SWRHL-58r
ENVIRONMENTAL MONITORING WITH THERMOLUMINESCENT DOSIMETERS
An Evaluation of the System and a Comparison to Photographic Methods
by
Chas. K. Fitzsimmons and William H. Horn
Southwestern Radiological Health Laboratory
Department of Health, Education, and Welfare
Public Health Service
Consumer Protection and Environmental Health Service
October 1969
This study performed under a Memorandum of
Understanding (No. SF 54 373)
for the
U. S. ATOMIC ENERGY COMMISSION
-------
LEGAL NOTICE
This report was prepared as an account of Government sponsored
work. Neither the United States, nor the Atomic Energy Commission,
nor any person acting on behalf of the Commission:
A. Makes any warranty or representation, expressed or implied,
with respect to the accuracy, completeness, or usefulness of the in-
formation contained in this report, or that the use of any information,
apparatus, method, or process disclosed in this report may not in-
fringe privately owned rights; or
B. Assumes any liabilities with respect to the use of, or for damages
resulting from the use of any information, apparatus, method, or pro-
cess disclosed in this report.
As used in the above, "person acting on behalf of the Commission" in-
cludes any employee or contractor of the Commission, or employee
of such contractor, to the extent that such employee or contractor of
the Commission, or employee of such contractor prepares, dissemin-
ates, or provides access to, any information pursuant to his employ-
ment or contract with the Commission, or his employment with such
contractor.
085
-------
SWRHL-58r
ENVIRONMENTAL MONITORING WITH THERMOLUMINESCENT DOSIMETERS
An Evaluation of the System and a Comparison to Photographic Methods
by
Chas. K. Fitzsimmons and William H. Horn
Southwestern Radiological Health Laboratory
Department of Health, Education, and Welfare
Public Health Service
Consumer Protection and Environmental Health Service
October 1969
This study performed under a Memorandum of
Understanding (No. SF 54 373)
for the
U. S. ATOMIC ENERGY COMMISSION
-------
ABSTRACT
In August 1965, the Southwestern Radiological Health Laboratory
put into operation a thermoluminescent dosimeter (TL.D) system
for monitoring gamma radiation exposure in the environment
surrounding the Nevada Test Site. A description of the equip-
ment and calibration technique is given. Precision of TLD
results at the 95% confidence level has been found to be ±3. 5%.
Accuracy is on the order of ±5%. Actual field data ranging from
background levels to about 1 R show TLD's to be more satisfac-
tory than film badges for the particular applications described.
-------
TABLE OF CONTENTS
ABSTRACT i
TABLE OF CONTENTS ii
LIST OF TABLES iii
LIST OF FIGURES iv
I. INTRODUCTION 1
II. DESCRIPTION OF EQUIPMENT i
III. CALIBRATION PROCEDURES 4
IV. PRECISION 7
V. RELIABILITY 9
VI. MEASUREMENT OF BACKGROUND BY THERMO-
LUMINESCENT DOSIMETRY 1 1
VII. CONCLUSIONS 13
REFERENCES IS
DISTRIBUTION
11
-------
LIST OF TABLES
Table 1. Comparison of Film Badge (FB) and TLD Data
from Nuclear Engineering Company Disposal
Site 14
Table 2. Average Background Exposure Rates 17
Table 3. Film Badge and TLD Stations 23
iii
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LIST OF FIGURES
Figure 1. Energy response of thermoluminescent CaF2:Mn 18
Figure 2. Fading of CaF2:Mn 19
Figure 3. Percent return of film badge and TLD data
during 1966 and 1967 20
Figure 4. Background exposure rates at selected locations
around the Nevada Test Site as determined by
TLD's 21
Figure 5. Film badge and TLD Stations, Environmental
Surveillance Program 22
IV
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I. INTRODUCTION
In August 1965, the Southwestern Radiological Health Laboratory
(SWRHL) put into operation a thermoluminescent dosimeter (TLD)
system for monitoring gamma radiation exposure in the off-site
environment. It was soon apparent that a large amount of experi-
mental work was necessary to fully realize the inherent potential of
the system. During the first year several questions were answered
and techniques developed to bring the system to a full-scale routine
monitoring program. The following projects have been completed
to a point where the results can be used routinely.
1. Perfection of a reader calibration technique.
2. Establishment of an individual correction factor for each
dosimeter.
3. Determination of the internal background due to 40K within
the dosimeter.
4. Development of a proper dedosing procedure.
5. Determination of the precision and reliability of the data.
Two other projects are still underway, that of determining the inherent
fading rate of the phosphor, and comparing the TLD to the film badge.
-------
II. DESCRIPTION OF EQUIPMENT
The dosimeter in use is a CaF2:Mn thermol amines cent device,
Model TL-1Z manufactured by Edgerton, Germeshausen & Grier, Inc.
(EG&G). The TL-12 consists of two component parts, a detector
(Model TL-32) and an energy compensating shield (Model TL-52).
The detector consists of a layer of thermoluminescent CaF^rMn
bonded to a helical heater element that is contained in an evacuated
glass envelope. The aluminum-lead-tin shield that houses the
detector is designed to compensate for the detector over-response in
the low energy region of the gamma ray spectrum. The energy
response is shown in Figure 1, both with and without the shield.
Operation of the dosimeter is based on the thermoluminescent prop-
erties of manganese-activated calcium fluoride . When the CaF^tMn
is exposed to ionizing radiation, valence electrons are raised to higher
metastable energy levels, often referred to as "electron traps. "
This stored energy is released in the form of light (green-orange for
Mn ) when the CaF?:Mn is heated. The released energy, propor-
tional to the cumulative dose received, is converted into an electrical
signal by a photomultiplier tube and recorded on a strip chart recorder
within the reader. After read-out the dosimeter may be reused. At
this writing, 1500 TLD's have been calibrated and are available for
use in the monitoring program.
The thermoluminescent dosimeter reader, Model TL-2B, or the
newer Model T1-3B, is an integrated system designed to read-out the
TLD's in both standard and micro sizes. The reader accepts the TLD
in a light tight chamber, heats it with a regulated current, and converts
-------
the emitted light energy into an electrical signal for display on the
built-in strip-chart recorder. Two "read-head" adapters are pro-
vided for inserting the different size dosimeters into the reader.
One adapter (TL-81) accommodates the vacuum tube-type detector
which is used in the routine monitoring program, and the other
(TL-81A) the needle micro-the rmolumine scent dosimeters.
The reader includes a recording photometer with power supplies
and control logic needed to read out the dosimeters. The control
logic sequences the recorder operation, dosimeter heating cycle,
automatic ranging circuit, and status indicator to effect a chart
record of the dosimeter's light emission. The automatic ranging
circuit operates when the recorder pen reaches full scale and
changes reader sensitivity in decade steps over a total of six
decades.
Dosimeter response to exposure is linear over the range from 5mR
to 5 kR. The chart can be read to three significant figures by esti-
mating the last digit for values greater than ten on the printed
scale.
-------
in. CALIBRATION PROCEDURES
A procedure for insuring the calibration of the Models TL-ZB and
TL/-3B reading instruments has been perfected. Twelve reference
dosimeters, type TL-12 devices which have an accurately established
correction factor near 1.00, are used as "primary" standards. Two
phosphorescent reference lights, one activated by C, the other by
63Ni, are used as "secondary" standards.
To perform a calibration, the reference dosimeters are exposed to a
known amount of l37 Cs gamma radiation. The exposure is measured
by taking the average reading of three or four condenser ionization
chambers (Victoreen or Landverk R-Meters). The recorder pen is
adjusted for zero and reference light values. One of the reference
dosimeters is read-out and the chart reading multiplied by the particu-
lar correction factor. If the result is not the same as the known ex-
posure, the difference is noted in percent and the reference light
values are readjusted correspondingly. The process is repeated with
each of the other reference dosimeters until the correct read-out is
obtained within 2% of the known exposure. The final reference light
value is then noted and the reader is ready for use. Readjustment
of the gain by means of the reference light may be required when
reading a large group of dosimeters, or if there is a time lapse
between batches of dosimeters. In order to assure electronic sta-
bility the reader is left on at all times, thus no warm up period is
required. It is recommended, however, to read-out two or three
dosimeters from the shelf before starting a batch.
-------
Once the reader has been calibrated, correction factors for all the
dosimeters can be determined. The dosimeters are exposed to 100
and 200 mR determined by the ion chambers, with a 0. 100 curie l37 Cs
source. Up to 200 dosimeters can be exposed at one time on a special
circular calibration table. Source-dosimeter distances available are
50 cm and 100 cm. Each dosimeter is exposed three times. The read-
out is performed within 24 hours after each exposure. If a reading
appears doubtful, the procedure is repeated until three read-outs .are
obtained within the reproducibility claimed by the manufacturer
(+ 1%). If this is not possible within a reasonable number of attempts,
the dosimeter is rejected.
The ion chamber value divided by the mean of the three dosimeter
readings is taken as the correction factor. Periodically, correction
factors are rechecked to assure dosimeter stability and retention of
sensitivity. It has been found that it is best to calibrate all dosimeters
even though the manufacturer provides this service. In view of this,
uncalibrated dosimeters are usually purchased at a reduced price and
calibrated as above. Correction factors range from 0.79 to 1. 26.
An inherent property of the TL-12 dosimeter is its "internal background"
caused by the presence of 40K in the material (potassium silicate)
which bonds the CaFotMn to the heating element. In order to determine
the magnitude of the internal background, all other sources of exposure
had to be accounted for. A large number of dosimeters were exposed
for varying time periods in locations of known background. In one
experiment a gun-barrel counting shield was used for which the back-
ground was well established at 0. 12 mR/day with an ion chamber. A
value of 0. 7 + 10% mR/day was calculated for the internal background
exposure rate. Subsequent tests by this laboratory have confirmed this
figure and have shown it to be a constant for all the dosimeters.
-------
That thermoluminescent phosphors retain the absorbed energy infor-
mation for long periods of time is not to say that some spontaneous
light emission does not occur. Electron traps of several energy levels
are involved and each has its own probability of decay to the ground
state. "Shallow" traps decay more rapidly as a rule than deeper ones.
Any loss of information by this process is called fading. Our studies
have shown that a given dosimeter exposed to 400 mR may fade 5% -
10% over a 30-day period. The bulk of the decay occurs in the first
5 or 6 days and then levels off for the duration of the period.
Figure 2 shows the percentage loss of luminescence -with time as
determined in one experiment. The data points are mean values with
+ one sigma shown by the vertical lines. The degree of fading is not
a simple function of time, and thus has not been included as a cor-
rection factor in the routine monitoring program. All such plots
exhibited a recovery after 5-10 days before continuing to decay.
Fading may be a function of dose rate as well as time. More
experimentation with the TL-12 is necessary to incorporate a cor-
rection for fading into the calculations.
The process of reading out the dosimeter virtually erases the dose
information and supposedly anneals the CaF2 for reuse. It has been
found, however, that some residual activation remains which can
increase readings taken on subsequent usag-e. Total dedosing is
achieved by placing the TL-32 (without shield) in a 350°C oven for
at least 12 minutes. Dedosing is accomplished as close to issue time
as possible to reduce background.
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IV. PRECISION
In the process of determining the fading rate, standard deviations
we're calculated for each group of dosimeters. The means were
assumed to be normally distributed. Thirty-six groups of eleven
dosimeters each were exposed to 400 mR. An overall estimate of
the variance yielded a coefficient of variation of 1.8%. Thus, at
the 95% confidence level, the true mean is expected to be within
+ 3. 5% of a given single dosimeter reading.
For comparison it should be noted that controlled exposures of
Du Pont 508 film dosimeters yielded a dispersion of values nearly
twice that of TLD's. For film, the standard deviation was least at
exposures near 500 mR and increased for both lower and higher
exposures. A more recent comparison of TLD and film data col-
lected from September 1966 to July 1967 shows an even greater
difference between the two types of dosimeters than the controlled
experiments (Table 1). Four locations around the perimeter of the
Nuclear Engineering radioactive waste disposal site near Beatty,
Nevada, were equipped with three TLD's (Type TL-12) and five film
badges (Du Pont Type 545). The only unique aspect of these locations
compared to the other film-TLD locations in the network is the
relatively high monthly exposure (50-1000 mR). As a result, the
film badges as well as the TLD's register positive readings and the
two can be compared directly. Type 545 film has a single component
emulsion and is inclosed by a reusable plastic holder. A lead strip
contained in the holder is folded around the film packet to reduce
energy dependence. The badge is designed to measure low exposures
of the relatively high gamma energies of fission products.
7
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Analyses of variance were performed on the data. For each month
and location, the mean of the three TLD or five film badge values
was calculated. The differences between the values and their re-
spective means were then calculated as percentages. These calcu-
lations normalized the data by removing the effects of monthly and
geographical variations. Assuming a normal distribution of per-
centages, the variance estimates were calculated for the two types
of dosimeters. It was found that the dispersion of values about the
mean film badge reading was nearly five times that of the TLD's.
The standard error for film badges was 20. 2%, and for TLD's, 4. 2%
of the respective means.
Using the same data in a randomized block design (blocked by months),
the hypothesis that the mean film badge reading and the mean TLD
reading for a given month and location are equal was tested. At the
95% confidence level no significant difference in the means was
detectable. There is reason to believe there is some difference in
response between the two types of dosimeters, however, especially
at low exposures. Further work is being done in pursuit of this
problem. For comparison purposes the accuracy (calibration) of
both the film badge and the TLD is assumed to be without error. In
actuality, the accuracy of the TLD calibration is about + 5 to 10%
while that of the film is claimed to be + 10 to 20%. The range of the
film is limited to . 05 to 3. 0 R.
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V. RELIABILITY
By the nature of their construction, the XL-12 dosimeters are quite
insensitive to environmental hazards such as heat, light, water, age,
handling, and processing. A minimal number of anomalies in the
data makes the TLD system very reliable. During summer months,
heat damage to film badges is the most common cause of data loss.
A plot of data recovered as a percent of dosimeters issued each
month shows a striking seasonal variation for film data (Figure 3).
Occasional loss of TLD data is attributable to either a lost or de-
stroyed dosimeter, or a reader malfunction.
4
Earlier studies of the effect on environmental heat on film badges
showed that serious errors in readings were produced when the tem-
perature during exposure was 20 F greater than that during process-
ing. Storage at high temperatures before exposure increased the
base fog and possibly the emulsion sensitivity which produced errors
as great as 75%.
Reliability is a must for an effective monitoring system. During the
period from June 16 to July 15, 1966, the following data were col-
lected from the dosimeter station at the Nuclear Engineering facility
near Beatty, Nevada:
TLD Readings Film Badge Readings
1. 1034 mR 1. Light Damage-
2. 995 mR 2. Light Damage*
3. 1040 mR 3. Light Damage
4. Light Damage-i
No Data
Possible Exposure of 3-4 R
5. Light DamageJ
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If data such as the above were returned from an incident involving
possible personnel exposure, it could cause obvious problems if
only film badges had been issued.
10
-------
VI. MEASUREMENT OF BACKGROUND BY
THERMOLUMINESCENT DOSIMETRY
Figure 5 shows the present off-site coverage maintained by the do-
simetry program. In general the dosimetry stations fall in the same
area as other PHS off-site surveillance activities. Most routine
milk or air sampling locations have TLD's also. Some TLD locations
are in uninhabited areas, but are maintained to provide a tighter net-
work of dosimeters around the Nevada Test Site.
The exposure rates of a number of selected stations are represented
in Figure 4. The locations are listed approximately in a counter-
clockwise order around the test site starting from Las Vegas.
Exposure rates in mR/day were calculated by dividing the net monthly
exposures by the number of days the dosimeters were in the field.
No known releases of activity occurred during this period so the
values obtained are assumed to represent natural backgrounds.
Table 2 lists the yearly mean, the range of monthly values, and the
standard error (coefficient of variation) for each of the seventeen
locations represented in Figure 4. If the fluctuation in background
can be assumed to be random, then some predictions based on sta-
tistical tests should be possible. For example, once the dispersion
of values around a mean background value at a particular location is
established, an upper limit to the expected background exposure for
any month can be set. Values above the expected value would be sus-
pected of unnatural origin. The average coefficient of variation for
the seventeen stations was 59% (among location monthly means, each
month having three replications). An arbitrary limit of 2 or 3 standard
-------
errors above the mean would establish the minimum detectable
signal above normal background. The major problem with the sta-
tistical approach is how to decide which values are to be included in
the background average and which are to be excluded. Deleting
marginal values, e.g. , three sigma above the current average,
might bias the estimate of the true mean.
12
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VII. CONCLUSIONS
The TLD system described above has proved to be well suited to
environmental monitoring for gamma radiation. Approximately one
year was spent in preparation for the full scale program which
promises to provide some very interesting data. Probably some of
the best estimates of natural background exposure rates and their
fluctuations around the Nevada Test Site have been obtained with
TLD's. The TLD's seem to be quite insensitive to environmental
hazards, especially heating, which is the greatest hazard to the film
badge during the summer months.
The precision, as well as the accuracy, of TLD's is better than that
which normally is attained with film badges. By virtue of their
reusability, calibration of TLD's does not depend on a representative
sample of a batch of dosimeters, but rather on a constantly updated
correction factor for each individual dosimeter.
The capability of the dosimeter to measure background levels of
exposure has increased the sensitivity of the dosimetry program by
a factor of ten.
13
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Table 1. Comparison of film badge (FB) and TLD data from Nuclear
Engineering Company disposal site.
Date Dosim-
Issued Collected eter
Avg. Exp.
Exposures (mR)
North Fence
09/29/66
ll/OZ/66
11/30/66
01/04/67
02/02/67
03/09/67
04/06/67
05/03/67
06/01/67
01/04/67
02/02/67
11/02/66
11/30/66
01/04/67
02/02/67
03/09/67
04/06/67
05/03/67
06/02/67
07/20/67
02/02/67
03/09/67
FB
TLD
FB
TLD
FB
TLD
FB
TLD
FB
TLD
FB
TLD
FB
TLD
FB
TLD
FB
TLD
FB
TLD
FB
TLD
120
156
0
35
50
35
0
45
120
36
60
58
50
61
85
91
85
51
South
60
64
35
70
145
156
0
37
55
37
30
42
35
37
55
66
60
64
100
95
75
52
Fence
45
64
160
72
125 125 145
138
30 0 0
33
45 50 45
35
20 20 0
43
0 125 35
38
60 60 55
64
60 55 55
62
100 90 115
92
90 75 80
53
30 30 35
64
145 65 160
71
132
150
30.
36.
49.
35.
23.
43.
78.
37.
58.
62.
56.
62.
98.
92.
81.
52.
40.
64.
113
71.
0
6
0
7
3
3
8
0
0
7
0
3
0
7
0
0
0
0
0
14
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Table 1. Comparison of film badge (FB) and TLD data from Nuclear
Engineering Company disposal site, (continued)
Date Dosim-
Issued Collected eter
Avg. Exp.
Exposures (niR)
South Fence (continued)
03/09/67
04/06/67
05/03/67
06/01/67
09/29/66
11/02/66
11/30/66
01/04/67
02/02/67
03/09/67
04/06/67
FB
04/06/67
TLD
FR
05/03/67
TLD
FB
06/02/67
TLD
fTTa
07/20/67
TLD
FB
11/02/66
TLD
11/30/66 FB
TLD
VR
01/04/67
TLD
FB
02/02/67
TLD
FB
03/09/67
TLD
FB
04/06/67
TLD
FB
05/03/67
TLD
295
270
70
72
105
89
0
64
East
125
134
115
178
85
102
30
63
45
60
140
150
80
75
285
266
60
69
90
108
0
67
Fence
135
128
115
177
90
98
35
65
45
'63
305
154
95
76
300 235 220
272
70 65 60
76
105 115 105
98
95 90 105
61
130 120 135
125
110 135 125
185
90 90 90
104
35 35 0
74
0 14S 45
60
145 170 150
145
105 95 105
73
267
269
65.0
72.3
104
98. 3
96.7
64.0
129
129
120
180
89.0
101
33.8
67.3
70.0
61.0
182
150
96.0
74.7
15
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Table 1. Comparison of film badge (FB) and TLD data from Nuclear
Engineering Company disposal site, (continued)
Date Dosim-
Issued Collected eter
05/03/67
06/01/67
09/29/66
11/02/66
11/30/66
01/04/67
02/02/67
03/09/67
04/06/67
05/03/67
06/01/67
06/02/67
07/20/67
11/02/66
11/30/66
01/04/67
02/02/67
03/09/67
04/06/67
05/03/67
06/02/67
07/20/67
East
FB
TLD
FB
TLD
FB
TLD
FB
TLD
FB
TLD
FB
TLD
FB
TLD
FB
TLD
FB
TLD
FB
TLD
FB
TLD
Fence
100
98
0
148
West
295
274
560
563
70
67
140
182
280
294
125
129
780
636
420
577
90
78
Avg. Exp.
Exposures (mR)
(continued)
110
102
0
158
Fence
250
295
555
513
75
69
145
183
260
303
130
108
665
776
530
563
115
75
105 110 105
94
180 0 0
146
260 225 255
292
560 560 560
541
75 75 85
61
145 120 155
190
380 395 290
293
125 125 110
127
575 600 695
626
450 480 645
514
125 110 110
83
106
98.0
180
151
258
287
559
539
76.0
65.7
141
185
321
297
123
121
663
679
505
551
110
78.7
Note: Zeros indicate nondetectable exposure or no data due to
damage. Zero values are not averaged.
16
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Table 2. Average background exposure rates (mR/day) for the period
October 1966 to September 1967.
Location
Las Vegas, Nevada
Warm Springs Ranch, Nev.
St. George, Utah
Pioche, Nevada
Alamo, Nevada
Hancock Summit, Nevada
Garrison, Utah
Duckwater, Nevada
Warm Springs, Nevada
Clark's Station, Nevada
Austin, Nevada
Tonopah, Nevada
Groom Lake, Nevada
Lathrop Wells, Nevada
Sho shone, California
Mammoth Lake, California
Barstow, California
Yearly
Mean
0. 272
0.247
0. 280
0.347
0. 387
0.549
0. 378
0.415
1.092
0.478
0.412
0.419
0.362
0.406
0.278
0.375
0.379
Range of Percent
Monthly Coefficient of
Means Variation
0. 175-0.619
0. 143-0.490
0. 152-0.483
0. 206-0.542
0. 243-0.596
0. 357-0.790
0. 167-0.780
0. 184-0.701
0.285-1.529
0. 254-0.770
0.222-0.762
0.256-0.632
0. 194-0.541
0.219-0.575
0. 120-0.417
0. 198-0.529
0.262-0.472
85
67
54
43
45
37
79
58
70
51
73
75
50
40
61
80
34
17
-------
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a
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® shielded
.01
0.1
Effective Energy
MEV
1O
Figure 1. Energy response of thermoluminescent CaFoiMn.
(Data provided by manufacturer)
-------
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99%
98%
2
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o 97%
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"5
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Figure 2. Fading of
-------
DO
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Figure 3. Percent return of film badge and TLD data during 1966 and 1967.
-------
mR/DAY
AT:
DATE
LAS VEGAS
NEVADA
WARM SPRINGS
RANCH
NEVADA
ST. GEORGE
UTAH
PIOCHE
NEVADA
ALAMO
NEVADA
HANCOCK SUMMIT
NEVADA
GARRISON
UTAH
DUCKWATER
NEVADA
WARM SPRINGS
NEVADA
CLARK STATION
NEVADA
AUSTIN
NEVADA
TONOPAH
NEVADA
GROOM LAKE
NEVADA
LATHROP WELLS
NEVADA
SHOSHONE
CALIFORNIA
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Figure 4. Background exposure rates at selected locations
around the Nevada Test Site as determined by TLD's.
21
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Figure 5. Film badge and TLD Stations, Environmental Surveillance Program.
2Z
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Table 3. Film badge and TLD stations.
1. Adaven, Nevada 30.
2. Alamo, Nevada 31.
3. Ash Meadows, Nevada (32)
4. Austin, Nevada (33)
(5) Baker, California 34.
6. Bars tow, California 35.
7. Battle Mountain, Nevada (36)
8. Beatty, Nevada
9. Beaver Dam Summit, Utah 37.
(10) Big Pine, California (38)
11. Bishop, California 39.
12. Blue Eagle Ranch, Nevada 40.
13. Blue Jay, Nevada 41.
14. Butler Ranch, Nevada 42.
(15) Cactus Springs, Nevada 43.
16. Caliente, Nevada 44.
17. Carlin, Nevada (45)
18. Casey's Ranch, Nevada 46.
19. Cedar City, Utah (47)
20. Clark Station, Nevada 48.
21. Coyote Summit, Nevada (49)
22. Currant, Nevada 50.
23. Currant Maint. Sta., Nevada 51.
24. Currie, Nevada (52)
25. Death Valley Junction, Cal. 53.
26. Desert Game Range, Nev. 54.
27. Diablo, Nevada 55.
28. Duckwater, Nevada 56.
29. Dunphy, Nevada 57.
Elgin, Nevada
Elko, Nevada
Ely, Nevada (Airport)
Eureka Maint. Sta. , Nev.
Fallini's Ranch, Nevada
Furnace Creek, California
Gardner Ranch, White
River Valley, Nevada
Garrison, Utah
Geyser, Nevada
Goldfield, Nevada
Gold spar Mine, Nevada
Groom Lake, Station A, Nev.
Groom Lake, Station B, Nev.
Halleck, Nevada
Hancock Summit, Nevada
Hiko, Nevada
Hot Creek Ranch, Nevada
Independence, California
Indian Springs, Nevada
Klondike, Nevada
Las Vegas, Nevada
Lathrop Wells, Nevada
Lockes Ranch, Nevada
Logandale, Nevada
Lone Pine, California
Lida, Nevada
Lida Junction, Nevada
Lund, Nevada
23
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Table 3. Film badge and TLD stations, (continued)
58. Mammoth Lake, California
(59) McGillivary Ranch, Nevada
60. Mesquite, Nevada
61. Modena, Utah
(62) Mt. Springs Summit, Nevada
63. Nevada Farms, Nevada
64. New Castle, Utah
65. Nuclear Engineering Co.
(North), Nevada
66. Nuclear Engineering Co.
(South), Nevada
67. Nuclear Engineering Co.
(East), Nevada
68. Nuclear Engineering Co.
(West), Nevada
69. Nyala Ranch, Nevada
70. Oasis, Nevada
(71) Olancha, California
72. Pahranagat Lake, Nevada
73. Pahrump, Nevada
74. Pinecreek, Nevada
75. Pioche, Nevada
76. Queen City Summit, Nevada
(77) Randsburg, California
78. Reed Ranch, Nevada
79. Ridgecrest, California
(80) Road "D" and Hwy. 95, Nevada
81. Round Mountain, Nevada
82. Ruby Valley, Nevada
83. St. George, Utah
84. Scottys Junction, Nevada
85. Selback-Strickland Ranch
(Amargosa Desert), Nevada
86. Shell Oil Site, R. R. Valley,
Nevada
87- Shoshone, California
88. Sunny side, Nevada
89. Tonopah, Nevada
(90) Tonopah (Airport), Nevada
91. Tonopah Test Range, CPI,
Nevada
92. Tonopah Test Range, Main Gate
(Point Able), Nevada
93. Ursine, Nevada
94. Valley of Fire, Nevada
95. Warm Springs, Nevada
96. Warm Springs Ranch, Nevada
97. Wells, Nevada
98. Wendover, Utah
0. = TLD & 5 FB
(0) = 5 FB St.
24
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REFERENCES
1. SCHULMAN, J. H. Survey of luminescence dosimetry. Lumi-
nescence Dosimetry. USAEC Rep CONF-650637:3-33 (April 1967),
Clearinghouse for Federal Scientific and Technical Information,
National Bureau of Standards, U. S. Department of Commerce,
Springfield, Virginia 22151.
2. FACEY, R. A. Dose-rate effect in phosphorescence and thermo-
luminescence. Health Physics 12:715-717(1966).
3. HORN, W. H. Photographic dosimetry, fourth supplemental evalua-
tion. Unpublished Rep. Radiological Safety Division, Health,
Medicine, and Safety Department, Reynolds Electrical and
Engineering Co., Mercury, Nevada 89023 (November 1, I960).
4. HORN, W. H. Effects of temperature on dosimetry film. Unpub-
lished Rep. Radiological Safety Division, Health, Medicine, and
Safety Department, Reynolds Electrical and Engineering Co. ,
Mercury, Nevada 89023 (I960).
25
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DISTRIBUTION
1 - 20 SWRHL, Las Vegas, Nevada
21 Robert E. Miller, Manager, NVOO/AEC, Las Vegas, Nevada
22 R. H. Thalgott, Test Manager, NVOO/AEC, Las Vegas, Nevada
23 Henry G. Vermillion, NVOO/AEC, Las Vegas, Nevada
24 Chief, NOB/DASA, NVOO/AEC, Las Vegas, Nevada
25 Robert R. Loux, NVOO/AEC, Las Vegas, Nevada
26 D. W. Hendricks, NVOO/AEC, Las Vegas, Nevada
27 Mail & Records, NVOO/AEC, Las Vegas, Nevada
28 Martin B. Biles, DOS, USAEC, Washington, D. C.
29 Director, DMA, USAEC, Washington, D. C.
30 JohnS. Kelly, DPNE, USAEC, Washington, D. C.
31 P. Allen, ARL/ESSA, NVOO/AEC, Las Vegas, Nevada
32 Gilbert J. Ferber, ARL/ESSA, Silver Spring, Maryland
33 - 37 Charles L. Weaver, CPEHS, PHS, Rockville, Maryland (5)
38 Regional Representative, BRH, PHS, Region IX, San Francisco,
California
39 Bernd Kahn, BRH, PHS, Cincinnati, Ohio
40 Northeastern Radiological Health Lab. , Winchester, Mass.
41 Southeastern Radiological Health Lab. , Montgomery. Ala.
42 W. C. King, LRL, Mercury, Nevada
43 John W. Gofman, LRL, Livermore, California
14 H. L. Reynolds, LRL, Livermore, California
45 Roger Batzel, LRL, Livermore, California
46 Ed Fleming, LRL, Livermore, California
47 Wm. E. Ogle, LASL, Los Alamos, New Mexico
48 Harry S. Jordan, LASL, Los Alamos, New Mexico
49 Victor M. Milligan, REECo, Mercury, Nevada
50 Clinton S. Maupin, REECo, Mercury, Nevada
51 Byron Murphey, Sandia Corporation, Albuquerque, N. Mex.
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Distribution (continued)
52 R. H. Wilson, University of Rochester, N. Y.
53 - 54 DTIE, Oak Ridge, Tennessee
55 R. S. Davidson, Battelle Memorial Institute, Columbus, Ohio
56 Dave Snelling, State Health Dept. , Little Rock, Ark.
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