2008
BARC/2008/E/007B
AR
C/2008/E
/007
PERFORMANCE CHARACTERISTICS OF CaSO4: DY BASED INDIGENOUSTHERMOLUMINESCENT DOSIMETERS FOR ENVIRONMENTAL RADIATION MONITORING
byM. P. Chougaonkar, R. A. Takale, P.G. Shetty, Y. S. Mayya
andV. D. Puranik
Environmental Assessment Division
BARC/2008/E/007B
AR
C/2
008/
E/00
7
GOVERNMENT OF INDIAATOMIC ENERGY COMMISSION
BHABHA ATOMIC RESEARCH CENTREMUMBAI, INDIA
2008
PERFORMANCE CHARACTERISTICS OF CaSO4: DY BASED INDIGENOUSTHERMOLUMINESCENT DOSIMETERS FOR ENVIRONMENTAL RADIATION MONITORING
by
M. P. Chougaonkar, R. A. Takale, P.G. Shetty, Y. S. Mayya
and
V. D. PuranikEnvironmental Assessment Division
BIBLIOGRAPHIC DESCRIPTION SHEET FOR TECHNICAL REPORT(as per IS : 9400 - 1980)
01 Security classification : Unclassified
02 Distribution : External
03 Report status : New
04 Series : BARC External
05 Report type : Technical Report
06 Report No. : BARC/2008/E/007
07 Part No. or Volume No. :
08 Contract No. :
10 Title and subtitle : Performance characteristics of CaSO4:Dy based indigenousthermoluminescent dosimeters for environmental radiation monitoring
11 Collation : 26 p., 11 figs., 3 tabs.
13 Project No. :
20 Personal author(s) : M.P. Chougaonkar; R.A. Takale; P.G. Shetty; Y.S. Mayya; V.D. Puranik
21 Affiliation of author(s) : Environmental Assessment Division, Bhabha Atomic ResearchCentre, Mumbai
22 Corporate author(s) : Bhabha Atomic Research Centre,Mumbai-400 085
23 Originating unit : Environmental Assessment Division,BARC, Mumbai
24 Sponsor(s) Name : Department of Atomic Energy
Type : Government
Contd...
BARC/2008/E/007
BARC/2008/E/007
30 Date of submission : April 2008
31 Publication/Issue date : May 2008
40 Publisher/Distributor : Associate Director, Knowledge Management Group andHead, Scientific Information Resource Division,Bhabha Atomic Research Centre, Mumbai
42 Form of distribution : Hard copy
50 Language of text : English
51 Language of summary : English, Hindi
52 No. of references : 19 refs.
53 Gives data on :
60
70 Keywords/Descriptors : DYSPROSIUM; CALCIUM SULFATES; ACCURACY;THERMOLUMINESCENT DOSEMETERS; PERFORMANCE TESTING; ENVIRONMENT;RADIATION MONITORING; GAMMA RADIATION; FEASIBILITY STUDIES;DOPED MATERIALS
71 INIS Subject Category : S46
99 Supplementary elements :
Abstract : Dysprosium doped calcium sulphate based Thermoluminescent Dosimeter (TLD) cards,generally used for personal dosimetry applications in India were redesigned and modified to suit theenvironmental gamma radiation monitoring applications. Characteristics of the new TLDs, necessary forenvironmental gamma radiation monitoring were studied and found to be satisfactory in every respect.The TLDs were field tested together with the calcium fluoride powder based capsule TLDs and the resultswere found to be very satisfactory. This report describes the design parameters, characteristics of theTLDs and results of comparison studies between the two systems that were carried out in all the DAEinstallations where the environmental gamma radiation monitoring is being carried out for more than threedecades.
1
Performance Characteristics of CaSO4:Dy based indigenous
Thermoluminescent Dosimeters for Environmental Radiation
Monitoring
M. P. Chougaonkar, R. A. Takale, P. G. Shetty, Y. S. Mayya and V. D. Puranik
Environmental Assessment Division, Bhabha Atomic Research Centre, Mumbai, 400085
Abstract:
Dysprosium doped calcium sulphate based Thermoluminescent Dosimeter (TLD) cards, generally used for personal dosimetry applications in India were redesigned and modified to suit the environmental gamma radiation monitoring applications. Characteristics of the new TLDs, necessary for environmental gamma radiation monitoring were studied and found to be satisfactory in every respect. The TLDs were field tested together with the calcium fluoride powder based capsule TLDs and the results were found to be very satisfactory.
This report describes the design parameters, characteristics of the TLDs and results of comparison studies between the two systems that were carried out in all the DAE installations where the environmental gamma radiation monitoring is being carried out for more than three decades.
Introduction:
Environmental monitoring of all the nuclear facilities under Department of Atomic
Energy (DAE) is an important programme of the Health Safety and Environment Group,
BARC, under which releases of radioactivity to the environment, solid, liquid or gaseous
wastes if any, are monitored. The programme assesses adequacy of the controls, set by the
international bodies like International Atomic Energy Agency (IAEA) and in Indian
context, Atomic Energy Regulatory Board (AERB) on the release of radioactive materials
to the environment. The programme also assures the public at large that the nuclear
industry does not add to the radiation levels in the environs of the establishment. Radiation
monitoring, in High Background Radiation Areas (HBRAs), is also important to study the
2
effects of the elevated radiation levels on the human health and to attempt a possible
correlation between them.
Thermoluminescent Dosimeters (TLDs) offer a very reliable and inexpensive tool
for measuring the gamma radiation dose since the TLDs are very sensitive; reusable and do
not require constant manual attendance or other infrastructural facilities like electricity,
water etc. They can therefore be deployed at any remote place where no infrastructure
facilities exist. The information stored in the TLDs remains stored unless heated and thus
they are useful in monitoring remote locations by mailed TLDs in which the TLDs are
mailed to the designated organisation, deployed at a location for a predetermined period of
time, retrieved and sent back to the monitoring laboratory where they are read off and the
radiation exposure evaluated.
Environmental gamma radiation monitoring, using TLDs, around all the nuclear
facilities in India is being carried out for over three decades (1-4) using this methodology.
The TLDs have also been used in the indoor dosimetry of the High Background Radiation
Areas (HBRAs) in the southwestern state of Kerala (5-7), in addition to various research
projects for baseline surveys in different regions in India.
Materials:
These programmes have essentially been based on naturally occurring calcium
fluoride powder as TLD phosphor. Fifty mg of the processed calcium fluoride powder in
the particle size range 75-150 μm, properly processed and annealed, is filled in two brass
capsules of 8mm length, 3mm ID & 1mm wall thickness through a constant volume
3
vibrator dispenser. Two such capsules sealed in a watertight packet make one TLD as
shown in (Fig. 1). The loose powder in the grain size 75-150 μm ensures higher sensitivity
while the cylindrical geometry ensures the near isotropic response to gamma rays. The
brass capsule also makes the dosimeter response less energy dependent.
Fig. 1: A Photograph of a typical powder based TL dosimeter using brass filled CaF2 powder. (a) Brass capsules, (b) Brass capsules opened, (c) TLD packet and (d) TLD packed in PVC; ready for deployment.
These TLDs have been thoroughly tested for performance characteristics as set by
American National Standards Institute (ANSI)(8) and have been found to be quite
satisfactory for environmental gamma radiation monitoring in India (Table I). Participation
in many International Inter-comparisons of Environmental Dosimeters (IIEDs), in
collaboration with US Department of Energy (US DoE) has proved the efficacy of this
system (Fig. 2) (9). It was observed that the values obtained by the laboratory using CaF2
based TLDs have always been within 10% of the organisers’ values and as seen in the
4
figure, the overall performance of the TLDs vis a vis the IIEDs has been within 4% of the
organisers’ values.
Table 1: Performance Characteristics of CaF2 Powder based environmental TLDs(11)
Characteristics Performance of CaF2 powder based TLDs.
1 Energy dependence + 20 % between 50 and 1250 keV.
2 Environmental exposure response + 1 %of the true exposure using Ra226 calibration.
3 Fading 3 % in 3 months of continuous exposure.
4 Directional response Nearly isotropic.
5 Self dose- rate 26.8 μGy /year.
6 Precision + 5 %.
7 Accuracy (1 -20 mR range) + 10 %.
0.0 0.2 0.4 0.6 0.80.0
0.2
0.4
0.6
0.8
Y = 0.96(+/- 0.03)X r = 0.99
BAR
C va
lues
(mG
y)
Organiser's values (mGy)
Fig. 2: Results of different International Inter-comparisons of Environmental Dosimeters. The slope of the correlation curve, 0.96 (1 expected) indicates that the performance of the TLDs has been consistently within 4% of the organisers’ values.
5
Being powder based, this system is labor intensive and cannot cater to increased
requirement of environmental monitoring and other R&D activities like population
dosimetry in the HBRAs in India and other multi-institutional R&D projects. In order to
meet the increased demand for monitoring new stations, it was necessary to go for new,
state of the art, TLDs together with a fully automatic TLD reader system. This was
achieved by using an indigenously developed automated PC based TLD badge reader
system (10) wherein 50 TLDs can be loaded at a time and read off one after the other using
the automatic badge reader system
The card based TLD system on the other hand, used in personal monitoring
purposes, uses CaSO4:Dy as TL phosphor, first prepared by Yamashita et al (12), (<70μm
grain size) and is used in the form of Teflon embedded discs (13.3mm dia. & 0.8mm thick)
containing 70mg of CaSO4:Dy and 210 mg of Teflon. Three such discs are mechanically
clipped over three symmetrical circular holes each of diameter 12mm, on a nickel-plated
aluminum card (52 mm X 30 mm X 1 mm). The first disc is sandwiched between a pair of
1mm of aluminum and 1mm of Cu filters, copper filter being nearer to the disc. The
second disc is sandwiched between a pair of 1.5mm thick plastic filters. The third disc is
positioned under a circular open window. The various filters help in gamma, X-ray and
beta dose estimation. The readout of the disc under 1mm of Al and 1mm of Cu filters gives
directly the gamma dose. The TLD badge is covered with a wrapper and sealed in a
polythene pouch. The pouch protects the card from radioactive and chemical
contamination. The dosimetric characteristics of the TLD badge have been studied in
details and are reproduced in Table 2.
6
Table 2: Performance characteristics of the TLD using CaSO4:Dy powder (13)
Characteristics Performance of CaSO4:Dy based card TLDs.
1 Energy dependence ± 20% for 30keV to 3MeV
2 Environmental exposure response ± 8% of the true exposure using Cs137 calibration
3 Fading < 7 % in 6 months
4 Directional response Non - isotropic
5 Self dose- rate 120 µGy/year
6 Precision ±10%
7 Accuracy (1 -20 mR range) ±25%
Preliminary performance tests were carried out using these TLDs (without any
modifications) together with the CaF2 based powder TLDs. Based on the experiences, the
card TLDs were thoroughly modified and were subjected to rigorous quality control tests
in the laboratory as well as tests in the field. What follows in the report is the results of the
tests that were carried out and also the performance of the TLDs vis a vis powder based
TLDs.
Feasibility tests:
In order to assess the feasibility of using the CaSO4:Dy based personal monitoring
TLDs for the purpose of environmental gamma radiation monitoring, a preliminary
performance test was carried out by deploying the CaF2 powder based environmental TLD
and CaSO4:Dy card based personal TLDs together.
Two field test experiments were carried out to study the feasibility of use of
personnel monitoring TLDs in the environmental gamma radiation monitoring
applications(14). In the first, twelve personnel monitoring TLDs together with
7
environmental TLDs were deployed in the normal background areas for a period of three
months. The agreement between the two readings based on the TLD systems was found to
be rather poor and was attributed to the facts that the personnel monitoring TLDs, being
card shaped, are less isotropic in response compared to CaF2 TLDs, which are made of
powder filled in cylindrical brass capsules. In addition, the personnel monitoring
dosimeters, in the existing design, can yield the gamma radiation dose based on only one
disc. There is no mechanism to check the reproducibility of the reading that is possible in
the case of environmental TLD.
In the second exercise, 105 personnel monitoring TLDs were deployed together
with environmental TLDs in HBRAs for a period of four months. The retrieved TLDs
were processed by the respective units using their established protocols. The exposures
were expressed in the units of air kerma (μGy) and normalized for a period of 90 days.
It was observed that the readings obtained in the HBRAs showed good agreement.
Correlation analysis carried out between these data with the environmental TLDs along Y-
axis and the personnel monitoring TLDs along X-axis (Fig. 3) indicated a good linear
correlation between personnel monitoring and environmental TLDs, having a regression
coefficient of 0.96. The slope of the line is 1.07, very near to the expected value of unity.
The performance of the personal TLDs in environmental gamma radiation monitoring in
the HBRAs is as seen in Fig. 3.
The observation was also in concordance with the earlier observation (15) and
indicates that the TLDs used for personal monitoring purpose are suitable for
environmental dosimetry too if the radiation levels are higher than normal. In the case of
8
readings in low background areas however, where the air dose values ranged between 89-
218 μGy/90 days, the agreement between the two dosimeters was rather poor implying that
the personnel monitoring TLDs could not be used in the normal radiation background areas
in the present form and needed modifications.
0 200 400 600 800 1000 1200 1400 1600 1800 20000
200
400
600
800
1000
1200
1400
1600
1800
2000
μGy
μGy
Y = 1.07(+/- 0.01) Xr = 0.96n = 105
CaF 2 b
ased
env
ironm
enta
l TLD
s
CaSO4:Dy based PMS TLDs
Fig. 3: Intercomparison of PMS (CaSO4:Dy based) TLDs with EAD (CaF2 based) TLDs.
Following modifications were therefore made in the CaSO4:Dy based card TLDs to
make the personal monitoring TLD badge useful in the environmental monitoring:
1. Change in the dopant concentration: In place of the phosphor with 0.05% Dy,
concentration of 0.2% was used. This increased the sensitivity of the phosphor from 29
times the TLD 100 for 0.05% Dy concentration to 35 times that of TLD 100 for
CaSO4:Dy with 0.2% (16,17).
9
2. No. of elements for gamma radiation measurements: Rather than using only one
disc for gamma radiation as is done in personal TLD, two discs were covered with
1mm copper filters so that the reproducibility of the reading could be verified. At the
same time, the modified TLD consists of only two elements instead of three as in
personal TLD, thereby reducing the reading time by 33 %.
3. Copper filters for both the discs: Unlike in the personal monitoring TLDs, both the
discs were covered with 1 mm Copper filters from both the sides thereby making the
TL response less energy dependent.
4. Redesigning of plastic cassette: The plastic cassette covering the TLD card was
completely modified so as to be able to remove the exposed card and load it easily in
the TLD reader.
The TLD cards were prepared by fixing two discs with the wire clamps and were
placed in the cassette so that the discs were properly covered by the copper strips. This was
achieved with the help of a notch made on the card as well as in the cassette. The TLD
assembly is as shown in Fig 4.
.
Fig. 4: A typical photograph of Card based TLD using CaSO4: Dy phosphor.
10
The TLD discs as well as cards were thoroughly washed with acetone and dried.
The discs were then fixed on the cards with the help of spring clips. The TLDs were then
annealed at 250oC for the period of 3 hours in an oven with air circulation. After the
annealing, the oven was switched off and the TLDs were allowed to cool down naturally to
room temperature.
Background readings of all the TLDs were then recorded using automatic TLD
badge reader indigenously developed by BARC (18). Only those discs were selected that
showed the background reading within 10% of the average reading of about 15 counts.
The modified TLDs were subjected to various performance checks as follows.
Methods, Results and Discussion (19):
1) Determination of Lowest Detectable Dose (LDD):
Freshly annealed TLDs were taken and the background readings were recorded
using the automatic TLD badge reader. Average background readings and the standard
deviation were determined. As seen in Fig. 5, the average background were found to be 15
± 3 counts. The distribution of the 70 such background readings was observed to be normal
and 61 of the 70 readings were found to be within 2σ, indicating the closeness of the data.
The same TLDs were then used for determination of calibration factor. Ten TLDs
each were exposed to a standard 137Cs gamma-source (662 keV), traceable to IAEA
primary standards, for known exposures of 88,176,264 and 352 μGy respectively. The
calibration factor was found to be 0.48 μGy/count and is shown in Fig. 6. Based on the 3
11
times standard deviation of the background readings, the LDD was determined as
3*3*0.48 ∼ 5 μGy. The LDD of the TLDs was therefore 5 μGy.
10 15 200
2
4
6
8
10
12
14 Average counts 15 + 3LDD = 3*3*0.48 = 4.3 μGy
Num
ber o
f occ
uran
ces
TL Counts
Fig. 5 Distribution of background TL signal of 77 freshly annealed TLDs. 90% of the TLDs
are seen to have the background between 15± 2.98. The standard deviation of 2.98 gives
the LDD of 5 μGy.
0 50 100 150 200 250 300 3500
100
200
300
400
500
600
700
800 Response = 5 + 2.07*calibration doseCalibration factor = 1/2.07 = 0.48 μGy/counts
TL (c
ount
s)
DOSE (μGy)
Fig. 6: A typical calibration factor. Reciprocal of the slope of the dose response line
(counts/μGy) gives the calibration factor (μGy/counts)
12
2) Energy Dependence:
CaSO4 based TLDs, due to the high Zeff. are known to exhibit energy dependence if
proper care is not taken. The dosimeters, as described above, are designed in such a way
that the phosphor discs are covered on both sides by a 1mm thick copper filter for
attenuation of low energy photons. The energy dependence of the arrangement was
assessed by exposing 10 TLDs each to 88 μGy of X-ray/gamma radiation of various
energies. Three sets of readings were taken for various arrangements viz.
i) Only bare cards were exposed.
ii) Cards only with plastic cassettes were exposed
iii) Cards with 1mm copper filters in the plastic cassettes were exposed to the gamma
radiations
In each case, the TL response for energies, either of X-ray or gamma radiation was
compared with that for 137Cs (662keV). Fig. 7 shows the normalised TL response for the
TLDs for each energy normalised with respect to that due to 662 keV (137Cs source). It is
worth noticing the facts that
1. In the first two arrangements, where there was no metallic filter, the dependence of
the response on energy is quite prominent and there is hardly any difference in the
TL response.
2. When the TLD card is covered with 1 mm copper filter encased with plastic
cassette is practically energy independent.
13
0 200 400 600 800 1000 1200 1400
0.1
1
10
Rela
tive
TL in
tens
ity
Energy (keV)
No Filter Only Plastic Filter Plastic + 1mm Copper
Fig. 7: Energy dependence of TLDs. The TLDs with copper filter of 1 mm thickness is seen
to be sufficient to make the TLDs almost energy independent of the gamma/X-ray energy.
3) Accuracy and Precision
Freshly annealed TLDs were given a known exposure of 126, 189 and 252 μGy
using a 137Cs gamma source and were read off. The exposure values were evaluated using
the calibration factor and the precision and accuracy were calculated as shown in Table 3.
It is seen from the Table that the precision of the readings is about 5% of the
delivered value while the accuracy is within 7% of the delivered value. American National
Standard Institute criteria for environmental TL dosimeters (ANSI N545) specify that the
field results should be within 30% of the delivered values. It is seen from the table that all
the values are well within the limit specified in ANSI N545.
14
Table 3: Accuracy and Precision of the CaSO4:Dy card based environmental TL Ds.
Delivered Dose (μGy) Observed dose (μGy) Precision % Accuracy %
126 123 ± 5.3 4 2
189 180 ± 8.8 5 5
252 234 ± 10.9 5 7
4) Angular dependence:
Angular dependence, an important characteristic of the TLDs, decides whether the
TLD is suitable for the environmental radiation monitoring as the radiation in environment
is incident from all the sides and it is essential that the response of the TLD is as isotropic
as possible. The TLDs were exposed at different angles of incidence from the point
radiation source. A known exposure of 20mR of 137Cs source was given to the TLDs and
were read off using the TLD badge reader.
The angular dependence of the TLDs, normalized to perpendicular incidence, is
shown in Fig. 8. It can be seen, from the figure, that the response at all the angles of
incidence is very much within 30% of the normal incidence and hence fulfills the ANSI
criteria. It may be remembered here that the work was carried out using a calibration
source that can be taken as a point source. Small variation in the distance between source
and the individual disc can matter in the response in the laboratory experiment whereas the
exposure in environment is from an infinite source and as such the variation in response
with respect to the true value is expected to be much smaller. The TLDs thus can be said
to be isotropic in response.
15
Fig. 8: Angular dependence of the TLD. TL response for all the TLDs was observed to be
within 10% of the normal incidence value excluding 900 angle.
5) Fading of the TL Signal
It is necessary to know the fading characteristics of the TLDs before they are put to
use. Earlier studies reported that the fading is typically 1% per month (4,5). These studies
were carried out for the modified design of CaSO4: Dy based TLDs. Freshly annealed
TLDs were given an exposure of 200 μGy and were stored in lead pot. Two TLDs were
read off at regular intervals ranging 4 days to 90 days. It was observed that there was a
fading of about 7% during the first month as shown in Fig. 9. Long-term fading studies are
in progress.
16
0 5 10 15 20 25 300.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
Nor
mal
ised
exp
osur
e
No. of Days
Fig.9: Fading characteristics of the CaSO4:Dy card based environmental TLDs. About
7% loss in the signal over the period of 30 days is observed.
6) Field Tests
In the initial field studies, freshly annealed TLDs were deployed together with CaF2
based TLDs at 36 different locations for a period of 90 days. The retrieved CaF2 based
TLDs were read using the TLD reader used regularly for environmental TL monitoring
work while the modified TLDs were read using automatic TLD card reader. The data
collected over two such quarters, over the period of 180 days, was used in the present
analysis. The correlation between the results obtained using two different TLD systems, as
shown in Fig. 10. The correlation between the readings for card based modified TLDs
with the powder based environmental TLDs is seen to be excellent with a slope of 1.00
(expected 1) with correlation coefficient r of 0.99 and implies the goodness of fit. This
17
clearly indicates that the card based TLDs in the modified form are very much comparable
with the CaF2 based TLDs and can be used for the environmental gamma radiation
monitoring. It is worth noting that majority of the readings, 50 out of 72, are less than 500
μGy/90 days, thus it is clear that the TLDs after modifications in the design, are suitable
for environmental gamma radiation.
0 1000 2000 3000 40000
1000
2000
3000
4000
5000
Pow
der T
LD (μ
Gy/
90 d
ays)
Card TLD (μGy/90 days)
Y = 1.00 (+/-0.01)Xr = 0.99
Fig. 10: Intercomparison of the gamma radiation levels obtained using two different TLDs
36 locations. The slope of 1.00 (expected unity) indicates the excellent matching between
the modified TLDs and the ones that are in use for over three decades Fifty of 72 data
points are seen to be less than 500 μGy/a.
Based on the experience obtained during the work, the TLDs were deployed at all
the locations in all the DAE stations during the years 2006-07 on trial basis. CaF2 based
TLDs were also simultaneously deployed as the performance indicator. The comparison
between these two systems with a huge data of more than 1000 readings (Fig. 11) further
18
confirms, with the correlation parameters of slope =1 and r= 0.91, that the card based
TLDs have satisfied the performance criteria and the suitability of these TLDs for the
environmental gamma radiation dosimetry programme is established.
0 1000 2000 3000 4000 50000
500
1000
1500
2000
2500
3000
3500
4000
4500
5000Y =1.00(+/- 0.009)X, r = 0.91Data points : 1053 From all the stations except Trombay
Dos
e m
easu
red
usin
g C
ard
TLD
(μG
y/q)
Dose measured using powder TLD (μGy/q)
Fig. 11: Intercomparison of the gamma radiation levels obtained using two different TLDs
at all the DAE establishments during the period 2006-2007. The slope of 1.00 (expected
unity) indicates the excellent matching between the modified TLDs and the ones that are in
use for over three decades.
Conclusions:
The CaSO4:Dy based card TLDs, which were modified based on the preliminary
field tests in HBRAs, were thoroughly studied for suitability in the environmental gamma
radiation monitoring applications. It was found that
1. The modified TLD have the LDD of 5 μGy.
19
2. With the introduction of 1 mm copper filter, the TLDs are almost energy
independent.
3. The TL response of the TLDs is almost isotropic.
4. The TLDs exhibit the precision and accuracy of 5 % and 7% respectively.
5. The TLDs show fading up to about 7% initially, although later on, there is no
further loss of signal.
6. Performance tests of the TLDs in the field indicate that the TLDs are very
much comparable with the CaF2 powder based TLDs.
The modified TLDs, which are card based and can be read on an automatic
TLD card reader, can be therefore used in the environmental radiation-monitoring
programme.
Acknowledgements:
Thanks are due to S/Shri O. P. Masand and Munish Kumar , PMS, RP&AD
for their kind help in analysing the PMS TLDs in the initial performance tests.
Thanks are also due to Shri S. Kannan Head, RP&AD and Smt. Ratna Pradip,
RSSD, BARC for modifying suitably and providing the automatic TLD badge
reader.
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20
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21
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