CC BY
71
Results of the IAEA personal dosimetric measurements programme in support of the International Chernobyl Project*
Richard V. Griffith
International Atomic Energy Agency
Результаты программы МАГАТЭ по индивидуальным дозиметрическим измерениям в поддержку Международного чернобыльского проекта
Ричард В.Г риффит
Международное агентство по атомной энергии
Пленочные дозиметры производства КОДАК США Тип 3 были распределены среди жителей семи населенных пунктов трех республик, подвергшихся воздействию чернобыльской аварии. На основании показаний 5641 дозиметра можно ожидать, что 90% населения получили менее 1.2 мЗв в течение 1990 года - года измерений. Менее 2.5% должны были получить годовую дозу больше 6 мЗв и только 11 человек получили облучение в дозах более 27 мЗв.
Данные, полученные на счетчиках всего тела для 9058 жителей, показывают диапазон средних годовых доз внутреннего облучения от 0.11 мЗв до максимального значения 0.99 мЗв в небольшом населенном пункте на Украине. Диапазон отражает не только разброс в значениях локального загрязнения цезием, но и различия между населенными пунктами в ограничениях на потребление тех или иных продуктов.
Результаты свидетельствуют, что во время проведения программы измерений внутреннее облучение вносило основной вклад в индивидуальные дозы. Хотя соответствующие данные не приводятся в работе, но полученные результаты в целом согласуются с результатами, опубликованными советскими учеными.
Целью сличения показателей счетчиков всего тела была оценка общего качества измерений, прежде всего 134Cs и 137Cs, произведенных на приборах в зонах, подвергшихся воздействию в результате чернобыльской аварии. Следует помнить, что сличение проводилось спустя 4 года после аварии. Поэтому результаты не обязательно отражают качество измерений, осуществленных в течение первых месяцев после аварии.
МАГАТЭ не располагает специальными критериями для оценки функционирования счетчиков всего тела. Однако качество результатов сопоставления может быть соотнесено с требованиями, содержащимися в публикации МАГАТЭ Safety Series No. 84, Basic Principles for Occupational Radiation Monitoring [6], параграф 4.1.5., где утверждается, что: “В случае рутинного индивидуального мониторинга внешнего излучения относительная неопределенность от -50% до +100% при 95% уровне достоверности приемлема для годовых дозовых эквивалентов в области одной пятой от требуемого предела. Если, однако, значения близки по порядку к годовым пределам, относительные неопределенности не должны превышать -33% и +50% при 95% уровне достоверности.” .... “Сходные требования должны, в принципе, также применяться в случае рутинного индивидуального мониторинга для внутреннего облучения, но на практике такие малые неопределенности как 50% редко возможны .”
В 5 из 36 измерений, проведенных в институтах СССР (таблица 8), результаты находились за пределами диапазона ± 30% по сравнению с референтными значениями. Один результат был немного больше 50% относительно референтного значения. В последнем случае измерение было сделано на неэкранированной пробе с использованием фантома, вдвое превышавшего положение “Marinelli”.
На основании распределения результатов сличения с достаточным основанием можно заключить, что участвовавшие в сличении институты способны проводить измерения внутреннего цезия с точностью, которая приемлема и адекватна для целей радиационной защиты.
Следует также отметить, что в 4 случаях из 5, когда результаты выходили за пределы диапазона ± 30% от референтного значения, измерения проводились на фантомах,
представляющих собой детей. Хотя различия не слишком велики, они указывают на необходимость особого внимания к калибровке счетчиков, предназначенных для измерений детей.
* Acknowledgement is made to Mr. Robert Ouvrard, Acting Head of the Radiation Safety Services Section of the IAEA, for providing the technical measurements on which this article is based.
Introduction
The accident at Unit 4 of the Chernobyl nuclear power plant occurred on 26 April, 1986. In October, 1989 the Government of the former USSR requested the International Atomic Energy Agency to organize and co-ordinate an assessment of the guidance given by the Soviet authorities following the accident to persons living in radiologically contaminated areas and an evaluation of measures to safeguard the health of the population.
As part of the international assessment programme, two projects were implemented by the IAEA to provide independent measurements of the external and internal doses received during the period of the assessment programme by individuals in selected settlements. A total of 12,000 personal dosimeters were distributed to evaluate the external dose to the population, and approximately 9,000 whole body measurements were made.
Moreover, during a mission to the Soviet Union in August 1990 it was concluded that an intercomparison of USSR, IAEA and of the Austrian whole body counters used for in vivo measurement of 137Cs would be valuable in corroborating large scale measurements of the USSR population. The IAEA arranged to obtain use of a standard, adult phantom from the United States for this intercomparison. Additional phantom sets from the Leningrad Institute of Sea Transport Hygiene and the All-Union Scientific Centre of Radiation Medicine, Kiev, were later included in the intercomparison.
External Dosimetry
External dosimetry was carried out under the limited project resources and within a short time scale. As a result, the measurements were not as extensive and sensitive as the Project scientists would have preferred. The results, therefore, only provide an indication of the maximum exposure that would have been received by the majority of the monitored population at the time of the measurements.
Film badge dosimeters were provided by the Service Central de Protection Contre les Rayonnements Ionisants (SCPRI) in France for use in the independent assessment of external doses. Three sets of dosimeters were distributed in the UkrSSR, BSSR, and RSFSR. The first set of 4000 dosimeters was distributed in seven settlements in May 1990 and collected in July 1990. At the time of collection an additional 4000 dosimeters were distributed. These were collected in October 1990. The third set was distributed in December 1990 and collected in February 1991.
The dosimeters were brought to each settlement by members of the international project, who explained the external dosimetry project to the population. The
dosimeters were distributed to individuals selected by the local authorities in each settlement on the basis of predetermined criteria. In addition to the original seven settlements that were included in the first set, dosimeters were distributed in six settlements that were chosen as low radiation control areas in which independent project medical examinations were performed by the medical staff of the Chernobyl Project.
The most important criteria in measuring the dose to a representative sample of the population for each location surveyed were sex, age and occupation. The personal dosimeters were distributed to an approximately equal proportion of men and women. It was intended that individuals of all ages would be provided with dosimeters. However, at the first and second distribution periods most of the children were not present in the settlements because they had been sent to summer camps outside the affected areas. Occupation was also an important factor because of different times spent working indoors or outdoors.
The participants were instructed to carry the dosimeters in a pocket in their clothing in the upper half of the body, and to place it by the bedside while they slept. This procedure was to be continued until the dosimeters were collected.
The film type used in the dosimeters was KODAK US Type 3. This film has two emulsions on one film. Filters of copper (0.2 mm) and lead (1 mm) were used. The energy response is ±10% from 500 to 1000 keV. The detection limit of this method is 0.2 mSv, and the accuracy is consistent with ICRP recommendations (33% to +50%). The films were processed by conventional manual methods at SCPRI and the results were reported to the IAEA laboratory for evaluation.
For the first two sets, 7961 dosimeters were distributed to individuals or the local authorities and 5979 dosimeters were returned to SCPRI for reading. A set of dosimeters was used for background dose measurements or testing. In some cases, insufficient information on the individual was provided to allow inclusion of the datum. Table 1 presents the summary results for the 5641 personal dosimeters exposed for approximately two months in the selected settlements, divided into four ranges of dose.
The higher measurements, in most cases, could be attributed to the individual living in a slightly more contaminated area, or were due to their profession (i.e., forest worker). In five cases analysis of the patterns on the film indicated that the dosimeters had been exposed to x rays, probably intentionally. A few outliers of higher exposures were measured. These could not be explained by the external dose rate measured in the areas. It is suspected that these were from 'hot spots' in the environment or the individuals wearing them spent long periods of time outdoors.
Internal Dosimetry
During the period 5 July to 7 September 1990 a whole body counting campaign was conducted in the BSSR, RSFSR and UkrSSR. Over 9,000 measurements were made, using a mobile whole body counting van provided to the project by the SCPRI, France (Fig. 1). The measurements included (a) reference measurements of a calibration phantom, as well as of van staff, for quality control, and (b) replicate measurements. Some of the measurement results were found to be in error. Therefore, the results for 9,058 people are reported here. The counting locations, dates and number of people counted are summarized in Table 2.
The mobile van is equipped with four chair counters. Each counter has a 7.62x7.62 cm cylindrical NaI crystal housed in a collimated lead shield (Fig. 2). The person is positioned for counting so that the shield is centered on the chest, over the region of the lungs, and in contact with the body. The counting period was 5 minutes. The background counting rates of the counters were determined by inserting a conical plastic plug into the collimator.
During counting, the person being measured provided some self shielding, thus reducing the counter background. Unfortunately, the degree of self shielding was variable, depending on the mass of the person. This is a particularly a problem in evaluating results for small children. The counting procedure as established by SCPRI did not make provision for corrections based on body mass.
The data were processed with a Canberra S35 multichannel analyser connected to an Amstrad portable computer using software developed at SCPRI. Results were recorded on diskette and displayed on computer printout. The SCPRI data-unfolding process is intended to accommodate up to three radionuclides. However, the counting statistics were often poor, so only results for 137Cs are presented in this report. From information provided by whole body counting specialists in Kiev and Minsk, based on their counting results, the ratio of 137Cs to 134Cs was approximately 6.5. Results of this ratio for an environmental sample, dried green peas grown in the Chernobyl region and assayed in December 1990, ranged from 7.9 to 8.8. This would be equivalent to 7.2 in August 1990, the mid-point of the whole body counting project.
The limit of detection (LOD) as defined by the data-processing software of the mobile van is three times the background count standard deviation. Because of the high variability in background from one town to another, the LOD is variable. In addition, the efficiency depends significantly on the size of the person being counted. Therefore, a single value cannot be quoted. However, a typical LOD for an adult is about 0.74 kBq
(0.02 |xCi), while for a small child the value drops to about 0.19 kBq (0.005 |xCi).
Since the mobile van was designed for operational emergency-response applications, the calibration is based on a 70-kg reference man, 170 cm tall. The activity, A (in Bq), had normally been determined by the SCPRI staff using the following calibration:
Countrate
A =--------------------, (1)
0.0003 x CF
where CF is the correction factor for body size:
CF = 2.088 - (1.695 x BSF), (2)
where BSF is the body size factor: [Weight/Height]1/2 (weight in kg and height in cm). CF = 1 for reference man.
The design of the counters in the counting van is such that only activity in the torso is detected. For adults this means that the mass of tissue seen by the counter is roughly constant. Following a review of the counting procedure, it was concluded that the calibration was reasonably accurate in the weight range 50 to 90 kg. However, for individuals outside that range the results could be significantly in error. For a child weighing 20 kg with a height of 100 cm, for example, the original calibration would overestimate the caesium burden by a factor of 2.6. Therefore, it was recommended that a modified correction factor based only on weight be used [2]:
70
CF =---------------------. (3)
Weight( kg )
The original and modified correction factors are displayed graphically in Fig. 3. All data presented in this report have been derived using the revised calibration factors.
During the measurement programme, a plastic cylindrical phantom provided by SCPRI was used to check the counting efficiency on a daily basis. In addition, a few members of the van staff had measurable levels of 137Cs. They were also counted at regular intervals. These results are presented in Table 3. Three of the people who were routinely counted had been checked by the IAEA whole body counter in Seibersdorf, and these results have been taken to be the reference values.
At the end of the counting programme, the van returned to Seibersdorf. At that time, the calibration of each counter was checked with (a) a standard bottle phantom obtained from the Battelle Pacific Northwest Laboratory in the USA and (b) two liquid filled manikins from Salzburg University simulating an adult female and a child. The bottle phantom contained 11.2 kBq 137Cs in a solid polyurethane tissue substitute. Since
the Salzburg phantoms had activity levels that were too low to be useful, those additional results are not presented here.
Summary statistics and internal dosimetry results for the nine settlements in the BSSR, RSFSR and UkrSSR are presented in Tables 4-6. These include the number of persons counted, weight, age, total body burden, specific body burden (body burden/weight), and estimated annual dose based on specific body burden. Since the measurements were made at only one time, it is impossible to determine time dependent changes in the internal body levels. Therefore, a constant intake was assumed.
A conversion factor for specific body burden to dose rate of 2.5 |xSv/a per Bq/kg was used to calculate annual dose [3]. The annual dose in future years will be reduced in proportion to the reduction in environmental caesium levels.
It can be expected that the results for a given population will have a log normal distribution, i.e., the log of the variable x is normally distributed. In this case, the variable is the specific body burden. Comparison of the distribution of specific body burden for each village with an estimate of the best fit for a log normal distribution is presented in Fig. 4. It is clear that the quality of agreement varies from village to village, and that, in some cases, non-statistical factors influence the results. One such influence is the assignment of the value of the detection limit to those measurements at or below that limit. The practice obviously biases the low activity results upwards.
This effect can be seen more clearly in the cumulative normal probability plots of the log of the specific body burden shown in Fig. 5. The overlying straight lines represent the distribution that would be expected for a population having a log normal distribution without additional influences. These plots also demonstrate deviation from the expected distribution at higher values of the specific body burden. The reason for this deviation has not been definitely identified. A possible explanation is that it is the result of a small subset of the population that does not observe the dietary restrictions imposed by local authorities, or that dietary habits (such as eating large quantities of forest mushrooms) predispose members of the population to higher body burdens.
The distributions of annual doses are derived from the specific body burden multiplied by the constant dose factor. There is, thus, no need to illustrate these results. Age-dependent distribution is an important concern. However, the scatter plots shown in Fig. 6 do not indicate a strong age dependence.
Intercomparison of Whole Body Counters
The IAEA arranged to obtain use of a standard, adult phantom from the Battelle Pacific Northwest Laboratories in the United States. The phantom is a "Bush" or "Bottle" type [4, 5] filled with solid, polyurethane tissue substitute and labelled uniformly with 137Cs. The total quantity at the time of the intercomparison was 11,170 Bq (0.3 |xCi). A solid matrix was necessary to avoid the practical problems of handling radioactive liquids during transport. Although accurate measurement of the caesium level in children is a major concern, it was not possible to locate a standard child phantom with a solid matrix.
Counting was performed in the SCPRI counting van, with the IAEA chair counter and with a whole body counter of the Austrian Research Centre during the week starting 17 September 1990. The phantom was then taken to the USSR and used there in various institutes. The intercomparison programme was completed in December 1990 with a final counting of two USSR phantom systems at Seibersdorf. The USSR institutes that participated in the intercomparison programme and the counter characteristics are listed in Table 7.
At the invitation of the IAEA, two USSR phantoms were brought for counting to Seibersdorf in December 1990, namely a block phantom from the Leningrad Institute of Sea Transport Hygiene and another phantom in the form of a bag of dried peas from the All-Union Scientific Centre of Radiation Medicine. Equivalent configurations from both phantom systems were counted, representing (a) a small child, (b) a child of about age 10, and (c) a small adult. In addition, samples of the dried peas used in the Kiev phantom were assayed. Counting was done both in the IAEA chair counter and the counter of the Austrian Research Centre. It must be noted that the IAEA counter is intended only for adults, and it is not specifically calibrated for children. The Austrian Research Centre also normally only counts adults. Therefore, the results of the measurements made using the child phantoms should be viewed accordingly.
The results of the phantom intercomparison measurements are presented in Table 8. Under the conditions of the intercomparison, it was agreed that the results from the USSR counters would not be specifically identified. Therefore, the participating institutes in the USSR are indicated only by numbers in Table 8. However, each USSR facility has been provided a tabulation of the intercomparison results together with specific identification of its own data.
Summary Dosimetry Programme
Film dosimeters of the KODAK US Type 3 were distributed to member of the population in seven settlements in the three Republic effected by the Chernobyl accident. Results from 5,641 dosimeters indicted that 90% of the population could expect to receive less than 1.2 mSv during the 1990 measurement year. Less than 2.5% should have received an annual exposure greater than 6 mSv, with only 11 individuals exposed to levels over 27 mSv.
Whole body counting results for 9,058 people reflected a range of average annual internal exposures from 0.11 mSv to a maximum of 0.99 mSv for a small settlement in the Ukraine. The range indicates not only a range in local cesium contamination values, but differences between settlements in restrictions on food consumption.
The results indicate that, at the time of the measurement programme, external exposure was the major contributor to individual doses. Although not reviewed here, the results are also generally consistent with those of the reported by the soviet scientists.
Whole body counter intercomparison
The purpose of the whole body counter intercomparison was assessment of the general quality of the measurements, primarily of 134,13 Cs, made the counting systems in the region effected by the Chernobyl accident. It must be remembered that the intercomparison was conducted 4 years following the accident. Therefore the results do not necessarily reflect the quality of measurements that were performed in the months immediately following accident.
The IAEA does not have specific criteria for the acceptability of the performance of whole body counters. However, the quality of the intercomparison results can be compared with guidance provided in IAEA Safety Series No.84, Basic Principles for Occupational Radiation Monitoring [6], paragraph 4.1.5, where it is stated that:
"In the case of routine individual monitoring for external radiation relative uncertainties of -50% and +100% at the 95% confidence level are acceptable for annual dose equivalents in the range of one-fifth of the derived limit. If, however, values are of the order of the annual limits, the relative uncertainties should not exceed -33% and +50% at the 95% confidence level." ...
"Similar requirements should, in principle, also apply in the case of routine individual monitoring for internal contamination, but in practice uncertainties as small as 50% are rarely possible."
In 5 of 36 measurements reported from institutes in the USSR (Table 8), the results were outside of a range of ± 30% compared with the reference values. One result was slightly more than 50% above the reference value. In the latter case, the measurement was made with an unshielded probe used with the phantom doubled over in the "Marinelli" position.
Based on the distribution of the intercomparison results, it can reasonably be concluded that the participating institutes are capable of performing internal caesium measurements within an accuracy that is acceptable and adequate for radiation-protection purposes.
It should also be noted that 4 out of the 5 instances of results outside the range of ± 30% from the reference value occurred with phantoms representing children. Although the differences are not excessive, they do suggest the need for additional attention to the calibration of counters for measurements of children.
References
1. International Atomic Energy Agency (1991), The
International Chernobyl Project: Technical Report.
Assessment of Radiological Consequences and Evaluation of Protective Measures. Report by an International Advisory Committee. International Atomic Energy Agency, Vienna, Austria, STI/PUB/885.
2. Steger (1990), F., Private Communication.
3. UNITED NATIONS (1988), Sources, Effects and Risks of Ionizing Radiation (Report to the General Assembly). Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), E.8IX.7, UN, New York (1988).
4. Bush, F. (1949), The Intergral Dose Received From a
Uniformly Distributed Radioactive Isotope, Br. J.
Radiology, 22, 96.
5. Burns, L., Noel, L. and Kramer, G.H. (1990). Construction and Characterization of Elliptical (BOMAB) Phantoms, Human Monitoring Technical Document, Report No. HM-TD-90-1 (Bureau of Radiation and Medical Devices, Ottawa).
6. International Atomic Energy Agency (1991), Basic Principles for Occupational Radiation Monitoring. International Atomic Energy Agency, Vienna, Austria, Safety Series Report No.84.
Table 1 - Summary results of external dose measurements in a two month monitoring period
Group I Group II Group III Group IV
Number of < 0.2 mSv 0.2-1 mSv 1 to 4.5 mSv > 4.5 mSv
Settlement measurements Estimated Annual Dose Equivalent
< 1.2 mSv 1.2 - 6 mSv 6 - 27 mSv > 27 mSv
BSSR
Bragin 395 383 (97.0%) 8 (2.0%) 4 (1.0%) -
Veprin 716 635 (88.7%) 66 (9.2%) 15 (2.1%) -
Korma 843 774 (91.8%) 64 (7.6%) 5 (0.6%) -
Total 1954 1792 (91.7%) 138 (7.0%) 24 (1.2%) -
RSFSR
Novozybkov 1106 862 (77.9%) 142 (12.8%) 92 (8.3%) 10 (0.9%)
Zlynka 780 664 (85.1%) 112 (14.3%) 4 (0.5%) -
Total 1886 1526 (80.9%) 254 (13.5%) 96 (5.0%) 10 (0.5%)
UkrSSR
Polesskoe 987 954 (98.6%) 31 (3.1%) 1 (0.1%) 1 (0.1%)
Ovruch 814 801 (98.2%) 7 (0.85%) 6 (0.7%) -
Total 1801 1755 (97.4%) 38 (2.1 %) 7 (0.4%) 1
Table 2 - Location, date and number of persons counted during the internal dosimetry campaign
Settlement Date of measurements Number of persons counted
BSSR
Korma 10-14 July 1990 719
Veprin 15-21 July 1990 1064
Bragin 5-11 August 1990 1154
RSFSR
Zlynka 22-28 July 1990 998
Novozybkov 29 July-4 August 1990 1453
UkrSSR
Ovruch 12-18 August 1990 1153
Polesskoe 19-25 August 1990 1003
Rakitnoe 26 August-1 September 1990 1320
Daleta 2-7 September 1990 194
Total 9058
T able 3 - Results of whole body counting in the mobile van for purposes of quality assurance
Subject Counter Reference activity (kBq) Measured activity (kBq) Standard deviation Number of measurements
(kBq) (%)
Phantom 1 131 139 2.55 1.8 16
2 134 4.62 3.4 19
3 134 5.62 4.2 23
4 136 7.36 5.4 25
Average 136 5.92 4.4 83
Person 1 1 3.26 3.00 0.59 19.3 9
2 2.66 2.29 0.52 21.9 10
3 2.81 0.78 27.5 7
4 3.00 0.44 15.0 12
Average 2.78 0.63 22.9 38
Person 2 1 3.37 4.77 0.37 7.4 8
2 3.22 4.29 0.56 12.5 4
3 3.92 0.52 13.0 8
4 3.88 0.30 7.4 8
Average 4.22 0.56 13.5 28
Person 3 1 1.44 1.00 69.7 4
2 2.59 0.81 31.7 5
3 2.96 0.92 31.7 10
4 2.96 1.04 35.3 12
Average 2.70 1.11 40.5 31
Person 4 1 3.37 0.92 27.2 12
2 3.18 1.00 31.2 9
3 3.63 0.96 26.8 13
4 4.11 0.37 9.4 8
Average 3.55 0.92 26.3 42
Person 5 Average 1.26 2.26 1.59 71.4 5
Table 4 - Summary results of the IAEA whole body counting project in BELARUS
Settlement Statistical quantity Weight (kg) Age (years) 137Cs total body burden (kBq) 137Cs specific body burden (Bq/kg) Annual dose based on specific body burden (mSv)
Bragin Average 71.5 40.1 3.10 44.4 0.11
Population Median 73 39 2.10 32.1 0.08
sample: Geometric mean 67.9 34.8 2.20 31.9 0.08
1154 Standard deviation 19.5 17.6 5.70 90.5 0.23
Minimum 12 2 0.280 6.6 0.02
Maximum 135 89 130 2110 5.3
Lower quartile 61 28 1.30 20.2 0.05
Upper quartile 84 54 3.50 48.2 0.12
Veprin Average 64.6 36.5 3.20 46.7 0.12
Population Median 69 38 1.50 24.2 0.06
sample: Geometric mean 58.9 28.7 1.60 27.4 0.07
1064 Standard deviation 22.7 20.0 6.10 78.1 0.20
Minimum 10 2 0.090 2.16 0.0054
Maximum 125 86 107 1370 3.4
Lower quartile 55 18 0.650 12.9 0.03
Upper quartile 80 53 3.50 51.4 0.13
Korma Average 67.6 38.5 3.40 50.6 0.13
Population Median 70 38 2.30 36.4 0.09
sample: Geometric mean 62.0 31.1 2.00 32.7 0.08
719 Standard deviation 22.3 19.2 5.10 66.5 0.17
Minimum 10 1 0.100 2.83 0.0071
Maximum 118 85 67.0 932.9 2.3
Lower quartile 60 26 0.800 18.2 0.05
Upper quartile 81 54 4.00 57.5 0.14
Table 5 - Summary results of the IAEA whole body counting project in the RUSSIAN FEDERATION
Settlement Statistical quantity Weight (kg) Age (years) 137Cs total body burden (kBq) 137Cs specific body burden (Bq/kg) Annual dose based on specific body burden (mSv)
Novozybkov Average 69.3 40.4 5.60 78.0 0.20
Population Median 72 42 3.00 43.4 0.11
sample: Geometric mean 65.1 34.4 3.00 45.3 0.11
1455 Standard deviation 20.1 17.7 11.0 131 0.33
Minimum 11 2 0.160 6.5 0.02
Maximum 130 85 180 2200 5.50
Lower quartile 60 29 1.40 23.0 0.06
Upper quartile 83 54 6.10 85.3 0.21
Zlynka Average 66.7 38.7 7.80 116 0.29
Population Median 70 39 4.00 67 0.17
sample: Geometric mean 62.0 31.6 4.10 65.4 0.16
998 Standard deviation 21 19.3 12.0 172 0.43
Minimum 10 2 0.160 7.3 0.02
Maximum 120 96 170 1990 5.0
Lower quartile 59 25 1.70 31.9 0.08
Upper quartile 80 53 8.70 132 0.33
Table 6 - Summary results of the IAEA whole body counting project in the UKRAINE
Settlement Statistical quantity Weight (kg) Age (years) 137Cs total body burden (kBq) 137Cs specific body burden (Bq/kg) Annual dose based on specific body burden (mSv)
Daleta Average 55.84 22.0 23.0 396 0.99
Population Median 55 16 15.0 279 0.70
sample: Geometric mean 49.1 16.2 12.0 249 0.62
194 Standard deviation 25.2 16.4 30.0 425 1.1
Minimum 13 2 0.280 13.3 0.03
Maximum 115 67 320 3750 9.4
Lower quartile 35 10 5.60 135 0.34
Upper quartile 78 31 31.0 524 1.3
Ovruch Average 69.3 38.6 13.0 185 0.46
Population Median 72 42 5.00 77.9 0.20
sample: Geometric mean 64.5 32.7 5.70 88.1 0.22
1153 Standard deviation 20.9 16.9 25.0 353 0.89
Minimum 11 3 0.300 8.2 0.02
Maximum 130 80 280 4060 10
Lower quartile 62 28 2.30 37.6 0.09
Upper quartile 83 52 13.0 182 0.46
Polesskoe Average 73.9 36.8 5.70 76.2 0.19
Population Median 75 36 2.20 29.9 0.08
sample: Geometric mean 70.1 32.2 2.50 35.0 0.09
1003 Standard deviation 19.8 15.8 12.0 158 0.40
Minimum 14 3 0.170 5.3 0.01
Maximum 140 76 170 1960 4.9
Lower quartile 65 26 0.820 13.4 0.03
Upper quartile 85 50 5.33 70.6 0.18
Rakitnoe Average 67.1 33.9 10.0 143.9 0.36
Population Median 70 35 5.30 77.4 0.19
sample: Geometric mean 63 29.0 5.30 83.6 0.21
1320 Standard deviation 20.1 15.6 15.0 203 0.51
Minimum 13 2 0.170 9.0 0.02
Maximum 120 76 180 2524 6.30
Lower quartile 59 24 2.30 42.3 0.11
Upper quartile 80 45 12.0 163 0.41
Table 7 - Participants in the IAEA whole body counting intercomparison programme and counter characteristics
Institute Location Counter type Detector 137Cs background rate (counts/s)
Institute of Biophysics Moscow Stool, CIB-2 Chair, CIB-1 Ge, 100 cm3 Nal, 350 cm3 1.2
Ministry of Public Health Minsk Cherikov Krasnopolje Stool, QBM-1 Chair, CIB-1 Chair, CIB-1 Stool NE 110, 5100 cm3 Nal, 1770 cm3 Nal, 200 cm3 Nal, 1310 cm3 24.8 4.9 3.2
Institute of Sea Transport Leningrad Chair Nal, 200 cm3 1.8
Institute of Radiation Hygiene Novozybkov Chair, CIB-1 Nal, 200 cm3 1.7
All Union Centre of Radiation Medicine Kiev Stool Nal, 2060 cm3 8.6
Ministry of Public Health Kiev Chair Nal, 200 cm3 5.1
Table 8 - Intercomparison results for phantoms counted at institutes in the USSR, in Austria and in the mobile van
Reporting institute and/or type of counter Measured activity (Bq/kg)
Bottle phantom Infant phantom Child phantom Adult phantom Bag phantom of dry peas
74 kg 10.8 kg 24.3 kg 63 kg 15.5 kg 27.7 kg 58.4 kg
USSR 1 148
USSR 2 138
190
USSR 4 132 3420 3500 3120
USSR 5 165 3390 3390 3330
USSR 6 120 3900 3910 2840
USSR 7 160 4210 4350 3900
USSR 8 165
USSR 9 90 4110 3340 3520
USSR 10 4800 2640
USSR 11 4450 2520
USSR 12 172 3090 3060 3380
USSR 13 109 3220 3340 2960
Van 1 160
Van 2 148
Van 3 152
Van 4 136
IAEA 120 2150 2360 2190 477 507 485
ARC 130 3850 3810 3220 684 610 673
Reference value 151 3190 3190 3190 570
587
574
Relative frequency Relative frequency
Fig. 3. Correction factors for detectors in mobile van.
* - For a person 1.70 m tall. The value based on the body size factor (BSF) was intended to be used only for adults. The modified correction factor based on weight, CF(w), is more appropriate also for children and has been applied
to measurements of the International Project.
Log Cs concentration (Bq/kg)
c
Log Cs concentration (Bq/kg) d
Fig. 4. Frequency distribution of the logarithm of the concentration of Cs in the body. Measurement results of the International Chernobyl Project in selected settlements.
b
a
Relative frequency Relative frequency
1 2 З
Log 137Cs concentration (Bq/kg)
h
Log Cs concentration (Bq/kg) i
Fig. 4. (continue) Frequency distribution of the logarithm of the concentration of 137Cs in the body. Measurement results of the International Chernobyl Project in selected settlements.
9
Cumulative percentage Cumulative percentage Cumulative percentage
concentration (Bq/kg)
e
concentration (Bq/kg) f
Fig. 5. Log-normal probability distribution of annual dose in 1990 from 137Cs in the body. Measurement results of the International Chernobyl Project in selected settlements.
0 12 3 4
Log Cs concentration (Bq/kg) i
Fig. 5. (continue) Log-normal probability distribution of annual dose in 1990 from 137Cs in the body. Measurement results of the International Chernobyl Project in selected settlements.
b
Fig. 6. Scatter diagram of concentration of Cs in the body as a function of age. Measurement results of the International Chernobyl Project in selected settlements.
a
concentration (Bq/kg) concentration (Bq/kg) concentration (Bq/kg)
Age (years)
e
Age (years) f
Age (years)
g
Age (years) h
Fig. 6. (comtinue) Scatter diagram of concentration of 137Cs in the body as a function of age. Measurement results of the International Chernobyl Project in selected settlements.
—1—I—.—.—,—.—I—I—1—. . I 1 I . ■ 1 1 1
! Zlynka
: ■ " ■ I ■■ i." . ’ 1
■ . -у -I • . ..|'l !'■:■ .5 i-l1. ■ .■ 1
: ip; 1:=:=S::j j-i:*- := -
^ : =;:: ::
0 20 40 60 80 100
Age (years)
i
Fig. 6. (comtinue) Scatter diagram of concentration of 137Cs in the body as a function of age. Measurement results of the International Chernobyl Project in selected settlements.
Fig. 7. Bottle calibration phantom with 137Cs filled polyurethane.
