Assessment of dose components to Estonian population
Date
2012-08-17
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Abstract
Selleks, et teada saada millist kiirgusdoosi saavad Eesti elanikud, tuleb vaadelda erinevaid komponente, mis võivad doosi tekitada. Mitmeid doositekitajaid on erinevate uuringute raames juba hinnatud, kuid seni puudusid veel paar olulist komponenti.
Käesolevas töös määratleti järgmised täiendavad komponendid:
• 210Pb sisaldust õhus. Mõõtmisel kasutati Harku filterjaamadest kogutud filtreid. Mõõdetud eriaktiivsused osutusid natukene kõrgemaks kui sarnastel pikkus- või laiuskraadidel mõõdetud tulemused, ehk siis aritmeetiline keskmine oli 0.37 mBq m-3. Aastane elaniku kiirgusdoos sellest komponendist tulenevalt on suurusjärgus 0.09 mSv ning see on eelkõige tingitud sisedoosist.
• Ehitusmaterjalides leiduvad looduslikud radionukliidid võivad olla väga olulisteks elanikudoosi tekitajateks. Käesoleva uurimistöö raames määrati looduslike radionukliidide sisaldus 53 erinevas Eestis kasutatava ehitusmaterjali proovis. Aktiivsuse kontsentratsioonide alusel hinnatud ehitusmaterjalide aktiivsusindeksi I väärtused asuvad piirides 0.02 kuni 0.74. See viitab sellele, et ehitusmaterjalide kasutamisel ei ole vaja kasutada piiranguid. Levinumate ehitusmaterjalide jaoks tehti doosihinnangud siseruumides ja selle alusel saadud elaniku aastased kiirgusdoosid jäävad vahemikku 0.16–0.44 mSv.
• Atmosfääris toimunud tuumakatsetuste ja Tšernobõli avarii tulemusel keskkonda sattunud radiotseesiumi (134Cs ja 137Cs) käitumise uurimiseks kasutati 20-25 cm sügavusi pinnaseproove Kirde-Eestis. Proovid võeti sellest piirkonnast eelkõige seetõttu, et Tšernobõli avarii tulemusena tuvastati seal suurimad sadenemised maapinnale. Pinnaseproove võeti enam kui 30 punktis.Radiotseesiumist põhjustatud keskmine aastane elanikudoos on 0.0009 mSv.
Võttes arvesse juba teadaolevad elanikudoosi komponendid ning lisades siis juurde käesoleva töö raames hinnatud, võib väita, et Eesti elaniku kiirgusdoos on keskmiselt 3.23 mSv aastas. Sellele lisandub veel meditsiinist põhjustatav doos.
For assessment of the dose to Estonian population there is a need to assess the doses at least from the all major components. Several dose components have been assessed; however in the current study the following additional components were assessed: • 210Pb content was measured using aerosol airfilter samples. An arithmetic mean value was estimated to be 0.37 mBq m-3, which is slightly higher than those expected at a location of comparable latitude and longitude. The annual dose due to this component is of the order of 0.09 mSv. Dose caused by 210Pb in the air is determined mainly by the ingestion pathway. • Radionuclides naturally occurring in building materials may significantly contribute to the annual doses. During the study 53 samples of commonly used raw materials and building products were collected and measured. Their mean values were in the ranges 7–747 Bq kg–1 for 40K, 4.4–69 Bq kg–1 for 226Ra, and 0.8–86 Bq kg–1 for 232Th. The activity index I in the 53 different building materials varied from 0.02 to 0.74 and the radium equivalent, from 6 to 239. The average annual dose for the people, caused by the building materials of dwellings was estimated to be in the range from 0.16 mSv to 0.44 mSv. • Radiocaesium in the environment is caused from nuclear weapons testing and Chernobyl accident fallout. The deposition and vertical depth distribution of 134Cs and 137Cs in the natural undisturbed soil profiles down to 20-25 cm were studied at locations in the North Eastern Estonia, which were most strongly affected by the Chernobyl fallout in 1986. The average annual dose from radiocaesium was estimated to be 0.0009 mSv. Taking into account the previous studies about the components of the dose to Estonian population and adding the results of the current study, we can conclude that the average annual dose to member of the public is 3.23 mSv. There is only one major component missing from this assessment and this is doses due to the medical exposures.
For assessment of the dose to Estonian population there is a need to assess the doses at least from the all major components. Several dose components have been assessed; however in the current study the following additional components were assessed: • 210Pb content was measured using aerosol airfilter samples. An arithmetic mean value was estimated to be 0.37 mBq m-3, which is slightly higher than those expected at a location of comparable latitude and longitude. The annual dose due to this component is of the order of 0.09 mSv. Dose caused by 210Pb in the air is determined mainly by the ingestion pathway. • Radionuclides naturally occurring in building materials may significantly contribute to the annual doses. During the study 53 samples of commonly used raw materials and building products were collected and measured. Their mean values were in the ranges 7–747 Bq kg–1 for 40K, 4.4–69 Bq kg–1 for 226Ra, and 0.8–86 Bq kg–1 for 232Th. The activity index I in the 53 different building materials varied from 0.02 to 0.74 and the radium equivalent, from 6 to 239. The average annual dose for the people, caused by the building materials of dwellings was estimated to be in the range from 0.16 mSv to 0.44 mSv. • Radiocaesium in the environment is caused from nuclear weapons testing and Chernobyl accident fallout. The deposition and vertical depth distribution of 134Cs and 137Cs in the natural undisturbed soil profiles down to 20-25 cm were studied at locations in the North Eastern Estonia, which were most strongly affected by the Chernobyl fallout in 1986. The average annual dose from radiocaesium was estimated to be 0.0009 mSv. Taking into account the previous studies about the components of the dose to Estonian population and adding the results of the current study, we can conclude that the average annual dose to member of the public is 3.23 mSv. There is only one major component missing from this assessment and this is doses due to the medical exposures.
Description
Väitekirja elektrooniline versioon ei sisalda publikatsioone.
Keywords
Eesti, elanikkond, kiirgusdoos, Estonica kogu, Estonia, population, radiation dosage