Radiation
Michael H. Fox
Why We Need Nuclear Power
The Environmental Case
A brief summary of radiation.  Read Chapter 6 for a more detailed
discussion.

Radiation is a kind of elementary particle or electromagnetic wave that
can interact with matter and transfer energy to it.  Ionizing radiation has
enough energy to kick an electron out of an atom, creating an ion pair
(a positive atom and a free electron).  Non-ionizing radiation (such as
UV) does not have enough energy to ionize atoms.  Radiation of
concern for nuclear power is strictly ionizing radiation.

Ionizing radiation consists of alpha particles (α), beta particles (β),
gamma rays (γ), X-rays, protons and neutrons.  Alpha particles are
identical to helium nuclei, consisting of 2 protons and 2 neutrons, and
they are emitted in radioactive decay of elements such as uranium,  
plutonium and radon.  Beta particles are identical to electrons but they
come from the nucleus in radioactive beta decay.  Gamma rays and X-
rays are both electromagnetic radiation and may have the same
energy.  They can have either wave or particle properties.  For the
purposes of radiation biology, they act like particles and are known as
photons.  The only true distinction between them is that gamma rays
come from the nucleus and X-rays come from electron interactions.  
Neutrons are uncharged particles that are in the nucleus. Protons are
very similar to neutrons except that they have a positive charge.  
Neutrons are very important in nuclear fission processes.  Protons are
not an important type of radiation in nuclear processes, though they are
the principal component of cosmic rays.

Radiation is a completely natural phenomenon.  We are all exposed to
radiation from natural background sources, including cosmic rays,
gamma radiation from uranium, thorium and radium in rocks, alpha
radiation from radon in the soil, and internal sources from food we eat
that has natural radionuclides.  The level of
background radiation
varies substantially depending on where you live.  Cosmic radiation
goes up exponentially with altitude, so it is more important in the
mountains than at lower elevations.  Terrestrial radiation from rocks is
higher in mountainous regions because of the presence of radium,
uranium, thorium and radon.  As a result, people who live in Colorado
experience a background radiation dose nearly three times higher than
that of people who live in coastal areas of Florida and Texas.  

There is nothing fundamentally different about radiation from nuclear
power and natural radiation.  Alpha, beta and gamma radiation are the
same, no matter where they come from.  The only thing that matters for
biological consequences is the dose of radiation that one is exposed
to.  Dose is a somewhat complicated subject, however, because the
various forms of radiation can cause different amounts of damage in
biological systems such as cells and DNA.  The standard measure of
dose is Sieverts [or milliSieverts (mSv) or microSieverts (μSv).  Click
here for a detailed discussion of
dose.