Environmental Impact of Potential Accidental Releases from Nuclear Energy Systems situation in Belarus

Transcription

1 Environmental Impact of Potential Accidental Releases from Nuclear Energy Systems situation in Belarus Viktoryia Kliaus Republican Scientific-Practical Centre of Hygiene Laboratory of Radiation Safety Minsk, Belarus 1 st Consultancy Meeting of INPRO Collaborative Project ENV-PE October 2012, IAEA HQ, Vienna, Austria

2 NPP in Belarus Type: NPP-2006 III+; Reactor: WWER (PWR)-1200; Planned construction time: 54 month; Lifetime: 50 years; The reactor power: 1200 MW(e), 3200 MW(th). General layout of Belarusian NPP was developed for 2 power units (launch: 2018 and 2019 years)

3 NPP Location Ostrovets site: Vitebsk Lithuanian border 25 km Vilnius (Lithuania) 50 km Daugavpils (Latvia) 150 km Suwalki (Poland) 200 km Riga (Latvia) 300 km Warsaw (Poland) 400 km Kiev (Ukraine) 550 km Vienna (Austria) 900 km Grodno Ostrovets site Minsk Mogilev Gomel Brest Decree of the President 418 «On Siting and Design of a Nuclear Power Plant» (September 15, 2011)

4 NPPs near Belarus

5 Risk Concept in National Standards New Sanitarian Rules and Standards Requirements to Radiation Safety (under approval, will be amended in the 4 Qtr 2012) states that: Radiation risk is a likelihood of occurring of detrimental health effects due to radiation exposure Risk of cancer death for the public living in the vicinity of the NPP which may arise as a result of nuclear power plant operation should not exceed 0.1 % of the sum of all risks of fatal cancers resulting from other causes Risk of death for the public living in the vicinity of the NPP which may be caused by a reactor accident should not exceed 0.1 % of the sum of all risks of death caused by other accidents

6 InterRas version 1.3 (The International Radiological Assessment System) Code developed for the IAEA and based on RASCAL code (developed for the U.S. Nuclear Regulatory Commission) Consistent with the generic assessment procedures (TECDOC- 955) A set of 3 tools to assist with dose assessment: DECAY Calculator FM-DOSE - Field Measurement to Dose ST-DOSE - Source Term to Dose Limitation : calculations up to 50 km from the source

7 Source Term to Dose Model (ST-DOSE) Inputs assessment of plant conditions or estimated source term meteorological information Outputs estimates of integrated doses and consequences

8 Source term options and Event times Isotopic Release Rates Isotopic Concentrations Gross Release, Analyst Specified Mix Reactor accidents based on: Plant Conditions Containment Monitor Reading Spent Fuel Pool 5 dates and times: shutdown (start of decay) release to containment release to environment end of release end of exposure

9 Meteorological Conditions One set of conditions is required*; a maximum of four is allowed Conditions are uniform over the entire model area Default conditions: wind at 3 m/s from 270 deg (from West) stability class D (neutral) mixing layer height 500 meters no precipitation *Meteorological conditions were provided by the Ministry of Environment

10 Transport and Diffusion Models Straight line Gaussian plume receptors on a polar grid distances are 1, 2 and 5 km; every 10 degrees around used for doses inside 5 km Lagrangian trajectory Gaussian puff receptors on square 31x31 Cartesian grid with 50 km radius used for doses beyond 5 km Deposition dry - based on deposition velocity wet - based on washout; function of precipitation type & intensity

11 Exposure Pathways Atmospheric Dispersion Cloud External Inhalation Ground External Ground Deposition Food consumption

12 InterRas calculates: Dose assessment Cloudshine dose from the plume Groundshine dose from deposited radionuclides Inhalation dose from the plume Total effective dose Thyroid dose (from iodine only) It was also calculated: Ingestion dose (based on ground contamination)

13 Dose assessment beyond 50 km D i km D j km r r i j a Where D i km dose to public located at the distance i from the source; D j km dose to public located at the distance j from the source; r i distance i from the source where public is located, km; r j distance j from the source, km; a parameter which depends on stability class. The value of this parameter varies between 1.5 and 3. *Martin, J.A. Doses While Travelling under Well Established Plumes / J.A. Martin // Health Physic Vol. 32. Р

14 Food Consumption Product Intake, kg/y (l/y)* Cow milk Cow milk products Meat Green vegetables Inhalation rate : 1.2 m 3 /h [ICRP 75] State Committee of Statistics and Analysis of the Republic of Belarus Data Book, 2009

15 Population distribution around NPP Number of citizens Sector Direction Distance from the NPP, km N-NNE NNE-NE NE-ENE ENE-E E-ESE ESE-SE SE-SSE SSE-S S-SSW SSW-SW SW-WSW

16 Design Basis Accident (DBA) Plant Conditions Heat power Core damage Leak rate Parameter Release pathway reduction mechanisms Release height Consider building wake effects Value MW(th) 100 % gap release 0.004% / h filters are assumed to blow out, containment spray system is able to activate. 0 m yes Release from the containment

17 Release to the environment in case of DBA, Bq Nuclide Activity, Bq Nuclide Activity, Bq Кr-85 1,10E+11 Kr-85m 4,40E+12 Кr-88 1,30E+13 I-131 4,70E+11 I-132 6,70E+11 I-133 9,50E+11 I-135 8,30E+11 Xe-131m 1,80E+11 Xe-133m 1,10E+12 Xe-135 6,10E+12 Cs-134 4,20E+10 Cs-136 1,70E+10 Rb-88 1,30E+13 Ba-137m 2,70E+10 Kr-87 8,90E+12 Xe-133 3,20E+13 Xe-135m 1,30E+11 Xe-138 3,20E+13 I-134 1,00E+12 Cs-137 2,70E+10 Total activity of the accidental release is 1, Bq.

18 Total Effective Dose in case of DBA, msv Near zone of the NPP (till 5 km) Far zone of the NPP (till 50 km)

19 Thyroid Dose in case of DBA, msv (mgy) Near zone of the NPP (till 5 km) Far zone of the NPP (till 50 km)

20 Dose to Public in case of DBA Distance from the NPP, km Cloudshine dose from the plume, msv Groundshine dose from deposited radionuclides, msv Inhalation dose from the plume, msv Total Effective Dose, msv Thyroid Dose *, msv ** * Thyroid dose includes only dose from iodine. ** All the dose values below 10 μsv will be equated to zero.

21 Internal Dose to Public from Ingestion in case of DBA Maximum dose from ingestion of contaminated food in case of DBA will be observed at the distance of about 10 km from the NPP; Maximum dose values from ingestion contaminated by Cs-137 milk will achieve several tens of msv (e.g. 0.1 msv at 10 km), from ingestion leafy vegetables hundredth part of msv. Maximum equivalent thyroid dose from ingestion contaminated by 131 I milk and leafy vegetables several tens of msv (e.g. 0.6 msv).

22 Beyond Design Basis Accident (BDBA) Plant Conditions Parameter Value Heat power MW(th) Core damage Leak rate Release pathway reduction mechanisms Release height Consider building wake effects % core melt 0.02% / h filters are assumed to blow out, containment spray system is unable to activate 0 m yes Release from the containment

23 Release to the environment in case of BDBA, Bq Nuclide Activity, Bq Nuclide Activity, Bq Nuclide Activity, Bq Кr-85 1,00E+13 Kr-85m 4,2E+14 Kr-87 8,4E+14 Кr-88 1,2E+15 Sr-89 3,9E+13 Sr-90 1,5E+12 Sr-91 4,60E+13 Y-91 3,30E+12 Mo-99 1,80E+13 Tc-99m 1,80E+13 Ru-103 1,20E+13 Ru-106 2,70E+12 Sb-127 1,2E+13 Sb-129 6,9E+13 Te-129m 1,1E+13 Те-131m 2,5E+13 Te-132 2,5E+14 I-131 4,1E+14 I-132 5,8E ,3E+14 I-134 9,2E+14 I-135 7,3E+14 Xe-131m 1,7E+13 Xe-133 3,0E+15 Xe-133m 1,1E+14 Xe-135 5,8E+14 Xe-138 3,0E+15 Cs-134 2,6E+13 Cs-136 1,0E+13 Cs-137 1,70E+13 Ba-140 8,8E+13 La-140 4,40E+12 Ce-144 1,2E+13 Np-239 2,3E+14 Rb-88 1,2E+15 Rh-106 2,7E+12 Te-129 1,10E+13 Xe-135m 1,2E+14 Ba-137m 1,70E+13 Total activity of the accidental release is 1, Bq. Pr-144 1,2E+13

24 Total Effective Dose in case of BDBA, msv Near zone of the NPP (till 5 km) Far zone of the NPP (till 50 km)

25 Thyroid Dose in case of BDBA, msv (mgy) Near zone of the NPP (till 5 km) Far zone of the NPP (till 50 km)

26 Dose to Public in case of BDBA Distance from the NPP, km Cloudshine dose from the plume, msv Groundshine dose from deposited radionuclides, msv Inhalation dose from the plume, msv Total Effective Dose, msv Thyroid Dose *, msv * Thyroid dose includes only dose from iodine.

27 Internal Dose to Public from Ingestion in case of BDBA Maximum dose from ingestion of contaminated food in case of BDBA will be observed at the distance of about 10 km from the NPP; Maximum dose values from ingestion contaminated by Cs-137 milk and meat will achieve few msv (e.g. 3.2 msv), from ingestion leafy vegetables tens of msv. Maximum equivalent thyroid dose from ingestion contaminated by 131 I milk and leafy vegetables dozens of msv (e.g msv).

28 Transboundary impact Distance from the NPP, km Total Effective Dose*, msv Thyroid Dose *, mgy *Doses to public in case of BDBA

29 The Hygienic Requirements to Nuclear Power Plant Design and Operation Generic criteria for protective actions and other response actions in emergency exposure situations to reduce the risk of stochastic health effects Generic criteria for acute doses for which protective actions and other response actions are to be undertaken under any circumstances to avoid or to minimize severe deterministic health effects Guidance values for limiting exposure of emergency workers Limited dose rates for protective actions in radiation emergency exposure situation Emergency zones and radius sizes for reactors with power more than 1000 MW (th) Generic action levels for foodstuff

30 Generic Criteria for Acute Doses for which Protective Actions and other Response Actions are Expected to be Undertaken under any Circumstances to Avoid or to Minimize Severe Deterministic Effects External acute exposure ( less than 10 hours) AD Red marrow : 1 Gy AD Fetus : 0.1 Gy AD Tissue : 25 Gy at 0.5 cm AD Skin : 10 Gy to 100 cm 2 Internal exposure (Δ=30 days)* AD (Δ) Red marrow : 0.2 Gy for radionuclides with atomic number Z 90 2 Gy for radionuclides with atomic number Z 89 AD (Δ) Thyroid : 2 Gy AD (Δ) Lung : 30 Gy AD (Δ) Colon : 20 Gy AD (Δ) Fetus : 0.1 Gy *For this particular case Δ means the period of in utero development

31 Generic Criteria for Protective Actions and other Response Actions in Emergency Exposure Situations to Reduce the Risk of Stochastic Effects Generic criteria H thyroid 50 msv in the first 7 days Iodine thyroid blocking E H fetus 100 msv in the first 7 days 100 msv in the first 7 days Examples of protective actions and other response actions Sheltering; evacuation; decontamination; restriction of consumption of food, milk and water; contamination control; public reassurance Projected dose that exceeds the following generic criteria: Take protective actions and other response actions early in the response E H fetus 100 msv per annum 100 msv for the full period of in utero development Temporary relocation; decontamination; replacement of food, milk and water; public reassurance Dose that has been received and that exceeds the following generic criteria: Take long term medical actions to detect and to effectively treat radiation induced health effect E 100 msv in a month Screening based on equivalent doses to specific radiosensitive organs (as a basis for medical follow-up), counselling H fetus 100 msv for the full period of in utero development Counselling to allow informed decisions to be made in individual circumstances

32 Summary Belorussian National Norms and Standards are in compliance with international requirements Proposal for a future activity in the framework of the INPRO ENV-PE Project : to develop a standard scenarios of potential accidents for harmonization of approaches in different countries Country needs : to be aware of other countries methods and approaches to model and assess potential accident to purchase a software for dose/risk assessment in case of potential accident releases

33 Thank you for your attention! Viktoryia KLIAUS Senior scientist, PhD Republican Scientific-Practical Centre of Hygiene Laboratory of Radiation Safety Minsk, Belarus