Radiation Concepts Definitions Ionizing Radiation energy in the

Radiation Concepts

Definitions Ionizing Radiation energy in the form of particles or waves, given off by unstable (radioactive) atoms or by accelerated charged particles Radioactive Material any material which emits ionizing radiation Radioactive Contamination radioactive material in an unwanted place 101 -04

Radiation Radioactive Atom Ionizing Radiation Alpha Particle Neutron Particle Beta Particle Gamma Ray (X Ray)

Radioactive Material Gamma Ray Radioactive Material - any material containing atoms that emit radiation.

Contamination External Radiation Contamination

Radioactive Contamination - is radioactive material in an unwanted place.

Ionizing Radiation Neutrons and Protons Ejected Electron Ionization Radiation Ionizing Radiation - radiation with enough energy to remove an electron from its atom.

Alpha Particle a Characteristics Range Shielding Hazards Sources • +2 charge • 2 protons • 2 neutrons • Large mass • Very short range • 1" -2" in air • Paper • Outer layer of skin • Internal • Plutonium • Uranium • Radium • Thorium • Americium a a a

Beta Particle b Characteristics Range Shielding Hazards Sources • -1 charge • Small mass • Plastic safety glasses • Thin metal • Skin and eyes • Can be internal • Radioisotopes • Activation Products • Sealed sources • Short range • About 10' in air

Gamma Ray g Characteristics Range Shielding Hazards Sources • No charge • No mass • Similar to x-rays • Lead • Steel • Concrete • External (whole body) • Can be internal • X-ray machines • Electron microscopes • Sealed sources • Accelerators • Nuclear reactors • Radioisotopes • Long range • About 1100' in air Paper Plastic Lead

Neutron Particle h Characteristics Range Shielding Hazards Sources • No charge • Found in nucleus • Water • Plastic • External (whole body) • Fission • Reactor operation • Sealed sources • Accelerators • Extended range Paper Lead Water

Radiation Units roentgen (R) • measures exposure (ionization) of air by X-rays & gamma-rays rad (radiation absorbed dose) • measures energy deposited in any material by any type of ionizing radiation rem (Roentgen Equivalent to Man) • estimates biological damage or health risk due to absorption of ionizing radiation • unit of dose equivalent

Radioactivity Units Measure the number of nuclear transformations (disintegrations) which occur in a certain time period Curie (abbreviated, Ci) = 37, 000, 000 disintegrations per second (dps) = 2, 200, 000, 000 disintegrations per minute (dpm) 2 of Radioactive contamination measures an amount activity over a unit of surface area. e. g. 5000 dpm/100 cm 2

Prefixes Used with Radiation Units Prefix Symbol Translation Numerical Value Scientific Notation Tera T 1 trillion 1, 000, 000 1012 Giga G 1 billion 1, 000, 000 109 Mega M 1 million 1, 000 106 Kilo k 1 thousand 1, 000 103 Milli m 1 thousandth 1/1, 000 10 -3 Micro m 1 millionth 1/1, 000 10 -6 Nano n 1 billionth 1/1, 000, 000 10 -9 Pico p 1 trillionth 1/1, 000, 000 10 -12

Prefixes – Examples Nuclear plant - 1000 megawatts (MW) electric power 1 kilogram (kg) weighs 2. 2 pounds Chest X-Ray dose = 5 millirem (mrem) Biochemist might use a 10 micro. Curie (m. Ci) source 10 n. Ci/100 cm 2 = low level radioactive contamination Natural radium content of soil = 1 pico. Ci/gram (p. Ci/g)

millirem Abbreviation: mrem 1000 mrem = 1 rem millirem - is the basic unit of radiation dose equivalent. It measures biological risk in humans.

Half-Life The time required for the amount of radioactive material to decrease by one-half 1200 1000 800 Activity 600 400 200 0 New 1 Half. Life 2 Half- 3 Half. Lives 4 Half. Lives

Acute Radiation Dose Acute radiation dose refers to persons who receive large amounts of radiation over a short period of time.

Chronic Radiation Dose Chronic radiation dose refers to persons who receive small amounts of radiation over a long period of time.

Chronic Radiation Dose Chronic radiation dose refers to persons who receive small amounts of radiation over a long period of time. There is a slight risk that cancer may be caused by chronic radiation doses. This risk level is very small compared to the natural occurrence rate of cancer.

LNT Assumption The previous statements assume a Linear, No-Threshold (LNT) response to radiation. There is a growing body of scientific evidence that this assumption is incorrect, and that low levels of radiation exposure are not harmful. There is also evidence that low levels of radiation exposure can have a beneficial (i. e. , hormesis) effect.

Four Ways Radioactive Material Can Enter the Body Inhalation • Breathing • Smoking Absorption Wound or Cut Ingestion • Eating • Drinking • Chewing

Biological Effects of Radiation Cells are undamaged. Cells are damaged, repair damage and operate normally. Cells are damaged, repair damage and operate abnormally. Cells die as a result of damage.

Health Effects • Radiation effects on cell chromosomes: Somatic Effects observed in the exposed individual Heritable (Genetic) Effects observed in future generations of exposed individual

RW I Affecting Factors Biological Damage • • • Total radiation dose Dose rate Type of radiation Area of body exposed Cell sensitivity Individual sensitivity 102 -13

The RW fetus is MORE I sensitive than an adult.

No Heritable Effects from Ionizing Radiation Have Been Observed in Humans Heritable effects have been observed in laboratory animals.

The average annual dose to the general population from natural background and man-made sources is 360 mrem. Terrestrial Sources Radon Cosmic Radiation Radon Internal Sources Other

Average Annual Dose Cosmic 28 mrem Radon 200 mrem Terrestrial 28 mrem Internal 40 mrem Medical X-Rays 40 mrem Nuclear Medicine 14 mrem Natural Sources Man-Made Sources Other 3 mrem Consumer Products 10 mrem

Comparison of Radiation Dose

Relative risk of dying: RW I 1 in a million odds. • Smoking 1. 4 cigarettes (lung cancer) • Eating 40 tablespoons of peanut butter • Eating 100 charcoal broiled steaks • 2 days in New York City (air pollution) • Driving 40 miles in a car (accident) • Flying 2500 miles in a jet (accident) • Canoeing for 6 miles • Receiving 10 mrem radiation dose (cancer)

Risk – Loss of Life Expectancy Days of Average Life Expectancy Lost Due to Various Causes Being an unmarried male Smoking (1 pack/day) Being an unmarried female Being a coal miner 25% overweight Alcohol abuse (U. S. average) Being a construction worker Driving a motor vehicle All industries Radiation: 100 mrem/yr x 70 years Coffee 3500 2250 1600 1100 777 365 227 207 60 10 6

Basic Protective Measures Time Distance Shielding