Nuclear Accident Situation Awareness Lessons from Chernobyl

Model Building Process Hypothesis Select Model Construct Model Validate Model If Model Not Valid, Return to Select Model Operate Model

Case Data: Chernobyl Release Physical Environment Organisms Public Health

Nuclear Scenarios Physical Environmental issues What was released? When was it released? Where did it go? How long does it take to disappear?

Nuclear Scenarios Biological issues Which isotopes are incorporated by organisms? When are the incorporated? How and where are they incorporated? How long does it take to disappear? How do human exposures impact health and welfare?

Radioactivity Measurements 1 Bequerel (Bq) is 1 decomposition per second 1 kBq is 103 Bq 1 MBq is 106 Bq (Megabequerel) 1 GBq is 109 Bq (Gigabequerel) 1 TBq is 1012 Bq (Terabequerel) 1 PBq is 1015 Bq (Pentabequerel) 1 Gray (Gy) is a general measure for absorbed radiation 1 Sievert = 10 rem is a unit for human dosimetry

Source: UNSCEAR Report-Annex J www.unscear.org/docs/reports/annexj.pdf Radionuclide releases from the damaged reactor occurred mainly over a 10-day period, but with varying release rates. From radiological perspective, 131I and 137Cs are the most important; responsible for most of the radiation exposure received by the general population.

Source: http://www.oecd-nea.org/rp/reports/2003/nea3508-chernobyl.pdf

Case Data: Chernobyl

Case Data: Chernobyl

Case Data: Chernobyl

Case Data: Chernobyl

Case Data: Chernobyl

Case Data: Chernobyl

Case Data: Chernobyl

Case Data: Chernobyl Physical Environmental issues What was released? When was it released? Where did it go? Airborne Terrestrial Aquatic How long does it take to disappear?

Radioactive Cloud

Case Data: Chernobyl

Case Data: Chernobyl Physical Environmental issues What was released? When was it released? Where did it go? Airborne Terrestrial Aquatic How long does it take to disappear?

Terrestrial Deposition from Air and Direct Contact (water, debris, etc) Form of radionuclide Particulate Gaseous Aqueous Amount of radiation Half-life 131I : 8 d, 137Cs: 30 y, 89Sr: 52 d, 90Sr: 28 y, 95Zr: 65 d Migration paths

131I Ground Deposition: Chernobyl

131I in Air at Chernobyl

137Cs Data: Chernobyl

137Cs Ground Deposition

137Cs Ground deposition

131I/137Cs ratio (decay-corrected)

90Sr and 238Pu on Ground

Case Data: Chernobyl Physical Environmental issues What was released? When was it released? Where did it go? Airborne Terrestrial Aquatic How long does it take to disappear?

Terrestrial Migration Paths Vertical Migration (percolation process driven by gravity and water) Rate varies with soil type and terrain Mineral soils slow: ~90% of 137Cs and 90Sr in top 0-5 cm Peaty soils faster: 40%-70% of 137Cs and 90Sr in top 5 cm Natural meadows slow Elimination paths Absorbed in plant roots (and organisms) Radioactive decay

Terrestrial Clearance of Radionuclides Meadows in mineral soil (upper 0-10 cm of soil) 137Cs clearance half-time is estimated at 10-25 years (half-life of isotope is 30 years) 90Sr clearance half-time is estimated at 7-12 years (half-life of isotope is 28 years) Implications?

Terrestrial Clearance of Radionuclides

Case Data: Chernobyl Physical Environmental issues What was released? When was it released? Where did it go? Airborne Terrestrial Aquatic How long does it take to disappear?

Sources of Aquatic Radionuclides Direct deposition (air and waste) Water runoff from surface distribution (rain, etc.) Percolation to water table

90Sr and 238Pu on Ground

Aquatic Distribution of Radionuclides Pripyat river Dnepr basin

Radionuclides in Reservoirs in Bq/liter (1986-1998) Kiev Kremenchug Kahkovka EPA maximum contaminant level (MCL) for beta emitters: 0.296 Bq/L

Aquatic Distribution of Radionuclides EPA MCL for beta emitters: 0.296 Bq/L

Aquatic Distribution of Radionuclides EPA MCL for beta emitters: 0.296 Bq/L

Aquatic Distribution of Radionuclides EPA MCL for beta emitters: 0.296 Bq/L

Case Data: Chernobyl Biological issues Which isotopes are incorporated by organisms? When are the incorporated? How and where are they incorporated? How long does it take to disappear? How do human exposures impact health and welfare?

Human Radiation Exposure http://www. epa Three routes of tissue exposure Inhalation (Upper Airway, Larynx, Trachea, Bronchi, Lungs) Ingestion (Digestive tract) External (Skin)

Human Radiation Exposure http://www. epa Three routes of tissue exposure Inhalation (Upper Airway, Larynx, Trachea, Bronchi, Lungs) Ingestion (Digestive tract) External (Skin)

Human Radiation Exposure http://www. epa Inhalation (Nasal, oral, pharyngeal cavities, Larynx, Trachea, Bronchi, Lungs) Type F: Fast dissolution and a high level of blood absorption (Americium [Am], Cesium [Cs]) Type M: Intermediate rates of dissolution and levels of blood absorption Type S: Slow dissolution and a low level of absorption to blood Type V: Vapor Type G: Gas No Absorption

Respiratory tract model 4. Calculation of Quantities from: homepage.ntlworld.com/alan.birchall/Internal%20Dosimetry... Respiratory tract model Nasal passage Anterior Posterior Pharynx Larynx Trachea (17 mm) Main bronchus (12 mm) Bronchi (2 - 9 mm) Oral Bronchioles (0.5 - 2 mm) Terminal bronchiole, (0.5 mm) Respiratory (0.4 mm) Alveolar duct, (0.3 mm) + alveoli 28482

Respiratory tract model 4. Calculation of Quantities Quantities from: homepage.ntlworld.com/alan.birchall/Internal%20Dosimetry... Respiratory tract model 5 main regions ET1 ET2 BB Al bb Extrathoracic airways Bronchiolar Bronchial Alveolar interstitial 25475

Respiratory tract model (biokinetics) 4. Calculation of Quantities Respiratory tract model (biokinetics) Particle transport Environment GI Tract

Respiratory tract model (biokinetics) 4. Calculation of Quantities Respiratory tract model (biokinetics) Absorption

blood organ 3. Calculation of Quantities We need to be able to calculate how many disintegrations there are in each organ blood organ

Respiratory tract model (biokinetics) 4. Calculation of Quantities Respiratory tract model (biokinetics) Particle transport Absorption

GI Tract Model 4. Calculation of Quantities Source Organs(4) Stomach Small Intestine (SI) Upper Large Intestine (ULI) Lower Large Intestine (LLI) Target Organs(1) Epithelial cells in the mucosal layer

4. Mathematical Models GI Tract Model

Urinary bladder contents 4. Mathematical Models Tissue Distribution models Gonads Blood Urinary bladder contents Urine Kidney Soft tissues Intermediate Rapid Slow Skeleton (with remodelling) ICRP 56+ type models Skeleton Cortical volume Cortical surface Cortical marrow Trabecular volume Trabecular surface Trabecular marrow Cortical and trabecular compartments specified in biokinetic model

Compartmental Distribution Models: What happens to a radionuclide in the body? http://www.cdc.gov/nceh/radiation/Savannah/docs/Chapter_10_083006.pdf

Biological Incorporation of Iodine 131I is major fission product of uranium, thorium and plutonium Concentrated by Thyroid Beta radiation in thyroid High levels kill tissue Lower levels are carcinogenic Uptake can be blocked by large doses of potassium iodide

131I Exposure and Thyroid Cancer

131I Exposure and Thyroid Cancer

131I Exposure and Thyroid Cancer

131Iodine and Thyroid Cancer Largely papillary and particularly aggressive in nature often self-presenting with local invasion and/or distant metastases More prevalent in children aged 0 to 5 years at the time of the accident, and in areas assessed to be the more heavily contaminated with 131I Seem to have a shorter latent period than expected Increasing rate for children younger than 5 years in 1986

131I Exposure and Thyroid Cancer

Other radionuclides 137Cs accumulates in soft tissues, particularly muscle 90Sr accumulates in bone “No increase of congenital abnormalities, adverse pregnancy outcomes or any other radiation induced disease in the general population, either in the contaminated regions or in Western Europe, could be attributed to this exposure sixteen years after the accident.”

Calculate Your Radiation Dose http://www.epa.gov/radiation/understand/calculate.html