Radiation Overview Presented by Capt. Colbrunn (Tank) Xenia Twp Fire Dept

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Radiation Overview Presented by Capt. Colbrunn (Tank)

Xenia Twp Fire Dept

Used with permission from

Wright-Patterson AFB Radiation Safety office

-Unclassified -

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Ionizing radiation consists of electromagnetic or particulate radiations capable of interacting with the atom causing removal of one or more electrons such that the atom has a resulting net positive charge

Ionizing Radiation

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• Radioactivity - a property of some species of atoms to spontaneously emit radiation(s) usually by disintegration of the nuclei of the atoms

• Radiation - the energy or particles emitted when a radionuclide transforms or disintegrates (radiation is not the same as radioactivity)

• Radionuclide - a nuclide that emits radiation(s)

DEFINITIONS

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Ionizing

Non-ionizing

Ionizing Vs Non-ionizing

x-ray machine

microwave

radar

AM/FM

gamma ray

(Matching Game)

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• curie (Ci)– The activity of 1 gram of 226Ra

– 3.7 x 1010 disintegrations per second (dps)

• becquerel– one disintegration per second (dps)

• one dps is NOT synonymous with the number of particles emitted by the isotope in one second

Activity

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• The interval at which a radionuclide decays to one-half the original activity

• Each radionuclide has its own characteristic half-life

• Half-lives range from microseconds to billions of years

Half -life

Radionuclide Half-life 57Co 270 days241Am 433 years 63Ni 100 years226Ra 1600 years

109Cd 464 days

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• Alpha ()

• Beta minus ()

• Beta positive () (positron) and Electron Capture

• Gamma (associated with other types of decay)

Decay Methods

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Line of Stability

A Z N# of

stablenuclides

even even even 159

odd even odd 53

odd odd even 50

even odd odd 4

266

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• Roentgen (R)– the measure of the number of ion-pairs produced by

gamma radiation in a certain volume of air

Exposure

+ ++

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• RAD (Radiation Absorbed Dose)– an absorbed radiation dose of 100 ergs per gram

– energy deposited by any ionizing radiation in a unit mass of any absorber

• Gray (Gy)– 1 Gy = 100 rads

DOSE

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DOSE

• REM (RAD Equivalent Man)– the absorbed dose (RAD) multiplied by a quality factor to

equalize biological consequences

• Sievert (Sv)– 1 Sv = 100 rems

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Radiation Quality Factor x-ray 1

gamma 1

beta 1

alpha 20

neutron (unknown energy) 10

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• Exposure - the delivery of radiation to an individual that results in the receipt of a radiation dose

• Contamination - radioactive material distributed in an unwanted place or location

Exposure Vs Contamination

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No biological sensors of ionizing radiation

Must depend on instruments

Interaction with matter principles used

Detection is dependent on type of radiation

OFF

BATT

x10Kx1K

x100x10

RESET

AUDIO

ON

0

2040 60

80

100

COUNTS/MINGENERAL

ELECTRICGE

ALPHA SURVEY METER LEA75-1854 SER.NO.

|||||||| ||

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Dose Vs Dose Rate• Dose - generic term that means absorbed dose, dose

equivalent, effective dose equivalent or total effective dose equivalent (mrem)

• Dose Rate - the rate at which a dose is being delivered per a time interval (mrem per hour)

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Radiation Type In Air Typical Shielding Material Used

Alpha inches paper or aluminum foil

Beta feet aluminum or Lucite

Gamma hundreds lead or concrete

of feet

Why does alpha have a higher quality factor?

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• Dose Equivalent (HT) - the product of the absorbed dose in tissue, quality factor, and all other necessary modifying factors at the location of interest.

• Effective Dose Equivalent (HE) - the sum of the products of the dose equivalent to the organ or tissue (HT) and the weighting factors (WT) applicable to each of the body organs or tissues that are irradiated (HE = WT HT)

Internal Dose

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Organ or Tissue WT

Gonads 0.25

Breast 0.15

Red Bone Marrow 0.12

Lung 0.12

Thyroid 0.03

Bone Surfaces 0.03

Remainder 10.30

Whole Body 1.00

1 0.30 results from 0.06 for each of the “remainder” organs (excluding the skin and the lens of the eye) that receivethe highest dose.

ORGAN DOSE WEIGHTING FACTORS

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• Committed Dose Equivalent (HT,50) - the dose equivalent to organs or tissues of reference (T) that will be received from an intake of radioactive material by an individual during the 50-year period following the intake

• Committed Effective Dose Equivalent (HE,50) - the sum of the products of the weighting factors applicable to each of the body organs or tissues that are irradiated and the committed dose equivalent to these organs or tissues (HE,50 = WT HT,50)

Internal Dose

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• Total Effective Dose Equivalent (TEDE) - the sum of the deep-dose equivalent (for external exposures) and the committed effective dose equivalent (for internal exposures)

TEDE = Deep Dose + CEDE

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• Direct – ionization and excitation

» radiation + H2O H2O+ + e-

H+ + OH-

» radiation + H2O Ho + OHo (free radical)

– occurs anywhere in body

• Indirect – Radicals react with biological molecule and damage it

– Radicals combine

» OHo + OHo H2O2 (hydrogen peroxide)

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Cell Division

Normal

Parent

CellDivision

DaughterCells

IrradiatedCell

GrowthNo Division

IrradiatedCell

Mutant cells (death, altered DNA)

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Dose (REM)

Effect(Risk)

0 100 450 1000

Linear/Threshold

Confirmed Data

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Most to least radiosensitive

Immature male sex cells

White blood cells

Bone marrow cells

Epithelial cells of the intestine

Cells such as the skin covering external surfaces

Cells that line the closed cavities of the body (i.e., heart, blood vessels)

Bone cells

Nerve cells

Brain cells

Muscle cells

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Two types of exposure

• Acute - a single accidental exposure to a high dose during a short period of time

• Chronic - a long-term, low level exposure

Radiation Effects

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• Factors– Type of radiation

– Absorbed dose

– Dose distribution

– Age

• Stages– Initial (nausea, vomiting)

– Latent

– Manifest illness

– Recovery

Acute Exposures

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Dose Effect

1 rad to bone marrow20-50 rad (whole body)>90-150 rad (whole body)300 rad (skin)450 rads (whole body)600-900 rad, (local to eye)>1000 -4000 rads (whole body)10,000 rads (whole body)1000-6000 (localized)

risk of leukemiablood changesmild radiation sicknesserythemaLD 50/30cataractsdeath in 1 to 2 weeksdeath in hours to dayscancer treatments

Acute Exposure

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• Cancer– leukemia

– bone

– lung

– skin

– etc.

• Genetic

• Life shortening

Chronic Exposure (Delayed Effects)

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• Somatic - effects which occur to an individual being exposed during their lifetime

• Genetic - effects that are act on the offspring of the individual being exposed

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• Stochastic– effects that occur by chance

– occur among unexposed as well as among exposed

– in radiation, main effects are cancer and genetic effects

• Non-Stochastic– certain minimum dose must be exceeded for effect

– magnitude of effect increases with size of dose

– clear causal relationship between exposure and effect

Dose-Response Characteristics

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• The human population has always received radiation exposure from natural sources such as cosmic, dietary, and soil.

• Additional sources of exposure are medical exposures, occupations exposures and some industrial and consumer products.

RISKS

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Annual effective dose equivalent in the U.S. population Source Average Dose (mrem)

• Natural sources– Radon 200

– Other 100

• Occupational 0.9

• Nuclear fuel cycle 0.05

• Consumer products– Tobacco

– Other 5-13

• Misc. Environ Sources 0.006

• Medical– Diagnostic x-ray 39

– Nuclear medicine 14

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Food40K

pCi/kg

226Ra

pCi/kg

Banana 3520 1

Brazil nuts 5600 1000-7000

Carrot 3400 0.6-2

White potatoes 3400 1-2.5

Beer 390 ---

Red meat 3000 0.5

Lima bean raw 4640 2-5

Drinking water --- 0-0.17

Natural Radioactivity in Food

Ref: http://www.physics.isu.edu/radinf/natural.htm

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Cosmic 8%

Terrestrial 8%

Internal 11%

Radon 55%

Medical X-rays 11%

Nuclear Medicine 4%

Consumer Products 3%

Other <1% Occupational Nuclear Fuel Cycle Fall out Misc

Sources ofRadiation Exposure

Average Exposure 360 mrem/yr

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Source of Radiation (excludes indoor radon)

1. Cosmic Radiation: 40 mrem a sea level (Add 1 mrem for each 100 feet elevation)

2. House Construction: Wood: 35 mrem Concrete: 50 mrem Brick: 75 mrem 3. Water and Food a. U.S. average 25__ b. Heavy smoker (add 30 mrem) c. Drink beer (add 1 mrem for each 100 bottles) _____

4. Air a. Natural - U.S. average 5 b. Weapons testing 2 5. Transcontinental Flights: Add 4 mrem for each 5000 miles in flight

6. Radium Dial Wrist Watch: (add 2 mrem)

7. Television: U.S. average 2__ 8. Radioactivity in Human Body a. Dose to yourself (K-40) 20__ b. Sleep with spouse (add 0.3 mrem) c. Dose to yourself (C-14) 0.2

9. Medical and Dental Diagnosis a. U.S. average 55 mrem or b. For each chest, teeth, head neck and bone x-ray, add 20 mrem c. For each spinal column and kidney x-ray , add 200 mrem d. For each stomach, intestines and gall bladder x-ray, add 250 mrem

10. Live in the vicinity of large coal-fired power plant (add 0.1 mrem)

11. Live in the vicinity of large geothermal power plant (add 1 to 100 mrem)

12. Nuclear Power Plants: a. If you live (1) At boundary fence (fraction of year spent times 5 mrem)

(2) One mile away (fraction of year spent times 0.5 mrem)

(3) Five miles away (fraction of year spent times 0.05 mrem ______ b. General U.S. population: Add 0.01 mrem

Total mrem/year

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RISKS

• It is estimated that if 100,000 persons of all ages received a whole body dose of 10 rad of gamma radiation in a single brief exposure, about 800 extra cancer deaths would be expected to occur during their remaining lifetimes (BEIR V)

• It is estimated that if 100,000 persons of all ages received a continuous lifetime whole body dose of 100 mrad per year, about 550 extra deaths would be expected. (BEIR V)

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• To prevent the occurrence of clinically significant radiation-induced deterministic effects by adhering to dose limits that are below the apparent threshold levels; and

• To limit the risk of stochastic effects, cancer and genetic effects, to a reasonable level in relation to societal needs, values, benefits gained and economic factors

Objectives of Radiation Protection

NCRP No. 116

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• Time

• Distance

• Shielding

External Radiation Protection Measures

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• dose rate x exposure time = total dose

20 mRem/hr x 30 min = 10 mRem

• Reduce time reduces exposure

TIME

1000 mR/hr for 2 minutes = ________________

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• Radiation exposure decreases with increasing distance

• Decrease by inverse square law

• Double the distance decrease the exposure by 4

DISTANCE

0100200300400

1 2 3 4

400

1002544

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Paper Plastic Lead Concrete

a42 Alpha

Beta

Gamma and X-rays

Neutron

01

n10

Shielding

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• Fire, Explosion, Instrument Damage, etc.– Secure the area– Keep Unauthorized persons away– Alert people within the vicinity– Notify Department of Energy (DOE)

» Initiate appropriate actions» Make appropriate written report

• Loss or Theft– Immediate notification of DOE and Nuclear Regulatory Commission

» Immediate notification of Radioisotope Committee» Make written report

– Immediately begin search

Response Actions

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Susan, I see youhave grown a footsince the last time I saw you !