Radiation And Radioactivity, Dr Xoubi

NE 101 Basics of Nuclear Engineering & Technology Chapter 4: Radiation and Radioactivity Dr. Ned Xoubi

‫الدكتور نضال الزعبي‬ Founder of the Nuclear Engineering Department Fall Semester 2007/ 2008

Radiation

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Ionizing Radiation
Alpha Particle
High energy, massive, slow, short range (3 cm in air), double charged
Beta Radiation
Medium range (about 5m in air), single charge.
Neutrons
No electrical charge

α β

γ


Electromagnetic radiation
Gamma Rays
X-ray Nuclear Engineering Department xoubi

   

Penetration

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Radioactivity  Radioactivity is the decay of unstable atoms by the emission of particles and electromagnetic radiation.

An atom with an unstable nucleus will “decay” until it becomes a stable atom, emitting radiation as it decays

Sometimes the new atom is also

unstable, creating a “decay chain”

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How Unstable Is It?
A curie (Ci) is equal to 3.7 x 1010 disintegrations per second.
Becquerel (Bq) is equal to 1 disintegration per second
The radioactive decay constant (  ) is the probability per unit time that an atom will decay
The radioactive half-life is the amount of time required for the activity to decrease to one-half its original value

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Some Isotopes & Their Half Lives ISOTOPE

HALFLIFE

Uranium

APPLICATIONS

billions of Found in nature Used to power nuclear reactor or years nuclear weapons.

Carbon-14

5730 y

Found in nature from cosmic interactions, used to “carbon date” items and for detection of tumors.

Cesium-137

30.2 y

Blood irradiators, tumor treatment through external exposure. Also used for industrial radiography.

Hydrogen-3

12.3 y

Labeling biological tracers.

Irridium-192

74 d

Implants or "seeds" for treatment of cancer. Also used for industrial radiography.

Technicium99m

6h

Brain, heart, liver (gastoenterology), lungs, bones, thyroid, and kidney imaging, Nuclear Engineering Department

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The Amount of Radioactivity is NOT Necessarily Related to Size
Specific activity is the amount of radioactivity found in a gram of material.
Radioactive material with long halflives have low specific activity.

1 gram of Cobalt-60 has the same activity as 1800 tons of natural Uranium Nuclear Engineering Department xoubi

   

Annual Dose from Background Radiation Total exposure

Man-made sources Medical X-Rays

Radon

11

55.0%

Other 1%

Internal 11% Man-Made 18% Cosmic 8%

Terrestrial 6%

Nuclear Medicine 4%

Consumer Products 3%

Total US average dose equivalent = 360 mrem/year Nuclear Engineering Department xoubi

   

Why is Radiation Harmful?
When radiation’s energy is deposited into our body’s tissues, that is a dose of radiation.
The more energy deposited into the body, the higher the dose.
Rem / Sievert are units of measure for radiation dose
Alters atoms
Damage to cells & DNA causes mutations and cancer
Much of the resulting damage is from the production of ions Nuclear Engineering Department xoubi

   

Types of Radiation Hazards Internal Contamination

External Exposure: whole-body or partial-body

External Contamination

Contaminated: external radioactive on the skin

External material:Exposure

internal radioactive material: inhaled, swallowed, absorbed through skin or wounds Nuclear Engineering Department xoubi

   

Types of Exposure & Health Effects
Acute Dose
Large radiation dose in a short period of time
Large doses may result in observable health effects – Early: Nausea & vomiting – Hair loss, fatigue, & medical complications – Burns and wounds heal slowly
Examples: medical exposures and accidental exposure to sealed sources


Chronic Dose





Radiation dose received over a long period of time Body more easily repairs damage from chronic doses Does not usually result in observable effects Examples: Background Radiation and Inhalation Internal Deposition Nuclear Engineering Department xoubi

   

Radiation and Contamination
Exposure to Radiation will not contaminate you or make you radioactive.
Contamination is Radioactive Material spilled someplace you don’t want it.
Contact with Contamination can contaminate you with the material.

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