r/EPA
Radidtio'1
Emissions Of Naturally
Occurring Radioactivity
Fireclay Mine And
Refractory Plant
LIBRARY
IVF-81-
U. S. ENVIRONMENTAL PROTECTION AGENCY
EDISON, N. L 08817
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Technical Note
ORP/LVF-81-1
EMISSIONS OF NATURALLY OCCURRING RADIOACTIVITY'-
FIRECLAY MINE AND REFRACTORY PLANT
Vernon E. Andrews
FEBRUARY 1981
Office of Radiation Programs - Las Vegas Facility
U.S. Environmental Protection Agency
Las Vegas, Nevada 89114
.. .'- -ROTECnON AGENCY
08817
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DISCLAIMER
This report has been reviewed by the Office of Radiation Programs - Las
Vegas Facility, U.S. Environmental Protection Agency, and approved for
publication. Mention of trade names or commercial products does not consti-
tute endorsement or recommendation for their use.
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PREFACE
The Office of Radiation Programs of the U.S. Environmental Protection
Agency carries out a national program designed to evaluate population exposure
to ionizing and nonionizing radiation, and to promote development of controls
necessary to protect the public health and safety. In response to the 1977
amendments to the Clean Air Act the Las Vegas Facility was given the
responsibility to collect field data on emissions to the atmosphere of natural
radioactivity from operations involved in the mining, milling, and smelting of
minerals other than uranium and coal. This report is one of a series which
describe an individual facility and the associated radioactivity emissions.
Readers of this report are encouraged to inform the Office of Radiation
Programs of any omissions or errors. Comments or requests for further
information are also invited.
Donald W. Hendricks
Director, Office of Radiation Programs
Las Vegas Facility
m
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CONTENTS
Page
PREFACE 111
LIST OF FIGURES vi
LIST OF TABLES vi
I. BACKGROUND 1
II. INTRODUCTION 2
III. SUMMARY 2
IV. PLANT OPERATIONS 3
V. SAMPLING LOCATIONS AND PROCEDURES 7
A. Site Selection 7
B. Mine Sampling Locations 9
C. Plant Sample Locations 9
D. Sampling Techniques 11
E. Sample Analysis 11
VI. SAMPLE RESULTS 12
A. Process Samples 12
B. Background Samples 15
C. Emission Samples 15
1. Mine Emission Samples 15
2. Plant Emission Samples 22
VII. POPULATION DISTRIBUTION 27
VIII. DISCUSSION OF RESULTS 31
IX. REFERENCES 33
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LIST OF FIGURES
Number Page
1 Globe Refractories Manufacturing Processes . . 4
2 Globe Refractories Inc., Newell, West Virginia 6
3 Ionizing Wet Scrubber Flow Schematic 8
4 Process Steps and Sampling Points at Globe Refractories 10
5 Wind Rose for August 7, 1978 16
6 Wind Rose for August 8, 1978 17
7 Wind Rose for August 9, 1978 18
8 Wind Rose for August 10, 1978 19
9 Particle Size Distribution for Mine Ventilation Exhaust -
First Shift 27
10 Particle Size Distribution for Mine Ventilation Exhaust -
Second Shift 28
11 Particle Size Distribution for Uncontrolled Kiln Outlet 29
12 Particle Size Distribution for Scrubber Outlet 30
LIST OF TABLES
Number Page
1 Process Sample Radionuclide Contents 13
2 Ambient Radon Concentrations at Globe Refractories
during August 7-10, 1978 14
3 Particulate Radioactivity Concentrations at Globe Refractories ... 20
4 Radon Emission Samples at Globe Refractories 21
5 Stack Flow Measurements 24
6 Annual Particulate Radioactivity Release Rate
Determined from Each Sample at Globe Refractories 25
7 Average Annual Particulate Radioactivity Release Rate
at Globe Refractories 25
VI
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I BACKGROUND
The Clean Air Act, as amended in August 1977, required the Administrator of
the Environmental Protection Agency (EPA) to determine whether emissions of
radionuclides into ambient air should be regulated under the Act. In
December, 1979, the Administrator listed radionuclides as a hazardous pollu-
tant under Section 112 of the Clean Air Act.
The naturally occurring radionuclides most likely to be emitted in signif-
icant quantities are those in the uranium-238 and thorium-232 decay series.
These radionuclides and their daughter products occur naturally in widely
varying amounts in the soils and rocks that make up the earth's crust.
Average values for uranium-238 and thorium-232 in soils are approximately 1.8
ppm (0.6 pCi/g) and 9 ppm (1 pCi/g) respectively (NCRP, 1975).
Almost all operations involving removal and processing of soils and rocks
release some of these radionuclides into the air. These releases become
potentially important when the materials being handled contain above-average
radionuclide concentrations or when processing concentrates the radionuclides
significantly above the average amounts in soils and rocks.
Because mining and milling operations involve large quantities of ore, and
because there is little information about how these activities release radio-
active emissions, EPA, in 1978, began to measure airborne radioactive
emissions from various mining, milling, and smelting operations.
Operations were selected for study on the basis of their potential to emit
significant quantities of naturally occurring radionuclides to the atmosphere.
Some of the factors in the selection included typical mine size, annual U.S.
production, measured working levels of radon daughters in underground mines
and associated ventilation rates, production rate and process of individual
facilities, and previous association with naturally occurring radionuclides.
Usually, we chose to look at large facilities in order to get statistically
significant results.
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These surveys were screening studies designed to identify potentially
important sources of emissions of radionuclides into the air. Any such
sources can then be studied in detail to determine whether or not a national
emission standard for hazardous pollutants is needed under the Clean Air Act.
II INTRODUCTION
Clay mining and manufacturing is a large industry with many mines and
mills across the country. Because fire clay has been reported to have high
radon daughter working levels in underground mines, (Goodwin, 1978) we studied
the fire clay mine and refractory brick plant operated by Globe Refractories,
Inc., in Newell, West Virginia.
PEDCo Environmental, under contract with EPA (PEDCo, 1978), conducted the
survey and collected samples. Before the survey, representatives of PEDCo
Environmental, EPA, and the U.S. Bureau of Mines selected sampling locations.
During the week of August 7, 1978, PEDCo Environmental, accompanied by an EPA
representative, conducted the sampling 'and measurement program, collecting
effluent and ambient particulate and gas samples as well as information on
plant operations. They also installed a meteorological tower for weather
measurements. Eberline Instrument Corporation did the radiological analysis
of the samples.
Ill SUMMARY
The survey at Globe Refractories mine and refractory brick plant was the
first in a series to determine the quantities of naturally occurring radio-
active materials emitted to the atmosphere from mining, milling, benefication,
and smelting operations, other than uranium and coal. This plant was selec-
ted, in part, because the Mine Safety and Health Administration (MSHA)
reported high radon daughter working levels (WL)* in the mine. EPA's WL
measurements in the mine were close to those reported
* The working level is defined as any combination of short-lived radon
daughter products in 1 liter of air that will result in the ultimate
emission of 1.3 x 10^ MeV of potential alpha energy. (U.S. Public Health
Service, 1957).
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by MSHA. EPA's samples of ventilation air, collected just before and just
after it reached the working face, measured 0.26 and 0.24 WL, respectively.
MSHA had reported 0.3 WL.
Ore samples collected from the mine contained average uranium-234 plus
uranium-238 concentrations of 2.3 picocuries/gram (pCi/g) or about 3.7 ppm,
about twice the typical value for soil. The high WL measurements are due to
the relatively high concentration of natural radioactivity and the relatively
low ventilation rate of about two air changes per day. The radon-222
emanation rate from the mine was determined to be 32 curies/year (Ci/y). The
total radon-222 release rate measured for the refractory operation was less
than 1 Ci/y.
The annual release rate of polonium-210 from the refractory was estimated
at 27 microcuries/year (uCi/y). Approximately 26 percent of the polonium-210
in the materials processed through a kiln without emission controls was dis-
charged to the atmosphere. Emissions of polonium-210 from materials processed
through two kilns equipped with an ionizing wet scrubber were estimated at
6 percent. Thus the ionizing wet scrubber removed about 77 percent of the
polonium-210 which entered it. About 0.11 percent of the uranium in the brick
material was emitted from the uncontrolled kiln and about 0.027 percent from
the kilns controlled by the scrubber.
IV PLANT OPERATIONS
Globe Refractories, Inc., in Newell, West Virginia, manufactures pouring
pit refractories. Figure 1 illustrates the manufacturing processes for the
products that Globe manufactures.
The clay used in the manufacture of refractory products is mined
underground next to the manufacturing plant (Figure 2). The mine produces 907
Mg (1,000 tons) of clay per day, 231,000 Mg (255,000 tons) per year operating
5 days per week. Two shafts with two reversible fans ventilate the mine; one
fan is housed above each shaft. The two fans, each rated at 1,133 m3/min
(40,000 cfm) operate in series, one fan pushes air into the mine while the
other draws air out.
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The clay is first crushed, then stored until small quantities of other
materials are added. Approximately 6,400 to 9,100 Mg (7,000 to 10,000 tons)
of bauxite and 11,000 Mg (12,000 tons) of Missouri clay are used per year.
The mix varies, depending on the types of bricks produced. The raw mix then
goes to a crushing, grinding, and screening operation before being stored
again until used. Since these operations are performed on dry materials in an
enclosed area, dust is generated. The dust is collected at several pick-up
points and passed through two baghouses at the rate of 567 m^/min (20,000
cfm) each. The cleaned air discharged from the baghouses is recirculated, so
there are no direct atmospheric discharges. However, natural ventilation of
the building produces some fugitive emissions. This operation processes 23.68
Mg (26.1 tons) per hour.
The bricks are mixed, pressed, and set in part of the same building
housing the dryer and kilns. Ventilation is through open ridge-line roof
monitors, doors, windows, and wall louvers. Water is added to the dry mix on
the second level and the mixture is loaded into presses on the first level.
Before they are fired, the bricks pass through the dryer at the rate of
25.36 Mg (27.95 tons) per hour. Ambient air drawn through the cool-down zone
of the kiln preheats and dries the brick. Particulate emissions from the
dryer exhaust stacks are very low, and the State requires no control device.
Dried products then pass into one of three kilns, called 4, 5A, and 5B,
all heated by natural gas to 1,100°C. Kilns 5A and 58 each process 10.9 Mg
(12 tons) per hour. Kiln 4 handles 3.49 Mg (3.85 tons) per hour. At the time
of sampling, the exhaust from kilns 4 and 5B passed through an ionizing wet
scrubber and discharged through a 45.7-m (150-ft) stack of 1.7-m (5.5-ft)
inside diameter. The exhaust from kiln 5A was discharged untreated through a
square stack 12.2 meters (40 ft) high by 1.7 meters (5.5 ft) square. At the
time of the survey a second scrubber system was being built to serve kiln 5A
and was expected to go on-line shortly.
The ionizing wet scrubber controls the opacity of Globe's stack emissions.
The opacity problem was caused by ammonium bisulfate, a condensable gas
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released because of the high concentration (0.7-1.0%) of pyrites in the Lower
Kittanning clay deposits. Otherwise, opacity is not a typical problem of
brick kiln operations.
Figure 3 is a schematic of the ionizing wet scrubber process. An initial
water spray cools kiln exhaust gases which then pass through three packed
columns and two ionizing sections. The gases cool from 270°C at the scrubber
inlet to 25°C at the outlet. Water is recycled through the flyash settling
basin (Figure 2). A small quantity of solid materials is recovered in the
scrubber.
Mine drainage and scrubber water is pumped to holding ponds and then to
the acid mine drainage pond for treatment prior to discharge into the Ohio
River. Because of the relatively low flow rate (0.13 to 0.21 m-Vmin) the
mine water was not considered a significant source of radon and was not
sampled.
The Globe Refractories mine normally operates two shifts per day, 5 days
per week from 6:30 A.M. to 9:30 P.M. The first shift prepares clay ore for
transport, the second shift conducts drilling and blasting operations. Ore is
crushed 20 hours per day, 6 days per week. Other plant operations are
continuous.
During the week of August 7, 1978, Globe Refractories produced refractory
sleeves in kiln 4. Kilns 5A and 5B produced ladle brick, refractory nozzle
block, and some refractory nozzles.
V SAMPLING LOCATIONS AND PROCEDURES
A. Site Selection
During their presurvey visit to the Globe site, PEDCo and EPA personnel
selected sampling locations and specified types of samples to be collected.
Sampling locations selected were:
1. Mine ventilation inlet.
2. Mine ventilation exhaust.
3. Crushing, grinding, and screening building.
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Recycled
Water
Recycled
Plus Fresh
Makeup
Water
Recycled
Water
Recycled
Water
Stack
Discharge
1
Third
Packed Column
Second
Ionizing Section
Second
Packed Column
First
Ionizing Section
1
Packed Column
Prescrubber
I
Water Spray
200-300 GPM
1
Kiln Exhaust
Water To
Settling Basin
For Recycling
Water To
Settling Basin
For Recycling
Water To
Settling Basin
For Recycling
Water To
Settling Basin
For Recycling
Figure 3. Ionizing Wet Scrubber Flow Schematic
8
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4. Mixing, pressing, and setting building.
5. Dryer exhaust stack.
6. Uncontrolled kiln (5A) exhaust.
7. Controlled kiln exhaust (4 and 5B).
8. Background sample at location upwind from plant.
Major process steps and sampling points are related schematically in Figure 4.
B. Mine Sampling Locations
Three-to-four-hour gas samples for radon-222 analysis were collected at
the mine ventilation inlet and the mine ventilation exhaust located 2.3 km
south-southeast of the ventilation inlet (Figure 2). Exhaust air discharges
through a 91-m (300-ft) drilled shaft. A horizontally mounted exhaust fan in
a small building atop the shaft forces the air through a turning vane section
to a vertical discharge 2.4 m (8 ft) square, 2.4 m above the surface. Gas
samples for radon-222 analysis and high volume size-fractionated samples were
collected in the room atop the exhaust shaft just ahead of the exhaust fan.
Gross particulate emission samples were collected at the vertical discharge.
The EPA Project Officer made radon daughter WL measurements at three
locations in the mine, using a portable, battery-operated air sampler to
collect samples. The filters were immediately counted on a portable alpha
counter and the results analyzed using the Thomas modification of the
Tsivoglou method for determining radon daughters in air (Thomas, 1971).
Samples were collected from the ventilation air before it arrived at the
mine's working area, after it left the working area, and at the bottom of the
exhaust shaft.
C. Plant Sample Locations
Gas samples of air in the crushing, grinding, and screening building were
collected for radon-222 analysis. The samples were collected above the
storage hoppers near an upper level window through which much of the room air
discharged.
Air samples for radon-222 analysis were also collected from the mixing,
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pressing, and setting area. Samples were collected from the third level of
the building below the open roof ventilator (ridgeline roof monitor).
Time-integrated gas samples for radon-222 analysis were collected from the
dryer exhaust stack above the dryer.
Gas samples, gross particulate emission samples, and size-fractionated
particulate samples were collected from the kiln stack serving kiln 5A and
from the exhaust stack of the ionizing wet scrubber serving kilns 4 and 58.
Ambient samples of particulates and gas were collected at the west end of
the plant property in an area normally upwind from the emission points. The
meteorology tower was also installed here.
D. Sampling Techniques
Whenever possible, surveyors collected samples using EPA reference methods
(40 CFR 60). Stack sampling points were selected according to EPA Method 1.
Stack gas velocity and volumetric flow rate were determined by EPA Method 2.
Gas samples for radon analysis were collected using EPA Method 3. Particulate
emissions and stack samples for particle size distribution were collected
following EPA Method 5.
A Rader Hi-Volume Sampler was used to sample mine particulate emissions
isokinetically. Size-fractionated samples of mine particulate emissions were
collected using a high volume air sampler with a Sierra high volume cascade
impactor head sampling at 1.13 m^/min (40 cfm).
Ambient airborne particulates were collected according to the EPA
reference method for determining airborne particulates (40 CFR 50).
E. Sample Analysis
Following EPA Reference Method 5, PEDCo made mass determinations on
size-fractionated particulate samples from the ventilation exhaust.
11
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Eberline Instrument Corporation (EIC) performed the radiological analyses.
They reported all results as radioactivity concentration plus or minus twice
the standard counting error. If the radioactivity concentration was less than
twice the standard error a lower limit of detection (LLD) has been reported.
The LLD is defined (Harley, 1977) as the smallest concentration of radioactive
material sampled that has a 95 percent probability of being validly detected.
Whole air samples were analysed for radon in 1.3-liter chambers coated
internally with a zinc-sulfide phosphor. Alpha particles striking the
phosphor cause scintillations which are detected by a photomultiplier tube
optically coupled to a window in one end of the chamber. The LLD reported as
of time of collection, varied from 0.11 picocuries/liter (pCi/1) to 0.21
pCi/1 depending on the background count rate of individual chambers and the
time between collection and analysis.
Airborne particulates on filters and process samples were analyzed by
completely dissolving the samples and separating the elements of interest
using radiochemical techniques. Analysts counted the separated elements, U,
Th, and Po, on alpha spectrometers for isotopic quantitation. Lead-210 was
separated; bismuth-210 was allowed to ingrow and was separated from the
lead-210 and then was counted on a beta counter to determine the lead-210.
Radon gas that emanated from the separated radium-226 was collected and
counted, as the whole air radon samples had been counted, to determine the
radium activity.
VI SAMPLE RESULTS
A. Process Samples
Samples of clay were collected from the top, middle, and bottom of the
layers being mined. One sample of the product leaving the crushing, grinding,
and screening operation, a sample of green brick before firing, and a sample
of fired brick were also collected. Analytical results indicated that
concentrations of elements of the uranium-238 decay chain increase with depth
in the ore bed. No statistically significant differences were found between
the results for the last three process samples. Results are shown in Table 1.
12
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Table 2. AMBIENT RADON CONCENTRATIONS
AT GLOBE REFRACTORIES DURING
August 7-10, 1978
Radon Concentration (pCi/l)a
Date
8/7
8/8
8/9
8/10
Time
1444-1844
1505-1900
0925-1405
1418-1822
1425-1645
0954-1402
1015-1400
1404-1818
1125-1530
1130-1510
Upwi nd Mi ne
<0.
0.12 ± 0.10
0.25 ±
0.14 ±
<0.14
0.26 ±
0.42 ±
0.42 ± 0.09C
<0.13c
0.53 ±
<0.12
<0.
Inlet
H
0.12
0.12
0.1QC
0.09C
0.18
21
Average13
<0.12
0.25 ± 0.
<0.14
0.31 ± 0.
0.53 ± 0.
<0.17
12
22
18
a. Uncertainties given for individual results are twice the standard
deviation based on counting results only. Uncertainties for
averages are twice the standard error of the mean.
b. For averaging purposes, less than detectable (<) values were
assumed to represent the ambient concentration with a 100%
uncertainty at two standard deviations.
c. Duplicate analyses.
14
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B. Background Samples
Prevailing winds during the time of year samples were collected tend to be
upriver along the Ohio River valley, or from the southwest. Meteorological
results, shown in daily wind roses in Figures 5 to 8, showed that this
condition prevailed during sampling and confirmed that the ambient station was
usually upwind of the plant. Table 2 shows that ambient radon concentrations
varied from less than 0.11 pCi/1 to 0.53 ± 0.18 pCi/1. Because of the
variability of ambient radon concentrations and the fact that the samples do
not represent continuous coverage, no overall average background is
calculated. Rather, the ambient concentrations from similar sampling periods
at the ambient station and mine inlet were averaged to obtain a background
which could be subtracted from stack concentrations measured during the same
periods.
Airborne particulates collected on air filters at the upwind background
sampling site were also analyzed. The analytical procedure requires that the
filter and collected particulates be completely dissolved. Since the filter
contains trace amounts of naturally occurring radioactivity, it was necessary
to consider how it contributes to the gross activity of the filter samples.
Eadie and Bernhardt (1976) conducted a study of the radioactivity content of
the various filters used at the Las Vegas Facility of the Office of Radiation
Programs. This study showed that Microsorban polystyrene fiber filters
generally have lower radioactivity than the glass fiber or cellulose filters
used. Thus, Microsorban filters were used where possible to reduce the
filters effect on the sample results and their estimated contribution was
subtracted from the measurements. Table 3 gives the calculated average
concentration of the radionuclides measured over each sampling period. No
isotopes of thorium were detected on any ambient air sample.
C. Emission Samples
1. Mine Emission Samples
Three radon samples were collected at the mine exhaust during 3 to 4 hour
periods representing each of the mine's two working shifts. Radon
concentrations, shown in Table 4, varied from 15 to 34 pCi/1. Ambient radon
concentrations did not measurably affect the mine discharge concentrations.
15
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330-
340
360°
020" 030°
320°
31 Oc
300°
290°
280°
270C
260°
250°
240°
230C
220'
CALM 15 6 1011 2021
WIND SPEED, mph
040°
050°
060C
070°
080°
090°
100°
110°
120°
130°
140°
210° 20O° 190° 180° 170° 160°
150°
Figure 5. Wind Rose for 8/7/78
16
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330°
340° 350° 360° 010° 020° 030=
320°
310=
300°
290°
280°
270°
260°
250°
240°
230°
220°
CALM1-5 6-1011 2021
WIND SPEED, mph
040°
050°
060°
070°
080°
090°
100°
110°
120°
130°
140°
210°
200° 190° 180° 170
160°
150°
Figure 6. Hind Rose for 8/8/78
17
-------
330J
340°
350°
360° 010°
020° 030°
320°
310°
300°
290°
280°
270°
260°
250C
240°
230°
220°
CALM 15 6 1011 2021
WIND SPEED, mph
040°
05O°
060°
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080°
090°
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120°
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170°
160°
15O°
Figure 7. Wind Rose for 8/9/78
18
-------
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340° 350° 360° 010°
020° 030°
320°
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280°
270°
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250°
240°
230°
220=
CALM 15 6-1011 2021
WIND SPEED, mph
040°
050°
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210
200° 190° 180° 170
160°
150°
Figure 8. Wind Rose for 8/10/78
19
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Table 4. RADON EMISSION SAMPLES
AT GLOBE REFRACTORIES
LOCATION
Mine
Exhaust
Kilns 4
and 5B
(Scrubber)
Kiln 5A
(No
Control )
Dryer
Crushing
Grinding,
Screening
Mixing5
Pressing,
Setting
DATE
8/7
8/8
8/8
8/9
8/9
8/10
8/7
8/8
8/9
8/10
8/7
8/8
8/9
8/10
8/7
8/8
8/9
8/10
8/7
8/8
8/9
8/10
8/7
8/8
8/9
8/10
TIME
ON OFF
1522
0945
1359
1010
1418
1145
1500
1415
1015
1120
1504
1350
1000
1128
1500
1400
1027
1119
1500
1350
1019
1135
1505
1405
1034
1123
1815
1357
1809
1412
1805
1530
1900
1800
1400
1350
1904
1750
1400
1530
1905
1750
1400
1540
1905
1800
1355
1545
1900
1811
1405
1527
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
ANNUAL
RADON CONCENTRATIONS (pCi/l)a EMMISSION
GROSS NET AVERAGE (Curies)
34
26
27
15
28
23
32
34
26
18
33
44
26
32
-------
However the concentration varied with the shifts. During the first shift,
radon concentrations varied from 15 to 26 pCi/1 net, averaging 21 pCi/1.
During the second shift, concentrations varied from 27 to 34 pCi/1, averaging
30 pCi/1. The overall average was 26 pCi/1.
Three airborne particulate samples were collected in the mine on August 8
from 1055 to 1230 hours to measure radon daughter working levels. At the same
time, a radon sample was being collected at the mine exhaust. A sample taken
upwind of the working face, just before the ventilation air reached the work-
ing face, measured 0.26 WL. A sample from downwind of the working face
measured 0.24 WL. A sample collected at the bottom of the 91-m (300-ft)
shaft, which carries mine air upward to the exhaust fan, measured 0.029 WL.
Most of the dust visible downwind of the working face had been lost before the
air reached the bottom of the exhaust shaft, about 500 m away. The rough
tunnel surfaces appeared to serve as impaction surfaces, removing airborne
particulates between the working area and exhaust shaft. This may also explain
the reduction in WL measured at the bottom of the exhaust shaft.
Gross isotopic activities of the high volume air samples collected at the
mine discharge did not differ significantly from the blank filter analyses.
Only the uranium-238 and radium-226 on the filter collected August 7 had net
results that were greater than the 2-sigma error terms. Visual examination of
the high volume cascade impactor sample sets collected with the high volume
air samples indicated that the airborne particulates consisted primarily of
diesel exhaust (PEDCo, 1978). Radioactivity concentrations were too low to
permit radionuclide analysis on the size fractionated samples of mine exhaust.
2. Plant Emission Samples
Radon-222 concentrations above ambient were measured in the effluents from
both kiln exhaust stacks and in the mixing, pressing, and setting area. No
radon concentrations different from ambient were measured in either the dryer
exhaust or in fugitive emissions from the crushing, grinding, and screening
building. Particulate radioactivity was measured in the two kiln exhaust
stacks.
22
-------
Air flow through the mixing, pressing, and setting area was estimated by
measuring air velocities at all openings with inflow as well as the size of
the openings. During sampling the ventilation rate in this area was estimated
at 5,100 cubic meters per minute (181,000 cfm). Stack air flow measurements
made during collection of the Method 5 particulate samples are summarized in
Table 5.
The calculated annual radon-222 emission rates were: kiln 5A, <0.15 Ci;
kilns 4 and 5B, <0.11 Ci; mixing, pressing, and setting area, <0.67 Ci.
Particulate stack emission samples, shown in Table 3, contained measurable
concentrations of uranium-234 and -238, thorium-230, and polonium-210.
Uranium-234 and -238 concentrations in the uncontrolled exhaust from kiln 5A
ranged from <0.1 to 0.3 pCi/m3. The concentrations measured in the ionizing
wet scrubber exhaust on kilns 4 and 5B ranged from 0.066 to 0.089 pCi/m3.
Thorium-230 concentrations measured in the kiln 5A emissions ranged from <0.04
to 0.48 pCi/m3. Those in the scrubber exhaust were <0.07 and 0.095
pCi/m3. Polonium-210 concentrations in the kiln 5A emissions were 44 to 53
pCi/m3, while those in the scrubber exhaust from kilns 4 and 5B were 15 and
18 pCi/m3-
The concentrations in Table 3 were multiplied by the flow rates in Table 5
to obtain the annual emission rates based on each sample shown in Table 6.
The results for each source were averaged and are presented in Table 7 as the
average annual release rate in pCi/y.
Mass distributions by aerodynamic particle size of the particulate emis-
sions from the mine and kiln stacks are shown in Figures 9 to 12. Figure 9
shows the particle size distribution in mine ventilation emissions during the
first shift when the major activity is loading and hauling clay ore from the
mine. The distribution would extrapolate to a geometric median diameter of
0.06 ym with a geometric standard deviation of 5. Due to the relatively small
size of particles emitted and the color of the backup filter, the particulate
emissions from the mine seem to result primarily from diesel exhaust.
23
-------
Table 5. STACK FLOW MEASUREMENTS
Sample
Location
Kiln 5A
Kiln 5A
Kiln 5A
Kiln 4+5B
Kiln 4+5B
Date
8/8
8/9
8/9
8/9
8/9
Time
1600-1700
1055-1210
1057-1211
1050-1240
1500-1652
Flow Rate
(sm3/min)*
984
1001
938
916
922
Temperature
(°C)
272
266
264
24.4
26.1
Stack
Height(m)
12.2
12.2
12.2
45.7
45.7
* Flow rate at standard conditions = 20°C, 760 mm Hg.
24
-------
Table 6. ANNUAL PARTICULATE RADIOACTIVITY RELEASE RATE DETERMINED
FROM-EACH SAMPLE AT GLOBE REFRACTORIES
Release
°o1nt
Kiln 5A
Kiln 5Ab
Kiln 5Ab
Kilns 4+5B
Kilns 4*58
Mine Exhaust
Mine Exhaust
Date Time
Collected
8/8 1600
8/8 1700
8/9 1055
8/9 1210
8/9 1057
3/9 1211
3/9 1050
8/9 1240
8/9 1500
3/9 1652
8/7 1610
8/7 1647
8/8 1015
3/8 1115
a. Uncertainties given Kith
b. Duplicate
Release
Point
K1ln 5A
(Uncontrolled)
Kilns 4+5B
(Scruober)
Mine
Exhaust
samples.
Table 7.
U-234
<130
39
<4
U-234
110 t
50
170 i
68
<110
43 -
22
34 ±
21
<3
<5
results are twice
Radioactivity Release Rate (uC1/y)*
U-235 U-238 fh-223 Th-230 Th-232 Ra-226 Pb-210
<30 85 i <20 260 s <20 0 <3,000
44 95
<5 140 t. <20 <20 <20 <540 <3,000
62
<30 <120 <6 <100 <6 0 <3,000
<20 44 j <20 <30 <20 <60 <2,000
22
<5 34 t <20 51 t <20 <30 <2,000
21 34
<2 4.4 t <4 <1 <4 96 i <200
4.0 12
<5 <4 <4 <4 <4 <20 <500
the standard deviation based on counting results only.
Po-210
27,000 t
8,800
25,000 ±
7,900
29,000 t
10,000
9,100 t
4,100
7,600 i
4,100
<200
<200
AVERAGh ANNUAL PARTICULATE RADIOACTIVITY RELEASE RATE
.AT GLOBE_ REFRACTORIES
J-235
<20
«4.6)a
<20
(1-3)3
<4
«0.18)a
Annual Release Rate (uCi/y)
U-238 Th-321! Th-230 fh-232 Ra-2?S Pb-21fl
<115 <15 <130 <15 <180 <3,000
40 <20 <40 <20 <50 <2,000
<4 <4 <3 <4 <50 <350
Po-210
27,000
3,400
<200
a. Values in parentheses are release rates calculated from average of U-234 and U-233 and
theoretical isotopic ratios in nature.
25
-------
Figure 10 shows the particle size distribution of mine emissions during-
the second shift when drilling and blasting are the major mining activities.
The geometric median diameter of this sample is 0.48 ym with a geometric
standard deviation of 6.7.
Figure 11 shows the particle size distribution of the emissions from the
uncontrolled stack of kiln 5A. The geometric median diameter is 14 ym with a
geometric standard deviation of 5.8.
The size distribution of particulates from the ionizing wet scrubber
serving kilns 4 and 5B, shown in Figure 12, demonstrates a geometric median
diameter of 4.3 ym with a geometric standard deviation of 2.8.
We did no radionuclide analysis on the individual stages of the size-
fractionated emission samples because we believed the levels were too low to
get reliable results. However, we have been able to perform such analyses on
similar samples from other facilities. The results from those samples show
that most of the polonium-210 is associated with the smaller particles. This
would be expected due to the evolution of polonium-210 as a vapor from the
fired brick.
VII POPULATION DISTRIBUTION
Globe Refractories is located in a rural area of low population density.
Homes are scattered around the mine exhaust, with the nearest about 150 m
northeast. A small riverside resort with several permanent residents is about
200 m north northeast of the plant. A light industrial area is adjacent to
the southwest plant boundary.
26
-------
200-
100-
90-
80-
70-
60-
50-
40-
30-
E
3
N
0)
"o
CO
a.
o
E
CO
c
•o
o
0)
20-
10-
9-
8-
7-
6-
5-
4-
3-
2-
0.5_
0.1.
I I I
0.01
III II I I I I I I
12 5 10 20 40 60
I I I I I I
80 90 95 98 99 99.8 99.99
Percent By Weight Smaller Than Indicated Size
Figure 9. Particle Size Distribution for Mine Ventilation Exhaust-
First Shift
27
-------
200
100-
90
80-
70
60
50-
40-
30-
£
3
0)
N
20-
10-
9
8-
7
6-
5-
4-
3-
2-
o
r
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Q_
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£
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0.1
i i i n i i i i i i i i i i i i i i i
0.01 12 5 10 20 40 60 80 90 95 9998 99.8 99.99
Percent By Weight Smaller Than Indicated Size
Figure 10. Particle Size Distribution for Mine Ventilation Exhaust -
Second Shift
28
-------
200-
100
90
80
70-
60-|
50
40-
30-
20-
H 10-
9-
03 8-
N
<75
0)
CO
Q.
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0.5-
0.1
i i i i iIIIIimTT
0.01 12 5 10 20 40 60
I I I I I I
80 90 95 98 99 99.8 99.99
Percent By Weight Smaller Than Indicated Size
Figure 11. Particle Size Distribution for Uncontrolled Kiln Outlet
29
-------
200-
I I
100-
90-
80-
70-
60-
50-
40-
30-
~ 20-
E
a.
o>
N
<75
(0
O.
O
E
CQ
C
>
•o
o
10-
9-
8-
7-
6-
5-
4-
3-
1_
0.5-
0.1.
I I I ITT
0.01 1 2
I I I I I I I I I I I I I I
5 10 20 40 60 80 90 95 9899 99.8 99.99
Percent By Weight Smaller Than Indicated Size
Figure 12. Particle Size Distribution for Scrubber Outlet
30
-------
VIII DISCUSSION OF RESULTS
Gross concentrations of radon-222 in the mixing, pressing, and setting
area and in the kiln exhausts ranged from ambient to approximately three times
ambient. The major point of release, however, occurred at the mine ventila-
tion exhaust where concentrations of radon-222 were two orders of magnitude
greater than ambient. The calculated annual release of 16 curies from the
mine ventilation exhaust accounts for more than 95 percent of the total
measured radon-222 release from the combined mine and plant operation. In
contrast, the particulate radioactivity release rate from the mine accounted
for less than 2 percent of the total particulate radioactivity from the
combined operations.
A map of the mine was used to estimate the surface area and volume subject
to ventilation. The actual contribution to the radon exhaust of any area of
the mine must be estimated because the ventilation air does not travel
uniformly through the mine. The total surface area subject to ventilation was
estimated at 0.98 km^; the ventilated volume at 7.9 x 105 m^.
Assuming uniform ventilation through the mine at a rate of 1133 m-Vmin
(40,000 cfm), the air is exchanged once every 700 minutes, or approximately
twice daily. The working area of the mine during the survey was near the
exhaust end of the ventilation flow. Except for the radon picked up from the
working face, the concentration of radon at the work area should have been
essentially the same as it was at the exhaust.
The majority of the particulate radioactivity released from the kilns was
due to polonium-210. The effluent from kiln 5A, released directly to the
atmosphere, discharges 27 mCi per year. An additional 8.4 mCi per year is
discharged from the ionizing wet scrubber that handles the effluents from
kilns 4 and 5B, yielding an annual total of about 35 mi Hi curies (mCi). The
effluents also contain about 150 yCi per year each of uranium-234,
uranium-238, and thorium-230, and an estimated 6.4 yCi of uranium-235.
31
-------
The average concentration of polonium-210 in the ore and process materials
was 1.1 pCi/g. Given the kiln's annual production rates, it was determined
that 26 percent of the polonium-210 included in the material processed through
kiln 5A is released to the atmosphere. In addition, 6 percent of the
polonium-210 passing through kilns 4 and 5B is discharged through the ionizing
wet scrubber. Thus, the ionizing wet scrubber cuts the polonium-210 emissions
by 77 percent.
The total uranium-234 plus uranium-238 concentration in the material
through the kilns was 2.3 pCi/g. Kiln 5A's release of about 245 yCi/yr for
the two isotopes constitutes about 0.11 percent of that processed. In
contrast, the release fraction through the ionizing wet scrubber on kilns 4
and 5B was 0.027 percent. Thus the ionizing wet scrubber cuts uranium
emissions by 75 percent, about the same as for polonium-210.
Measured release fractions of uranium-234 and -235, thorium-230, and
radium-226 from the kilns were approximately 1 percent of the polonium-210
release fractions. The kiln's operating temperature of 1,100°C appears to
readily vaporize polonium, which has a boiling point, in its elemental form,
of 1,040°C. The other naturally occurring radionuclides are much less
volatile at that temperature, but some vapor does seem to be given off.
The sample of natural gas fuel for the kilns contained 1.8 pCi of radon-
222 per liter. Kiln 5A consumed 17 m^/min (36,000 cubic feet per hour) of
fuel, releasing 31 nCi/min or 0.016 Ci/yr. That amount would be about 10
percent of the estimated amount of less than 0.15 Ci/yr released from the
kiln. Kilns 4 and 5B burn 23.8 m3/min (50,500 cfh). The 42.9 nanocuries/
minute that the fuel provides would total 0.023 Ci/yr, or about 20 percent of
the less than 0.11 Ci/yr released from the ionizing wet scrubber. Although
these figures suggest a 50 percent removal by the scrubber, the difference is
not statistically significant, and the results should not be used to imply a
removal efficiency.
32
-------
IX REFERENCES
Code of Federal Regulations, Title 40, Chapter I, Part 50, Appendix B.
Code of Federal Regulations, Title 40, Chapter I, Part 60, Appendix A.
Eadie, Gregory G., and David E. Bernhardt. Sampling and data reporting
considerations for airborne particulate radioactivity. USEPA, Office of
Radiation Programs-Las Vegas Facility. Las Vegas, Nevada, December 1976.
Goodwin, Aurel. Mine Safety and Health Administration. Personal
Communication, 1978.
Harley, J. H., Editor. HASL Procedures Manual. Department of Energy, Health
and Safety Laboratory, New York, New York, August 1977.
National Council on Radiation Protection and Measurements. Natural Background
Radiation in the United States, NCRP Report No. 45, 1975. Washington, D.C.
PEDCo Environmental, Inc. Emission test report. Collection of Airborne Radon
and Radioactive Particulates at Globe Refractories, Inc., Newell, West
Virginia. Cincinnati, Ohio, November 1978.
Thomas, Jess W. Health and Safety Laboratory, U.S. Atomic Energy Commission.
Personal communication, 1971.
U.S. Public Health Service Publication No. 494. Control of Radon and
Daughters in Uranium Mines and Calculations on Biological Effects, 1957.
33
-------
TECHNICAL REPORT DATA
(Please rtcd Instructions on the reverse before completing)
1. REPORT NO.
ORP/LVF-81-1
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
Emissions of Naturally Occurring Radioactivity:
Fireclay Mine and Refractory Plant
5. REPORT DATE
February 1981
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Vernon E. Andrews
8. PERFORMING ORGANIZATION REPORT NO,
9. PERFORMING ORGANIZATION NAME AND ADDRESS
U.S. Environmental Protection Agency
Office of Radiation Programs-Las Vegas Facility
P.O. Box 13416
Las Vegas, ;iavada 89114
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
Same as Above
13. TYPE OF REPORT AND PERIOD COVERED
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
This is the first in a series of reports covering work performed in
resoonse to the 1977 Clean Air Act Amendments
16. ABSTRACT
Atmospheric
a fireclay mine
The onlv signifi
analysis of the
radon released i
radioactivity.
was oolonium-210
the polonium-210
emissions of naturally occurring radioactivity were measured at
and the associated plant that produces refractory brick oroducts.
cant radioactive emission from the mine was radon-222. An
ore radioactivity and surface area of the mine indicated that the
s comparable to that from any similar surface area of similar
The major particulate radioactivity from the refractory operation
released as the brick was fired. Approximately 26 percent of
in green brick was driven off in the kilns.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS C. COSATI Field/Group
Natural radioactivity
Airborne wastes
Exhaust gases
Underground mining
Fireclay refractories
Technologically
enhanced
radioactivity
1808
1302
2102
0809
1102
18. DISTRIBUTION STATEMENT
Release to Public
19. SECURITY CLASS (This Report)
Unclassified
21. NO. OF PAGES
40
20. SECURITY CLASS (This page)
Unclassified
22. PRICE
EPA Form 2220-1 (Rev, 4-77) PREVIOUS COITION i s OBSOLETE
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