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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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