intervention for chronic and emergency exposure situations assessment and response during...

Intervention for Chronic and Emergency Exposure Intervention for Chronic and Emergency Exposure SituationsSituations

Assessment and Response during Assessment and Response during Radiological EmergencyRadiological Emergency

Dose Assessment OverviewDose Assessment OverviewLectureLecture

IAEA Post Graduate Educational Course in Radiation Protection and Safety of Radiation Sources

Module X.5 - Assessment and Response during Radiological Emergency

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IntroductionIntroduction

This This lessonlesson provides various methodologies for provides various methodologies for calculating doses and dose rates based on the calculating doses and dose rates based on the type of sources or radioactive materials involved type of sources or radioactive materials involved and the circumstances of the emergency and the circumstances of the emergency situationsituation

The Radiological Assessor may also find the The Radiological Assessor may also find the formulas and tables in this section useful in formulas and tables in this section useful in developing protective action recommendations developing protective action recommendations for the Emergency Manager during the early for the Emergency Manager during the early stages of an emergency situation when stages of an emergency situation when information regarding the radiation source or information regarding the radiation source or material is readily availablematerial is readily available


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ContentContent

Pathways of exposurePathways of exposure Estimation of effective doseEstimation of effective dose

Point sourcePoint source Line source and spillLine source and spill Ground contaminationGround contamination Skin contaminationSkin contamination InhalationInhalation IngestionIngestion

SummarySummary ProblemsProblems


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OverviewOverview

In the event of a radiation emergency In the event of a radiation emergency exposure of emergency workers or exposure of emergency workers or members of the public may occurmembers of the public may occur

Exposure may be external or internal Exposure may be external or internal and may be incurred by various and may be incurred by various pathwayspathways

The various routs by which The various routs by which individuals may be exposed will individuals may be exposed will determine the method to estimate the determine the method to estimate the effective doseeffective dose


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Pathways of ExposurePathways of Exposure

External External exposureexposure

Internal Internal exposure exposure


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Total Effective DoseTotal Effective Dose

Take into account all dominant routes by Take into account all dominant routes by which individuals were exposed in an which individuals were exposed in an accident and sum up the contributionsaccident and sum up the contributions

EETT = total effective dose = total effective dose

EEextext = effective dose from external radiation = effective dose from external radiation

EEinhinh = committed effective dose from inhalation = committed effective dose from inhalation

EEinging = committed effective dose from ingestion = committed effective dose from ingestion

T ext inh ingE E E E


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Dosimetric Information Dosimetric Information

Direct readings Direct readings from from personal dosimeterspersonal dosimeters Dose Dose assessments from personal assessments from personal

dosimeters such as film badges or dosimeters such as film badges or TLDTLDs s In case of In case of inhalationinhalation:: nose blows should nose blows should

be taken using material suitable for be taken using material suitable for assessing the activity removedassessing the activity removed

In case of In case of ingestioningestion:: the need to collect the need to collect urine and faecal samples should be urine and faecal samples should be consideredconsidered

The need for whole body or thyroid The need for whole body or thyroid monitoring should be consideredmonitoring should be considered


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Doses From External RadiationDoses From External Radiation

Where direct means of assessing doses is Where direct means of assessing doses is available, principally the use of personal available, principally the use of personal dosimeters for external exposure, this dosimeters for external exposure, this should be usedshould be used

If external doses are not measured directly If external doses are not measured directly they must be assessed by another meansthey must be assessed by another means


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Point SourcePoint Source

Possible input dataPossible input data Activity of the point sourceActivity of the point source Distance from the point sourceDistance from the point source Exposure durationExposure duration

OutputOutput Effective doseEffective dose Dose rateDose rate Distance to a point sourceDistance to a point source ActivityActivity


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TThe effective dosehe effective dose

TThe dose he dose raterate

1/ 2

d

d6 e

ext 2

A CF T 0.5E

X

1/ 2

d

d7

2

A CF 0.5D

X


11


The distanceThe distance

The activityThe activity

1

2

Da

D

1

xX

1 a

1/ 2

21 1

d

d7

D XA

CF 0.5

X1

x

M2M1


12

Line Source (Pipe)Line Source (Pipe)

InputInput Source activitySource activity Distance from the Distance from the

sourcesource Time of exposureTime of exposure

OutputOutput External effective doseExternal effective dose Dose ratesDose rates Source activity from Source activity from

dose rate dose rate measurements measurements

Effective doseEffective dose

Dose rateDose rate


6 1 eext

CF A TE

X

6 1CF AD

X

17

D XA

CF


13

SpillSpill

Effective doseEffective dose

Dose rateDose rate


2 2

ext 6 s e 2

X RE 2 CF A T ln

X

2 2

7 s 2

X RD 2 CF A ln

X

s 2 2

7 2

DA

X R2 CF ln

X


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Ground ContaminationGround Contamination

Effective dose from Effective dose from exposure to ground exposure to ground contamination can be contamination can be assessed based on:assessed based on: Comprehensive Comprehensive

radionuclide radionuclide concentrations on concentrations on groundground

Based on ambient dose Based on ambient dose ratesrates

Based on marker Based on marker radionuclide radionuclide concentration levels concentration levels

InputInput Radionuclide Radionuclide

concentrations on concentrations on groundground

Ambient dose rateAmbient dose rate

OutputOutput Effective dose from Effective dose from

depositiondeposition


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Based on comprehensive Based on comprehensive radionuclide concentrations on radionuclide concentrations on groundground

Based on ambient dose rateBased on ambient dose rate

n

ext g,i 4,ii 1

E C CF

nrepg,i 4,i

* i 1ext g n

repg,i 3,i

i 1

C CFE H

C CF


16


Based on marker radionuclide Based on marker radionuclide concentration levels concentration levels

Taking into account shielding and Taking into account shielding and partial occupancypartial occupancy

nrepg,i 4,i

sam i 1ext g,j rep

g,j

C CFE C

C

poext extE E [SF OF (1 OF)]


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Air ImmersionAir Immersion

InputInput Average Average

concentration of concentration of radionuclides in airradionuclides in air

Duration of exposureDuration of exposure

OutputOutput Effective dose from Effective dose from

external exposure to γ external exposure to γ radiation from the radiation from the plumeplume

Air immersion Air immersion dose dose

ext e a,i 9,ii

E T C CF


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Skin ContaminationSkin Contamination

InputInput Average surface Average surface

concentration of concentration of radionuclides on radionuclides on the skin or clothingthe skin or clothing

OutputOutput Equivalent dose Equivalent dose

(beta) to the skin(beta) to the skin

Skin beta doseSkin beta dose

s,i s,i 8,i b eH C CF SF T

s s,ii

H H


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Dose From Internal ContaminationDose From Internal Contamination

May arise from intakes of radionuclides, May arise from intakes of radionuclides, primary by primary by inhalationinhalation or or ingestioningestion

The dose depends onThe dose depends on The activity deposited in the bodyThe activity deposited in the body The energy of the emitted radiation absorbed The energy of the emitted radiation absorbed

by the organ andby the organ and The mass of the organ at riskThe mass of the organ at risk

Internal doses can not be measured Internal doses can not be measured directly – they have to be assessed by directly – they have to be assessed by some other meanssome other means


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InhalationInhalation


concentrations in airconcentrations in air Inhalation durationInhalation duration

OutputOutput

Committed effective Committed effective dose from inhalationdose from inhalation

Committed Committed equivalent dose to equivalent dose to the thyroidthe thyroid

Committed Committed effective dose from effective dose from inhalationinhalation

Committed Committed equivalent dose to equivalent dose to the thyroidthe thyroid

n

inh a,i 2,i ei 1

E C CF T

n

thy a,i 1,i ei 1

H C CF T


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IngestionIngestion


concentrations in concentrations in food, water or milkfood, water or milk

Radionuclide Radionuclide concentrations in soilconcentrations in soil

Time of intakeTime of intake

OutputOutput Committed effective Committed effective

dose from ingestiondose from ingestion

Committed effective Committed effective dose from consumption dose from consumption of food or soil of food or soil

n

ing f ,i f f ,i 5,ii 1

E C U DI CF

m 1/ 2T T 1.44


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SummarySummary

Basic methodologies for assessing Basic methodologies for assessing individual dose from external and internal individual dose from external and internal exposure were discussedexposure were discussed

RememberRemember In general, doses to individuals cannot be In general, doses to individuals cannot be

measured directly; some combination of measured directly; some combination of measurement and assessment is requiredmeasurement and assessment is required

All dominant routes by which individuals were All dominant routes by which individuals were exposed should be taken into accountexposed should be taken into account


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Where to Get More InformationWhere to Get More Information

See references on cover pageSee references on cover page


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Problem 1Problem 1

A 150 MBq point source of Co-60 is A 150 MBq point source of Co-60 is located 2.0 m from you. located 2.0 m from you. What is the What is the dose rate at your location?dose rate at your location?


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Problem 2Problem 2

A very long pipe contains 0.5 GBq/m A very long pipe contains 0.5 GBq/m of Cs-137. 5.0 m from a pipe a of Cs-137. 5.0 m from a pipe a technician is working for 30 min. technician is working for 30 min. What dose he will receive?What dose he will receive?


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Problem 3Problem 3

An Ir-192 source was stuck in a An Ir-192 source was stuck in a radiography tube – unshielded. The radiography tube – unshielded. The dose rate measured at a certain point dose rate measured at a certain point from the source was 0.65 mGy/h. 2.0 from the source was 0.65 mGy/h. 2.0 m closer in the “line of sight” the m closer in the “line of sight” the dose rate monitor showed 0.82 dose rate monitor showed 0.82 mGy/h. mGy/h. How far is the source?How far is the source?


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Problem 4Problem 4

In the air of the nuclear medicine In the air of the nuclear medicine laboratory the following laboratory the following concentration of I-131 was concentration of I-131 was measured 250 Bq/mmeasured 250 Bq/m33. Two technician . Two technician were working in the laboratory for 3 were working in the laboratory for 3 hours. hours. What is the committed What is the committed equivalent dose to the thyroid? What equivalent dose to the thyroid? What is the dose from external exposure?is the dose from external exposure?


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Problem 5Problem 5

After Chernobyl accident the environment After Chernobyl accident the environment in Europe was contaminated mainly by Cs-in Europe was contaminated mainly by Cs-134, Cs-137 and I-131. In one of the 134, Cs-137 and I-131. In one of the country the following levels of food country the following levels of food contamination were measured:contamination were measured:

FoodFoodCs-134Cs-134

[Bq/L or kg][Bq/L or kg]

Cs-137Cs-137[Bq/L or kg][Bq/L or kg]

I-131I-131[Bq/L or kg][Bq/L or kg]

MilkMilk 160160 330330 20002000

MeatMeat 250250 470470 220220

VegetablesVegetables 11001100 22002200 56005600


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Problem 5 - Cont’dProblem 5 - Cont’d

What is the committed effective dose What is the committed effective dose to an adult if the food was consumed to an adult if the food was consumed for 30 days?for 30 days?Consumption dataConsumption data

FoodFoodConsumption dataConsumption data

[kg/d][kg/d]

MilkMilk 0.300.30

MeatMeat 0.270.27

VegetablesVegetables 0.070.07

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