Potential Energy

Radiation is the one thing that scares most people about the whole idea of “nuclear”. Radiation Sickness, Radiation Burns, Radioactive Fallout… Again, I think most people’s ideas about “nuclear” were formed during the Cold War when, quite rightly, we all had a lot to fear from the threat of nuclear war. Let’s all just get one thing straight:

Nuclear Power Is Not Nuclear War.

They are as different as Jedis and Siths in ‘Star Wars’. Both Jedis and Siths use the Force. Jedis use it for good, Siths use it for evil. The Force itself is not inherently evil nor inherently good. Likewise, nuclear fission itself is not a moral nor immoral process. To approach it as anything other than amoral is as daft as believing there is some innate goodness or badness in ‘water’.

Anyway, the question ‘what exactly is radiation’ was top of my mind over the bank holiday weekend as my husband- a high-energy particle physicist at CERN- and I wandered around picturesque villages in the Pennines. While downing pints in the pub he gave me a first year physics course on radiation. This is what I learned:

Very basically, radiation is energy that is emitted in the form of electromagnetic waves or particles. There are lots of different types of radiation that you may have heard of: Solar Radiation, Thermal Radiation, Cosmic Radiation, Hawking Radiation… The most well-known kind of radiation, however, is Electromagnetic Radiation.

Electromagnetic Radiation is what allows you to listen to the radio or to quickly cook your food in your microwave oven as Radio Waves and Microwaves are on the low frequency end of the Electromagnetic Radiation spectrum.

Another type of Electromagnetic Radiation is Light - Infrared, Visible and Ultraviolet Light. Visible light is, of course, the light we see, Infrared is the type of light used in night vision equipment and Ultraviolet light is what tans our skin when we are outside.

If you’ve ever had an Xray at the doctor or the dentist, you’ve been bombarded with Electromagnetic Radiation. Xrays pass through the soft tissues of your body, but are blocked by dense tissues such as teeth or bones.

The highest frequency Electromagnetic Radiation is called Gamma Rays. Gamma Rays are produced in PET scans, astrophysical phenomena such as Gamma Ray bursts or in radioactive decay.

It’s important to point out that the boundary between what one calls Xrays and what one calls Gamma Rays can be vague - for example, a photon with an energy of 10 keV can be called either an Xray or a Gamma Ray. ALL types of Electromagnetic Radiation are photons, the only difference being the amount of energy carried by the photon.

For our purposes the only other types of radiation we need to be concerned with are Alpha Radiation, Beta Radiation and Neutron Radiation- all occur as result of nuclear fission either natural or man-made.

Alpha Radiation is essentially the same as a helium atom. The only difference being it doesn’t have any electrons. It only travels a few centimetres in the air and can be stopped by a piece of tissue paper.

Beta Radiation is the release of an electron from a neutron rich element. They have a range of a few metres in the air and can be stopped by a few millimetres of aluminium.

Neutron Radiation is made up of ‘free’ neutrons. It is a concern as it is very good at making almost everything it encounters radioactive. Neutron radiation is very penetrating, but can be shielded by water, plastic, borated metals, and concrete. No little animation, I’m afraid.

We are all immersed in naturally occurring radiation- from the buildings we live and work in, the food we eat, Cosmic Rays from space, medical treatments. Radon Gas makes up the majority of our annual radiation dose.

The levels of Radon Gas fluctuates depending on things like the geological make-up of the area or whether you open your windows or not. Simply by spending two weeks on holiday in Cornwall, you will receive more radiation in a year than you would living next to a nuclear power plant.

Too much radiation, as we all know, can be harmful…. but how much is ‘too much’ and do the different types of radiation have different effects on our bodies? My next post I will look into the effects of radiation on the human body.