EPA-600/4-76-035
August 1976
600476035
Environmental Monitor! i
FACTORS AFFECTIN
CaF2:Mn THERMOLUMINESCEN
FOR LOW-LEVEL E
RADIATI
Environmental Mon
Office
U.S. En
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I
RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into five series. These five broad
categories were established to facilitate further development and application of
environmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
This report has been assigned to the ENVIRONMENTAL MONITORING series.
This series describes research conducted to develop new or improved methods
and instrumentation for the identification and quantification of environmental
pollutants at the lowest conceivably significant concentrations. It also includes
studies to determine the ambient concentrations of pollutants in the environment
and/or the variance of pollutants as a function of time or meteorological factors.
This document is available to the public through the National Technical Informa-
tion Service. Springfield, Virginia 22161.
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EPA-600/4-76-035
August 1976
FACTORS AFFECTING THE USE OF CaF2:Mn THERUOLUMINESCENT
DOSIMETERS FOR LOW-LEVEL ENVIRONMENTAL
RADIATION MONITORING
by
K. C. Gross
E. J. McNamara
W. L. Brinck
Radiochemistry and Nuclear Engineering Branch
Environmental Monitoring and Support Laboratory
Cincinnati, Ohio 45268
ENVIRONMENTAL MONITORING AND SUPPORT LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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DISCLAIMER
This report has been reviewed by the Environmental Monitoring and
Support Laboratory—Cincinnati, U.S. Environmental Protection Agency, and
approved for publication. Mention -of trade names or commercial products
does not constitute endorsement or recommendation for use.
11
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FOREWORD
Environmental measurements are required to determine the quality
of ambient waters and the character of waste effluents. The Environ-
mental Monitoring and Support Laboratory - Cincinnati conducts research
to:
o Develop and evaluate techniques to measure the presence and
concentration of physical, chemical, and radiological
pollutants in water, wastewater, bottom sediments, and
solid waste.
o Investigate methods for the concentration, recovery, and
identification of viruses, bacteria and other microbiological
organisms in water.
o Conduct studies to determine the responses of aquatic
organisms to water quality.
o Conduct an agency-wide quality assurance program to assure
standardization and quality control of systems for
monitoring water and wastewater.
With the increased use of nuclear power for generation of
electricity, environmental radioactivity monitoring programs must be
improved and tested to measure accurately the radiation exposure to
affected individuals and population groups. The Environmental
Protection Agency is engaged in studies to develop methodology and
to provide information for evaluating such monitoring programs. One
element of this research is the evaluation of the use of thermo-
luminescent dosimetry for the measurement of external radiation dose
in the environment of these power stations.
Dwight G. Ballinger
Director
Environmental Monitoring and
Support Laboratory
Cincinnati
111
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ABSTRACT
An investigation was made of factors affecting the use of commercially-
produced CaFg:Mn thermoluminescent dosimeters for low level environmental
radiation monitoring. Calibration factors and self-dosing rates were
quantified for 150 thermoluminescent dosimeters. Laboratory studies were
made of precision, linear response to dose rate, effects of light, and
time-dependent fading. A standard laboratory procedure was devised and a
computer program was written to calculate, analyze, and store the large
amounts of data that were accumulated. Extensive environmental
measurements were subsequently carried out at the Vermont Yankee Nuclear
Power Station. The results of this investigation indicate that selected
dosimeters, when properly calibrated and corrected for self-irradiation,
can be used for accurate and reliable monitoring of low-level environmental
radiation.
IV
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CONTENTS
Page
I Introduction . 1
II Conclusion 1
III Physical Characteristics of the TLD System 2
IV Methods and Procedures 6
Calibration Procedures 6
Internal Background 8
Theoretical Error for Environmental Monitoring 9
Precision and Accuracy of Dosimeters as a Group 10
Computer Program 11
Time-Dependent Fading 14
Linearity 18
Effects of Exposure to Light 18
V Environmental Monitoring Results 20
VI References 21
VII Appendices 22
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LIST OF FIGURES
Number
1
2
3
4
5
G
Page
Bulb-Type Dosimeter and Shield 3
Response vs Energy Curve For Shielded Dosimeter 4
Strip Chart Recorder Output 5
Time-Dependent Fading 16
Two-Peaked Glow Curve 17
Linearity of Measured Dose vs Actual Dose 19
LIST OF TABLES
Number
3
4
5
6
7
8
Page
Contributions to Error in Calibration
Factor Determination for 9 mR Exposure
to Dosimeters in Group A 8
Contributions to Error in Internal
Background Determination for Group A
Dosimeters Left in Shield One Week 9
Trial Exposures of 10 Dosimeters 10
Simulated Environmental Exposure of
20 Dosimeters from Group A 11
Computer Printout of Individual TLD Data 12
Computer Printout of Average TLD Data 13
Computer Printout of Dose Rate Calculations 15
Time-Dependent Fading 17
VI
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SECTION I
INTRODUCTION
Accurate determination of radiation from nuclear power stations, of the
same magnitude as variations in the natural background radiation in the
vicinity, requires sensitive dosimeters capable of accurate and precise
measurements. To meet these requirements, techniques were developed to
calibrate and evaluate commercially available, glass-encapsulated CaF2:Mn
thermoluminescent dosimeters for gamma-ray measurements. These dosimeters
have been studied previously and have been found well suited for low-level
measurements(l-3). This report discusses the feasibility and the
practicability of this dosimeter as a reliable gamma radiation monitor.
SECTION II
CONCLUSION
The present investigation has shown that glass-encapsulated CaF2:Mn
dosimeters are capable of accurate and reliable measurements of low-level
environmental radiation. These dosimeters, when properly calibrated and
corrected for internal background, can play a vital role in the
environmental monitoring of operating nuclear power facilities, and can
measure environmental radiation exposures attributable to a facility at
levels as low as 8 mR/yr.
- 1 -
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SECTION III
PHYSICAL CHARACTERISTICS OF THE TLD SYSTEM
The thermoluminescent dosimeter (TLD) system studied consists of
CaF.>:Mn thermoluminescent dosimeters and a low-level thermoluminescent
dosimeter reader. The system was originally manufactured by EG&G, Inc.
but, with slight modification, is now manufactured by the Victoreen
Instrument Division. The dosimeter, (Victoreen Model 2600-46), shown in
Figure 1, consists of two manganese-activated thermoluminescent CaF2:Mn
chips, firmly attached to a flat heating element. The thermoluminescent
material and heating element are contained within a carbon dioxide-filled
glass bulb, 1.1 cm in diameter and 3.1 cm long. The bulb is housed in an
aluminum-lead-tin shield to reduce the dosimeter's non-linear response to
low-energy gamma rays. A curve of response versus energy for this detector
has been provided by the manufacturer and is reproduced in Figure 2(4).
The curve indicates that the response per roentgen shows only small
variation with photon energy above approximately 65 keV.
The semi-automatic reader unit (EG&G Model TL 3A) furnishes data in the
form of a glow curve which are permanently recorded on a 13 cm paper strip
chart. The reader is calibrated with a phosphorescent reference light
source with a physical configuration similar to that of the dosimeter. The
reader is equipped with a photomultiplier tube and a voltage discriminator
which allows the suppression of signals which are due to electrical
background noise. A reading head positions the dosimeter in a light-tight
chamber and passes a constant current of 6.5 amps through the heating
element. The photomultiplier tube then converts the emitted
thermoluminescence into an electrical current which is proportional to the
magnitude of the gamma-ray exposure. The plot of thermoluminescent light
output as a function of time is known as a glow curve. Examples of a
calibration glow curve and a typical readout glow curve are reproduced in
Figure 3. The magnitude of the exposure is determined by measuring the
height of the peak (see Figure 3b). To interpret the glow curve for the
dosimeter in Figure 3, it is necessary to ignore the horizontal "pip"
extending to the extreme right of the chart paper which indicates that the
reading exceeded full-scale deflection and the range switch automatically
stepped up to the next scale. In the case shown in Figure 3b, the range
changed once from the 0-5 unit scale to the 0-50 unit scale. The peak of
the main glow curve then fell at 47.2 units.
Available for this investigation were 100 dosimeters from one
manufacturer (EG&G) designated as Group A, and fifty dosimeters from a
second manufacturer (Victoreen Instruments Division) designated as Group B
(a redesigned and improved version of the EG&G dosimeter). The basic
difference between the two groups of dosimeters is that the Group B
dosimeters are designed with larger lead wires (0.98 mm diameter compared
with 0.84 mm for the Group A dosimeters) and the glass of the bulb material
for the Group B dosimeters contains a smaller amount of radioactive
potassium-40 impurities.
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Al-Pb-Sn Shield
Bulb-Type Dosimeter
Front View
Glow Envttop*
C02 Gat
CoF2'Mn Chip*
Spring Clip
Heating Eltmtnt
Ltod Wirtt
Side View
o
1.3 cm
Figure I Bulb-Type Dosimeter and Shield
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1.0
0.8
O.6
S0.4
o
i
0.2
O.I
10
20
40 6O 8O I02 2OO
Effective Energy, KeV
400 600 800 I03
Figure 2 Response vs. Energy Curve for Shielded Dosimeter
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10
DATE (3 June '7*+
2Q
DOSIMETER NO.
n d
40
50
a. 325 mR Calibration Standard
DATE
/3 June'
DOSIMETER NO.
FULL SCALE R READ BY H G | CHECKED BY
b. 47.2mR - One Scale Change
Figure 3 Strip Chart Recorder Output
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SECTION IV
METHODS AND PROCEDURES
CALIBRATION PROCEDURES
The glow curve peak height obtained in reading out an irradiated
detector is directly proportional to the amount of radiation exposure i.e.,
to the radiation dose received by the dosimeter material. However, the
constant of proportionality varies from dosimeter to dosimeter.
Consequently, calibration factors were obtained to convert peak heights, in
arbitrary units, to exposure in milliroentgen (mR). The calibration
factors for all dosimeters studied were obtained by exposing each dosimeter
a minimum of seven times to a known quantity of radiation and dividing the
dose by the reading produced. A 2 mCi 226Ra source, calibrated by the
National Research Laboratories of Canada, was used to expose the dosimeters
on a specially constructed calibration facility. The facility was designed
to provide reproducible positioning of the dosimeters and to minimize
errors introduced by scatter. It has a plexiglass source holder
permanently fixed at its geometric center and dosimeter holders fixed at
equal radial distances (50.0 cm) along the periphery. Since the source
strength and the distance between the source and the dosimeters are known,
the total exposure to the dosimeters for a given calibration experiment can
be determined by measuring the time during which the dosimeters are exposed
to the source. Throughout this study, the dosimeters were given exposures
ranging from 5 mR to 32 mR and read 24 hours later.
The mean calibration factors for the dosimeters from Group A varied
from 0.20 to 0.27 mR/reader unit. The average standard deviation of the
mean calibration factor for an individual dosimeter from Group A was 1.8
percent. The standard deviation of the entire population was 4.4 percent.
The mean calibration factors for Group B varied from 0.29 to 0.31 mR/reader
unit and the average of the individual standard deviations was 1.4 percent.
The standard deviation of the population for Group B was 2.0 percent.
The difference in sensitivity between Group A and Group B is attributed
to the previously mentioned design; differences between the two groups of
dosimeters. For the purpose of this study, unique calibration factors were
determined and used for each dosimeter. Using these individual calibration
factors, the error in the precision and reproducibility of this dosimeter-
reader system is not greater than 1.8 percent. However, if less precision
is required in a given monitoring situation, use of an average calibration
factor for the dosimeters from Group B would lead to an error not greater
than 3.3 percent.
The variation in response of any individual dosimeter between
successive readings can be attributed to several factors. These include
uncertainty in reader calibration, the error in peak height determination,
and the error in determining the actual exposure to the dosimeters.
Calibration of the reader involves adjustment of the zero position of
the strip chart recorder, the voltage of the photomultiplier tube, and the
- 6 -
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heater current. The adjustment of the strip chart recorder zero setting is
checked each time a group of dosimeters is to be read out. The adjustment
is necessary to nullify the variations in the photomultiplier tube dark
current. Dark current, the photomultiplier tube anode current measured
with no light source, has been observed to fluctuate over a small range
daily. The adjustment can be made by inserting the empty read head into
the reader and manipulating the zero control until a zero reading is
obtained on the chart recorder. The zero can easily be adjusted to within
£ 0.1 reader units; hence, the error attributable to the adjustment of the
zero is about 0.3 percent for a 9 mR exposure, and 0.9 percent for a 3 mR
exposure.
The high voltage on the photomultiplier tube is adjusted by inserting a
reference light source and adjusting the fine gain control until the pen
indicates the value assigned to the reference light. The potential error
introduced by the reproducibility of this adjustment is less than 0.6
percent if the same reference light source is used for every calibration.
The adjustment of the heater current to 6.5 amps is accomplished with
the aid of a built-in ammeter. This adjustment is very important because
fluctuations in the heating current, and hence the heating rate, can have
pronounced effects on the glow curve (5). The area under the glow curve is
not affected, but the shape of the curve is altered and the height of the
peak is shifted by a change in the heating rate. The current, when
adjusted properly, has not been observed to fluctuate with time; assuming
the setting is not changed manually, the source of error from this
adjustment can be considered minor (less than 0.1 percent of the total
error).
The peak height can be read to within ^0.2 reader units. The error in
this determination can amount to 0.6 percent for a 9 mR exposure, and 1.8
percent at 3 mR.
The uncertainty in the radium source strength for the source used to
expose the dosimeters is 2.2 percent. The error in the measurement of the
distance between the source and the detectors is about 0.2 percent at 50
cm. The uncertainty in the positioning of the detector inside its shield
contributes another 0.2 percent.
The dose which is due to scattering from the floor and ceiling of the
calibration facility room, as well as that which is due to air scatter, is
quantified and subtracted from the total dose. This is accomplished by
annealing three to five reference dosimeters and placing them behind a lead
brick so they are "shadowed" from the radium source. These reference
dosimeters will only measure the component of the total dose which is due
to scatter and the natural background. Since this component is being
subtracted out, the uncertainty in the calibration factors which may be due
to scatter can be neglected.
Other possible sources of error include the dose due to the ambient
background which the dosimeters receive between the time they are annealed
and the time they are read out. This error was minimized during this
investigation by storing the dosimeters in a large shield with 15-cm-thick
steel walls after exposure to the radium source until the time they are
read. The extra dose which is accumulated in this way is in the order of
0.069 +; 0.009 mR in one day. Thus, the error introduced here for a total
exposure of 9 mR is about 0.1 percent, and for a 3 mR exposure it is 0.3
percent. The error which is attributable to the fading of the dose between
the time of exposure and the time of readout (cf. page 27) is approximately
0.03 percent.
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All of these contributions to the total error have been tabulated in
Table 1 for a 9 mR exposure to the dosimeters in Group A. Each
contribution has been listed in the column on the right. A typical
calibration factor, using the above data was found to be 0.240 + 0.0056.
The calculations, including the determination of the error term by
propagation of errors, are shown in detail in Appendix A.
Table 1. Contributions to Error in Calibration Factor
Determination for 9 mR Exposure to Dosimeters in Group A
Component
Peak Height
Zero Adjustment
High Voltage
Time of Exposure
Ra Source, Measured at 50 cm
Distance, Source to Detector
Dose Due to Ambient Background
Fading of Dose
Internal Background
Value
37.5 + 0.2 units
+0.1 units
+_ 0.23 units
86.25 + 0.08 min
6.190 + 0.134 mR/hr
50.0 +_ 0.2 cm
0.069 + 0.006 mR
negligible
0.046 + 0.004 mR
INTERNAL BACKGROUND
The internal background (self irradiation) of the dosimeters is due to
radioactivity in the glass and metal components used to construct the
dosimeter. The internal backgrounds for all the dosimeters investigated
were determined by annealing and placing them in a storage container with
15-cm-thick steel walls for a period of one to two weeks. The natural
background within the container was measured with a tissue-equivalent
ionization chamber and confirmed with a high-pressure ionization chamber to
be 2.00 +_ 0.10 micro-roentgen (uR) per hour. The internal background for
the dosimeters was then obtained by subtracting the container background
dose from the total dose accumulated by each dosimeter.
Values obtained from this procedure ranged from 1.7 to 2.5 uR/hr in
Group A. The standard deviations for individual dosimeters in this group
varied from 0.06 to 0.27 uR/hr. The average internal background for the
group was 2.37 uR/hr and the average standard deviation was 0.13 uR/hr.
In Group B the internal backgrounds ranged from 1.5 to 1.8 uR/hr. The
individual standard deviations in this group varied from 0.04 to 0.15
- 8 -
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uR/hr. The average internal background for Group B was 1.63 uR/hr and the
average standard deviation was 0.09 uR/hr.
From the large spread in the values from Group A, it is apparent that
the internal background should be determined separately for each dosimeter.
On the other hand, all the dosimeters in Group B could be assigned the
average value for the entire group and the error introduced would be less
than 10 percent.
The various contributions to the theoretical error in the internal
background for a dosimeter from Group A are shown in Table 2. In arriving
at the values given in the table, it was assumed that the group of
dosimeters was left in the steel shield for a period of 168 hours.
Table 2. Contributions to Error in Internal Background
Determination for Group A Dosimeters Left in Shield One Week
Component
Calibration Factor
Time
Reading
Zero Adjustment
High Voltage
Ambient Background Outside
Shield
Background in Shield
Value
240 +5.6
168 + 0.17 hr
2.80 +_ 0.02 units
+ 0.01 units
+ 0.023 units
14 + 7.3 uR
2.00 + 0.10 uR/hr
The major source of error is the natural background in the shield.
Another large source of error is the uncertainty in the calibration factor.
The error due to the ambient background exposure which the dosimeters
accumulate in transit from the tins they are annealed to the time they are
placed in the steel storage shield, and from the time they are removed from
the storage shield until the time they are read out is small. The
resultant theoretical uncertainty in an internal background for a dosimeter
from Group A is 7.8 percent as computed in Appendix B by propagation of
errors.
THEORETICAL ERROR FOR ENVIRONMENTAL MONITORING
The theoretical error in measuring low-level environmental radiation
with the type of dosimeter used here will be a combination of the error in
the calibration factors and internal backgrounds, as well as the error in
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the determination of the time the dosimeters are actually in the
environment and the error in the readout produced.
The experimental error in the calibration factor for both groups of
dosimeters has been stated to be 2.3 percent. The experimental error in
the internal background is 7.8 percent. The error in the determination of
the peak height is about 1.3 percent for a 6 mR exposure, which is a
typical environmental exposure over a monitoring period of one month. The
time during which the dosimeters are in the environment can be determined
to within 0.1 percent.
Using propagation of errors, the theoretical error in the net dose rate
(environmental dose rate minus internal background) for a 6 mR total
exposure accumulated over a 700 hour monitoring period by the dosimeters in
Group A is calculated in Appendix C. The value of 4.1 percent represents
the precision or reproducibility of this dosimeter-reader system at a
typical environmental radiation level.
PRECISION AND ACCURACY OF DOSIMETERS AS A GROUP
Ten dosimeters whose calibration factors and internal backgrounds were
well known were chosen from Group A and a simulated environmental
measurement was made to quantify the precision attainable with dosimeters
used in a group. The selected dosimeters were annealed and placed in a
laboratory for ten one-month periods. The previously-discussed corrections
were applied to all readings and the results of the ten measurements are
listed in Table 3. The mean values listed in column 1 were obtained by
averaging the net dose rates over the ten dosimeters. The average standard
deviation from the mean (column 2) was 1.1 percent. This is considered
well within the range of the desired precision for environmental
measurements.
Table 3. Trial Exposures of 10 Dosimeters
Date
November 1973
December 1973
January 1974
February 1974
March 1974
April 1974
May 1974
June 1974
July 1974
August 1974
Mean
Dose Rate
(uR/hr)
9.02
8.84
8.83
8.71
8.00
8.78
8.89
8.48
8.72
8.95
Standard
Deviation
of Mean (%)
1.4
1.1
0.9
0.9
1.1
1.0
1.1
1.1
1.1
1.4
Maximum
Deviation
from Mean (%)
6.4
5.9
5.8
4.8
5.9
5.9
5.4
5.9
4.6
5.2
A similar measurement was subsequently made to determine the accuracy
of the mean value of a group of dosimeters. For this measurement, twenty
dosimeters were selected from Group A and were placed in the laboratory
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with a pressurized lonization chamber (PIC) and with a Nal(Tl) survey
meter. After an exposure time of 68 hours, the dosimeters were read out
and the readings obtained were converted to dose rates. Results are shown
in Table 4. The 1.4 percent higher value found from the survey meter
readings is attributed to the fact that it was used to obtain instantaneous
readings, whereas the dosimeters and the PIC were measuring continuously
over the 68-hour period. The performance is excellent when it is observed
that the dosimeters were exposed to a total environmental dose of 0.65 mR.
Table 4. Simulated Environmental Exposure
of 20 Dosimeters from Group A
Measurement
Technique
TLD (20 Dosimeters)
Pressurized lonization Chamber
Nal(Tl) Survey Meter
Mean
Dose Rate
(uR/hr)
9.63
9.61
9.70
Standard
Deviation
(%)
1.8
2.0
2.1
COMPUTER PROGRAM
Since calibration factors and internal backgrounds were measured
separately for each of the 150 dosimeters, large amounts of data were
accumulated. To simplify the calculation, analysis, and storage of these
data, a FORTRAN computer program listed in Appendix D, was written. The
program is designed to store the calibration factors and the internal
backgrounds for each dosimeter. It calculates the mean calibration factor
and internal background with the standard deviation for each dosimeter. It
then scans the data, eliminates readings which deviate by more than 3 sigma
from the mean, and calculates a new mean and a new standard deviation.
Finally, it averages the means of all the dosimeters and calculates the
standard deviation of the population and the standard deviation of the mean
for the entire batch of dosimeters. Examples of the print-outs produced by
the program are reproduced in Tables 5 and 6.
The data stored in the program can be updated at any time. Any of the
existing data can be altered or deleted (note options 1 and 3 on the output
sheets in Tables 5 and 6). Whenever any of the data change, all means and
standard deviations are automatically re-calculated. Also, when new data
cause refinement of a dosimeter's calibration factor, the program
recalculates the internal backgrounds using the new calibration factor.
The program also has the capability of performing dose rate
calculations. The readings for a batch of dosimeters, as well as the
number of hours the dosimeters were being exposed, are entered as input.
The program then takes the most up-to-date calibration factor and internal
background for each dosimeter in the group and calculates the total dose,
the dose rate, and the net dose rate for each dosimeter. The results are
printed out in tabular form, as well as the mean and standard deviation of
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TABLE 5
COMPUTER PRINTOUT OF INDIVIDUAL TLD DATA
what do you want to do?
code.
V4
0=obtain a print out of calibration factor data
l=add to or change calibration data
2=obtain a print out of internal background data
3=add to or change internal background data
4=obtain a list of tld's,calibration factors,and internal bkgs.
5=obtain statistical information on all tlds
6=perform dose rate calculations
you will get a print out for tlds n thru m
enter n and m
V401,425
tld
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
stop
time
cal. fact.
0.318
0.337
0.326
0.328
0.322
0.325
0.327
0.331
0.327
0.334
0.313
0.313
0.319
0.325
0.320
0.307
0.328
0.321
0.328
0.321
0.322
0.316
0.319
0.327
0.328
3 sees.
sigma
0.003
0.005
0.005
0.005
0.005
0.003
0.005
0.007
0.006
0.007
0.003
0.005
0.003
0.005
0.004
0.005
0.005
0.005
0.004
0.006
0.006
0.006
0.004
0.005
0.005
number of
readings
7
7
8
8
7
7
7
7
7
8
7
7
7
7
7
8
8
7
7
7
7
8
7
7
7
int. bkg
1.87
1.93
1.98
1.93
1.85
1.99
1.97
1.87
1.96
1.96
1.92
1.87
1.92
1.90
1.98
1.86
1.85
1.89
1.99
1.86
2.11
2.02
2.19
1.93
1.92
sigma
0.122
0.119
0.154
0.114
0.102
0.146
0.131
0.135
0.109
0.144
0.113
0.157
0.132
0.117
0.074
0.060
0.080
0.082
0.084
0.121
0.112
0.110
0.095
0.133
0.104
number of
readings
7
9
8
8
9
8
9
9
8
9
8
7
8
8
7
8
8
9
8
9
6
8
9
7
9
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TABLE 6
COMPUTER PRINTOUT OF AVERAGE TLD DATA
what do you want to do?
code. . . 0=obtain a print out of calibration factor data
l=add to or change calibration data
2=obtain a print out of internal background data
3=add to or change internal background data
4=obtain a list of tld's,calibration factors,and internal bkgs.
5=obtain statistical information on all tlds
6=perform dose rate calculations
V5
group a ;1 or group b ;2
type 1 or 2
VI
mean calibration factor 0.2596
standard deviation of the population 0.0113
standard deviation of the mean 0.0011
average of individual standard deviations 0.0047
after omitting values which deviate from the mean by
more than 3 sigma the new results are as follows,
mean calibration factor 0.2596
standard deviation of the population 0.0113
standard deviation of the mean 0.0011
mean internal background 2.3738
standard deviation of the population 0.3257
standard deviation of the mean 0.0326
average of individual standard deviations 0.1322
after omitting values which deviate from the mean by
more than 3 sigma the new results are as follows,
mean internal background 2.3555
standard deviation of the population 0.2711
standard deviation of the mean 0.0271
stop
time 2 sees.
- 13 -
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the net dose rate. The program also lists the numbers of any dosimeters
which deviate from the mean by more than two standard deviations. An
example of a printout produced for a batch of ten dosimeters from Group B
which were left in the field for a 730-hour monitoring period is reproduced
in Table 7. The doses listed in the table are in mR and the dose rate,
internal background, and net dose rate columns are in units of uR/hr.
A program of this nature eliminates a major source of human error and
greatly facilitates the handling of data for a large scale environmental or
laboratory investigation with the type of dosimeters studied here.
A second program, listed in Appendix E, was written to calculate and
store TLD environmental surveillance measurements. The operator merely
types in the number of the month, the hours the dosimeters were in the
field and the TLD numbers and associated readings. Printouts can be
obtained with a summary of data from each TLD at a location and the average
and standard deviation for that location. The averages for a location for
each of a number of months can also be obtained for annual reports or
comparison purposes.
TIME-DEPENDENT FADING
The spontaneous decay of electrons from shallow traps at normal
temperatures for different thermoluminescent materials has been observed
previously and is well documented. (6,7) An investigation was conducted in
an attempt to quantify this phenomenon for CaF2iMn.
Twenty-four dosimeters were chosen from group A and exposed to a known
quantity of 226fta gamma rays and read out after a specific time interval.
The measurements were repeated four times for each of a number of time
intervals from 0.5 hours to 3 days. Each reading was corrected for the
ambient background and the dosimeter's internal background. The readings
were normalized by dividing the average corrected reading at 24 hours by
the corrected reading at each other time period. This ratio gives a number
to multiply the readings by in order to standardize the measurements at 24
hours. There was no need to convert the dose to mR, because each time the
dosimeters were given the same dose.
Figure 4 and Table 8 show that fading is an exponential function of
time, with most of the decay in the first 4 hours following exposure.
Also, this investigation showed that fading is predictable and independent
of the previous thermal or exposure history. Table 8 also includes fade
information provided by the manufacturer, which compares well with the
results of this investigation.
- 14 -
-------
TABLE 7
COMPUTER PRINTOUT OF DOSE RATE CALCULATIONS
what do you want to do?
code.
V6
0=obtain a print out of calibration factor data
l=add to or change calibration data
2=obtain a print out of internal background data
3-add to or change internal background data
4"sobtain a list of tId's,calibration factors,and internal bkgs.
5=obtain statistical information on all tlds
6-perform dose rate calculations
enter the number of hours the tlds were in the field
V730
enter the number of tlds you have
V9
enter each of the tld numbers followed by its reading
V401,24.3 402,24.1 403,24.7 404,25.1 405,23.4 406,24.5
V407,28.3 408,24.1 409,25.0
tld
401
402
403
404
405
406
407
408
409
reading
24.30
24.10
24.70
25.10
23.40
24.50
28.30
24.10
25.00
cal fact
0.318
0.337
0.326
0.328
0.322
0.325
0.327
0.331
0.327
dose
7.73
8.13
8.04
8.22
7.55
7.97
9.27
7.98
8.18
dose rate
10.59
11.14
11.02
11.26
10.34
10.92
12.69
10.93
11.20
ib
1.87
1.93
1.98
1.93
1.85
1.99
1.97
1.87
1.96
net dose
8.71
9.21
9.04
9.33
8.49
8.93
10.73
9.06
9.24
rate
mean net dose rate = 9.19 micro roentgen per hour
standard deviation « 0.634 micro roentgen per hour
the following tlds deviated from the mean by more than 2 sigma
tld407
stop
time 3 sees.
- 15 -
-------
OJ
I
•n
£
Tim* After Exposure, hrs
p op
* o> d> — ro A
I
I I I I I I I I
ot o> o
4^ 0) QD
O 00
J I I I I I I I I I I I I I I T I I I I I I I I I
I I I I I I I I I I II I I I I Is
-------
Table 8. Time-Dependent Fading
Time after
exposure (hours)
.5
1.0
2.0
4.75
16.0
24.0
67.75
R&NEB
multiply reading by
.959
.964
.972
.982
.991
1.0
1.011
Victoreen
multiply reading by
.96
.97
.973
.983
.996
1.0
1.01
A second and even less stable electron trap was observed by delivering
large doses (10 R - 15 R) to the dosimeters with a 0.1-Ci 60Co source. The
dosimeters were read out immediately after exposure. When the dosimeters
were placed in the reader, they were observed to give off lieht even before
the heating cycle was initiated. When the dosimeter was heated, the
resulting glow curve had two distinct peaks. The first of these peaks, the
low-temperature peak, was observed to decay at room temperature with a half
life of less than 1 hour. Figure 5 shows a typical two-peak glow curve.
These results confirm the theory(4) that the main glow curve of CaF9:Mn
is really a composite curve formed by the superposition of multiple glow
peaks which arise from a distribution of electron traps of different
trapping characteristics. These traps of varying stability contribute to
the measured height of the main glow peak and hence affect the reading if
the dosimeter is read out before the low-temperature traps have had a
chance to decay out.
DATE I//9/7H-
DOSIMETER NO. *-. O 3 V>
READ BY
KG \
CHECKED BY
Figure 5 Two Ptaked Glow Curvt
- 17 -
-------
Since practically all of the fading occurs within the first day, it was
decided to allow at least 24 hours between exposure and readout for all
dosimeter calibrations. Therefore, for environmental monitoring situations
where the total dose is accumulated over a two to four week period, a
fading correction is not necessary. The only conceivable situation in
which a significant error could be introduced by this procedure would be in
the case of a particularly high dose being received by the dosimeters
immediately before they are picked up to be read out. The error in this
case could amount to 5 percent if the dosimeters are read out within an
hour. For 'environmental monitoring, this situation is considered unlikely.
LINEARITY
The linearity of response as a function of total exposure was
investigated by exposing six random batches of 20-30 dosimeters from Group
A to doses ranging from 0.9 mR to 12.5 mR, a typical range encountered in
environmental monitoring situations. All exposures were from 226Ra gamma
rays.
The readings obtained were converted to mR values and the results were
corrected for the internal background of the individual dosimeters. The
mean values of the corrected data are plotted in Figure 6.
A least squares fit of the data yields a response versus exposure curve
which is linear through zero with a standard deviation of 1.9 percent,
which reflects the eat ablished reproducibility of the dosimeter-reader
system.
EFFECTS OF EXPOSURE TO LIGHT
The fading rate of a dosimeter has been found to increase substantially
when the unshielded detector is exposed to visible light. When exposed to
office fluorescent light, the dosimeters have been observed to lose 4
percent of their readings in 20 minutes and 22 percent of their readings in
2 hours.
Exposure to sunlight, although not specifically studied here, has been
observed(l) to effect a 40 percent reduction in dose in 5 minutes and 90
percent reduction in 10 minutes. It is, therefore, imperative that the
detectors be left in their shields until they are read out.
Other effects, such as microwaves, ultraviolet and magnetic fields,
ultrasonic fields, and mechanical vibrations have not been observed to
affect the response of the dosimeters.
- 18 -
-------
4 6
Actual Dose, mr
8
K>
12
Figure 6 Linearity of Measured Dose vs. Actual Dose
- 19 -
-------
SECTION V
ENVIRONMENTAL MONITORING RESULTS
After all parameters had been determined with sufficient accuracy in
the laboratory, an environmental monitoring program was undertaken at the
Vermont Yankee Nuclear Power Station (BWR) in Vernon, Vermont. A detailed
report of this study has been prepared separately.(8) Results from the
study indicate that the natural background exposure rate can be determined
with a mean uncertainty (2a) of 0.3 uR/hr. Fluctuations in the natural
background due to snow cover on the ground can be observed and quantitated
with TLD's, and increases in the exposure rate as small as 0.9 uR/hr due to
plant operation are detectable.
- 20 -
-------
SECTION VI
REFERENCES
1. Partridge, J. E. and Windham, S. T. , "Suitability of Glass-Encapsulated
CaF2:Mn Thermoluminescent Dosimeters for Environmental Radiation
Surveillance," USEPA Rept. ORP-EERF 73-3 (June 1973).
2. Burke, G. de P., "Investigation of a CaF2:Mn Thermoluminescent
Dosimetry System for Environmental Monitoring," USAEC Rept. HASL-252
(April 1972).
3. Fitzsimmons, c. K. , Horn, W., and Klein, W. L., "A Comparison of Film
Badges and Thermoluminescent Dosimeters Used for Environmental
Monitoring," USEPA Rept. SWRHL-93r (May 1972).
4. Simon, William E., Victoreen Instrument Division, private communication
(March 1974).
5. Cameron, J. R., Suntharalingam, N., and Kenney, G. N.,
Thermoluminescent Dosimetry, University of Wisconsin Press (1968).
6. Spurniz, Z,, "Simultaneous Estimation of Exposure and Time Elapsed
Since Exposure Using Multipeaked Thermoluminescent Phosphors," Health
Physics 21, 755-761 (December 1971).
7. Schulman, J. H., Ginther, R. J., Gorbics, S. G., Nash, A. E., West, E.
J., and Attix, F. H., "Anomalous Fadings of CaF2:Mn Thermoluminescent
Dosimeters," International Journal of Applied Radiation and Isotopes,
Vol. 20, 523-529 (December 1968).
8. Brinck, W. L., Gross, K. C., Gels, G., Partridge, J., "Special Field
Study at the Vermont Yankee Nuclear Power Station," USEPA, Washington,
D. C. (In press).
- 21 -
-------
SECTION VII
APPENDICES
Appendix A. Theoretical Error in Calibration Factor Determination
Error in Readings (R)
Individual Errors
Zero Adjustment 0 ± 0.1 units
High Voltage 0 ± 0.23 units
Peak Height 37.5 ± 0.2 units
o(R) = V(0.1)2 + (0.23)2 + (0.2)2 - 0.32 units
i.e. R = 37.5 ± 0.32 units
Error in Source Strength at 50 cm (S)
Individual Errors
Distance (D) 50 ± 0.2 cm
Radium Mass (M) 1.884 ± 0.038 gm
—ft —2
Scattering Coefficient (S ) 8.65 x 10 cm Effect is so
Attenuation Coefficient (A) 9.11 x 10"5 cm'1
s (mR/h)
8.25 x 10* x 1.884 (e-9.11 x 10~5 x 50 + g ^ x 1Q-8 x (50)2)
5(T
6.190 mR/hr
f a(S)>2 = { 8'25 ; 1()3 (e^ + S D2)a(M)}2 + if
8'25 *™* ^ + 2 ScD>
D D
2 x 8.25 x 10 M (e + S I
D3 °
8'25 V°3 < e'9'11 x 10"5 X 5° + 8.65 x 10-8 x (50)2} 0.038J2
(SO/ /
- 22 -
-------
8.25 x 10* x 1.884 (_ 9>n x 1Q-5 e-9.11 x 10~5 x 50 + ,
50
x 10-8 x 50) - 2 x 8.25 x 103 x 1.884 (e-9.11 x 10'5 x 50 +
(50)
x 10"8 x (50)2) 0.2 ' 2
* 0.01784
o(S) = 0.134 mR/hr
i.e. S = 6.190 + 0.134 mR/hr
Error in Ambient Background (AB)
Individual Errors
Time from annealing, through exposure, to placing in
storage shield (TD1) 2.5+0.5 hrs
oL —
Time from removing from storage to
readout (TB£) 0.5 + 0.25 hrs
Time in storage shield (T ) 21+1.0 hrs
Average background in shield (B ) 2.00 + 0.10 uR/hr
s —
Average background outside
shield (B ) 9.0+1.0 pR/hr
o —
AB = (T ) + T )B + T B
Bl B2 o s s
- (2.5 + 0.5)9 + 21 x 2 - 69 uR
a(AB)
I 2
•• /{T,.,a(B )} + {B
/ Bl o <
V-MBso(Ts)}2
V
(2.5 x l.O)2 + (9.0 x 0.5)2 + (0.5 x 1.0)2+ (9.0 x 0.25)2
+ (21 x O.I)2 + (2.0 x l.O)2
- 6.34 vR
i.e. AB = 0.069 + 0.0063 mR
Error in Internal Background (IB)
From Appendix B,
IB = 1.92 + 0.15 uR/hr
or = 0.046 + 0.004 mR in 24 hrs.
- 23 -
-------
Error in Calibration Factor (CF)
Individual Errors
Reading (R) 37.5+0.32 units
Source Strength (S) 6.190 + 0.134 mR/hr
Ambient Background (AB) 0.069 + 0.0063 mR
Internal Background (IB) 0.046 + 0.004 mR
Exposure Time (T) 1.438 + 0.00278 hr
r,-r. ST + AB + IB
CF _
6.190 x 1.438 + 0.069 + 0.046
37.5
= 0.240 mR/unit
(CF) = /{| a(T)}2 + (|a(s)}2 + {^?1}2 + {^|^I}
y+{ST + AB + IB }2
R2
x 2.78 x :
,0.004.2 ,6.190 x 1.438 + 0.0069 + 0.046 ,2
"""VOTE/ \ T t\ X U • J Z)
J/>;> (37.5)2
= 5.6 x 10~ mR/unit
i.e. CF = 0.240 + 0.0056 mR/unit
- 24 -
-------
Appendix B. Theoretical Error in Internal Background Measurements
Error in Reading (R)
Individual Errors
Zero Adjustment +0.01 units
High Voltage + 0.023 units
Peak Height 2.80+0.02 units
0(R) = ^ (0.01)2 + (0.023)2 + (0.02)2 = 0.032 units
i.e. R = 2.80 + 0.032 units
(Note that this error is a factor of 10 lower than that used in the
calibration factor readings because the internal background measurements
read out on a more sensitive reader scale.)
Error in Ambient Background (AB)
Time from annealing to placing in
storage shield 1.0 hr
Time from removing from storage to
readout 1.0 hr
Time = 2 + 1 hrs
Average background in lab =9+1 yR/hr (7+1 uR/hr above shield
background)
a(AB) = <7 x !> +£ x D = 7.3 pR
AB = 14 + 7.3 uR
Error in Internal Background (IB)
Individual Errors
Calibration Factor (CF) 240 +5.6 uR/unit
Reading (R) 2.80+0.032 units
Ambient Background (AB) 14 + 7.3 pR
- 25 -
-------
Shield Background (SB) 2.00 + 0.10 pR/hr
Time (T) (Including two hours outside shield during annealing
and reading) 168 + 0.17 hrs
_ R(CF) AB
IB - - - SB
2.8(240) 14 _ ,
168 " 2-°° ~ 1>92 R/hr
o(IB) = {f a(CF)}2 + {^ o(R)}2+{^5>.}2 + (a(SB)}2
R(CF) - AB
T2
x 5-6)2 + (x °-032)2 + ()2 + (0-10)2
+(2.8x240-14x0>17)2
= 0.1507
i.e. IB = 1.92 + 0.15 yR/hr
g(IB) _ 0.15 _ . n?R 7 „„
-~ = - °'078 or 7'8%
- 26 -
-------
Appendix C. Theoretical Error for Environmental Monitoring
Individual Errors
Reading (R) 25.0+0.32 units
Calibration Factor (CF) 240 +5.6 pR/unit
Time (T) 700 + 1 hr
Internal Background (IB) 1.92+0.15 pR/hr
Net Dose Rate = - IB
o(Net Dose Rate) = W{£ o(CF)}2 + {%j- a(R)}2 + {a(IB)}2 + {^^- a(T)}2
(|^x5.6)2+(|§x0.32)2+(0.15)2
/25 x 240
(
490.000
- 0.273 pR/hr
i.e. Net Dose Rate » 6.65 + 0.27 pR/hr
a(Net Dose Rate) 0.273 - n.. . .„
Net Dose Rate ' 6^5~ = °'041 or 4'U
- 27 -
-------
Appendix D. Program for Data Storage and Management of TLD Calibration Factors
and Internal Backgrounds and for Performing Dose Rate Calculations
40 "THE PROGRAM IS DESIGNED TO STORE UP TO 15 CALIBRATION FACTORS "
50 "AND 15 INTERNAL BACKGROUNDS FOR 150 DOSIMETERS"
60
70 " THE PROGRAM USES SUBROUTINE STDEV WHICH ACCEPTS THE
80 "ONE DIMENSIONAL ARRAY X AS INPUT AND CALCULATES THE
90 "MEAN AND STANDARD DEVIATION OF THE ELEMENTS OF X"
100
110 REAL IB,MEAN, IB2,IB3,INTBKG,NDRC150),HOURS
120 DIMENSION READC150),NOC150),DOSEC150),DRC150), J2C150)
130 DIMENSION AVGCF2C150),SIGCF2C150),INTBKGC150,15),NUMBR1C150),NU
MBR2C150)
140 DIMENSION IBC150,15),CFC150,15),MEANC150)
150 DIMENSION SIGCFC150),AVGCFC150),CF2C150)
160 DIMENSION IB2C150),AVGIB2C150),N02C150)
170 DIMENSION AVGIBC150),SIGIBC150),SIGIB2C150)
180 GO TO 75
190
200 " CFCN,M) = CALIBRATION FACTOR NUMBER M FOR TLD NUMBER N
210 " IB = INTERNAL BACKGROUND
220 " IBCN,M) = INTERNAL BACKGROUND NUMBER M FOR TLD NUMBER N
230 " NDR = NET DOSE RATE IN MICRO » PER HOUR
240 " HOURS = NUMBER OF HOURS TLDS ARE IN FIELD CFOR DOSE RATE
250 " CALCULATIONS)
260 " DOSE = TOTAL DOSE ON DOSIMETERS
270 " DR = DOSE RATE (DOSE/HOURS)
280 " AVGCFCN) = MEAN CALIBRATION FACTOR FOR TLD NUMBER N
290 " AVGCF2CN) = NEW MEAN, CALCULATED AFTER OMITTING VALUES WHICH
300 " DEVIATE FROM AVGCFCN) BY MORE THAN 3 STANDARD DEVIATIONS
310 " SIGCFCN) = STANDARD DEVIATION OF CALIBRATION FACTORS FOR TLD
320 " NUMBER N
330 " SIGCF2CN) = NEW STANDARD DEVIATION AFTER OMITTING VALUES
340 " WHICH DEVIATE FROM AVGCFCN) BY MORE THAN 3 STANDARD
350 " DEVIATIONS
360
370 2 WRITEC6,3)
380 3 FORMATC'+','WHAT DO YOU WANT TO DO"')
390 WRITEC6,58)
400 58 FORMATC1 ','CODE. . . 0=OBTAIN A PRINT OUT OF CALIBRATION FA
CTOR DATA1)
410 WRITEC6,59)
420 59 FORMATC' ',10X,'1=ADD TO OR CHANGE CALIBRATION DATA')
430 WRITE(6,660)
440 660 FORMATC ',10X,'2=OBTAIN A PRINT OUT OF INTERNAL BACKGROUND
DATA')
450 WRITEC6,66l)
460 661 FORMATC' ',10X,«3=ADD TO OR CHANGE INTERNAL BACKGROUND DATA
- 28 -
-------
WRITEC6,662)
480 662 FORMATC1 '/10X,'4=OBTAIN LIST OF TLD)S,CALIBRATION FACTORS,
AND INTERNAL BKGS.')
490-WRITEC6,663)
500 663 FORMATC1 ',10X,»5=OBTAIN STATISTICAL INFORMATION ON ALL TLD
510 WRITEC6,664)
520 664 FORMATC ',10X,'6=PERFORM DOSE RATE CALCULATIONS')
530 "
540 " KKK IS READ IN AT EXECUTION TIME AND GIVES THE USER AN
550 " OPTION AS TO WHICH SECTION OF THE PROGRAM HE WISHES TO USE
560 "
570 75 READC5/") KKK
580 IFCKKK.EQ.O) GO TO 222
590 IFCKKK.EQ.l) GO TO 76
600 IFCKKK.EQ;2) GO TO 222
610 IFCKKK.EQ.3) GO TO 222
620 IF(KKK.EQ.4) GO TO 222
630 IFCKKK.EQ.5) GO TO 222
640 IFCKKK.EQ.6) GO TO 222
650 WRITEC6,77)
660 77 FORMATC'+','TRY AGAIN FUMBLE FINGERS')
670 GO TO 75
680
690 " THIS SECTION OF THE PROGRAM IS USED FOR ADDING A NEW GROUP
700 " OF CALIBRATION FACTORS OR FOR CHANGING ANY PREVIOUSLY STORED
DATA
710
720 76 CONTINUE
730 100 FORMATC1 ','NEW GROUP OF DATA CD/ CHANGE EXISTING DATA C2)
')
740 WRITEC6/100)
750 WRITEC6,102)
760 102 FORMATC' ','TYPE 1 OR 2')
770 105 READC5,55) KK
780 IFCKK.EQ.2) GO TO 103
790 IFCKK.EQ.l) GO TO 104
800 WRITEC6,77)
810 GO TO 105
820
830 " ALL CALIBRATION FACTORS FROM DATA FILE KG ARE READ IN
840
850 104 CALL OPENC2/'NAM1','INPUT')
860 READC2,55) CCCFCN,M),M=1,15),N=1,150)
870 908 CALL CLOSEC2)
880
890 " THE PROGRAM SORTS THROUGH THE READINGS FOR EACH DOSIMETER"
900 " UNTIL A ZERO READING IS FOUND, THEN READS IN A NEW CALIBRATIO
N"
910 " FACTOR FOR THAT DOSIMETER AND REPLACES THE ZERO READING WITH
IT."
920
930 WRITEC6,320)
940 320 FORMATC1 ','ENTER EACH TLD NUMBER AND ITS CAL. FACT.,'/1 WH
EN DONE, TYPE 0,0')
950 824 READC5,J:) N,X
951 IFCN.GT.150) GO TO 10
952 IFCN.EQ.O) GO TO 10
- 29 -
-------
960 CALL NUMBERCN,N1)
970 N=N1
1000 DO 822 M=l/15
1010 IFCCFCN,M).EQ.O.) GO TO 823
1020 822 CONTINUE
1030 823 CFCN.M)=X
1040 GO TO 824
1130 110 FORMATC' ','TYPE IN N,M,AND X. . .WHERE N IS THE NUMBER OF
THE TLD, M IS THE NUMBER1)
1140
1150 " THIS SEGMENT ENABLES THE USER TO REPLACE ANY INDIVIDUAL "
1160 " READING FOR ANY DOSIMETER BY TYPING IN THE NUMBER OF THE TLD
it
Il70 " THE NUMBER OF THE READING TO BE REPLACED, AND THE NEW C.F."
1180
1190 103 WRITEC6,110)
1200 WRITEC6,112)
1210 112 FORMATC1 ','OF THE READING YOU WISH TO REPLACE, AND X IS T
HE NEW CALIBRATION FACTOR')
1220 WRITEC6,113)
1230 113 FORMATC' ','THEN HIT RETURN. REPEAT FOR AS MANY TLDS AS Y
OU LIKE. ')
1240 WRITEC6,114)
1250 114 FORMATC1 ',' WHEN DONE, HIT RETURN AND TYPE 0,0,0')
1260
1270 " ALL CALIBRATION NUMBERS ARE READ IN FROM DATA FILE KG
1280
1290 CALL OPENC2,'NAM11,1INPUT1)
1300 READC2,") CCCFCN,M),M=1,15),N=1,150)
1310 CALL CLOSEC2)
1320 120 READC5,S!) NN,MM,XX
1350
1360 " NN = NUMBER OF TLD
1370 " MM = NUMBER OF CALIBRATION FACTOR YOU WISH TO CHANGE
1380 " XX = NEW CALIBRATION FACTOR
1390
1400 IFCNN.EQ.O) GO TO 10
1410 IFCMM.EQ.O) MM=15
1420 IFCMM.GT.15) MM=15
1421 CALL NUMBERCNN,N1)
1422 NN=N1
1430 CFCNN,MM) = XX
1440 GO TO 120
1450 10 CONTINUE
1460
1470 " ALL NEW DATA IS NOW WRITTEN ON DATA FILE KG
1480
1490 CALL OPENC2,'NAM1','OUTPUT')
1500 WRITEC2,*) CCCFCN,M),M=1,15),N=1,150)
1510 CALL CLOSEC2)
1520 IFCKKK.EQ.l) STOP
1530 222 CONTINUE
- 30 -
-------
1550 " READ IN ALL CALIBRATION FACTORS FROM DATA FILE KG"
1560
1570 CALL OPENC2,'NAM11,1INPUT')
1580 READ(2,«) CCCFCN,M),M=1,15),N=1,150)
1590 CALL CLOSEC2)
1600
1610 " COUNT THE NUMBER OF CALIBRATION FACTORS FOR EACH DOSIMETER
1620 " AND SET THE NUMBER EQUAL TO J
1630
1640 DO 15 N=l,150
1650 DO 133 JJ=1,15
1660 IFCCFCN,JJ).NE.O.) GO TO 14
16?0 J=JJ-1
1680 GO TO 933
1690 14 CF2CJJ)=CF(N,JJ)
1700 d=JJ
1710 133 CONTINUE
1720 933 CONTINUE
1730
1740 " FIND THE AVERAGE CALIBRATION FACTOR FOR EACH DOSIMETER
1750 " SET AVERAGE EQUAL TO AVGCF(N) AND STANDARD DEVIATION EQUAL T
0 SIGCF(N)
1760
1770 CALL STDEVCCF2,J,AVG,SIGMA)
1780 AVGCF(N)=AVG
1790 SIGCFCN)=SIGMA
1800 K=l
1810 DO 31 KK=1,J
1820
1830 " CALCULATE DD, THE DEVIATION FROM THE MEAN FOR EACH CALIBRATI
ON FACTOR
1840
1850 DD=ABSCCF2CKK)-AVGCFCN))
i860 IF(DD.GE.3s:SIGCFCN)) GO TO 31
1870 CF2CK)=CF2CKK)
1880 K=K+1
1890 31 CONTINUE
1900
1910 " CF2 NOW REPRESENTS ALL CALIBRATION FACTORS FOR TLD N WHICH D
0
1920 " NOT DEVIATE FROM THE MEAN BY MORE THAN 3 STANDARD DEVIATIONS
1930 " NOW FIND A NEW MEAN FOR CF2, SET THE NEW MEAN EQUAL TO AVGCF
2CN),
1940 " AND SET THE NEW STANDARD DEVIATION EQUAL TO SIGCF2CN)
1950 "
I960 CALL STDEVCCF2,K-1,AVG,SIGMA)
1970 AVGCF2CN)=AVG
1980 SIGCF2CN)=SIGMA
1990 NUMBR1CN)=J
2000 15 CONTINUE
2010 "
- 31
-------
2020 " NOW FIND THE MEAN OF THE AVERAGE CALIBRATION FACTORS FOR
2030 " THE ENTIRE BATCH AND SET THIS MEAN EQUAL TO AVGTOT
2040 " THEN FIND THE MEAN OF THE INDIVIDUAL STANDARD DEVIATIONS
2050 " AND SET THIS EQUAL TO AVGSIG1
2060 " FINALLY, CALCULATE THE STANDARD DEVIATION OF THE POPULATION
2070 " AND SET THIS EQUAL TO SM
2080
2090 IFCKKK.NE.5) GO TO 406
2100 WRI TEC6,400)
2110 400 FORMATC1 ','GROUP A CD OR GROUP B C2)1,/,' TYPE 1 OR 2')
2120 403 READC5/!:) K3
2130 IFCK3.EQ.1) GO TO 401
2140 IFCK3.EQ.2) GO TO 402
2150 WRITEC6,77)
2160 GO TO 403
2170 401 Nl=51
2180 N2=150
2190 DO 410 N=l,100
2200 N3=N+50
2210 AVGCF2CN)=AVGCF2CN3)
2220 410 SIGCF2CN)=SIGCF2CN3)
2230 CALL STDEVCAVGCF2,N,AVGTOT,SIGTOT)
2240 CALL STDEVCSIGCF2,N,AVSIGl,s:>
2250 SM=SIGTOT/SQRTCFLOATCN))
2260 GO TO 405
2270 402 Nl=l
2280 N2=50
2290 N=50
2300 CALL STDEVCAVGCF2,N,AVGTOT,SIGTOT)
2310 CALL STDEVCSIGCF2,N,AVSIG1,S)
2320 SM=SIGTOT/SQRTCFLOATCN))
2330 L=l
2340
2350 " CALCULATE D, THE DEVIATION FROM THE MEAN FOR EACH TLD
2360 " AND OMIT VALUES WHICH DEVIATE BY MORE THAN 3 SIGMA
2370 " THEN CALCULATE A NEW MEAN, STANDARD DEVIATION OF THE
2380 " NEW MEAN, AND THE STANDARD DEVIATION OF THE NEW POPULATION
2390
2400 DO 85 N=l,50
2410 D=ABSCAVGCF2CN)-AVGTOT)
2420 IFCD.GE.3"SIGTOT) GO TO 85
2430 CF2CD=AVGCF2CN)
2440 L=L+1
2450 85 CONTINUE
2460 CALL STDEVCCF2,L-1,AVGT2,SIGT2)
2470 SM2=SIGT2/SQRTCFLOATCD)
2480 GO TO 406
2490 405 CONTINUE
2500 L=l
2510 DO 407 N=l,100
2520 AVGCF2CN3)=AVGCF2CN)
2530 SIGCF2CN3)=SIGCF2CN)
- 32 -
-------
D=ABSCAVGCF2CN)-AVGTOT)
2550 IFCD.GE.S^SIGTOT) GO TO 407
2560 CF2CL)=AVGCF2CN3)
2570 L=L+1
2580 407 CONTINUE
2590 CALL STDEVCCF2,L-1,AVGT2,SIGT2)
2600 SM2=SIGT2/SQRTCFLOATCL))
2610 406 CONTINUE
2620 IFCKKK.EQ.2) GO TO 225
2630 IFCKKK.EQ.3) GO TO 520
2640 IFCKKK.EQ.4) GO TO 225
2650 IFCKKK.EQ.6) GO TO 225
2660 IFCKKK.EQ.5) GO TO 225
2670
2680 " THIS SEGMENT OF THE PROGRAM PRINTS OUT ALL CALIBRATION FACTO
R DATA
2690
2700 756 WRITE06,755)
2710 755 FORMATC' ','PRINTOUT FOR GROUP IIS, OR INDIVIDUALS |2S«)
2720 WRITEC6,102)
2730 READC5,") K3
2740 1FCK3.EQ.2) GO TO 759
2750 IFCK3.EQ.1) GO TO 757
2760 WRITEC6,77)
2770 GO TO 756
2780 759 CONTINUE
2790 WRITEC6,760)
2800 760 FORMATC1 ','ENTER THE NUMBER OF TLDS YOU WANT PRINTED OUT1
)
2810 READ(5,::) N01
2820 WRITEC6,76l)
2830 761 FORMATC1 ','ENTER THE NUMBERS OF THE TLDS')
2840 READC5,") CN02CI),I=1,N01)
2850 DO 752 N=1,N01
2860 CALL NUMBERCN02CN),L)
2870 NUM=NUMBR1CL)
2880 WRITEC6,753) NO2CN)/CCFCl./M)/M=l/NUM)
2890 753 FORMATC'0'/l3/7F9.4///4x/7F9.4)
2900 752 CONTINUE
2910 STOP
2920 757 CONTINUE
2930 WRITEC6,920)
2940 920 FORMATC' ','YOU WILL GET A PRINT OUT FOR TLDS N THRU M1)
2950 WRITEC6,121)
2960 121 FORMATC' ','ENTER N AND M»)
2970 READC5,") N1,N2
2980 CALL NUMBERCN1,N4)
2990 Nl=N4
3000 CALL NUMBERCN2,N5)
3010 N2=N5
3020 WRITEC6,43)
3030 43 FORMATC1 ','TLD'3X'CAL FACT'3X'MEAN'5X'SIGMA'3X'NEW MEAN'3X
'NEW SIGMA1)
- 33 -
-------
3040 DO 52 N=N1,N2
3050 CALL NUMB2CN,N7)
3060 WRITEC6,42)N7,CFCN,1),AVGCFCN),SIGCFCN),AVGCF2CN),SIGCF2CN)
3070 42 FORMATC1 ',I3,F9.3,F10.3,F9.3,2F10.3)
3080 NUM=NUMBR1CN)
3090 DO 52 M=2,NUM
3100 WRITEC6,4l) CFCN,M)
3110 41 FORMATC1 ',6X,F6.3)
3120 52 CONTINUE
3130 IFCKKK.EQ.O) STOP
3140 IFCKKK.EQ.l) STOP
3150
3160 " THIS SEGMENT OF THE PROGRAM ALLOWS THE USER TO ADD TO OR
3170 " CHANGE THE INTERNAL BACKGROUND DATA
3180
3190 520 WRITEC6,100)
3200 WRITEC6,102)
3210 130 READC5/O KK
3220 IFCKK.EQ.2) GO TO 131
3230 IFCKK.EQ.l) GO TO 132
3240 WRITEC6,77)
3250 GO TO 130
3260 "
3270 " IF THE USER WANTS TO ADD A NEW GROUP OF DATA, ALL THE DATA
3280 " FROM FILE IB ARE FIRST READ IN AND THE NEW READINGS ARE
3290 " INSERTED. THE DATA IS THEN REWRITTEN ONTO FILE IB
3300 "
3310 132 CALL OPENC3,'IB',1INPUT1)
3320 READC3,") CCIBCN,M),M=1,15),N=1,150)
3330 1033 CALL CLOSEC3)
3340 WRITEC6,431)
3350 431 FORMATC' ','ENTER THE NUMBER OF HOURS THE TLDS WERE IN THE
FIELD1)
3360 READC5,!!) HOURS
3370 WRITEC6,430)
3380 430 FORMATC' ','ENTER EACH TLD NUMBER AND ITS READING,'/• WHEN
DONE.TYPE 0,0')
3390 432 READC5/O N,X
3400 CALL NUMBERCN,N1)
3410 N=N1
3420 IFCN.GT.150) GO TO 134
3430 IFCN.EQ.O) GO TO 50
3440 DO 135 M=l,15
3450 IFCIBCN,M).EQ.O.) GO TO 136
3460 135 CONTINUE
3470 136 IBCN/M)=X!!1000/HOURS
3480 GO TO 432
3490 134 WRITEC6,433)
3500 433 FORMATC' ','TLD NUMBER TOO BIG, TRY AGAIN')
3510 GO TO 432
3520
3530 " HERE THE USER CAN CHANGE INDIVIDUAL DATA POINTS BY ENTERING
- 34 -
-------
3540 " THE NUMBER OF THE TLD, THE NUMBER OF THE READING TO BE
3550 " REPLACED, AND THE NEW READING
3560 "
3570 131 WRITE(6,110)
3580 WRITE(6,772)
3590 772 FORMATC* ','OF THE READING YOU WANT REPLACED, AND X IS THE
NEW INTERNAL BACKGROUND1)
3600 WRITEC6,113)
3610 WRITEC6,ll4)
3620 CALL OPENC3,'IB','INPUT')
3630 READ(3,}!) CCIB(N,M),M=1,15),N=1,150)
3640 CALL CLOSEC3)
3650 137 READ(5,'!) NN,MM,XX
3660 CALL NUMBER(NN,N1)
3670 NN=N1
3680 IFCNN.EQ.O) GO TO 50
3690 IFCMM.EQ.O) MM=15
3700 IBCNN,MM)=(XX+2.)/AVGCF2CNN)
3710 IFCXX.EQ.O.) IBCNN,MM)=0.
3720 GO TO 137
3730 50 CONTINUE
3740
3750 " ALL NEW INTERAL BACKGROUND DATA IS WRITTEN OF FILE IB
3760
3770 CALL OPENC3,'IB','OUTPUT')
3780 WRITEC3,*) CCIBCN,M),M=1,15),N=1,150)
3790 CALL CLOSEC3)
3800 STOP
3810 225 CONTINUE
3820
3830 " THE INTERNAL BACKGROUND DATA ARE READ IN AND THE STANDARD
3840 " DEVIATIONS FOR EACH DOSIMETER ARE CALCULATED
3850
3860 CALL OPENC3,'IB1,'INPUT1)
3870 READ(3,«,END=777) CCIBCN,M),M=1,15),N=1,150)
3880 777 CONTINUE
3890 CALL CLOSEC3)
3900 DO 61 N=l/150
3910 DO 62 dd=l,15
3920 IFClB(N,dd).NE.O.) GO TO 63
3930 J=JJ-1
3940 GO TO 962
3950 63 INTBKGCN,JJ) = IBCN/JJ)!SAVGCF2CN)-2.
3960 IB2CJJ)=INTBKG(N,dd)
3970 d=dd
3980 62 CONTINUE
3990 962 CONTINUE
4000 CALL STDEVClB2/d,AVG/SIGMA)
4010 AVGIBCN)=AVG
4020 SIGIB
-------
4050 " THE DEVIATION FROM THE MEAN IS CALCULATED AND ALL READINGS
4060 " WHICH DEVIATE FROM THE MEAN BY MORE THAN 3 SIGMA ARE LEFT OU
T
4070 " A NEW MEAN AND A NEW STANDARD DEVIATION ARE THEN CALCULATED
4080
4090 " THE NEW MEAN IS SET EQUAL TO AVGIB2 AND THE NEW STANDARD
4100 " DEVIATION IS SET EQUAL TO SIGIB2
4110
4120 DO 64 KK=1,J
4130 D=ABSCIB2CKK)-AVGIBCN)>
4140 IFCD.GE.3"SIGIBCN)) GO TO 640
4150 IB2(K)=IB2CKK)
4160 K=K+1
4170 640 CONTINUE
4180 64 CONTINUE
4190 CALL STDEVCIB2/K-1/AVG/SIGMA)
4200 AVGIB2(N)=AVG
4210 SIGIB2CN)=SIGMA
4220 NUMBR2(N)=J
4230 61 CONTINUE
4240
4250 " NOW THE STANDARD DEVIATION OF THE ENTIRE POPULATION IS
4260 " CALCULATED AND SET EQUAL TO AVGT3 AND THE STANDARD
4270 " DEVIATION OF THE INDIVIDUAL STANDARD DEVIATIONS (IF YOU
4280 " CAN DIG THAT) IS CALCULATED AND SET EQUAL TO AVSIG2
4290
4300 IFCK3.EQ.2) GO TO 408
4310 IFCKKK.NE.S) GO TO 436
4320 Nl=51
4330 N2=150
4340 DO 409 N=l,100
4350 N3=N+50
4360 AVGIB2CN)=AVGIB2CN3)
4370 SIGIB2(N)=SIGIB2(N3)
4380 409 CONTINUE
4390 CALL STDEV(AVGIB2,N,AVGT3,SIGT3)
4400 CALL STDEVCSIGIB2,N,AVSIG2,S)
4410 SM3=SIGT3/SQRT(FLOATCN))
4420 LL=1
4430 DO 411 N=l/100
4440 D=ABSCAVGIB2(N)-AVGT3)
4450 AVGIB2CN3)=AVGIB2CN)
4460 SIGIB2CN3)=SIGIB2CN)
4470 IFCD.GE.3"SIGT3) GO TO 411
4480 IB2CLL)=AVGIB2(N3)
4490 LL=LL+1
4500 411 CONTINUE
4510 CALL STDEVCIB2,LL-1,AVGT4,SIGT4)
4520 SM4=SIGT4/SQRTCFLOATCLL))
4530 GO TO 412
4540 408 N=50
4550 CALL STDEVCAVGIB2/N,AVGT3/SIGT3)
- 36 -
-------
4560 CALL STDEVCSIGIB2,N,AVSIG2,S)
4570 SM3=SIGT3/SQRTCFLOATCN»
4580 LL=1
4590 DO 88 N=l,50
4600
4610 " AGAIN, THE DEVIATION FROM THE MEAN IS CALCULATED AND THE
4620 " NUMBERS WHICH DEVIATE BY MORE THAN 3 SIGMA ARE TEMPORARALLY
4630 " OMITTED AND A NEW MEAN AND STANDARD DEVIATION IS CALCULATED
4640
4650 D=ABSCAVGIB2CN)-AVGT3>
4660 IF(D.GE.3!:SIGT3) GO TO 88
4670 IB2(LL)=AVGIB2CN)
4680 LL=LL+1
4690 88 CONTINUE
4700 CALL STDEVCIB2,LL-1,AVGT4,SIGT4)
4710 SM4=SIGT4/SQRT(FLOATCLL))
4720 412 CONTINUE
4730 436 CONTINUE
4740 IFCKKK.EQ.4) GO TO 70
4750 IFCKKK.EQ.6) GO TO 311
4760 IFCKKK.EQ.5) GO TO 80
4770
4780 " THIS SECTION OF THE PROGRAM PRINTS OUT ALL INTERNAL BACKGROU
ND
4790 " DATA. THE USER CAN PRINT OUT ANY SUBGROUP OF DATA FROM
4800 " TLD Nl THROUGH TLD N2
4810
4820 " TLD
4830 766 WRITEC6,755)
4840 WRITEC6/102)
4850 READC5/O K3
4860 IFCK3.EQ.2) GO TO 769
4870 IFCK3.EQ.1) GO TO 767
4880 WRITEC6,77)
4890 " TLD Nl THROUGH TLD N2
4900 GO TO 766
4910 769 CONTINUE
4920 WRITEC6,760)
4930 READC5,") N01
4940 WRITEC6,76i:>
4950 READC5,") (N02CI),!=!,N01)
4960 DO 762 N=1,N01
4970 CALL NUMBERCN02(N),L;>
4980 NUM=NUMBR2CD
4990 WRITECe^SS) N02CN),CINTBKGCL/M),M=1/NUM)
5000 762 CONTINUE
5010 STOP
5020 767 CONTINUE
5030 WRITEC6,920;>
5040 WRITE(6/121)
5050 READC5,") Nl,N2
5060 CALL NUMBERCN1/N4)
- 37 -
-------
5070 Nl=N4
5080 CALL NUMBERCN2,N5)
5090 N2=N5
5100 IFCN2.GE.150) N2=150
5110 WRITEC6,83)
5120 83 FORMATC' ','TLD'3X'INT BKG'4x»MEAN'5X'SIGMA'3X'NEW MEAN'2X'
NEW SIGMA1)
5130 DO 71 N=N1,N2
5140 CALL NUMB2CN,N9)
5150 WRITEC6,42) N9,INTBKGCN,1),AVGIBCN),SIGIBCN),AVGIB2CN),SIGIB2C
N)
5160 NUM2=NUMBR2CN)
5170 DO 71 M=2,NUM2
5180 WRITEC6,4l) INTBKGCN,M)
5190 71 CONTINUE
5200 70 CONTINUE
5210
5220 " CALIBRATION FACTORS AND INTERNAL BACKGROUNDS IN TABULAR
5230 " FORM FOR TLDS N THROUGH M. IT ALSO PRINTS OUT THE NUMBER
5240 " OF READINGS STORED IN MEMORY FOR EACH DOSIMETER.
5250
5260 IFCKKK.NE.4) STOP
5270 WRITEC6,920)
5280 WRITEC6,121)
5290
5300 " Nl AND N2 ARE READ IN
5310
5320 READ(5,!O N1,N2
5330 CALL NUMBERCN1,N4)
5340 CALL NUMBERCN2,N5)
5350 N1=N4
5360 N2=N5
5370 WRITEC6,15D
5380 151 FORMATC1 ',24X, 'NUMBER OF'^OX,'NUMBER OF')
5390 WRITEC6,8l)
5400 81 FORMATC1 ',ITLD'/2X/'CAL. FACT.',2X/'SIGMA1,2X,'READINGS',4
X,'INT. BKG'/2X/'SIGMA'/2X,'READINGS')
5410 DO 80 N=N1,N2
5420 CALL NUMB2CN,N8)
5430 WRITEC6,82) N8/AVGCF2CN)/SIGCF2CN)/NUMBR1CN)/AVGIB2CN)/SIGIB2C
N).NUMBR2CN)
5440 82 FORMATC1 ',I3/F10.3/F10.3,l6,Fl3.2,F10.3,l6)
5450 80 CONTINUE
5460
5470 " THIS SECTION OF THE PROGRAM PRINTS OUT ALL STATISTICAL
5480 " INFORMATION ON THE TWO GROUPS OF DOSIMETERS. SUCH INFOR-
5481 " MATION AS THE AVERAGE CALIBRATION FACTOR AND AVERAGE
5490 " INTERNAL BACKGROUND FOR THE ENTIRE BATCH OF DOSIMETERS
5500 " IS PRINTED OUT.
5510
5520 IFCKKK.NE.5) STOP
5530 WRITEC6,84) AVGTOT
- 38 -
-------
55^0 84 FORMATC'O',/,' MEAN CALIBRATION FACTOR=', T50,F?.4)
5550 WRITEC6,86) SIGTOT
5560 86 FORMATC'O','STANDARD DEVIATION OF THE POPULATION=',T50,F7.4
)
5570 WRITEC6,87) SM
5580 8? FORMATC'O1,'STANDARD DEVIATION OF THE MEAN=',T50,F7.4)
5590 WRITEC6,150) AVSIG1
5600 150 FORMATC'O','AVERAGE OF INDIVIDUAL STANDARD DEVIATIONS:',T5
0,F7.4)
5610 WRITEC6,888)
5620 888 FORMATC'O',/,' AFTER OMITTING VALUES WHICH DEVIATE FROM TH
E MEAN BY «)
5630 WRITEC6,94)
5640 WRITEC6,84) AVGT2
5650 WRITEC6,86) SIGT2
5660 WRITEC6,87) SM2
5670 WRITEC6,90) AVGT3
5680 90 FORMATC'O1,/,' MEAN INTERNAL BACKGROUND=',T50,F7.4)
5690 WRITEC6,86) SIGT3
5700 91 FORMATC'O1,'STANDARD DEVIATION OF THE POPULATION:',F5.2)
5710 WRITEC6,87) SM3
5720 92 FORMATC'O','STANDARD DEVIATION OF THE MEAN=',F5.2)
5730 WRITEC6,150) AVSIG2
5740 WRITEC6,888)
5750 WRITEC6,94)
5760 94 FORMATC' ','MORE THAN 3 SIGMA THE NEW RESULTS ARE AS FOLLOW
s,1)
5770 WRITEC6,90) AVGT4
5780 WRITEC6,86) SIGT4
5790 WRITEC6/87) SM4
5800 311 CONTINUE
5810 IFCKKK.EQ.5) STOP
5820
5830 " THIS SEGMENT OF THE PROGRAM PERFORMS DOSE RATE CALCULATIONS
5840 " THE NUMBER OF HOURS THE TLDS WERE IN THE FIELD AND ALL OF TH
E
5850 " READINGS FOR A BATCH OF TLDS ARE READ IN AS INPUT AND THE
5860 " PROGRAM CALCULATES THE TOTAL DOSE, THE TOTAL DOSE RATE, AND
5870 " THE NET DOSE RATE.
5880
5890
5900 WRITEC6,312)
5910 312 FORMATC' ','ENTER THE NUMBER OF HOURS THE TLDS WERE IN THE
FIELD1)
5920 READC5/!!) HOURS
5930 WRITEC6,316)
5940 316 FORMATC'O','ENTER THE NUMBER OF TLDS YOU HAVE')
5950 READC5,):) N3
5960 WRITEC6,317)
5970 317 FORMATC'O1,'ENTER EACH OF THE TLD NUMBERS FOLLOWED BY ITS
READING1)
- 39 -
-------
5980 READC5,") CNOCNN),READCNN),NN=1,N3)
5990 DO 827 13=1,N3
6000 CALL NUMBER(NOCI3),N6)
6010 827 NOCI3)=N6
6020 N3=N3+1
6030 DO 300 NN=1,N3
6040 IFCNO(NN).EQ.O) GO TO 301
6050 DOSE(NN)=READCNN)5:AVGCF2CNO(NN))
6060 DRCNN)=1000"DOSECNN)/HOURS
6070 NDRCNN)=DRCNN)-AVGIB2(NOCNN))
6080 300 CONTINUE
6090 301 WRITE(6,303)
6100 303 FORMATC1 ',' TLD',3X'READING',3X,'CAL FACT1, 4x 'DOSE ', 4X, 'D
OSE RATE',5X,'IB'jSX'NET DOSE RATE1)
6110 NN2=NN-1
6120 DO 302 N=1,NN2
6130 CALL NUMB2CNOCN),N7)
6140 WRITE(6,304)N7,READCN),AVGCF2CNOCN)),DOSE(N),DRCN),AVGIB2(NOCN
)),NDR(N)
6150 302 CONTINUE
6160 304 FORMATC' I/I3/^X,F6.2/5X,F6.3,3X^6.2,5X,F7.2/5X ,F4.2,5X
,F7.2)
6170
6180 " THE AVERAGE NET DOSE RATE AND THE STANDARD DEVIATION ARE
6190 " ARE CALCULATED
6200
6210 CALL STDEV(NDR,NN2/A,S)
6220 J=l
6230 DO 305 N=1,NN2
6240
6250 " ANY READINGS WHICH DEVIATE FROM THE MEAN BY MORE THAN 2
6260 " STANDARD DEVIATIONS ARE LOCATED AND PRINTED OUT
6270
6280 D=ABSCNDRCN)-A)
6290 IFCD.LE.2-S) GO TO 305
6300 J2(J)=NO(N)
6310 J=J+1
6320 305 CONTINUE
6330 WRITE(6/3l4) A
6340 WRITE(6,315) S
6350 315 FORMATC'O1,'STANDARD DEVIATION 5!I,F8.3,' MICRO ROENTGEN PE
R HOUR1)
6360 307 FORMATC'O','TLD',13)
6370 K=J-1
6380 WRITEC6,308)
6390 308 FORMATC'0','THE FOLLOWING TLDS DEVIATED FROM THE MEAN BY M
ORE THAN 2 SIGMA')
6400 IFCK.EQ.O) GO TO 309
6410 DO 306 I=1,K
6415 CALL NUMB2(J2CI),I5)
6420 WRITEC6,307) 15
- 40 -
-------
6430 306 CONTINUE
6440 STOP
6450 309 WRITE(6,310)
6460 310 FORMATC'O','NONE')
6470 314 FORMATC'O1,'MEAN NET DOSE RATE »',F8.2,' MICRO ROENTGEN PF.
R HOUR1)
6480 STOP
6490 END
6500 SUBROUTINE STDEVCX,J,AVG,SIGMA)
6510
6520 " THIS SUBROUTINE ACCEPTS A ONE DIMENSIONAL ARRAY X AND THE
6530 " NUMBER OF ELEMENTS IN THE ARRAY J AS INPUT AND CALCULATES
6540 " THE MEAN AND THE STANDARD DEVIATION OF THE ELEMENTS IN THE
6550 " ARRAY
6560
6570 IFCJ.GT.l) GO TO 3
6580 AVG=0.
6590 SIGMA=0.
6600 RETURN
6610 3 CONTINUE
6620 DIMENSION XC150)
6630 SUM1=0.
6640 DO 1 N=l,d
6650 1 SUM1=SUM1+X(N)
6660 AVG=SUM1/J
6670 SUM2=0
6680 DO 2 N=1,J
6690 D=X(N)-AVG
6700 2 SUM2=SUM2+D"D
6710 SIGMA=SqRT(SUM2/(J-l))
6720 RETURN
6730 END
6740 SUBROUTINE NUMBER(N1,N2)
6741 " THIS SUBROUTINE CONVERTS EACH TLD NUMBER TO A
6742 " NUMBER BETWEEN 1 AND 150
6743
6750 IF(Nl.NE.O) GO TO 11
6760 N2=0
6770 RETURN
6780 11 CONTINUE
6790 CALL OPENC4,'NUMBER','INPUT')
6800 DIMENSION KENC150)
6810 READC4,55) CKENCD,L=1,150)
6820 CALL CLOSEC4)
6830 DO 1 L2=l/150
6840 IFCN1.EQ.KENCL2)) GO TO 2
6850 1 CONTINUE
6860 WRITEC6,3)
6870 3 FORMATC1 ','YOU HAVE GIVEN A NON+EXISTANT TLD NUMBER YOU DUM
DUM1)
6880 WRITE(6,4)
- 41 -
-------
6890
D')
6900
6910
IT')
6920
6930
6940
6950
6960
6970
6980
6990
7000
7010
7020
7030
7040
7050
4 FORMATC1 ','NOW I HAVE TO STOP AND YOU HAVE TO START OVER AN
WRITEC6,5)
5 FORMATC1 ','THERE ISNT A THING IN THE WORLD WE CAN DO ABOUT
WRITEC6,6)
6 FORMATC' ','DO BE MORE CAREFUL NEXT TIME1)
STOP
2 N2=L2
RETURN
END
SUBROUTINE NUMB2CN1,N2)
DIMENSION NUMBERQ50)
CALL OPENC4,'NUMBER','INPUT')
READ(V=) CNUMBERCL),L=1,150)
CALL CLOSEC4)
N2=NUMBERCN1)
RETURN
END
- 42 -
-------
Appendix E. Data Management Program for TLD Environmental Surveillance
Measurements
20 1 FORMATC1 ','ADD READINGS CD, PRINTOUTS C2)1)
30 DIMENSION READC24,65)
40 DIMENSION X2C150).DOSEC24,65)
50 DIMENSION HOURSC24),CFC150,15)
60 REAL CF2C150),IBC150,15)
70 REAL NUMBC65),NDOSEC24,65),IB2C150)
80 DIMENSION AVGCFC150)
90 DIMENSION AVGIBQ50)
100 DATA NUMB/413,411.16,28,47,410,406,403.402,405%
110 ,301,425,426,417,415,401,424,19,300,434,431,427,420,409,430%
120 ,437,613,429,13,24,11,439,14,78,428,418,407,438,408,433,442,7
0,412.414,38.%
130 445,419,443,444,2,423,298,440,628,436,26,435,432,404,441%
140 ,608,416,33,422,4217
150 REAL NDRC24,65)
160 DIMENSION NOSC65),AVGDEVC65),DEVC24,65)
170 REAL NUMC65),MNDRC65,7),SIGMAC65,7)
180 DATA NOS/13,11,56,62,70,10,6,3,2,5,118,25,26,17,15,%
190 1,24,59,117,34,31,27,20,9,30,37,129,29,54,60,52,39,55,84,28,1
O rf Oft ft O*2 &
20o'42^80,12,14,65,45,19,43,44,51,23,115,40,136,36,61,35,32,4,41,
%
210 128,16,63,22,21/
220 READC5,55) KK
230 IFCKK.EQ.l) WRITEC6,2)
240 2 FORMATC1 ','ENTER MONTH NUMBER1)
250 IFCKK.EQ.l) READC5,") M
260 DIMENSION Ll(7)
270 DATA Ll/1,11,21,31,41,51,6l/
280 DIMENSION L2(7)
290 DATA L2/10,20,30,40,50,60,65/
300 IFCKK.EQ.l) WRITEC6,4)
310 4 FORMATC1 ','ENTER THE NUMBER OF HOURS THE TLDS WERE IN THE
FIELD1)
320 CALL OPENC1,'HOURS1,'INPUT')
330 READC1,X) HOURS
340 CALL CLOSEC1)
350 IFCKK.EQ.2) GO TO 42
360 READC5,'5) HOURSCM)
370 CALL OPENC1,'HOURS','OUTPUT')
380 WRITEC1,55) HOURS
390 CALL CLOSECD
400 42 CONTINUE
410 CALL OPENC2,'READ','INPUT')
420 READC2,«) READ
430 CALL CLOSEC2)
440 IFCKK.EQ.2) GO TO 43
450 5 FORMATC' ','ENTER EACH TLD NUMBER FOLLOWED BY ITS READING,
WHEN DONE TYPE 0,0')
460 385 CONTINUE
- 43 -
-------
470 READC5,X) N3,X
480 IFCN3.EQ.O) GO TO 40
490 CALL NUMBER(NUMB,N3)
500 IFCN3.EQ.999) GO TO 385
510 READCM,N3)=X
520 GO TO 385
530 40 CONTINUE
540 CALL OPENC2,'READ','OUTPUT')
550 WRITE(2,!:) READ
560 CALL CLOSEC2)
570 43 CONTINUE
580 IFCKK.EQ.l) STOP
590 10 CONTINUE
591 DO 18 1=1,24
592 IF(HOURSU).EQ.O) GOTO 19
593 18 CONTINUE
594 19 1=1-1
600 CALL OPENC7,*NAM1','INPUT')
610 READC7,!!) CCCF(M1,M2),M2=1,15),M1=1,150)
620 CALL CLOSEC7)
630 DO 26 N=l,65
640 DO 27 JJ=1,15
650 IFCCFCNOSCN),JJ).NE.O.) GO TO 28
660 d=Jd-l
670 GO TO 933
680 28 CF2(JJ)=CF(NOSCN)/Jd)
690 J=JJ
700 27 CONTINUE
710 933 CONTINUE
720 CALL STDEV(CF2,d,AVG,SIGMA)
730 AVGCFCN)=AVG
740 26 CONTINUE
750 CALL OPENC8,'IB','INPUT')
760 READC8,«) CCIBCM1,M2),M2=1,15),M1=1,150)
770 CALL CLOSEC8)
780 DO 11 N=l,65
790 DO 12 Nl=l,15
800 IFCIBCNOS(N)/N1).EQ.O.) GO TO 13
810 IB2CNl)=IBCNOSCN)/Nl)s!AVGCF(N)-2.
820 12 CONTINUE
830 13 CONTINUE
840 N1=N1-1
850 11 CALL STDEVCIB2,N1,AVGIB(N)/S)
860 DO 6 M=l,24
870 D06 N=l,65
880 IFCREADCM/N).EQ.O.) GO TO 6
890 DOSECM, N)=READCM, N)S!AVGCFCN)
900 NDOSECM/N)=DOSECM/N)-HOURS(M)"AVGIBCN)".001
910 NDRCM/N)=1000.!!NDOSECM/N)/HOURSCM)
920 6 CONTINUE
930 DO 22 M=l,I
940 DO 22 L=l,7
950 K1=L1CD
- 44 -
-------
960 K2=L2CL)
970 J=0
980 DO 49 I2=K1,K2
990 IFCNDRCM,I2).EQ.O) GO TO 49
1000 d=J+l
1010 X2CJ)=NDRCM,12)
1020 49 CONTINUE
1030 CALL STDEVCX2,J,MNDRCM,L),SIGMACM,L))
1040 SIGMACM,L)=SIGMACM,L)/SQRTCFLOATCJ))
1050 DO 60 I2=K1,K2
1060 IFCNDRCM,I2).NE.O) GO TO 6?
1070 DEVCM,I2)=100.
1080 GO TO 60
1090 67 DEVCM,I2)=CMNDRCM,L)-NDRCM,I2))/MNDRCM,L)
1100 DEVCM, I2)=100.!!DEVCM, 12)
1110 60 CONTINUE
1120 22 CONTINUE
1130 SUM=0.
1140 DO 62 L=l,7
1150 K1=L1(L)
1160 K2=L2(L)
1170 DO 62 I2=K1,K2
1180 J=0
1190 SUM=0.
1200 DO 61 M=1,I
1210 IFCDEVCM,I2).GT.99.) GO TO 6l
1220 d=J+l
1230 SUM=SUM+DEVCM,12)
1240 61 CONTINUE
1250 IF(SUM.EQ.O) GO TO 62
1260 IF(J.EQ.O) GO TO 62
1270 AVGDEV(I2)=SUM/J
1280 62 CONTINUE
1290 AVG=SUM1/J
1300 SUM2=0.
1310 WRITE(6,111)
1320 111 FORMATC1 ','GENERAL INFORMATION(l) OR SPECIFICC2)')
1370 15 READC5,") K
1380 IFCK.EQ.l) GOTO 16
1390 IFCK.EQ.2) GOTO 17
1400 IFCK.E0.3) GO TO 64
1410 WRITECb/14)
1420 14 FORMATC' ','TYPE 1 OR 2 DUM DUM')
1430 GO TO 15
1440 16 CONTINUE
1450 WRITECe^O) I
1460 20 FORMATC1 '/'THERE ARE',13,' MONTHS OF DATA IN STORAGE')
1470 DO 220 M=l,I
1480 IFCK.EQ.l) WRITECe^S) M
1490 55 FORMATC'0','MONTH',13)
1500 IFCK.EQ.l) WRITEC6,21)
1510 21 FORMATC'-','LOCATION',5X,'NET DOSE RATE',5X,'STDEV)
- 45 -
-------
1520 DO 220 L=l,7
1530 IFCK.EQ.l) WRITEC6,23) L,MNDRCM,L),SIGMACM, L)
15^0 23 FORMATC1 ' , l4, F17.4, F15.3)
1550 220 CONTINUE
1560 IFCK.EQ.l) STOP
1570 17 CONTINUE
1580 WRITEC6,41|)
1590 44 FORMATC1 ','ENTER MONTH NUMBER1)
1600 READC5,X) M
1610 DO 520 L=l,7
1620 WRITEC6,53) M,L
1630 53 FORMATC1 '///,' MONTH ',13,', LOCATION ',13)
1640 WRITEC6,45)
1650 45 FORMATC 'OVTLD',3X, 'READING', 6X,'CF',6X,'DOSE',6x,' IB1, 6
X,'NET DOSE RATE1)
1660 K1=L1CD
1670 K2=L2CD
1680 DO 46 N=K1,K2
1690 N3=NUMBCN)
1700 WRITEC6,47) N3,READCM,N),AVGCFCN),DOSECM,N),AVGIBCN),NDRCM,N
1710 47 FORMATC1 ',I3,F9.1,F11.3,F8.2,F10.2,F12.3)
1720 46 CONTINUE
1730 WRITEC6,51) MNDRCM,L)
1740 51 FORMATC1 ',//,' MEAN NET DOSE RATE =',F11.4)
1750 WRITEC6,52) SIGMACM,L)
1760 52 FORMATC1 ',/,' STDANDARD DEVIATION OF THE MEAN =',F11.4)
1770 520 CONTINUE
1780 IFCK.NE.3) STOP
1790 64 CONTINUE
1800 WRITECe^D
1810 71 FORMATC1 ',T10,'AVERAGE DEVIATION1,/,T10,» FROM MEAN%
1820 «,/, • TLDS9X,'PERCENT')
1830 DO 66 1=1,65
1840 M=NUMBCD
1850 WRITEC6,72) M^VGDEVCI)
I860 72 FORMATC' ',13,5X^10.3)
1862 IFCABSCAVGDEVCI)).GT.5.2) GO TO 80
1864 IFCABSCAVGDEVCI)).GT,4.) WRITEC6,8l)
1865 81 FORMATC'+',25X,'QUESTIONABLE TLD1)
1867 IFCABSCAVGDEVCI)).LT.0.1) WRITEC6,82)
1868 82 FORMATC'+',25X,'EXCELLENT DOSIMETER')
1870 GO TO 66
1872 80 CONTINUE
1874 IFCABSCAVGDEVCI)).GT.10.) WRITEC6,83)
1876 83 FORMATC'+',25X,'THROW THIS TLD AWAY1)
1878 IFCABSCAVGDEVCI)).LE.10.) WRITEC6,84)
1880 84 FORMATC'+',25X,'BAD TLD')
1882 66 CONTINUE
1884 STOP
1890 END
- 46 -
-------
1900 SUBROUTINE STDEVCX, J, AVG,SIGMA)
1910 DIMENSION XC150)
1920 IFCJ.GT.l) GO TO 3
1930 SIGMA=0.
1940 RETURN
1950 3 CONTINUE
I960 SUM1=0
1970 DO 1 N=1,J
1980 1 SUM1=SUM1+XCN)
1990 AVG=SUM1/J
2000 SUM2=0
2010 DO 2 N=l,d
2020 D=XCN)-AVG
2030 2 SUM2=SUM2+D5!D
2040 SIGMA=SQRTCSUM2/CJ-D)
2050 RETURN
2060 END
2070 SUBROUTINE NUMBER(NUMB,N)
2080 REAL NUMBC65)
2090 DO 1 L=l,65
2100 IFCN.EQ.NUMBCD) GO TO 2
2110 1 CONTINUE
2120 WRITEC6,3)
2130 3 FORMATC1 ','YOU HAVE PUT IN A NON-EXISTENT TLD NUMBER YOU
DUM DUM')
2140 N=999
2150 RETURN
2160 WRITEC6,4)
2170 4 FORMATC1 '/'NOW I HAVE TO STOP AND YOU HAVE TO START OVER
AND1)
2180 WRITEC6,5)
2190 5 FORMATC1 '/'THERE ISNT A THING IN THE WORLD WE CAN DO ABOU
T IT')
2200 WRITEC6,6)
2210 6 FORMATC1 ','DO BE MORE CAREFUL NEXT TIME1)
2220 STOP
2230 2 N=L
2240 RETURN
2250 END
- 47 -
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/4-76-035
2.
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
FACTORS AFFECTING THE USE OF CaF?:Mn THERMO-
LUMINESCENT DOSIMETERS FOR LOW-LEVEL
ENVIRONMENTAL RADIATION MONITORING
5. REPORT DATE
August 1976 (Issuing Date)
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
K. C. Gross, E. J. McNamara, W. L. Brinck
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Radiochemistry & Nuclear Engineering Branch
Environmental Monitoring & Support Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
CMnp.-inna.t.i . OH 452fi8
10. PROGRAM ELEMENT NO.
1HD621
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
same as 9
13. TYPE OF REPORT AND PERIOD COVERED
14. SPONSORING AGENCY CODE
EPA-ORD
15. SUPPLEMENTARY NOTES
16. ABSTRACT
An investigation was made of factors affecting the use of
commercially-produced CaF2:Mn thermoluminescent dosimeters for low level
environmental radiation monitoring. Calibration factors and self-dosing
rates were quantified for 150 thermoluminescent dosimeters. Laboratory
studies were made of precision, linear response to dose rate, effects
of light, and time-dependent fading. A standard laboratory procedure
was devised and a computer program was written to calculate, analyze,
and store the large amounts of data that were accumulated. Extensive
environmental measurements were subsequently carried out at the Vermont
Yankee Nuclear Power Station. The results of this investigation indi-
cate that selected dosimeters, when properly calibrated and corrected
for self-irradiation, can be used for accurate and reliable monitoring
of low-level environmental radiation.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. COS AT I Field/Group
Environmental Surveys, Nuclear
Power Plants, Radiation Dosimetry,
Thermoluminescence
Thermoluminescent
Dosimetry
7E
18. DISTRIBUTION STATEMENT
Release to public
19. SECURITY CLASS (ThisReport)
unclassified
21. NO. OF PAGES
54
20. SECURITY CLASS (Thispage)
unclassified
22. PRICE
EPA Form 2220-1 (9-73)
48
ttUSGPO: 1976 — 657-695/5495 Region 5-11
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Office of Research and Development
Technical Information Staff
Cincinnati, Ohio 45268
OFFICIAL BUSINESS
PENALTY FOR PRIVATE USE, $3OO
AN EQUAL OPPORTUNITY EMPLOYER
POSTAGE AND FEES PAID
U.S. ENVIRONMENTAL PROTECTION AGENCY
EPA-335
Special Fourth-Class Rate
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