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 www.epa.gov/nhsrc
technical  BR
             Evaluation of Five Technologies for the Mechanical Removal of
                   Radiological Contamination from Concrete Surfaces

       Background
       Because of its potential for deployment as a terrorist
       weapon in an urban setting, the radiological dispersion
       devise (ROD), the "dirty bomb," is a very real and
       significant danger. The National Response
       Framework, the federal document that details how the
       nation responds to such threats, identifies the U.S.
       Environmental Protection Agency (EPA) as a lead
       federal agency for decontamination following a
       radiological incident. This response to a radiological
       incident could include decontamination of buildings,
       equipment, and outdoor areas.                      	
       Thus, to support its designated role, EPA's National Homeland Security Research Center
       evaluated the performance of five mechanical decontamination tools for their ability to remove
       the radioactive isotope Cs-137 (Cesium-137) from the surface of unpainted concrete. In
       addition, NHSRC evaluated these tools for various deployment-related characteristics.
       The work, completed in 2010, is described in a series
       of reports. These peer-reviewed reports provide
       rigorous evaluations of the efficacy of five
       commercially-available surface cleaning tools of the
       type that could be employed to decontaminate
       concrete surfaces following an ROD incident
       releasing Cs-737.These reports can be accessed via
       the NHSRC website (www.epa.gov/nhsrc/). The
       reports provide information that emergency
       responders can use in  recommending or selecting
       appropriate technologies for use during cleanup
       operations. This information can also be used to
       assist federal, state, and local emergency
       management authorities and emergency response
       planners to prepare for radiological homeland security
       events.


       Results
       A summary of the decontamination efficacy results is presented in Table 1.  Unpainted
       concrete coupons (standardized samples) were contaminated with Cs-137 and the
       amount of contamination (radiological activity) deposited on each coupon was measured.
       Each  coupon was then treated with the decontamination technology under investigation
                               As part of U. S. EPA's Office of Research and
                               Development,  the National Homeland Security Research
                               Center (NHSRC) provides products and expertise to
                               improve our nation's ability to respond to environmental
                               contamination  caused by terrorist attacks on our nation's
                               water infrastructure, buildings and outdoor areas,

                               NHSRC conducts research related to:

                                   •   Detecting and containing contamination from
                                      chemical, biological, and radiological agents
                                   •   Assessing and mitigating exposure to
                                      contamination
                                   •   Understanding the health effects of
                                      contamination
                                   •   Developing risk-based exposure advisories
                                   •   Decontaminating and disposing of
                                      contaminated materials.
      March 2011
              This document does not constitute nor should be construed as an EPA endorsement of any particular
                                    product, service, or technology.

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 and the amount of contamination was re-measured. The efficacy of the decontamination
 technology is expressed as percent of contamination removed (%R) and decontamination
 factor (DF). These efficacy measures are determined based on the following relationships:
                                  %R = (1-Af/Ao) x 100%


                                        DF = Ao/Af
              %R = percent of contamination removed
              DF = decontamination factor
              Ao = radiological activity from the surface of the  coupon before decontamination
              Af = radiological activity from the surface of the coupon after decontamination

 For each technology, the product name in Table 1 is hyperlinked to the corresponding report in
 the EPA's Science  Inventory  database. Deployment-related characteristics are presented in
 Table 2 grouped by type of technology (grinding vs. ablative).

 Table 1. Decontamination Efficacy
Product
Dust Director with Wire Brush
Dust Director with Diamond Flap Wheel
CS Unitec Sander
River Technologies Rotating Water Jet
Empire Abrasive Blast n'Vac
Technology Type
Grinding
Grinding
Grinding
Ablative
Ablative
Decontamination Efficacy
%R
38 + 7
89 + 8
54 + 10

36 + 4
96 + 3
DF
1.6 + 0.2
14 + 8.5
2.3 + 0.07
1.6 + 0.09
41+21
 %R, percent of contamination removed; DF, decontamination factor
 Table 2. Deployment Characteristics
Parameter
Decontamination Rate
Applicability to irregular surfaces
Skilled labor requirement
Utilities required
Extent of portability
Setup time
Grinding Technologies
Approximately 1-3 m2/hr
Irregularities kept some grinding heads
from making good contact with the
surface; the more aggressive the
grinding head the greater the final
contact area
Brief training session adequate
1 10V for both grinder and vacuum
Very portable
30 minutes
Ablative Technologies
Approximately 5 m2/hr
Very applicable as surface is receiving
a pressurized blast of abrasive or
water; ablative technologies are not
dependent on the surface terrain
Brief training session adequate
High pressure air compressor, hot
water pressure washer
Equipment requirements more
significant, but hoses would likely
allow access to most locations
2 days to assemble equipment, but
once together setup would be minimal
March 2011
                     This document does not constitute nor should be construed as an EPA
                        endorsement of any particular product, service, or technology.

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 Table 2. Deployment Characteristics (con't)
            Parameter
     Grinding Technologies
     Ablative Technologies
   Secondary waste management
Very little waste as vacuum very
effective in dust collection
Water spray during water blasting was
difficult to contain and could cause
contaminant re-aerosolization which
would be a safety concern; grit
blasting vacuum worked well
   Surface damage
CSU Sander- minor visible surface
damage

DD Wire Brush - minor visible surface
damage, discoloration of surface

DD Diamond Flap Wheel - top 1-2
millimeters of coupon removed leaving
exposed aggregate
RT Rotating Water Jet - no visible
surface damage

EA Blast n'Vac - 1-2 mm of coupon
surface removed leaving exposed
aggregate
Technology Evaluation Reports Referenced

Drake, J. 2011. CS Unitec ETR180 Circular Sander for Radiological Decontamination.
Technology Evaluation Report. Washington, D.C.: U.S. Environmental Protection Agency.
EPA/600/R-11/018.

Drake, J. 2011. Empire Abrasive Blast N'Vac for Radiological Decontamination. Technology
Evaluation Report. Washington, D.C.: U.S. Environmental Protection Agency.  EPA/600/R-
11/014.

Drake, J. 2011.  Industrial Contractors Supplies, Inc. Surface Dust Guard with Diamond Wheel
for Radiological Decontamination. Technology Evaluation Report. Washington, D.C.: U.S.
Environmental Protection Agency.  EPA/600/R-11/013.
Drake, J. 2011. Industrial Contractors Supplies, Inc. Surface Dust Guard with Wire Brush for
Radiological Decontamination. Technology Evaluation Report. Washington, D.C.: U.S.
Environmental Protection Agency.  EPA/600/R-11/016.

Drake, J. 2011.  River Technologies LLC 3-Way Decontamination System for Radiological
Decontamination. Technology Evaluation Report. Washington, D.C.:  U.S. Environmental
Protection Agency.   EPA/600/R-11/015.
Contact Information
For more information, visit the NHSRC Web site at www.epa.gov/nhsrc

Technical Contact: John Drake (drake.john@epa.gov)

General Feedback/Questions: Kathy Nickel (nickel.kathy@epa.gov)
March 2011
                      This document does not constitute nor should be construed as an EPA
                         endorsement of any particular product, service, or technology.

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