETD demonstration NA removal of NA

APG, MD 21010 TNT(410) 671-2054

Note: NA = Not Available.

Points of Contact:

Contact Government Agency Phone Location

Technology USAEC (410) 671-2054 SFIM-AEC-ETD

Demonstration and Fax: (410) 612-6836 APG, MD 21010-5401

Transfer Branch