The Exposure of the Population of Israel to Natural Sources of Ionizing Radiation

Transcription

1 The Exposure of the Population of Israel to Natural Sources of Ionizing Radiation This study was partly funded by the NCAB L. Epstein 1,2, J. Koch 1, T. Riemer 1, I. Orion 2 and G. Haquin 1 1 Radiation Safety Division, Soreq Nuclear Research Center 2 Dept. of Nuclear Eng., Ben-Gurion University of the Negev

2 Average Exposure of the Population - World Exposure to natural sources of ionizing radiation msv/y Medical exposure msv/y msv/y UNSCEAR, 2010

3 Average Exposure of the Population - USA Exposure to natural sources of ionizing radiation - 3 msv/y Medical exposure 3 msv/y msv/y UNSCEAR, 2010

4 The Natural Sources of Ionizing Radiation Radionuclides in the earth s crust Internal exposure radon External exposure radionuclides in the building materials and the ground Internal exposure radionuclides in food and water Cosmic radiation Cosmic rays Cosmogenic radionuclides

5 Goals of the Study Assessment of the exposure of the population of Israel to natural sources of ionizing radiation Modeling the average exposure according to the local characteristics (geology, geography), as well as specific features of the local lifestyle Providing the results of the average exposure of the population of Israel to the UNSCEAR database

6 * Haquin G., Riemer T., Shamai Y., Margaliot M. Shirav-Schwartz M. Kenett R, Radon Survey of Israel, Soreq NRC report No. 3530; 2006 (in Hebrew). Average Indoor Radon Concentrations Radon survey in singlefamily houses Average (Bq/m 3)

7 Radon Survey in Apartments in Multistory Buildings Factors affecting the radon concentration in multistory buildings: Building materials Ventilation rate

8 Radon Survey in Apartments in Multistory Buildings cont 300 participants 1/3 new buildings (<10 y) Building materials with higher radionuclides concentrations Lower ventilation rate Dwelling Shielded Space (DSS) 2/3 old buildings (>20 y) Building materials with lower radionuclides concentrations Higher ventilation rate no DSS

9 The Distribution of Radon Concentrations in Apartments in Old and New Buildings Geometric mean Bq/m Bq/m 3

10 The Distribution of Radon Concentrations in DSS and in Living/Bedrooms in New Buildings Geometric mean Bq/m Bq/m 3

11 * Haquin G., Riemer T., Perrino C., Lahav D., Margaliot M. Atmospheric Radon and Radon Decay Products in Ashdod, Israel. Living with Global Changes in Environmental Sciences.ISEEQS, Rehovot; Average Radon Concentrations Group Outdoors Old Buildings New Buildings Single-family houses Geometric mean )Bq/m 3 ( 10* Geometric standard deviation A statistical significant difference was found: Between radon concentrations in single-family houses and apartments in multistory buildings Between radon concentrations in new and old multistory buildings Between the DSS and the living/bedroom in the same apartment (in new buildings)

12 The Average Dose due to Radon Inhalation Average radon concentration indoors 31.1 Bq/m 3 Based on the distribution of apartment types (single-family houses, apartments in old and new multistory buildings). The average annual dose due to radon inhalation msv Based on the new ICRP conversion factor from radon exposure to dose (2009 ICRP Statement on Radon, ICRP Pub. 115)

13 Indoor Exposure Average radionuclides concentrations in building materials Building material Concrete without coal ash Concrete with 1.5% coal ash Concrete with 6% coal ash Hollow Concrete Block Autoclaved Aerated Concrete Gypsum Density (kg/m 3 ) Concentration (Bq/kg) 232 Th Ra K Using a model* * de Jong P., van Dijk J.W.E. Modeling Gamma Radiation Dose in Dwellings due to Building Materials. Health Physics 94: 33-42; 2008b.

14 Indoor Exposure cont Building material Gypsum wall Autoclaved Aerated Concrete Hollow Concrete Block without coal ash Concrete without coal ash Density (kg/m 3 ) Dose rate* (nsv/h) Concrete with 1.5% coal ash * According to the location of the wall (inner/outer) and the presence of doors and windows. Average dose rate indoors - 25 nsv/h

15 Radionuclides in the Earth s Crust Outdoor Exposure Aerial survey + ground measurements High dose rates Mount Scopus Group Dose Rate (nsv/h) 15 D<18 18 D<21 21 D<24 24 D<27 27 D<30 Low dose rates The Coastal Plain The average dose rate outdoors 20 nsv/h

16 Internal Exposure to the Natural Radionuclides Internal exposure as a result of food and water consumption Based on worldwide average concentrations of radionuclides in foodstuffs and water Adaptation to the Israeli diet Internal exposure to thoron Worldwide average thoron concentration Average annual dose msv

17 Cosmic Radiation Assessment of the exposure in the 120 most populated cities and towns in Israel (85% of the population) Using the EXPACS model* Taking into account latitude and altitude * Sato T., Yasuda H., Niita K., Endo A. and Sihver L., Development of PARMA: PHITS based Analytical Radiation Model in the Atmosphere, Radiat. Res. 170, ;

18 Cosmic Radiation cont The average annual dose: Place of exposure Outdoors Indoors Weighted total Average dose (msv) Range )msv( Annual dose from cosmogenic radionuclides - 12 μsv

19 The Average Annual Dose to the Population of Israel from Natural Sources Radon Source of Exposure External Exposure Indoors Outdoors Total Internal exposure other than radon 40 K in food 238 U and 232 Th decay chains in food 238 U and 232 Th decay chains in air Thoron Total Cosmic radiation Cosmic rays Cosmogenic radionuclides Total Total Annual effective dose (msv/y) Range (msv/y)

20 The Contribution of the Different Sources to the Average Annual Dose Internal Exposure from Radon 59% Cosmic Radiation 11% External Exposure 10% Internal Exposure other than Radon 20%

21 Summary The average annual dose to the population of Israel from all natural sources msv The worldwide average 2.4 msv Radon is the main contributor 60% of the dose Statistically significant differences between radon concentrations in building types and even room types Application of the updated ICRP conversion factor from radon exposure to dose

22 Thank You