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Application of the track method for radon measurement in Ukraine
Nucl. Tracks Radiat. Meas., Vol. 21, No. 3, pp. 433--436, 1993
0969-8078/93 $6.00 + .00 © 1993 Pergamon Press Ltd
Printed in Great Britain
APPLICATION OF THE TRACK METHOD FOR R A D O N M E A S U R E M E N T IN U K R A I N E V. A. NIKOLAEV,*M. G. BUZVNN[Y,*I. B. Votoeaw,f A. V. GROMOV,fA. S, Kluvor,J ~ g ~ , f I. P. Los,* A. V. Z~.~SKIY* and Yu. A. TOmUN~ *V. G. Khiopin Radium Institute, St Petersburg, 197022, Russia; fAll-Union Research Centre for Radiation Medicine, Melnikov's str. 53, Kiev 50, 254050, Ukraine; :~Health Ministry of Ukraine, "LARANr', Lazyrnaiy str. 1, Nikolaev, 327058, Ukraine Abstract--The results of measurements of the radon volume activity in the atmosphere of premises, obtained by the track method, are presented. On the basis of the ~ t s carried out one can conclude that the problem of radon is urgent in Ukraine, especially for living premises located on the Ukrainian crystalline shield and represented by one-storey buildings.
1. INTRODUCTION THE VOLUMEactivity of radon in the air of inhabited premises depends on a number of factors: the geological characteristics of the soil and underlying rocks, the construction and materials of the buildings, the ventilation, the climate features of the region, etc. (Nazaroff and Nero, 1988; Krisyuk, 1983). Ukraine is located mainly in the territory of the Ukrainian crystalline shield (UCS), which causes increased concentrations of ground radon. In connection with this for health protection aims, information on buildings located on the UCS, for example, in the Cherkassy, Kirovograd and Zaporozhye regions is of primary interest. It is also interesting to compare these data with those obtained for the regions partly located on the UCS, such as Kiev, Zhitomir and Nikolaev, as well as outside the UCS territory--the Poltava region and the Chernobyl district (Kiev region).
1 crn2 in area from an exposed film, to increase the reliability of measurements. The radiometers were placed in the premises for 1-2 months by research in co-operation with the sanitary services of Ukraine. After exposure the detectors were taken out of the chambers and sent to the V. G. Khlopin Radium Institute, where they were counted by means of spark counters AIST and ISTRA (Fig. 2).
(b)
(.) 4
m
2. M E T H O D S AND E Q U I P M E N T An apparatus complex based on the track method was used for the measurements (Vorobiev et al., 1990; Vorobiev et al., 1991). A new maximally simplified radon chamber, shown in Fig. I, was used as a passive track radiometer for mass measurements. The chamber is made of plastic, provided with a silicon rubber filter ensuring a time for radon diffusion into the chamber of 2 h. A cellulose nitrate detector is placed on the internal cylindrical surface of the chamber. The chamber's diameter and height ensure optimal conditions for recording 222Rn, 21*po and 214p0 (see Fig. l(b)), so that the radiometer response is high enough (see Table 1), despite the one-sided irradiation of the film. (The design also allows twosided irradiation of the CN-detector placed in a special holder.) It is possible to use 2-3 detectors
2
,,2
1 i 1
2 H~sht ~ m ) II
|0
42 1 1
2
$
4
Diameter (era)
FIo. 1. Passive track radiometer of radon. (a) 1: Plastic cylinder; 2: CN-detector, 3: plug with apertures and silicon rubber filter. (b) Radiometer response, depending on the chamber's height and diameter.
433
434
V. A. N I K O L A E V et al. Table 1. Recording properties of the radon passive track radiometer Type of film and etching conditions
Recording efficiency in 2n geometry (%)
Background (em -2)
Response (pulse m 3 month/Bq)
36_.+ 3
10+4
1.3 +0.4
LR-115-11, alkali solution NaOH = 1.22 gem -3, 150 min, 50°C
FIG. 2. Spark counters (a) AIST; and (b) ISTRA.
Table 2. Equivalent equilibrium concentrations of 222Rn in living premises of Ukraine (1989-1990) % of results exceeding (Bqm -3) Number of measurements
Maximum
Average
Standard deviation
100
200
57 31 28 42 29 78 38
255 238 516 176 506 448 180
44 73 117 66 108 124 40
43 71 114 62 1l 5 81 39
11 30 32 25 26 59 9
2 10 14 0 11 14 0
Many-storey buildings (ground floor) Poltava 123 Zhitomir 25 Kiev 34 Kirovograd 24 Cherkassy 26 Sum: 232 Mean: 49
176 53 73 67 290
31 31 49 38 101
25 19 15 25 63
2 0 0 0 42
0 0 0 0 8
Many-storey buildings (above the ground floor) Poltava 134 Zhitomir 32 Zaporozhye 31 Kiev 49 Kirovograd 23 Cherkassy 51 Nikolaev 9 Sum: 329 Mean: 30
131 158 44 87 31 349 25
25 35 29 22 19 63 10
22 39 10 18 7 65 9
1 8 0 0 0 14 10
0 0 0 0 0 4 0
Region One-storey buildings Poltava Zhitomir Zaporozhye Kiev Kirovograd Cherkassy Nikolaev Sum: 302 Mean: 81
RADON MEASUREMENT IN U K R A I N E
435
One-storey buildings Many-storey buildings (ground floor) ['--"] Many-storey buildings (above ground floor) 120 100 80
~
60 4O 2O
Region Cherkas. Kirovogr. Zaporozh, Zhitom. K i n v s k . Poltava. Percent of I OO 100 90 70 30 0 territory on UCS FIG. 3. 222Rn concentrations in living premises of some regions of Ukraine for different buildings.
The equipment was calibrated in a reference radon
atmosphere in a special box of the St Petersburg Research Institute for Radiation Hygiene. 3. MEASUREMENT,
RESULTS
AND
DISCUSSION
The results of measurements of the radon volume activity in the atmosphere of premises, obtained by the methods described above, were recalculated into
nI 30
~
e
y
the equivalent equilibrium concentration (EEC) with an equilibrium coefficient 0.5. Summarized data on some regions of Ukraine are presented in Table 2. As expected, higher values of EEC were observed in the regions located on the UCS, which is connected with an increased content of 2Z6Ra in the soils and underlying rocks, as well as a relatively greater number of adobe and clay houses. In Fig. 3 it is shown that there is a correlation of EEC with the part of a region's territory located on the UCS. One-storey
buildings
20 I0 o
0
too
nr / ~ 60 I I ~ ' ~ 40
200
I
300
I
I
400
500
Bq m -3
Many-storey buildings (groundfloor)
20 Z
o
0
I00
80
I
I
I
300
400
500
Bq m-3
Many-storey buildings (above ground floor)
60 40 20 o
I
200
0
,
100
I
200
I
300
I
400
I
5OO
Bq m -3
Rn-222 concentration FIG. 4. Frequency distribution of 22ZRnequivalent equilibrium concentrations in living premises of the Ukraine
436
V.A. NIKOLAEV et al.
buildings, as a rule, reveal higher concentrations than the ground floors of many-storeyed buildings, because clay and adobe houses have a better connection with ground radon than modern buildings. Application of different construction materials only slightly influences the volume activity of radon in premises; some increase in radon concentration is noticed in brick many-storeyed buildings as compared with panel buildings. In Fig. 4 particular sample distributions of EEC in living premises of the Ukraine are presented. The distributions are governed by the log normal law, the average values being essentially higher than the world ones; a considerable number of houses is found, especially in the Cherkassy region, where the EEC exceeds the levels of 100 and 200 Bq m -3. An analysis of the distributions obtained shows that in Ukraine there is a considerable probability (fractions per cent of a housing estate) where the EEC may exceed 1500 Bq m -3. Houses in the regions located outside the UCS, as a rule, do not have high values of radon volume activity, which is confirmed by data on the Poltava region, the Chernobyl district and the urban settlement Polesskoe. The EEC in living premises of these areas (the Chernobyl town: 3 measuring points, the Chernobyl district: 8 points, Polesskoe: 47 points) have values of 10-20 Bq m -3. The low values of EEC may be explained by both the character of the underlying rocks and an enhanced ventilation of the premises.
On the basis of the measurements carried out it is possible to conclude that the problem of radon is urgent for Ukraine, especially for living premises located on the UCS and represented by one-storey buildings. Acknowledgements--The authors express their thanks to employees of the sanitary services of Ukraine for their help in placing radiometers for exposure, as well as to E. M. Krisyuk and M. V. Terentiev for equipment calibration in the reference atmosphere of radon.
REFERENCES
Kopchenov V. E., Kozunov A. V., Krivokhatskiy A. S. and Nikolaev V. A. (1989) Automated spark counter, ISTRA. Nucl. Tracks Radiat. Meas. 16, 69-70. Krisyuk E. M. (1983) The Radiative Background o f Dwellings. Energy Press, Moscow (in Russian). Nazaroff W. W. and Nero A. V. (eds) (1988) Radon and its Decay Products in Indoor Air. John Wiley, New York. Vorobiev I. B., Krivokhatskiy A. S., Nekrasov E. V., Nikolaev V. A., Potapov V. G. and Terentiev M. V. (1990) Method and facilities for measurement of volumetric activity of radon in air of radon laboratories and hospitals. Hygiene and Sanitaria No. 3 71-72 (in Russian). Vorobiev I. B., Krivokhatskiy A. S., Krisyuk E. M., Nikolaev V. A., Pautov V. P. and Terentiev M. V. (1991) Structure and application of equipment assembly for measurement of radon volume activity in houses and soils. Poster No 191, 15th Int. Conf., Particle Tracks in Solids 3-7 Sept. 1990, Marburg, F.R.G.
0969-8078/93 $6.00 + .00 © 1993 Pergamon Press Ltd
Printed in Great Britain
APPLICATION OF THE TRACK METHOD FOR R A D O N M E A S U R E M E N T IN U K R A I N E V. A. NIKOLAEV,*M. G. BUZVNN[Y,*I. B. Votoeaw,f A. V. GROMOV,fA. S, Kluvor,J ~ g ~ , f I. P. Los,* A. V. Z~.~SKIY* and Yu. A. TOmUN~ *V. G. Khiopin Radium Institute, St Petersburg, 197022, Russia; fAll-Union Research Centre for Radiation Medicine, Melnikov's str. 53, Kiev 50, 254050, Ukraine; :~Health Ministry of Ukraine, "LARANr', Lazyrnaiy str. 1, Nikolaev, 327058, Ukraine Abstract--The results of measurements of the radon volume activity in the atmosphere of premises, obtained by the track method, are presented. On the basis of the ~ t s carried out one can conclude that the problem of radon is urgent in Ukraine, especially for living premises located on the Ukrainian crystalline shield and represented by one-storey buildings.
1. INTRODUCTION THE VOLUMEactivity of radon in the air of inhabited premises depends on a number of factors: the geological characteristics of the soil and underlying rocks, the construction and materials of the buildings, the ventilation, the climate features of the region, etc. (Nazaroff and Nero, 1988; Krisyuk, 1983). Ukraine is located mainly in the territory of the Ukrainian crystalline shield (UCS), which causes increased concentrations of ground radon. In connection with this for health protection aims, information on buildings located on the UCS, for example, in the Cherkassy, Kirovograd and Zaporozhye regions is of primary interest. It is also interesting to compare these data with those obtained for the regions partly located on the UCS, such as Kiev, Zhitomir and Nikolaev, as well as outside the UCS territory--the Poltava region and the Chernobyl district (Kiev region).
1 crn2 in area from an exposed film, to increase the reliability of measurements. The radiometers were placed in the premises for 1-2 months by research in co-operation with the sanitary services of Ukraine. After exposure the detectors were taken out of the chambers and sent to the V. G. Khlopin Radium Institute, where they were counted by means of spark counters AIST and ISTRA (Fig. 2).
(b)
(.) 4
m
2. M E T H O D S AND E Q U I P M E N T An apparatus complex based on the track method was used for the measurements (Vorobiev et al., 1990; Vorobiev et al., 1991). A new maximally simplified radon chamber, shown in Fig. I, was used as a passive track radiometer for mass measurements. The chamber is made of plastic, provided with a silicon rubber filter ensuring a time for radon diffusion into the chamber of 2 h. A cellulose nitrate detector is placed on the internal cylindrical surface of the chamber. The chamber's diameter and height ensure optimal conditions for recording 222Rn, 21*po and 214p0 (see Fig. l(b)), so that the radiometer response is high enough (see Table 1), despite the one-sided irradiation of the film. (The design also allows twosided irradiation of the CN-detector placed in a special holder.) It is possible to use 2-3 detectors
2
,,2
1 i 1
2 H~sht ~ m ) II
|0
42 1 1
2
$
4
Diameter (era)
FIo. 1. Passive track radiometer of radon. (a) 1: Plastic cylinder; 2: CN-detector, 3: plug with apertures and silicon rubber filter. (b) Radiometer response, depending on the chamber's height and diameter.
433
434
V. A. N I K O L A E V et al. Table 1. Recording properties of the radon passive track radiometer Type of film and etching conditions
Recording efficiency in 2n geometry (%)
Background (em -2)
Response (pulse m 3 month/Bq)
36_.+ 3
10+4
1.3 +0.4
LR-115-11, alkali solution NaOH = 1.22 gem -3, 150 min, 50°C
FIG. 2. Spark counters (a) AIST; and (b) ISTRA.
Table 2. Equivalent equilibrium concentrations of 222Rn in living premises of Ukraine (1989-1990) % of results exceeding (Bqm -3) Number of measurements
Maximum
Average
Standard deviation
100
200
57 31 28 42 29 78 38
255 238 516 176 506 448 180
44 73 117 66 108 124 40
43 71 114 62 1l 5 81 39
11 30 32 25 26 59 9
2 10 14 0 11 14 0
Many-storey buildings (ground floor) Poltava 123 Zhitomir 25 Kiev 34 Kirovograd 24 Cherkassy 26 Sum: 232 Mean: 49
176 53 73 67 290
31 31 49 38 101
25 19 15 25 63
2 0 0 0 42
0 0 0 0 8
Many-storey buildings (above the ground floor) Poltava 134 Zhitomir 32 Zaporozhye 31 Kiev 49 Kirovograd 23 Cherkassy 51 Nikolaev 9 Sum: 329 Mean: 30
131 158 44 87 31 349 25
25 35 29 22 19 63 10
22 39 10 18 7 65 9
1 8 0 0 0 14 10
0 0 0 0 0 4 0
Region One-storey buildings Poltava Zhitomir Zaporozhye Kiev Kirovograd Cherkassy Nikolaev Sum: 302 Mean: 81
RADON MEASUREMENT IN U K R A I N E
435
One-storey buildings Many-storey buildings (ground floor) ['--"] Many-storey buildings (above ground floor) 120 100 80
~
60 4O 2O
Region Cherkas. Kirovogr. Zaporozh, Zhitom. K i n v s k . Poltava. Percent of I OO 100 90 70 30 0 territory on UCS FIG. 3. 222Rn concentrations in living premises of some regions of Ukraine for different buildings.
The equipment was calibrated in a reference radon
atmosphere in a special box of the St Petersburg Research Institute for Radiation Hygiene. 3. MEASUREMENT,
RESULTS
AND
DISCUSSION
The results of measurements of the radon volume activity in the atmosphere of premises, obtained by the methods described above, were recalculated into
nI 30
~
e
y
the equivalent equilibrium concentration (EEC) with an equilibrium coefficient 0.5. Summarized data on some regions of Ukraine are presented in Table 2. As expected, higher values of EEC were observed in the regions located on the UCS, which is connected with an increased content of 2Z6Ra in the soils and underlying rocks, as well as a relatively greater number of adobe and clay houses. In Fig. 3 it is shown that there is a correlation of EEC with the part of a region's territory located on the UCS. One-storey
buildings
20 I0 o
0
too
nr / ~ 60 I I ~ ' ~ 40
200
I
300
I
I
400
500
Bq m -3
Many-storey buildings (groundfloor)
20 Z
o
0
I00
80
I
I
I
300
400
500
Bq m-3
Many-storey buildings (above ground floor)
60 40 20 o
I
200
0
,
100
I
200
I
300
I
400
I
5OO
Bq m -3
Rn-222 concentration FIG. 4. Frequency distribution of 22ZRnequivalent equilibrium concentrations in living premises of the Ukraine
436
V.A. NIKOLAEV et al.
buildings, as a rule, reveal higher concentrations than the ground floors of many-storeyed buildings, because clay and adobe houses have a better connection with ground radon than modern buildings. Application of different construction materials only slightly influences the volume activity of radon in premises; some increase in radon concentration is noticed in brick many-storeyed buildings as compared with panel buildings. In Fig. 4 particular sample distributions of EEC in living premises of the Ukraine are presented. The distributions are governed by the log normal law, the average values being essentially higher than the world ones; a considerable number of houses is found, especially in the Cherkassy region, where the EEC exceeds the levels of 100 and 200 Bq m -3. An analysis of the distributions obtained shows that in Ukraine there is a considerable probability (fractions per cent of a housing estate) where the EEC may exceed 1500 Bq m -3. Houses in the regions located outside the UCS, as a rule, do not have high values of radon volume activity, which is confirmed by data on the Poltava region, the Chernobyl district and the urban settlement Polesskoe. The EEC in living premises of these areas (the Chernobyl town: 3 measuring points, the Chernobyl district: 8 points, Polesskoe: 47 points) have values of 10-20 Bq m -3. The low values of EEC may be explained by both the character of the underlying rocks and an enhanced ventilation of the premises.
On the basis of the measurements carried out it is possible to conclude that the problem of radon is urgent for Ukraine, especially for living premises located on the UCS and represented by one-storey buildings. Acknowledgements--The authors express their thanks to employees of the sanitary services of Ukraine for their help in placing radiometers for exposure, as well as to E. M. Krisyuk and M. V. Terentiev for equipment calibration in the reference atmosphere of radon.
REFERENCES
Kopchenov V. E., Kozunov A. V., Krivokhatskiy A. S. and Nikolaev V. A. (1989) Automated spark counter, ISTRA. Nucl. Tracks Radiat. Meas. 16, 69-70. Krisyuk E. M. (1983) The Radiative Background o f Dwellings. Energy Press, Moscow (in Russian). Nazaroff W. W. and Nero A. V. (eds) (1988) Radon and its Decay Products in Indoor Air. John Wiley, New York. Vorobiev I. B., Krivokhatskiy A. S., Nekrasov E. V., Nikolaev V. A., Potapov V. G. and Terentiev M. V. (1990) Method and facilities for measurement of volumetric activity of radon in air of radon laboratories and hospitals. Hygiene and Sanitaria No. 3 71-72 (in Russian). Vorobiev I. B., Krivokhatskiy A. S., Krisyuk E. M., Nikolaev V. A., Pautov V. P. and Terentiev M. V. (1991) Structure and application of equipment assembly for measurement of radon volume activity in houses and soils. Poster No 191, 15th Int. Conf., Particle Tracks in Solids 3-7 Sept. 1990, Marburg, F.R.G.