Intervention for Chronic and Emergency Exposure Situations Assessment and Response during Radiological Emergency Dose Assessment Overview Lecture IAEA Post Graduate Educational Course in Radiation Protection and Safety of Radiation Sources

Module X.5 - Assessment and Response during Radiological Emergency2 Introduction l This lesson provides various methodologies for calculating doses and dose rates based on the type of sources or radioactive materials involved and the circumstances of the emergency situation l The Radiological Assessor may also find the formulas and tables in this section useful in developing protective action recommendations for the Emergency Manager during the early stages of an emergency situation when information regarding the radiation source or material is readily available

Module X.5 - Assessment and Response during Radiological Emergency3 Content l Pathways of exposure l Estimation of effective dose n Point source n Line source and spill n Ground contamination n Skin contamination n Inhalation n Ingestion l Summary l Problems

Module X.5 - Assessment and Response during Radiological Emergency4 Overview l In the event of a radiation emergency exposure of emergency workers or members of the public may occur l Exposure may be external or internal and may be incurred by various pathways l The various routs by which individuals may be exposed will determine the method to estimate the effective dose

Module X.5 - Assessment and Response during Radiological Emergency5 Pathways of Exposure l External exposure l Internal exposure

Module X.5 - Assessment and Response during Radiological Emergency6 Total Effective Dose l Take into account all dominant routes by which individuals were exposed in an accident and sum up the contributions n E T = total effective dose n E ext = effective dose from external radiation n E inh = committed effective dose from inhalation n E ing = committed effective dose from ingestion

Module X.5 - Assessment and Response during Radiological Emergency7 Dosimetric Information l Direct readings from personal dosimeters l Dose assessments from personal dosimeters such as film badges or TLDs l Dose assessments from personal dosimeters such as film badges or TLDs l In case of inhalation: nose blows should be taken using material suitable for assessing the activity removed l In case of ingestion: the need to collect urine and faecal samples should be considered l The need for whole body or thyroid monitoring should be considered

Module X.5 - Assessment and Response during Radiological Emergency8 Doses From External Radiation l Where direct means of assessing doses is available, principally the use of personal dosimeters for external exposure, this should be used l If external doses are not measured directly they must be assessed by another means

Module X.5 - Assessment and Response during Radiological Emergency9 Point Source l Possible input data n Activity of the point source n Distance from the point source n Exposure duration l Output n Effective dose n Dose rate n Distance to a point source n Activity

Module X.5 - Assessment and Response during Radiological Emergency10 Point Source l The effective dose l The dose rate

Module X.5 - Assessment and Response during Radiological Emergency11 Point Source l The distance l The activity X1X1 x M2M2 M1M1

Module X.5 - Assessment and Response during Radiological Emergency12 Line Source (Pipe) l Input n Source activity n Distance from the source n Time of exposure l Output n External effective dose n Dose rates n Source activity from dose rate measurements l Effective dose l Dose rate l The activity

Module X.5 - Assessment and Response during Radiological Emergency13 Spill l Effective dose l Dose rate l The activity

Module X.5 - Assessment and Response during Radiological Emergency14 Ground Contamination l Effective dose from exposure to ground contamination can be assessed based on: n Comprehensive radionuclide concentrations on ground n Based on ambient dose rates n Based on marker radionuclide concentration levels l Input n Radionuclide concentrations on ground n Ambient dose rate l Output n Effective dose from deposition

Module X.5 - Assessment and Response during Radiological Emergency15 Ground Contamination l Based on comprehensive radionuclide concentrations on ground l Based on ambient dose rate

Module X.5 - Assessment and Response during Radiological Emergency16 Ground Contamination l Based on marker radionuclide concentration levels l Taking into account shielding and partial occupancy

Module X.5 - Assessment and Response during Radiological Emergency17 Air Immersion l Input n Average concentration of radionuclides in air n Duration of exposure l Output n Effective dose from external exposure to γ radiation from the plume l Air immersion dose

Module X.5 - Assessment and Response during Radiological Emergency18 Skin Contamination l Input n Average surface concentration of radionuclides on the skin or clothing l Output n Equivalent dose (beta) to the skin l Skin beta dose

Module X.5 - Assessment and Response during Radiological Emergency19 Dose From Internal Contamination l May arise from intakes of radionuclides, primary by inhalation or ingestion l The dose depends on n The activity deposited in the body n The energy of the emitted radiation absorbed by the organ and n The mass of the organ at risk l Internal doses can not be measured directly – they have to be assessed by some other means

Module X.5 - Assessment and Response during Radiological Emergency20 Inhalation l Input n Radionuclide concentrations in air n Inhalation duration l Output n Committed effective dose from inhalation n Committed equivalent dose to the thyroid l Committed effective dose from inhalation l Committed equivalent dose to the thyroid

Module X.5 - Assessment and Response during Radiological Emergency21 Ingestion l Input n Radionuclide concentrations in food, water or milk n Radionuclide concentrations in soil n Time of intake l Output n Committed effective dose from ingestion l Committed effective dose from consumption of food or soil

Module X.5 - Assessment and Response during Radiological Emergency22 Summary l Basic methodologies for assessing individual dose from external and internal exposure were discussed l Remember n In general, doses to individuals cannot be measured directly; some combination of measurement and assessment is required n All dominant routes by which individuals were exposed should be taken into account

Module X.5 - Assessment and Response during Radiological Emergency23 Where to Get More Information l See references on cover page

Module X.5 - Assessment and Response during Radiological Emergency24 Problem 1 A 150 MBq point source of Co-60 is located 2.0 m from you. What is the dose rate at your location?

Module X.5 - Assessment and Response during Radiological Emergency25 Problem 2 A very long pipe contains 0.5 GBq/m of Cs m from a pipe a technician is working for 30 min. What dose he will receive?

Module X.5 - Assessment and Response during Radiological Emergency26 Problem 3 An Ir-192 source was stuck in a radiography tube – unshielded. The dose rate measured at a certain point from the source was 0.65 mGy/h. 2.0 m closer in the “line of sight” the dose rate monitor showed 0.82 mGy/h. How far is the source?

Module X.5 - Assessment and Response during Radiological Emergency27 Problem 4 In the air of the nuclear medicine laboratory the following concentration of I-131 was measured 250 Bq/m 3. Two technician were working in the laboratory for 3 hours. What is the committed equivalent dose to the thyroid? What is the dose from external exposure?

Module X.5 - Assessment and Response during Radiological Emergency28 Problem 5 After Chernobyl accident the environment in Europe was contaminated mainly by Cs- 134, Cs-137 and I-131. In one of the country the following levels of food contamination were measured: FoodCs-134 [Bq/L or kg] Cs-137 I-131 Milk Meat Vegetables

Module X.5 - Assessment and Response during Radiological Emergency29 Problem 5 - Cont’d What is the committed effective dose to an adult if the food was consumed for 30 days? Consumption data Food [kg/d] Milk0.30 Meat0.27 Vegetables0.07