Radioactivity Chapter 9 Nuclear Changes

Radioactivity  Radioactive materials have unstable nuclei.  They emit particles/energy to become stable.  Isotopes are generally radioactive. Why do you think that is?

Four Different Types of Radioactivity  Alpha  Protons and Neutrons are emitted  Beta  1 electron is emitted  Gamma  Light is emitted  Neutron  Neutrons are emitted

So Why Is It Dangerous?  It’s not ALWAYS dangerous, but most of the time it is.  The energy/particles that are emitted travel through the air and hit the atoms it meets. This disturbs the atoms.  Do you think you want disturbed atoms in your body?

How Do We Prevent too much Radiation Exposure??  Shielding!  Shielding is the materials that are between the radioactive source and the detector or person.  The purpose of shielding is to reduce the amount of radiation that one person or object receives.

Shielding  Alpha particles Stopped by paper or the skin Stopped by paper or the skin Present little or no hazard external to body Present little or no hazard external to body Internal hazard (if it gets in the body) Internal hazard (if it gets in the body)  Beta particles Stopped by light metals (aluminium) and plastics Stopped by light metals (aluminium) and plastics Internal and external hazard Internal and external hazard

Shielding  Gamma rays  Stopped by very dense materials (lead, concrete)  Easily pass through the human body  Internal and external hazard  Neutrons  Stopped by materials containing hydrogen atoms, such as water, polyethylene, and concrete  Internal and external hazard

Shielding: Alphas, Betas, Gammas and Neutrons

Where Does the Radiation Come From?  The radiation you receive can be either Natural or Man-made

Sources of Radiation: Natural  Cosmic: Sun Sun  Terrestrial: sources in the earth’s crust Soil (radon) Soil (radon) Water Water Vegetation (Bananas) Vegetation (Bananas)  Internal: sources in the human body Potassium-40 Potassium-40 Carbon-14 Carbon-14 Lead-210 Lead-210

Sources of Radiation: Man- made  Medical  X-rays  Cancer treatments  Commercial  TV  Lantern mantels  Smoke detectors  Fuel cycle (nuclear power)

Determining Your Personal Annual Radiation Dose

Average Annual Dose to Ionizing Radiation  All living creatures constantly receive a certain amount of radiation from outer space, the soil, food we ingest or even the air we breathe.  The sources of radiation fall under two categories: natural and man-made, collectively known as background radiation.  The average annual personal dose from background radiation is approximately 350 mRem/year.

What To Do  In this activity, you will estimate your personal annual radiation dose using the Background Information Worksheet provided. When doing this activity, keep in mind that the amount of  terrestrial radiation varies in different parts of the world due to different concentrations of uranium and thorium in soil.  cosmic radiation varies in different parts of the world due to differences in elevation and to the effects of the earth’s magnetic field.

Procedure  Complete the worksheet and tally the total.  For central Ohio, the average elevation is about 825 feet above sea level  approximate dose is 28 mRem/year from cosmic radiation.  For every hour in an airplane, you receive 0.5 mRem  Make sure to use 30 mRem/year for the second entry.  In central Ohio, we are not within 50 miles of a power plant. However in southern Ohio, there are many coal plants along Ohio River.