Dose Assessment for Population around New NPP in Belarus EMRAS II WG1 Meeting, “Reference Methodologies for Controlled Discharges” IAEA HQ, Vienna, 22-24 September 2009 Viktoryia Kliaus Minsk, Belarus

Where is Belarus situated? RUSSIA BELARUS POLAND UKRAINE It is surrounded by Lithuania and Latvia to the northwest and Russia to the north and east. Ukraine lies to the south and southeast and Poland to the west.

Facts about Belarus Minsk LOCATION - Eastern Europe An inland country. It is surrounded by Lithuania and Latvia to the northwest and Russia to the north and east. Ukraine lies to the south and southeast and Poland to the west TIME - GMT +2 AREA - 207,595 sq km (80,153 sq miles) POPULATION - 9,7 million (2009) CAPITAL CITY - Minsk - Population 1,7 million CURRENCY - Belarus Rubel (BYB) LANGUAGE(S) - Belarussian and Russian RELIGION(S) Christian with an Eastern Orthodox and Roman Catholic majority, Jewish and Muslim minorities Minsk

The Competence of State Organizations in the Area of Nuclear and Radiation Safety Council of Ministers National Commission of Radiation Protection Ministry of Health Ministry of Ecology Ministry of Emergency Situations Department of Nuclear and Radiation safety Approve medical standards, rules and hygienic norms Established the unified system of control and registration of individual doses In this structure one can see the structure and main functions of Belarusian State organizations according to the Law “About Radiation Safety of Population” Head organization is the Council of Ministers The authority in our country is Department of Nuclear and radiation safety. Organize carrying out of the radiation monitoring of environment Licensing According to the Law “About Radiation Safety of Population”

Possible location of the NPP NPP in Belarus Type: NPP-2006; Reactor: WWR (PWR)-1200; General contractor: “Atomstroieksport” (Russia); Possible location: Ostrovets, Kukshinovo, Krasnaya Polyana areas; Planned construction time: 54 month; Lifetime at 90% capacity factor : expected 50 years; The WWR 1200 will produce: 1200 MW(e) electric power and 3200 MW(th) heat power. Grodno Brest Minsk Vitebsk Mogilev Gomel Ostrovets area Kukshinovo area Krasnaya Polyana Belarus is considering the development the NPP NPP – 2006 is an evolution project, based on the NPP with reactor WWR-1000. It is known that NPP 2006 based on 2 projects: Npp-92 and NPP91/99. There are a lot of such reactors in different countries: Russia (7 power units), Ukraine ( 11 power units), Bulgaria (2 power units) and Czech (2 power units) There are 3 possible areas for building the NPP, the Ostrovets area is priority. Possible location of the NPP

Model of the Belarusian NPP NPP in Belarus Safety features: containment building and missile shield; Dose for public during normal operation: 100 µSv/year; During normal operation such types of NPP make an insignificant impact on environment (radiation impact no more than 0,1 – 0,01 from background radiation level). General layout of Belarusian NPP was developed for 2 power units Model of the Belarusian NPP

Regulatory limit values Dose limits in planned exposure situations Type of limit Dose limits Occupational Public Effective dose 20 mSv/year, averaged over defined periods of 5 years, but it should not exceed 50 mSv in any single year 1 mSv/year for any consistent 5 years, but it should not exceed 5 mSv in any single year Safety criteria and project dose limits should be estimated in accordance with National Standards of Radiation Safety, that are based on the ICRP recommendations and in accordance with IAEA recommendations. The Commission has concluded that the existing dose limits that it recommended in Publication 60 continue to provide an appropriate level of protection (ICRP, 1991b). For occupational exposure in planned situations (in case of normal operation of the NPP), the Commission continues to recommend that the limit should be expressed as an effective dose of 20 mSv per year, averaged over defined 5 year period (100 mSvin 5 years), with the further provision that the effective dose should not exceed 50 mSv in any single year. For public exposure in planned situations, the Commission continues to recommend that the limit should be expressed as an effective dose of 1 mSv in a year. However, in special circumstances a higher value of effective dose could be allowed in a single year, provided that the average over 5 years does not exceed 1 mSv per year. Limits on effective dose are for the sum of relevant effective doses from external exposure in the specified time period and the committed effective dose from intakes of radionuclides in the same period. For adults, the committed effective dose is computed for a 50-year period after intake, whereas for children it is computed for the period up to age 79 years. According to the Standards of Radiation Safety-2000

Regulatory limit values Values of radioactive discharges from NPP with WWR-1000 in case of normal operation NPP Rare radioactive gases I-131 Со-60 Сs-134 Сs-137 ТBq (% from leakage) MBq (% from leakage) NPP with WWR-1000 and WWR-440 Novovoronezhskaya 110 (16) 1700 (9,4) 350 (4,7) 41 (4,6) 140 (7) Kolskaya 4,2 (0,6) 134 (0,7) 88 (1,2) 0,01 53 (2,7) Rostovskaya 0,2 (0,02) 57 (0,3) 0,8 (0,01) 0,2 (0,03) 0,1 (0,01) Balakovskaya 223 (1,2) 7,7 (0,1) 2,4 (0,3) 7 (0,4) Kalininskaya 49 (7) 512 (2,8) 4,1(0,1) 0,7 (0,1) 1,8 (0,1) Radioactive fall-out in case of normal operation of the NPP formed accommodation of radionuclides on the soil surface with including these radionuclides into the biological circulation and migration of radionuclides in food chains. As this fall-out is very unintense so the concentration of radionuclides in agricultural products and into the human’s organism will be very low Штатные радиоактивные выпадения при нормальной эксплуатации реактора определяют постепенное накопление радиоактивных веществ на поверхности почвы с вовлечением их в биологический круговорот и миграцией по пищевым цепочкам. В силу низкой интенсивности этот вид выпадений определяет очень низкое содержание радионуклидов в сельскохозяйственной продукции и вносит малый вклад в дозу внешнего и внутреннего облучения биоты.

The Concept of ‘Critical Group’ The ‘critical group’ concept is used for the purpose of protection of the public in Belarus to characterize an individual who is representative of the most highly exposed individuals in the population (ICRP 1977, 1985); It is important to consider some aspects : The location and age distribution of the potentially exposed group; Dietary habits; Special occupational habits; The type of dwelling; Behavior factor. We used the concept of critical group in case of normal operation of the NPP. Such groups in the population may be in the vicinity of the installation or at some distant location; they may include adult males, adult females, pregnant women, and children; they may be individuals who eat foodstuffs prepared in a special way or produced in a particular location; or they may be people in a particular industry...The concept of critical group provides a sound and practical way of complying with the Commission’s recommendations concerning members of the public....’

The Concept of the ‘Representative Person’ For the purpose of protection of the public, it is necessary to characterize an individual who is representative of the most highly exposed individuals in the population. This individual is defined as the ‘representative person’. The representative person may be hypothetical. Nevertheless, it is important that the habits used to characterize the representative person are typical habits of a small number of individuals representative of those most highly exposed and not the extreme habits of a single member of population. The dose to this individual is the equivalent of, and replaces, the mean dose in the ‘critical group’ described in previous ICRP recommendations. The representative person may be hypothetical. Nevertheless, it is important that the habits ( e.g. consumption of foodstuffs, breathing rate, location, usage of local resources) used to characterise the representative person are typical habits of a small number of individuals representative of those most highly exposed and not the extreme habits of a single member of population. Consideration may be given to some extreme or unusual habits, but the should be not dictate the characteristics of the representative persons considered.

The Concept of the ‘Representative Person’ The Commission now recommends the use of the ‘representative person’ for the purpose of radiological protection of the public instead of the earlier critical group concept (ICRP, 2006b) So Today Belarus revises National Standards according to the new ICRP concept of the ‘representative person’ The Commission now recommends the use of the ‘representative person’ for the purpose of radiological protection of the public instead of the earlier critical group concept So Belarus now overwieving National Standards according to the new ICRP concept of the ‘representative person’ (Permissible Levels of Concentration of Radionuclides in Food Products, Standards of Radiation Safety-2000, Main Hygienic Rules and Norms-2002) Permissible Levels of Concentration of Radionuclides in Food Products Standards of Radiation Safety-2000 Main Hygienic Rules and Norms-2002

Dose assessment process Public exposures can occur from natural radiation sources, which may be modified by human activities, from technical installations, or from combinations of such sources. It depends on the specific regulations or aims which situation has to be considered. The annual effective dose to members of the public is the sum of the effective dose obtained within one year from external exposure and the committed effective dose from radionuclides incorporated within this year. The dose is usually not obtained by direct measurements as for occupational exposure but is mainly determined by environmental measurements, habit data and modelling. Thus it can be estimated from: • Simulation and prediction of effluents from the technical installation or source during the design period • Effluent monitoring during the operational period • Radioecological modelling (pathway analysis or environmental transport e.g. from the release of radionuclides and transport through soil-plants –animals to humans). Sum to give annual effective dose for critical group

Total Effective Dose Total Effective Dose ET = total effective dose Eext = effective dose from external radiation Einh = committed effective dose from inhalation Eing = committed effective dose from ingestion During dose assessment it is the need to take into account all dominant routes by which individuals were exposed in an accident and sum up the contributions Thus external exposure is possible from the cloud with the radionuclides which are released from installations, by being on radioactively contaminated soil or swimming in contaminated water. The doses can be calculated from the activity concentrations in the environment by modelling and computation. Internal exposures can occur by inhalation of airborne radionuclides from the cloud or by ingestion of contaminated food or water. The expected committed doses can be calculated by using appropriate models and habit data.

Effective Dose from Ingestion The dose from consumption of food or dirt: Eing – Effective dose from ingestion, mSv; Сf,i –Activity concentration in food of isotope i , kBq/kg; Uf,i –The amount of a food consumed by the population of interest, per day; CF5,i – Ingestion dose conversion, mSv/kBq; DIi – Days of intake is the period food is assumed to be consumed. If T1/2 > 21 days use 30 days. If T1/2 < 21 days use the mean life (Тm) of the isotope. Т1/2 – Radiological half-life; RF – Reduction Factor is the fraction of the contamination remaining after decay or some process j used to reduce the contamination before food is released for consumption. Eing – Effective dose from ingestion, mSv Сf,i –Activity concentration in food of isotope i , kBq/kg Uf,i –The amount of a food/consumed by the population of interest per day. CF5,i – Ingestion dose conversion, mSv/kBq DIi – Days of intake is the period food is assumed to be consumed. If T1/2 > 21 days use 30 days. If T1/2 < 21 days use the mean life (Тm) of the isotope. Т1/2 – Radiological half-life. RF – Reduction Factor is the fraction of the contamination remaining after decay or some process j used to reduce the contamination before food is released for consumption.

Effective Dose from Ingestion Consumption of milk, l/day Consumption of milk products, g/day Age, years Rural population Urban population <1 0,24 0,30 1-2 0,22 2-7 0,20 7-12 0,50 0,25 12-17 0,51 >17 Age, years Rural population Urban population <1 10 70 1-2 75 130 2-7 85 145 7-12 190 175 12-17 230 180 >17 260 Consumption of different products in Belarus according to official statistic data

Effective Dose from Ingestion Consumption of leaf vegetables, g/day Ingestion dose conversion, mSv/kBq Age, years Rural population Urban population <1 1-2 3 2-7 6 7 7-12 20 18 12-17 28 25 >17 30 Age, years Radionuclide Cs-137 I-131 <1 2,1E-02 1,8E-01 1-2 1,2E-02 2-7 9,6E-03 1,0E-01 7-12 1,0E-02 5,2E-02 12-17 1,3E-02 3,4E-02 >17 2,2E-02 Consumption of different products in Belarus according to official statistic data Ingestion dose conversion – Publication 115

Effective Dose from Inhalation The effective dose from inhalation E ing – Effective dose from inhalation, mSv Cair – concentration of radionuclide in the air, Bq/m3 DCF – effective inhalation dose conversion factor for adults, Sv/Bq BR – breathing rate, m3/h t – exposure durations, h In this fofmula: E ing – Effective dose from inhalation, mSv Cair – concentration of radionuclide in the air, Bq/m3 DCF – effective inhalation dose conversion factor for adults, Sv/Bq BR – breathing rate (m3/h) t – exposure durations

Effective Dose from Inhalation Breathing rate Age, years Breathing rate, m3/h <1 2.86 1-2 5.17 2-7 8.72 7-12 14.2 12-17 20.11 >17 22.22 Means of Breathing rate in Belarus

Doses from External Radiation Thus external exposure is possible from the cloud with the radionuclides which are released from installations, by being on radioactively contaminated soil or swimming in contaminated water; The doses can be calculated from the activity concentrations in the environment by modeling and computation. The exposure pathway is important because it determines protective actions that would be effective for the public and the methodology for assessing its potential radiological consequences. In general, doses to individuals cannot be measured directly. Some combination of measurement and assessment is required. the relevant quantity is effective dose or equivalent dose to an individual tissue expressed in Sv or equivalent. Organ equivalent doses (thyroid, skin) are measured using specific counting techniques. At higher doses and dose rates where deterministic effects may be of concern the relevant quantity is absorbed dose (measured in Gy). Total effective dose can be estimated by taking into account all dominant routes by which individuals were exposed in an accident and by summing up those contributions. Natural dose rate, shielding, partial occupancies may also be taken into account.

Doses from External Radiation Additional dose rate from the new NPP activity As planning doses levels are very low it will be a big uncertainties of dose assessment; The critical group will be persons who spend a lot of time outside. 0,1 µSv/h Natural dose rate Natural dose rate, shielding, partial occupancies may also be taken into account. Doses from External Radiation cosist of Natural dose rate and an Additional dose rate from the new NPP activity. An Additional dose rate from the new NPP activity will be more less than Natural dose rate so it will be a big uncertainness of dose assessment. So the critical group are people who spend a lot of time into the open air (for ex. agricultural workers) External dose or dose-rate measurements – made for example by electronic direct reading dosimeter, thermoluminescent dosimeter or a dose rate monitor – will provide a good indication of the doses absorbed by the whole body from penetrating gamma radiation. If external doses are not measured directly they must be assessed by another means. One of the way is to do it manually using adequate equations. Few possibilities will be explained in the following slides.

Summary For dose assessment of population around new NPP in Belarus from internal and external exposure are used: methods based on the monitoring of radiation situation round the NPP; peculiarity of food consumed by the population round the NPP.

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