EPA 600/R-11/014 | May 2011 | www.epa.gov/ord

Office of Research and Development

National Homeland Security Research Center

Empire Abrasive Blast 

N’Vac for Radiological 

Decontamination 

Technology Evaluation Report
EPA 600-R-11-014

May 2011

Technology Evaluation Report

Empire Abrasive Blast N’Vac for 

Radiological Decontamination 

United States Environmental Protection Agency 

Cincinnati, OH 45268
ii

Disclaimer

The U.S. Environmental Protection Agency (EPA), through its Office of Research and 

Development’s National Homeland Security Research Center, funded and managed this 

technology evaluation through a Blanket Purchase Agreement under General Services 

Administration contract number GS23F0011L-3 with Battelle. This report has been peer and 

administratively reviewed and has been approved for publication as an EPA document. Mention 

of trade names or commercial products does not constitute endorsement or recommendation for 

use of a specific product.

Questions concerning this document or its application should be addressed to:

John Drake

National Homeland Security Research Center

Office of Research and Development

U.S. Environmental Protection Agency

26 West Martin Luther King Dr.

Cincinnati, OH 45268

513-569-7164

drake.john@epa.gov
iii

Foreword

The Environmental Protection Agency (EPA) holds responsibilities associated with homeland 

security events: EPA is the primary federal agency responsible for decontamination following a 

chemical, biological, and/or radiological (CBR) attack. The National Homeland Security 

Research Center (NHSRC) was established to conduct research and deliver scientific products 

that improve the capability of the Agency to carry out these responsibilities.

An important goal of NHSRC’s research is to develop and deliver information on 

decontamination methods and technologies to clean up CBR contamination. When directing 

such a recovery operation, EPA and other stakeholders must identify and implement 

decontamination technologies that are appropriate for the given situation. The NHSRC has 

created the Technology Testing and Evaluation Program (TTEP) in an effort to provide reliable 

information regarding the performance of homeland security related technologies. TTEP 

provides independent, quality assured performance information that is useful to decision makers 

in purchasing or applying the tested technologies. TTEP provides potential users with unbiased, 

third-party information that can supplement vendor-provided information. Stakeholder 

involvement ensures that user needs and perspectives are incorporated into the test design so that 

useful performance information is produced for each of the tested technologies. The technology 

categories of interest include detection and monitoring, water treatment, air purification, 

decontamination, and computer modeling tools for use by those responsible for protecting 

buildings, drinking water supplies and infrastructure, and for decontaminating structures and the 

outdoor environment. Additionally, environmental persistence information is also important for 

containment and decontamination decisions. 

NHSRC is pleased to make this publication available to assist the response community to prepare 

for and recover from disasters involving CBR contamination. This research is intended to move 

EPA one step closer to achieving its homeland security goals and its overall mission of 

protecting human health and the environment while providing sustainable solutions to our 

environmental problems.

Jonathan G. Herrmann, Director 

National Homeland Security Research Center
iv

Acknowledgments

Contributions of the following individuals and organizations to the development of this document are 

gratefully acknowledged. 

United States Environmental Protection Agency (EPA) 

 John Drake

Emily Snyder

Sang Don Lee

Lukas Oudejans

David Musick

Kathy Hall

Eletha Brady-Roberts

Jim Mitchell

University of Tennessee

Howard Hall

United States Department of Energy’s Idaho National Laboratories

Battelle Memorial Institute
v

Contents

Disclaimer....................................................................................................................................... ii

Foreword........................................................................................................................................iii

Acknowledgments.......................................................................................................................... iv

Abbreviations/Acronyms.............................................................................................................. vii

Executive Summary.....................................................................................................................viii

1.0 Introduction.............................................................................................................................. 1

2.0 Technology Description........................................................................................................... 3

3.0 Experimental Details................................................................................................................ 5

3.1 Experiment Preparation ................................................................................................... 5

3.1.1 Concrete Coupons................................................................................................. 5

3.1.2 Coupon Contamination ......................................................................................... 6

3.1.3 Measurement of Activity on Coupon Surface ...................................................... 7

3.1.4 Surface Construction Using Test Stand ................................................................ 7

3.2 Evaluation Procedures ..................................................................................................... 8

4.0 Quality Assurance/Quality Control........................................................................................ 10

4.1 Intrinsic Germanium Detector ....................................................................................... 10

4.2 Audits............................................................................................................................. 11

4.2.1 Performance Evaluation Audit............................................................................ 11

4.2.2 Technical Systems Audit .................................................................................... 12

4.2.3 Data Quality Audit.............................................................................................. 12

4.3 QA/QC Reporting .......................................................................................................... 12

5.0 Evaluation Results ................................................................................................................. 13

5.1 Decontamination Efficacy ............................................................................................. 13

5.2 Deployment and Operational Factors............................................................................ 14

6.0 Performance Summary........................................................................................................... 17

6.1 Decontamination Efficacy ............................................................................................. 17

6.2 Deployment and Operational Factors............................................................................ 17

7.0 References.............................................................................................................................. 19
vi

Figures

Figure 2-1. Blast N’Vac as assembled for testing (left). Closeup of Blast N’Vac 

vacuum head (right). ................................................................................................. 4

Figure 2-2. Blast N’Vac abrasive grit reservoir, HEPA filter, and collection drum. ................... 4

Figure 3-1. Demonstration of contaminant application technique. .............................................. 6

Figure 3-2. Containment tent: outer view (left) and inner view with test stand containing 

contaminated coupons (right). ................................................................................... 7

Figure 3-3. Operator applying Blast N’Vac to concrete coupon.................................................. 9

Figure 5-1. Test coupon surfaces before (left) and after (right) treatment with the 

Blast N’Vac. ............................................................................................................ 14

Tables

Table 3-1. Characteristics of Portland Cement Clinker Used to Make Concrete Coupons ........ 5

Table 4-1. Calibration Results – Difference from Th-228 Calibration Energies...................... 10

Table 4-2. NIST-Traceable Eu-152 Activity Standard Check .................................................. 11

Table 5-1. Decontamination Efficacy Results........................................................................... 14

Table 5-2. Operational Factors Gathered from the Evaluation ................................................. 16
vii

Abbreviations/Acronyms

ANSI

ASTM

BQ

Cs

cfm

cm

American National Standards Institute

American Society for Testing and Materials

Becquerel

cesium

cubic feet per minute

centimeters

DARPA Defense Advanced Research Projects Agency

DF decontamination factor

DHS U.S. Department of Homeland Security

DOD Department of Defense

EPA

Eu

ft

HEPA

IEEE

INL

U.S. Environmental Protection Agency

europium

feet

High Efficiency Particle Air

Institute of Electrical and Electronics Engineers

Idaho National Laboratory

keV

mg

mL

L

m

m

2

μCi

kilo electron volts

milligram

milliliter

liter

meter

square meter

microCuries

NHSRC

NIST

National Homeland Security Research Center

National Institute of Standards and Technology

ORD Office of Research and Development

%R percent removal

PE

psi

performance evaluation

pounds per square inch

QA quality assurance

QC quality control

QMP

RDD

quality management plan

radiological dispersion device

RML

RSD

Radiological Measurement Laboratory

relative standard deviation

TSA technical systems audit

TTEP

Th

Technology Testing and Evaluation Program

thorium
viii

Executive Summary

The U.S. Environmental Protection Agency’s (EPA) National Homeland Security Research 

Center (NHSRC) is helping to protect human health and the environment from adverse impacts 

resulting from acts of terror by carrying out performance tests on homeland security 

technologies. Through its Technology Testing and Evaluation Program (TTEP), NHSRC

evaluated the performance of the Empire Abrasive Blast N’Vac (hereafter referred to as the Blast

N’Vac) and its ability to remove radioactive cesium (Cs)-137 from the surface of unpainted 

concrete.

Experimental Procedures. The Blast N’Vac is a heavy duty abrasive grit blasting technology

that removes bound Cs from a surface by blasting away the concrete surface. Eight 15 centimeter 

(cm) × 15 cm unpainted concrete coupons were contaminated with approximately 1 microCurie 

(μCi) of Cs-137 per coupon and allowed to age for seven days. The amount of contamination 

deposited on each coupon was measured using gamma spectroscopy. The eight contaminated

coupons were placed in a test stand (along with one uncontaminated blank coupon) that was

designed to hold nine concrete coupons in a vertical orientation to simulate the wall of a 

building. Each coupon was treated with the Blast N’Vac, and the decontamination efficacy was 

determined by calculating both a decontamination factor (DF) and percent removal (%R). 

Important deployment and operational factors were also documented and reported. 

Results. The decontamination efficacy attained by the Blast N’Vac was evaluated for each 

individual concrete coupon used during the evaluation. When the decontamination efficacy 

metrics (DF and %R) of the eight contaminated coupons were averaged together, the average 

%R for the Blast N’Vac was 97 ± 2% the average DF was 58 ± 52. Hypothesis testing was 

performed to determine if there were significant differences among the %R values determined 

for the coupons in each row (top, middle, and bottom) of the test stand. No differences were 

found.

Following the manufacturer’s recommendations, the Blast N’Vac was used with size 24 

aluminum oxide abrasive grit. The rate at which the Blast N’Vac was used to decontaminate a 

vertical surface was approximately 2.7 square meters (m2

) per hour, with significant visual 

surface destruction and some secondary waste. The texture of the concrete surface is not relevant

to the efficacy of the Blast N’Vac and similar blasting technologies. Battelle observed that,

because of the aggressiveness with which the abrasive grit removes concrete surfaces, 

irregularities within the surface would not impact the effectiveness of the technology. The Blast 

N’Vac required a source of compressed air that provided at least 400 cubic feet per minute (cfm)

of air flow at a pressure of 120 pounds per square inch (psi). An Ingersoll-Rand 75902 dieselpowered air compressor was the only source of power required for the operation of the Blast 

N’Vac. Such a large air compressor is not a common piece of equipment. Therefore, the size and 

availability of the compressor required may limit the locations where the Blast N’Vac can be 

used.
ix

A very limited evaluation of cross-contamination was performed. During an actual 

decontamination of a vertical surface, the higher elevation surfaces would likely be 

decontaminated first, possibly exposing the lower elevation surfaces to secondary contamination. 

To simulate an actual scenario, one uncontaminated coupon was placed in the bottom row of the 

test stand and decontaminated using the Blast N’Vac in the same way as the other coupons. 

Following decontamination using the Blast N’Vac, this uncontaminated coupon did not exhibit

measurable activity, suggesting that cross contamination was minimal. It should be noted that

very small amounts of blasting abrasive grit (individual grains) were found throughout the 

containment tent and there was some abrasive grit that collected at the base of the test stand. 

.
1

1.0 Introduction

The U.S. Environmental Protection 

Agency’s (EPA) National Homeland 

Security Research Center (NHSRC) is 

helping to protect human health and the 

environment from adverse effects 

resulting from acts of terror. NHSRC is 

emphasizing decontamination and 

consequence management, water 

infrastructure protection, and threat and 

consequence assessment. In doing so, 

NHRSC is working to develop tools and 

information that will improve the ability 

of operational personnel to detect the 

intentional introduction of chemical, 

biological, or radiological contaminants 

on or into buildings or water systems, to 

contain or mitigate these contaminants, 

to decontaminate affected buildings 

and/or water systems, and to dispose of 

contaminated materials resulting from 

clean-ups.

NHSRC, through its Technology Testing 

and Evaluation Program (TTEP), works 

in partnership with recognized testing 

organizations; stakeholder groups 

consisting of buyers, vendor 

organizations, and permitters; and 

through the participation of individual 

technology developers in carrying out 

performance tests on homeland security 

technologies. The program evaluates the 

performance of homeland security 

technologies by developing evaluation 

plans that are responsive to the needs of 

stakeholders, conducting tests, collecting 

and analyzing data, and preparing peerreviewed reports. All evaluations are 

conducted in accordance with rigorous 

quality assurance (QA) protocols to 

ensure that data of known and high 

quality are generated and that the results 

are defensible. TTEP provides highquality information that is useful to 

decision makers in purchasing or 

applying the evaluated technologies and 

in planning clean-up operations. TTEP 

provides potential users with unbiased, 

third-party information that can 

supplement vendor-provided 

information. Stakeholder involvement 

ensures that user needs and perspectives 

are incorporated into the evaluation 

design so that useful performance 

information is produced for each of the 

evaluated technologies.

Under TTEP, NHSRC recently 

evaluated the performance of the Empire 

Abrasive Blast N’Vac (Langhorne, PA;

hereafter referred to as the Blast N’Vac)

in removing radioactive isotope Cs-137 

from concrete. A peer-reviewed test/QA 

plan was developed according to the 

requirements of the quality management 

plan (QMP) for TTEP. The evaluation 

generated the following performance 

information:

# Decontamination efficacy, defined as 

the extent of radionuclide removal 

following use of the Blast N’Vac, 

and the possibility of crosscontamination.
2

# Deployment and operational factors,

including the approximate rate of 

surface area decontamination, 

applicability to irregular surfaces, 

skilled labor requirement, utility 

requirements, portability, secondary 

waste management, and technology

cost.

This evaluation took place from August

11, 2009 until October 13, 2009. All of 

the experimental work took place in a 

radiological contamination area at the 

U.S. Department of Energy’s Idaho 

National Laboratory (INL). This report 

describes the quantitative results and 

qualitative observations gathered during 

this evaluation of the Blast N’Vac. The 

contractor, Battelle, and EPA were 

responsible for QA oversight. The 

Battelle QA Manager conducted both a 

technical systems audit (TSA) and a data 

quality audit of the evaluation data. 
3

2.0 Technology Description

The following description of the Blast 

N’Vac is based on information provided 

by the vendor and was not verified 

during this evaluation.

Blast N’Vac is a heavy duty abrasive grit 

blasting technology that also collects the 

spent abrasive grit by means of a 

blasting head surrounded with a vacuum 

collection shroud. During this 

evaluation, the Blast N’Vac was used 

with size 24 aluminum oxide abrasive

grit. The Blast N’Vac was powered 

entirely by compressed air. An IngersollRand 75902 diesel-powered air 

compressor provided approximately 400 

cubic feet per minute (cfm) of 

compressed air at approximately 120 

pounds per square inch (psi). The Blast 

N’Vac is plumbed to provide not only an 

adequate amount of compressed air to 

perform the abrasive grit blasting but 

also adequate suction to perform the 

abrasive grit recovery. The air 

compressor was not provided by Empire 

Abrasive, but is considered a required 

utility for operation of the technology. In 

addition, while not tested as part of this 

evaluation, the Blast N’Vac came 

equipped with blasting heads shaped 

specifically for work in corners.

Figure 2-1 shows the Blast N’Vac 

blasting gun used during this evaluation. 

The photograph on the right clearly 

shows the inner blasting head and the 

vacuum shroud surrounding the blasting 

head. Figure 2-2 shows (from left to 

right) the abrasive grit reservoir, the high 

efficiency particle air (HEPA) filter, and 

the abrasive grit collection drum situated 

on a skid. The Blast N’Vac can also be 

equipped to recycle abrasive grit

continuously, but that feature was not 

used during this evaluation in order to 

minimize the amount of equipment at 

risk of becoming contaminated with 

radiological material. Therefore, the 

abrasive grit was blasted and collected 

for disposal in the collection drum. All 

components in Figure 2-2 were 

successfully protected from 

contamination and were returned 

following the evaluation.
4

Figure 2-1. Blast N’Vac as assembled for testing (left). Close-up of Blast N’Vac 

vacuum head (right).

Figure 2-2. Blast N’Vac abrasive grit reservoir, HEPA filter, and collection drum.
5

3.0 Experimental Details

3.1 Experiment Preparation

3.1.1 Concrete Coupons

The concrete coupons were prepared 

from a single batch of concrete made 

from Type II Portland cement. The

ready-mix company (Burns Brothers 

Redi-Mix, Idaho Falls, ID) that supplied 

the concrete for this evaluation provided 

the data which describe the cement 

clinker used in the concrete mix. For 

Type II Portland cement, the American 

Society for Testing and Materials 

(ASTM) Standard C 150-71 specifies

that tricalcium aluminate account for

less than 8% of the overall cement 

clinker (by weight). The cement clinker 

used for the concrete coupons was 4.5% 

tricalcium aluminate (Table 3-1). For 

Type I Portland cement the tricalcium 

aluminate content should be less than

15%. Because Type I and II Portland 

cements differ only in tricalcium 

aluminate content, the cement used 

during this evaluation meets the 

specifications for both Type I and II 

Portland cements. 

Table 3-1. Characteristics of Portland Cement Clinker

 Used to Make Concrete Coupons

Cement Constituent Percent of Mixture

Tricalcium Silicate 57.6

Dicalcium Silicate 21.1

Tricalcium Aluminate 4.5

Tetracalcium Aluminoferrite 8.7

Minor Constituents 8.1

 

The wet concrete was poured into 0.9 

meter (m) square plywood forms with 

the exposed surface “floated” to allow

the smaller aggregate and cement paste 

to float to the top, and the concrete was 

then cured for 21 days. Following 

curing, the squares were cut to the 

desired size with a laser-guided rock 

saw. For this evaluation, the “floated” 

surface of the concrete coupons was 

used. The coupons were approximately 

4 centimeters (cm) thick, 15 cm × 15 cm 

square, and had a surface finish that was 

consistent across all the coupons. The 

concrete was representative of exterior 

concrete commonly found in urban 

environments in the United States as 

shown by INL under a previous project 

sponsored by the U.S. Department of 

Defense (DOD), Defense Advanced

Research Projects Agency (DARPA) and 
6

U.S. Department of Homeland Security 

(DHS).

2

3.1.2 Coupon Contamination

Eight coupons were contaminated by 

spiking individually with 2.5 milliliters 

(mL) of aqueous solution that contained

0.26 milligrams (mg)/liter (L) Cs-137 as 

a solution of cesium chloride,

corresponding to an activity level of 

approximately 1 microCurie (μCi) over 

the 225 cm2 surface. Application of the 

Cs in an aqueous solution was justified 

because even if Cs were dispersed in a 

particle form following a radiological 

dispersion device (RDD) or “dirty 

bomb” event, morning dew or rainfall 

would likely occur before the surfaces 

could be decontaminated. In addition, 

from an experimental standpoint, it is

much easier to apply liquids, rather than 

dry particles, homogeneously across the 

surface of the concrete coupons. The 

liquid spike was delivered to each 

coupon using an aerosolization 

technique developed by INL (under a

DARPA/DHS project2

) and described in 

detail in the test/QA plan, and then 

allowed to age for seven days. 

The aerosol delivery device was 

constructed of two syringes. The plunger 

and needle were removed from the first 

syringe and discarded. Then, a 

compressed air line was attached to the 

rear of the syringe. The second syringe 

contained the contaminant solution and 

was equipped with a 27 gauge needle,

which penetrated through the plastic 

housing near the tip of the first syringe. 

Compressed air flowing at a rate of 

approximately 1 - 2 L per minute created

a turbulent flow through the first 

syringe. When the contaminant solution 

in the second syringe was introduced, 

the solution became nebulized by the 

turbulent air flow. A fine aerosol was 

ejected from the tip of the first syringe,

creating a controlled and uniform spray 

of fine liquid droplets onto the coupon 

surface. The contaminant spray was 

applied all the way to the edges of the 

coupon, which were taped (after having 

previously been sealed with polyester 

resin) to ensure that the contaminant was 

applied only to the surfaces of the 

coupons. The photographs in Figure 3-1 

show this procedure being performed 

using a nonradioactive, nonhazardous 

aqueous dye to demonstrate that the 2.5 

mL of contaminant solution is 

effectively distributed across the surface 

of the coupon.

Figure 3-1. Demonstration of contaminant application technique.
7

3.1.3 Measurement of Activity on 

Coupon Surface

Gamma radiation from the surface of 

each concrete coupon was measured to 

quantify contamination levels both 

before and after evaluation of the Blast 

N’Vac. These measurements were made 

using an intrinsic, high purity 

germanium detector (Canberra LEGe 

Model GL 2825R/S, Meriden, CT). 

After being placed in the detector, each 

coupon was measured until the average 

activity level of Cs-137 from the surface 

stabilized to a relative standard deviation 

of less than 2%. Gamma-ray spectra 

acquired from Cs-137 contaminated 

coupons were analyzed using INL 

Radiological Measurement Laboratory 

(RML) data acquisition and spectral 

analysis programs (PCGAP, Idaho 

National Engineering and Environmental 

Laboratory, Idaho Falls, ID; 

INEEL/EXT-2000-00908;

http://www.inl.gov/technicalpublications

/Documents/3318133.pdf). Radionuclide 

activities on coupons were calculated 

based on efficiency, emission probability

and half-life values. Decay corrections 

were made based on the date and the 

duration of the counting period. Full 

RML gamma counting QA/quality 

control (QC), as described in the test/QA 

plan, was employed and certified results 

were provided. 

3.1.4 Surface Construction Using Test 

Stand

To evaluate the decontamination 

technologies on vertical surfaces 

(simulating walls), a stainless steel test 

stand was fabricated that held three rows 

of three concrete coupons. A test stand, 

approximately 9 feet (ft) × 9 ft, was 

erected within a containment tent. The 

concrete coupons were placed into 

holders so their surfaces extended just 

beyond the surface of the stainless steel 

face of the test stand. Eight of the nine 

coupons placed in the test stand were 

contaminated with Cs-137, which has a 

half-life of 30 years. One 

uncontaminated coupon was placed in 

the bottom row of the test stand and 

decontaminated using the Blast N’Vac in 

the same way as the other coupons. This 

coupon was placed there to observe 

possible secondary contamination 

caused by the decontamination higher on 

the wall. Figure 3-2 shows the 

containment tent and the test stand 

loaded with the concrete coupons. 

Figure 3-2. Containment tent: outer view (left) and inner view with test stand 

containing contaminated coupons (right).
8

3.2 Evaluation Procedures

The containment tent consisted of two 

rooms. One room contained the test 

stand to hold the contaminated coupons 

and the other room (the shorter part of 

the tent as shown in Figure 3-2) held the 

collection drum. The abrasive grit hoses 

(both blasting and vacuum) connected to 

the blasting head in the room with the 

test stand through a small opening in the 

tent wall between the two rooms. The 

abrasive grit reservoir and air 

compressor were located outside the 

containment tent. The positive pressure 

blasting hose was connected directly to 

the blasting head through a small 

opening in the outer tent wall, through 

the smaller room, and also through a 

small opening in the tent wall between 

the two rooms. The vacuum line was 

connected first to the collection drum 

and then to the collection shroud 

surrounding the blasting head, through 

the same openings in the tent. Each of 

the tent openings was taped closed 

around the hoses. Figure 3-3 shows the 

smaller diameter blasting hose and the 

larger diameter vacuum hose connecting 

to the blasting head as the operator 

applies the Blast N’Vac to a concrete 

coupon.

The nine concrete coupons in the test 

stand were blasted with the Blast N’Vac 

starting with the top row and working 

from left to right, then proceeding to the 

middle and bottom rows. The coupons 

were blasted in this manner to simulate 

an approach that would likely be taken 

in an actual decontamination event,

where higher wall surfaces would be 

decontaminated first because of the 

possibility of secondary contamination 

lower on the wall. 

The flow of abrasive grit was controlled

by a trigger on the blasting head; the 

vacuum flow was controlled by an on/off 

valve near the abrasive grit reservoir. 

Therefore, the vacuum ran during the 

entire evaluation and the abrasive grit 

flow was easily turned on and off 

between coupons. Each coupon was 

blasted for approximately 30 seconds. 

However, the operator made certain he 

had covered the entire surface before 

progressing to the next coupon, so the 

actual times for eight out of nine 

coupons ranged from 22 to 35 seconds. 

One coupon had taken 80 seconds 

because of periodic diminished flow of 

abrasive grit. The pressure conditions 

during blasting were 66 psi on the 

blaster and 50 psi for the vacuum (as 

measured on the gauges near the 

abrasive grit reservoir). The temperature 

and relative humidity were recorded 

before and after the approximately one 

hour test. These conditions did not vary 

significantly in the room where the 

evaluation was performed. Over the 

duration of testing, the temperature was 

steady at 19.8 °C and the relative 

humidity was 36%. 
9

Figure 3-3. Operator applying Blast N’Vac to concrete coupon.
10

4.0 Quality Assurance/Quality Control

QA/ QC procedures were performed in 

accordance with the program QMP and 

the test/QA plan for this evaluation. 

4.1 Intrinsic Germanium Detector

The germanium detector was calibrated

once each week. The calibration was 

performed in accordance with

standardized procedures from the 

American National Standards Institute 

(ANSI) and the Institute of Electrical 

and Electronics Engineers (IEEE).3 In 

brief, detector energy was calibrated 

using thorium (Th)-228 daughter gamma 

rays at 238.6, 583.2, 860.6, 1620.7, and 

2614.5 kilo electron volts (keV). This 

calibration was performed three times 

throughout the evaluation and 

documented by the RML. Table 4-1 

gives the difference between the known 

energy levels and those measured 

following calibration. The energies were 

compared to the previous 30 calibrations 

to confirm that the results were within 

three standard deviations of the previous 

calibration results. All the calibrations 

fell within this requirement.

Table 4-1. Calibration Results – Difference from Th-228 Calibration Energies

Date

Calibration Energy Levels (keV)

Energy 1 

238.632

Energy 2 

583.191

Energy 3 

860.564

Energy 4 

1620.735

Energy 5 

2614.533

8-25-2009 -0.005 0.014 -0.031 -0.199 0.031

9-21-2009 -0.003 0.009 -0.040 -0.125 0.015

10-13-2009 -0.003 0.008 -0.011 -0.180 0.020

Gamma ray counting was continued on 

each coupon until the activity level of 

Cs-137 on the surface had a relative 

standard deviation (RSD) of less than 

2%. This RSD occurred within the initial 

1 hour of counting for all the coupons 

measured during this evaluation. The 

final activity assigned to each coupon 

was a compilation of information 

obtained from all components of the 

electronic assemblage that comprise the 

"gamma counter," including the raw data 

and the spectral analysis described in 

Section 3.1.3. Final spectra and all data 

that comprise the spectra were sent to a 

data analyst who independently 

confirmed the "activity" number arrived 

at by the spectroscopist. When both the 

spectroscopist and an expert data analyst 

independently arrived at the same value

the data were considered certified. This 

process defines the full gamma counting 

QA process for certified results. 
11

The background activity of the concrete 

coupons was determined by analyzing

nine arbitrarily selected coupons from 

the stock of concrete coupons used for 

this evaluation. The ambient activity 

level of these coupons was measured for 

at least two hours. No activity was 

detected above the minimum detectable 

level of 2×10-4 μCi on these coupons. 

Because the background activity was not 

detectable (and the detectable level was 

more than 150 times lower than the postdecontamination activity levels), no 

background subtraction was required.

Throughout the evaluation, a second 

measurement was taken on 10 coupons 

in order to provide duplicate 

measurements to evaluate the 

repeatability of the instrument. Half of 

the duplicate measurements were 

performed after contamination prior to 

application of the decontamination 

technology and half were performed 

after decontamination. Five of the

duplicate pairs showed no difference in 

activity levels between the two 

measurements; the other five duplicate 

pairs had a difference of 2% between the 

two measurements, within the acceptable 

difference of 5%. 

4.2 Audits

4.2.1 Performance Evaluation Audit

RML performed regular checks of the 

accuracy of the Th-228 daughter 

calibration standards (during the time 

when the detector was in use) by 

measuring the activity of a National 

Institute of Standards and Technology 

(NIST)-traceable europium (Eu)-152 

standard (in units of Becquerel, BQ) and 

comparing to the accepted NIST value. 

Results within 7% of the NIST value are 

considered to be within acceptable 

limits. The Eu-152 activity comparison 

is a routine QC activity performed by 

INL, but for the purposes of this 

evaluation the activity comparison 

serves as the performance evaluation 

(PE) audit, an audit that confirms the 

accuracy of the calibration standards 

used for the instrumentation critical to 

the results of an evaluation. Table 4-2 

gives the results of each of the audits 

applicable to the duration of the

evaluation. All results are below the 

acceptable difference of 7%.

Table 4-2. NIST-Traceable Eu-152 Activity Standard Check

Date

NIST Activity 

(BQ) 

INL RML 

Result (BQ)

Relative 

Percent 

Difference

8-18-2009 124,600 122,400 2%

9-10-2009 124,600 122,600 2%

10-12-2009 124,600 122,300 2%
12

4.2.2 Technical Systems Audit

A TSA was conducted during testing at 

INL to ensure that the evaluation was 

performed in accordance with the 

test/QA plan and the TTEP QMP. As 

part of the audit, the actual evaluation 

procedures were compared with those 

specified in the test/QA plan and the 

data acquisition and handling procedures 

were reviewed. No significant adverse 

findings were noted in this audit. The 

records concerning the TSA are stored 

indefinitely with the Battelle QA

Manager.

4.2.3 Data Quality Audit

The Battelle QA Manager verified all of 

the raw data acquired during the 

evaluation and transcribed into 

spreadsheets for use in the final report. 

The data were traced from the initial raw 

data collection, through reduction and 

statistical analysis, to final reporting, to 

ensure the integrity of the reported 

results. 

4.3 QA/QC Reporting

Each assessment and audit was 

documented in accordance with the 

test/QA plan and the QMP. The Battelle 

QA Manager prepared the draft 

assessment report and sent it to the Test 

Coordinator and Battelle TTEP Program 

Manager for review and approval. The 

Battelle QA Manager then sent the final 

assessment report to the EPA QA 

Manager and Battelle staff.
13

5.0 Evaluation Results

5.1 Decontamination Efficacy

The decontamination efficacy of the 

Blast N’ Vac was measured for 

contaminated coupons in terms of 

percent removal (%R) and 

decontamination factor (DF). Both of 

these measurements provide a means of 

representing the extent of 

decontamination accomplished by a 

technology. The %R gives the extent as 

a percent relative to the activity and the 

DF is the ratio of the initial activity to 

the final activity or the factor by which 

the activity was decreased. These terms 

are defined by the following equations: 

%R = (1-Af/Ao) × 100% and DF = Ao/Af

where Ao is the radiological activity 

from the surface of the coupon before 

application of the Blast N’Vac and Af is 

radiological activity from the surface of 

the coupon after treatment. While the 

DFs are reported in Table 5-1, the 

narrative describing the results focuses

on the %R.

Table 5-1 gives the %R and DF for the 

Blast N’Vac. All coupons were oriented 

vertically. The target activity for each of 

the contaminated coupons (predecontamination) was within the 

acceptable range of 1 μCi ± 0.5 μCi. The 

overall average (plus or minus one 

standard deviation) of the contaminated 

coupons was 1.17 μCi ± 0.04 μCi, a 

variability of 3%. The postdecontamination coupon activities were 

less than the pre-decontamination 

activities showing an overall reduction 

in activity. The %R (calculated as 

described above) averaged 97% ± 2% 

and the DF averaged 58 ± 52. Overall, 

the %R ranged from 92% to 99% and the 

DF ranged from 12 to 178. The coupon 

with the DF of 178 was observed to have 

exhibited a relatively high DF as the rest 

of the coupons had DFs that were 

substantially lower. The very high DF 

was caused by the extremely low postdecontamination activity for that

coupon. It is not clear why the coupon 

was decontaminated more extensively 

than the others. 

Paired t-tests were performed to 

determine whether location (top, middle, 

or bottom) on the test stand affected the 

decontamination efficacy. No significant 

difference between any of the rows was 

found. The bottom middle coupon was 

not contaminated to test the possibility 

of cross-contamination. Activity of the 

uncontaminated coupon was measured 

after the Blast N’Vac had been applied 

to all nine coupons. No activity was 

detected on that coupon, suggesting that 

cross-contamination due to the 

application of the Blast N’Vac was 

minimal.
14

Table 5-1. Decontamination Efficacy Results

Coupon 

Location in 

Test Stand

Pre-Decon Activity 

μCi / Coupon

Post-Decon Activity 

μCi / Coupon %R DF

Top left 1.19 0.007 99 178

Top middle 1.19 0.026 98 46

Top right 1.15 0.028 98 41

Center left 1.14 0.094 92 12

Center middle 1.19 0.015 99 82

Center right 1.24 0.033 97 38

Bottom left 1.12 0.028 98 40

Bottom right 1.14 0.042 96 27

Average 1.17 0.034 97 58

Std. Dev 0.04 0.026 2 52

5.2 Deployment and Operational 

Factors

A number of operational factors were 

documented by the Blast N’Vac 

operator. One of the factors was damage 

to the surface of the concrete coupons. 

Figure 5-1 shows photographs of a 

coupon before and after blasting with the 

Blast N’Vac. The surface of the coupon 

at the right has been removed by the 

Blast N’Vac and the aggregate layer of 

concrete has been exposed. This is 

evidenced by the large pieces of gravel 

and sand that are visible. Because of the 

extensive surface removal, the 

effectiveness of the Blast N’Vac will 

have to be weighed against the amount 

of surface damage caused by the 

decontamination technology. 

Figure 5-1. Test coupon surfaces before (left) and after (right) treatment with the 

Blast N’Vac.

Another important factor to consider is 

the personal protection of the technology 

operators. During this evaluation, the 

radiological control technicians required 

the operators to wear full anticontamination personal protective 

equipment that included a full face 

respirator with supplied air. This level 

of personal protection was required by 

the INL RCTs because of the likelihood 

of airborne radiological contamination 

due to the act of blasting. However, 

each situation will need to be considered 

independently by local RCTs to 

determine the proper level of personal 

protection.
15

Table 5-2 summarizes qualitative and 

quantitative practical information gained

by the operator during the evaluation of 

the Blast N’Vac. All of the operational 

information was gathered during use of 

Blast N’Vac on the concrete coupons 

inserted into the test stand. Some of the 

information given in Table 5-2 could 

differ if the Blast N’Vac were applied to 

a larger surface or surfaces made up of 

different types of concrete.
16

Table 5-2. Operational Factors Gathered from the Evaluation

Parameter Description/Information

Decontamination 

rate 

Technology Preparation: Upon initial receipt, it took 1.5 days to get the components 

assembled and the abrasive grit valve to function properly. Initially, we provided 

approximately 250 cfm of compressed air, however that flow rate did not allow the 

proper function of the abrasive grit valve. Once we provided approximately 400 cfm 

of compressed air at 120 psi the valve began to function well.

Application: Approximately 30 seconds per concrete coupon for most coupons during 

this evaluation corresponds to an application rate of 2.7 m2

/hour; less or more time 

per coupon may result in different levels of radiological decontamination.

Applicability to 

irregular surfaces

Irregular surfaces will not be a problem for the Blast N’Vac as the abrasive grit

blasting is an aggressive decontamination technique, thus removing the surface of the 

concrete and making the operation of the Blast N’Vac independent of the surface 

characteristics of the concrete. In addition, while coupon configurations other than a 

flat square were not tested as part of this evaluation, the Blast N’Vac came equipped 

with blasting heads shaped for work in corners and was designed to maintain the 

ability to recover the abrasive grit following blasting.

Skilled labor 

requirement

Adequate training would likely require approximately one hour. In addition to the 

assembly and operation of the Blast N’Vac, topics would need to include precautions 

unique to pressurized blasting, the theory of operation, and troubleshooting. 

The operator experienced a significant level of exertion as he completed the 

evaluation. The weight of the Blast N’Vac, in combination with the additional weight 

and awkwardness of the attached blasting and vacuum hoses, increased the level of 

effort required to use the Blast N’Vac. Depending on what row of the test stand is 

being used, the operator was required to bend over, stand on the floor, or stand on a 

ladder. These factors will exclude some people from operating the Blast N’Vac. 

However, most people who are used to performing physical labor should not have 

any problem operating the unit.

Utilities required 400 cfm compressed air at 120 psi is the sole utility requirement. 

Extent of portability The limiting factors of portability for the Blast N’Vac will include the availability of 

400 cfm compressed air (longer hoses may require higher flow/pressure air and 

vacuum). In addition, the skid containing the abrasive reservoir and HEPA filter is 

approximately 3 ft by 8 ft and weighs several hundred pounds. Therefore, it is a 

factor that would have to be considered to allow for portability.

Amount of spent 

blasting media

Following blasting of nine coupons, approximately 20 pounds of abrasive grit was 

used and approximately 5 pounds of concrete waste was collected. 

Secondary waste 

management

An estimated 95% of the abrasive grit was collected by the vacuum. There was very 

little dust visible during the evaluation. However, very small amounts of blasting 

abrasive grit (individual grains) were found throughout the containment tent 

including at the base of the test stand. This abrasive was vacuumed up at the close of 

the evaluation. The radiological control technicians overseeing the evaluation

determined that there was no secondary-contamination due to this wide distribution of 

small amounts of abrasive grit. The activity of the grit and dust collected by the 

vacuum or vacuum filter was not measured quantitatively. However, given the 

effectiveness of the Blast N’Vac, presumably the waste had significant activity levels.

Surface damage Surface removed and aggregate exposed. See description and photograph in text.

Cost As evaluated, the price of the Blast N’Vac would be $11,840. This price includes the 

blasting equipment only and not the compressed air required for operation or the 

blasting grit. 
17

6.0 Performance Summary

This section presents the findings from 

the evaluation of the Blast N’Vac for 

each performance parameter evaluated.

6.1 Decontamination Efficacy

The decontamination efficacy (in terms 

of %R) attained by the Blast N’Vac was 

evaluated for each individual concrete 

coupon used during the evaluation. 

When the decontamination efficacy 

metrics (DF and %R) of the eight 

contaminated coupons were averaged 

together, the average %R for the Blast 

N’Vac was 97 ± 2% the average DF was 

58 ± 52. Hypothesis testing was 

performed to determine if there were 

significant differences among the %R

values determined for the coupons in 

each row (top, middle, and bottom) of 

the test stand. No differences were 

found.

6.2 Deployment and Operational 

Factors

Following the manufacturer’s 

recommendations, the Blast N’Vac was 

used with a size 24 aluminum oxide 

abrasive grit. The rate at which the Blast 

N’Vac was used to decontaminate a 

vertical surface was approximately 2.7 

m

2 per hour, with significant visual 

surface destruction and some secondary 

waste. The texture of the concrete 

surface is not relevant to the efficacy of 

the Blast N’Vac and similar blasting 

technologies. Battelle observed that,

because of the aggressiveness with

which the abrasive grit removes concrete 

surfaces, irregularities within the surface 

would not impact the effectiveness of the 

technology. The Blast N’Vac required a 

source of compressed air that provided at 

least 400 cfm of air flow at a pressure of 

120 psi. An Ingersoll-Rand 75902 

diesel-powered air compressor was the 

only source of power required for the 

operation of the Blast N’Vac. Such a 

large air compressor is not a common 

piece of equipment. Therefore, the size

and availability of the compressor may 

limit the locations where the Blast 

N’Vac can be used. 

A very limited evaluation of crosscontamination was performed. During an 

actual decontamination of a vertical 

surface, the higher elevation surfaces 

would likely be decontaminated first, 

possibly exposing the lower surface to 

secondary contamination. To simulate an 

actual scenario, one uncontaminated 

coupon was placed in the bottom row of 

the test stand and decontaminated using 

the Blast N’Vac in the same way as the 

other coupons. Following 

decontamination, this uncontaminated 

coupon did not exhibit measurable 

activity suggesting that cross 

contamination was minimal. While 

cross-contamination on the test stand 
18

seemed to be minimal, very small 

amounts of blasting abrasive grit

(individual grains) were found 

throughout the containment tent and 

there was some abrasive grit that 

collected at the base of the test stand.
19

7.0 References

1. ASTM Standard C 150-07, 

“Standard Specification for Portland 

Cement.” ASTM International, West 

Conshohocken, PA, www.astm.org, 

2007.

2. Radionuclide Detection and 

Decontamination Program. Broad 

Agency Announcement 03-013, U.S. 

Department of Defense (DOD) 

Defense Advanced Research Projects 

Agency (DARPA) and the U.S. 

Department of Homeland Security, 

classified program.

3. Calibration and Use of Germanium 

Spectrometers for the Measurement 

of Gamma Emission Rates of 

Radionuclides. American National 

Standards Institute. ANSI N42.14-

1999. IEEE New York, NY (Rev. 

2004). 
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