Natural Radionuclides by Gammaspectrometry In the Belgrade, Capital City in Yugoslavia for 1998, 1997 and 1996

Transcription

1 Natural Radionuclides by Gammaspectrometry In the Belgrade, Capital City in Yugoslavia for, and D.M.Vukovic 1, D.Markovic 2 1 Institute for occupational and radiological health, Deligradska 29, Belgrade, Yugoslavia 2 Faculty for physical chemistry, Studentski trg 12/1, Belgrade, Yugoslavia INTRODUCTION From total radiation that the humans were exposed there is about 68% from natural sources, (called natural phone), 31% from medical sources 0.6% from fallout, 0.5% from other sources (from airplane, TV) 0.15% from nuclear power plants. What ever is radiation into the environment it is important the gamma dose rate that is capable to change genetic structure of humans causing different diseases. Natural radiation on the earth was separated as 1. EXTERIOR RADIATION, which including cosmic radiation, radiation from the soil, radiation into the air and natural radionuclides into the drinking water and the food. Cosmic radiation comes mostly from protons, alpha radiation and some nuclides. Radiation from the soils comes from radionuclides of urans and thorium families and natural and 86 Rb. Extra radiation from some soils comes from radon. Radiation into the air and the food comes from, 226 Ra, and depends of the purity of environment (extra sources of contamination). 2. INTERIOR RADIATION, which comes from our bodies with normal metabolism and healthy populations. Radiation comes from and 14 C, as the traces from radium and thorium into the skeleton. Each region, parts of earth or country should have legal and organizational aspects known as radiation monitoring program. The form of monitoring program is determined by number of factors as: type and amount radionuclides expected into the environment, principle routes of exposure (fallout or nuclear power plant or other type of contamination), the ways in which the environment is used (water supplies, agricultural region), characteristic of population, its distribution, social activities, means of earning its livelihood, dietary habits and the origin of the food it consumes. The law also gives general guidelines for radiation monitoring programs, which also could be divided into the sub levels. The law also provides rules that special institutions with appropriate equipment and education of personals are included. Each book of regulations deals with the specific section of the radiation protection in more details about how to collect samples and on which period. Today with modern equipment of the ionizing chamber it is possible to made continuous measuring of EXTERNAL gamma dose rate into the air, basically first indicator of unusual source of radiation contamination. The external radiation dose burden estimates are of course also useful in the later phase, especially supported by sensitive passive personal dosimeter reading, like TLD. Other source of contamination offer is due to transfer of pollution. For that type of contamination it is necessary to collect as rapidly as possible data on amount of atmospheric deposition. The soil and the food were collected, twice a year. The water and the milk were collected monthly. Speaking of the measuring methods high resolution gamma spectrometry proved as the only method which could without systematic error cover a wide range of specific activities, identify presence of the majority of radionuclides which are present in the samples and determine their specific activity. Belgrade as a capital city of Yugoslavia with more that 2,5 million populations is important point into the radiation-monitoring program of Yugoslavia. Geographical data about place were collected sample. more geographic coordinate Above places Information north east the sea Belgrade The city and suburb , m METHODS, samples and instrumentations The following samples were collected on the location of Belgrade, Capital City of Yugoslavia. Fall out: Collected samples on the end of months, dried on 1 liter and prepared for equilibrium and measurement by gamma spectrometry. Soil: Soil, arable and rude were collected from the agricultural farm, in the suburb of Belgrade, called Jabucki rit, dried and prepared for equilibrium and measurement by gammaspectrometry Water: Drinking water were collected, liters, dried on 1 liter for marineli, and prepared for 1

2 equilibrium and measurement by gammaspectrometry. Human food: Human food, mostly milk, meat, vegetable and fruit of that region were prepared as ash and measurement by gammaspectrometry. Animal food: Animal food were collected from the agricultural farm, in the suburb of Belgrade, called Jabucki rit, and prepared for equilibrium and measurement by gamma spectrometry. From time to time, depends of type of sample, it is prepared as ash. All samples were counted on appropriate geometry (marinelli beakers or other adopted from laboratory) with a hyper pure germanium detectors EG&G ORTEC with relatively efficiency 25% and resolutions 1.85 KeV on MeV. The detector was contained in 10cm thick lead well internally lined with cadmium and copper folios. Through a linear amplifier the detector was connected to an 8192 channel pulse height analyzer on the line to a personal computer. Data analysis was performed taking into account sample geometry, self-absorption in the sample and background. Gamma dose rate was measured on Ionizing chamber RSS-112 from Reuters Stocks, madden from two main parts, circular ionizing chamber volumes 8 liters and sustainable electronics. The measurements are automatic, every each 5s, but averaged values stored in 15 minute's interval as a file. Number of stored values is 220 values, and as interval 15 minutes, on presented instrument each moment is possible to controlled gamma dose rate in the 55 hours ago. Instrument is connected with computer and data could be transferred automatically and memorize permanently. Error of presenting gamma dose rate in the air on that way is 5%. RESULTS AND DISCUSSION RESULTS OF EXTERNAL CONTAMINATION As it is mentioned increasing gamma dose rate into the air is the first indicator of exposing of radiation contamination. In Belgrade in the back yard of the Institute for occupational and radiological health was installed automatic ionizing chamber, RSS-112. Stored results were presented as monthly values in Table 1/EC. Table 1/EC. Place: Belgrade, unit µgy/h, multiplied by x10-3 GAMMA DOSE RATE month Jan. Feb. Mar. Apr. May June July Aug. Sep. Oct. Nov. Dec. min med max min med max min med max Activities of the aerosol presented as a monthly value are in Table 3/EC. Activity of fallout presented as a monthly value is in Table 2/EC. Activity of both aerosols and fallout is presented over activity of natural nuclides and 226 Ra, and non-natural. As can be notified mainly activity in fall out is from natural in both types of sample. Activities of soil for all tree years, and are shown on tree separated Tables 4/ECa, 4/ECb and 4/ECc. Activity of soils are presented over activity of natural nuclides, 226 Ra, 232 Th, 234 Th, 235 U, 238 U, 214 Bi, some rare but toxic elements 7 Be and 208 Tl and non-natural. As can be notified mainly activity in the soils are from natural, (interval of values Bq/kg), 214 Bi (interval of values Bq/kg), 226 Ra, (interval of values Bq/kg), 232 Th (interval of values Bq/kg), 234 Th, (interval of values Bq/kg). 2

3 Table 2/EC. Place: Belgrade, unit Bq/m 3 3 AEROSOL month Jan. Feb. Mar. Apr. May June July Aug. Sep. Oct. Nov. Dec Ra Ra ± Ra ± ± Table 3/EC. Place: Belgrade, unit Bq/l ± ± ± FALL OUT month Jan. Feb. Mar. Apr. May June July Aug. Sep. Oct. Nov. Dec Ra ± Ra ± 226 Ra ± ± ± ± ± ±3.0 4± ± ± 12.9± ± 11.8± ± 0.53± ± ± 0.90± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 4.8 Both urans are notified: 238 U on the border of delectability (back ground, low concentration of that elements, experimental errors) with values could be zero or values ( ) Bq/kg and 235 U also with low activity but with better experimental errors are in interval Bq/kg. Two toxic elements 7 Be and 208 Tl are

4 monitored and registered in traces. Non natural was registered too, in intervals of activity Bq/kg. Table 4/ECa. Place: Belgrade, units Bq/kg SOIL rude arable 0-10cm 10-20cm 20-cm 0-10cm 10-20cm 20-cm, June and November 384±16 560±21 447±17 548±21 323±14 570±19 400±15 550±21 322±13 511±18 453±18 638± ± ± ± ± ±0.9 6± 19.4± ± ± ± ± ± Ra 33.6± ± ± ± ± ± ± ± ± ± ± ± Th 29.4± ±3.1.8± ± ± ± ± ± ± ± ± ± Th U 1.52± ± ± ± ± ± ± ± ±0.44 9± ± ± U Be 15.1± ± ±3.2 2± ± ± ± ± 24.7± ± ± ± Bi 31.8± ± ± ± ± ± ± ± 24.7± ± ± ± Tl 9.83± ± ± ± ± ± ± ± ± ± ± ±0.9 Table 4/ECb. Place: Belgrade, units Bq/kg SOIL rude arable 0-10cm 10-20cm 20-cm 0-10cm 10-20cm 20-cm, April 677± ± ± ± ± ± ± ± ± ± ± ± Ra 37.2 ± ± ± ± ± ± Th 44.4 ± ± ± ± ± ± Th U 2.20 ± ± ± ± ± ± U Be 28.6 ± ± ± ± BI.9 ± ± ± ± ± ± Tl ± ± ± ± ±0.47 Values of activity of two rivers, Danube and Sava, were estimated too for all tree years, and. Activities of these two rivers on which are town settled are presented over activity of natural nuclides 40 K, 226 Ra, 232 Th, 234 Th, 235 U, 238 U, 214 Bi, some rare but toxic elements 7 Be and 208 Tl and non natural. Data was not presented but mainly activity in both rivers are from natural,with remarks that values of total activity of all radionuclides per sample was not higher than one or two Bq/l. Activity of sediment of river Danube is estimated too. Data are for years and are shown in table 5/EC. 4

5 Table 4/ECc. Place: Belgrade, units Bq/kg SOIL rude arable 0-10cm 10-20cm 20-cm 0-10cm 10-20cm 20-cm, June and November Ra Th 9.72± ± ± ± ± ± ± ± ± ± ± Th U 0.52± ±7 7± ±0.17 9± ± ± ±0.68 7± ± ±9 1.11±7 238 U Be 4.38± ± ± ± ± ± ± ± ± ± ±2.3 ± 214 BI 17.7± ± ± ± ± ± ± ±1.8.0± 19.1± ± ± Tl ± ± ± ±0.5 Table 5/EC. Place river Danube for 234 Th 228 Ac 226 Ra 214 Bi 40 K 137 Cs 134 Cs SEDIMENT sediment S1 sediment S2 sediment S3 sediment S4 Bg/kg Bg/kg Bg/kg Bg/kg 32± ±3 34±4 36±2 20±1 22±1 29±1 41±4 24±2 26±3 35±4 36±2 20±1 22±1 32±1 571±16 348±11 374±11 425±12 40±1 15±1 1.3± 1.4±0.1 36± ±9 37±9 39±2 27±2 20±2 28±1 45±5 38±6 26±3 26±3 40±2 32±2 33±1 32±1 570±16 447±13 483±15 445±12 46±2 39±1 0.4± ± 1.4± ±9 31± ±6 33±2 33±2 20±1 22±1 36±11 38±11 37±6 31±3 32±1 32±1 22±1 504±14 504±14 405±11 401±11 38±1 38±1 5.3± 0.8± 0.5± 0.5± ±5 17±5 34±2 31±13 26±2 26±2 22±2 22±1 35±5 35±5 26±2 31±8 27±1 341±11 341±11 406±16 435±12 28±1 28±1 18±1 1.4±

6 RESULT OF INTERNAL CONTAMINATION A lot of parameters indicate the internal radiological contaminations: drinking water, milk, different type of human food. Activities of both drinking water and milk presented over activity of natural nuclides and 226 Ra. Data are in Tables 1/IC. and 2/IC. In the same time as a control calculated activity of non natural and 134 Cs (result not in the table) is estimated too. Table 1/IC. Place: Belgrade, units Bq/kg, 6 DRINKING WATER month Jan. Feb. Mar. Apr. May June July Aug. Sep. Oct. Nov. Dec ± x Ra x ± 226 Ra x Ra ± ± ± ± ± ± ± ± Activity of drinking water comes from natural nuclides and 226 Ra and are in interval values 1-110mBq/l Values are mostly as 0.11 what mean that could be even lower under the limit of delectability. Same situation was obtained with non-natural cesium. Values of activity for milk are in Table 2/IC. Table 2/IC. Place Belgrade units Bql MILK month Jan. Feb. Mar. Apr. May June July Aug. Sep. Oct. Nov. Dec. 50.4± 45.5± ± ± 52.0± ± 61.1± ± ± ± ± ±3 52 9± ± Ra ± ± ± ± ± ± 1.4 5± 41.6± ± ± ± ± ±2 74±2 55±2 50± ±5 38± ± Ra ± ± ± 340± ± 38.4± ± ± ± ± 100± ± ± ± 110±5 70±2 100± ± ± 32.6± ± Ra As can be notified activity of natural is dominant what is expectable for estimated sample. Activity 59.4± 2.2

7 of 226 Ra is negligible and is interval for all tree years. Activity of is in the shadowed column. Values indicate a presence of that nuclide in the milk as allowed concentrations due to Chernobyl accident. Activities of human food for all tree years are Tables 3/IC, 4/IC and 5/IC. Like in the previous situation mainly activity comes from natural. There is evidence for presence natural 226 Ra with activity not higher than 10 Bq/kg with one or few exceptions. In the same time as a control calculated activity of non-natural shadowed columns. Activities of fishes from Danube are only for year and data are in Table 6/IC. Activity is mainly from natural typical for fish. As could be notified selection was to check activity of typical fish in International River Danube. Table 3/IC.Place Belgrade units Bq/kg Sample month HUMAN FOOD x Ra food for baby February 44.3± anion May 76.8± salad May 101.0± spinach May 173.1± cheery May 73.9± vegetable October 310.0± ±2 4.2 bread October.9 ± potato October 219.1±6.8 7± Table 4/IC. Place Belgrade units Bq/kg sample month HUMAN FOOD 226 Ra 2 cheese June 183.4± food for baby June 3 ± potato October 154.3± tomato October 72.1 ± bean December 539.0± Grain December 105.0± Robbery October 35.4 ± Spinach November 8805 ± Apple December 1627± Cabbage December 6738 ± food for baby December 92.1 ± Table 5/IC.Place Belgrade units Bq/kg sample month 7 HUMAN FOOD 226 Ra food for baby June 22.5 ± yogurt December 48.9 ± ± vegetable August ± ± salad August 91.8 ±4.1 1 ± anion June 66.2 ±3.4 1 ± tomato November 79.7 ±3.8 3 ± Food for baby April 36.2 ± Food for baby April ± Activities of the animal food for all tree years are Tables 7/IC. As an in the previous situation mainly activity comes from natural. There is evidence for presence of natural 226 Ra with activity not higher than 10 Bq/kg too. In the same time as a control was calculated activity of non-natural and notified allowed activities. That activity is consequence of Chernobyl accident and fallout in the regions with about 20 nuclear

8 power plants in the neighbored. Table 6/IC. Place river Danube in the year Time Sample Radio Nuclide FISH mixture of som karas stuka karas white fish saran different (kind of (kind of (kind of (kind of (kind of kind of river fish) river fish) river fish) river fish) river fish) fish activity (Bq/kg fresh sample) 234 Th Ac ± Ra ± Bi ±0.1 ± K 71±2 26±1 35±2 140±8 81±2 78±2 55±2 137 Cs ±0.1 ±0.1 ± ± ±0.1 ± Cs Table 7/IC. Place Belgrade sample month ANIMAL FOOD x Ra Grass, clover June 612± Grass, clover June 915±28 163± Alfa alfa June 856± Grass, clover June 447± Grass, clover September 314± hay October 678± ± Grass, clover November 662± ±1 9.8 hay November 299± ± Fish powder January 208±8 0.45± Animal oil beet January 3± ± mixture January 150±7 0.19± maiz February 77 ± vegetable february 475± Animal powder February 360± ±6 8.3 hay April 529± ± hay April 9± ±7 5.5 Grass, clover April 180±7 0.± CONCLUSION Qualitative and quantitative knowledge of natural radioactivity in the ecosystems is important in itself since it concerns the most abundant radionuclides on the Earth and the radiation protection problems. It is also valuable as a reference term to determine the relative importance of artificial radioactivity from authorized waste discharges from nuclear plants and fallout from atmospheric weapon testing and nuclear accidents. DOSE ON POPULATIONS for gamma ray dose rates in the air over radioactive rocks and soils could be calculated by equations 8

9 D = C K C Ra C Th C, concentration of different radionuclides in Bq/kg, D is expressed in nsv/h (In this paper we did not present that type of calculations): DOSE ON POPULATIONS for gamma ray dose rates due to ingestion is so complicated and there is a lot have computed models. Still different population has different type of food, different habits in the way as they treat and prepared foods and on the end eat. Still, it is important to know haw much activity is your daily meal. Registered activities from ecosystems over chosen samples, in the regions of Belgrade indicate only radiation from natural sources. Non-natural radionuclides in traces are not surprise because of accident in Chernobyl in 1986, and in the neighboring countries there is nuclear power plants. And shortly activities are: Gamma dose rate into the air has allowed values, interval of middle values are (70-120) µgy/h, multiplied by x10-3 and maximal (88-170) µgy/h, multiplied by x10-3 and maximal Activities of aerosols are mainly due to. Activities of 226 Ra and are negligible if you compare with activity of. Activities of fallout are mainly due to activity of natural, ( Bq/l). Activities of soil, are presented over activity of natural nuclides, 226 Ra, 232 Th, 234 Th, 235 U, 238 U, 214 Bi, some rare but toxic elements 7 Be and 208 Tl and non natural. Values are:, Bq/kg), 214 Bi ( Bq/kg), 226 Ra ( Bq/kg), 232 Th ( Bq/kg), 234 Th ( Bq/kg) 238 U ( ) Bq/kg, 235 U ( Bq/kg. 7 Be and 208 Tl are registered in traces. Non natural was registered too, with intervals of values Bq/kg. Activities of rivers Danube and Sava was controlled and total activity from both rivers (both series thorium and urans are included) are not higher than one or two Bq/l. Activities of drinking water are activity of natural (2-110 mbq/l), with comment that experimental conditions indicate that these values could be even lower. Activities of human food, the food for baby and the milk are ( Bq/l) and (9-0 mbq/l). Activities of food for baby are ( Bq/kg) and was ( Bq/kg). Activities of radium are under the limit of experimental conditions. Activity of vegetable is variable, depends of type of vegetable or fruits, but activity comes from natural. Activity of and 226 Ra is under the limit of experimental conditions. Acknowledgment: I would like to say thanks to Nebojsa Vukovic, for help into the sorting text. I would like to say thanks to Department for electrochemistry, of Vukelic Nikola on Faculty for physical chemistry for help. And college into the Institute of occupational and radiological health, environment laboratory in Belgrade. REFERENCES 1. G. Djuric, D.Lj. Popovic, On some problems of radionuclides in environment, XIX Yugoslav symposium from radiation protection, Golubac June (), pp G.C. Bonazzola and R. Ropolo Distribution of fallout radionuclides in soil, plants and honey, Health Physics Vol. 60, No. 4. pp (1991) 3. Draganic Radioactive isotopes and radioactivity book Belgrade 4. Formal paper (Sluzbeni list) of Yugoslavia No. 84 year Formal paper (Sluzbeni list) of Yugoslavia No. 40 year F.A.Tikhomirov Long-Lived Man Made Radionuclides in the Soil Plant Systems, CHAPTER 12. pp (1986) 7. J.H.Harley Naturally Occurring Sources of Radioactive Contamination, CHAPTER 6. pp.59 (1986) 8. L.Doretti, D.Ferrara, G.Barison, R Gerbais, G. Battiiston, Natural radionuclides in the muds and waters used in thermal therapy in Abano terme, Italy Radiation Protection Dosimetry Vol. 45. No 1/4 pp (1992) 9. F.Fernandez, J.C.Lozano, J.M.G.Gomez, Natural radionuclides in ground water in western Spain Radiation Protection Dosimetry Vol. 45. No 1/4 pp (1992) 10. LAmbrechts, L.Foulquier, J.Garnier-Laplace, Natural radionuclides in the aquatic components of the main French rivers Radiation Protection Dosimetry Vol. 45. No 1/4 pp (1992) 9

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