1. Nuclear Accident Situation Awareness
Lessons from Chernobyl

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

3. Case Data: Chernobyl Release Physical Environment Organisms
Public Health

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

5. 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?

6. 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

7. 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.

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

9. Case Data: Chernobyl

10. Case Data: Chernobyl

11. Case Data: Chernobyl

12. Case Data: Chernobyl

13. Case Data: Chernobyl

14. Case Data: Chernobyl

15. Case Data: Chernobyl

16. 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?

17. Radioactive Cloud

18. Case Data: Chernobyl

19. 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?

20. 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

21. 131I Ground Deposition: Chernobyl

22. 131I in Air at Chernobyl

23. 137Cs Data: Chernobyl

24. 137Cs Ground Deposition

25. 137Cs Ground deposition

26. 131I/137Cs ratio (decay-corrected)

27. 90Sr and 238Pu on Ground

28. 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?

29. 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

30. Terrestrial Clearance of Radionuclides
Meadows in mineral soil (upper 0-10 cm of soil)
137Cs clearance half-time is estimated at 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?

31. Terrestrial Clearance of Radionuclides

32. 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?

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

34. 90Sr and 238Pu on Ground

35. Aquatic Distribution of Radionuclides
Pripyat river
Dnepr basin

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

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

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

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

40. 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?

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

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

43. 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

44. 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
( mm)
Terminal
bronchiole,
(0.5 mm)
Respiratory
(0.4 mm)
Alveolar duct,
(0.3 mm)
+ alveoli
28482

45. 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

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

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

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

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

50. 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

51. 4. Mathematical Models
GI Tract Model

52. 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

53. Compartmental Distribution Models: What happens to a radionuclide in the body?

54. 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

55. 131I Exposure and Thyroid Cancer

56. 131I Exposure and Thyroid Cancer

57. 131I Exposure and Thyroid Cancer

58. 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

59. 131I Exposure and Thyroid Cancer

60. 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.”

61. Calculate Your Radiation Dose