Radiation Made Simple

Have you ever wondered what radiation actually is? How it causes sickness and cancer and why people deem it so dangerous? If so keep reading as this article aims to explain simply what radiation is and how it affects us.

What Causes Radiation

Radioactive decay occurs when an unstable nucleus (the centre of an atom) rearranges itself to become more stable. It can do this by repositioning its protons and neutrons, converting protons to neutrons (and vice-versa) or by ejecting some of its protons and neutrons. This can happen several times in a decay cycle and occurs randomly. The time taken for half of the atoms in a sample to decay is called the half-life.

The structure of an atom

There are three ways a nucleus can release radiation. When a nucleus rearranges, energy is released in the form of a photon called a gamma ray. If a nucleus ejects mass, it does it in the form of a helium nucleus (called an alpha particle) or a neutron. When a nucleus converts a proton to a neutron or a neutron to a proton it releases a positron or an electron respectively, known as a beta particle. A nucleus will often have two or more of these happen at the same time.

The Four Types Of Radiation

As previously mentioned, there are four main types of radiation which each have different properties such as penetration and ionisation. Ionisation power is the ability of a form or radiation to strip electrons off (or donate electrons too) other atoms. The penetration power is the ability of radiation to pass through barriers such as walls. In general, ionisation power is inversely proportional to penetration power (as one goes up the other goes down) as the radioactive particle will lose energy as it ionises atoms around it and so can’t travel as far. From least ionising to most ionising the four types are are:

Neutron Emission

Neutrons are high speed neutrally charged particles, meaning they are not very ionising as they have no charge and so have no attraction to electrons. Their lack of charge means that not much can stop them from getting to you but this is nothing to worry about as they aren’t very harmful to human health (in Hiroshima and Nagasaki, neutron radiation accounted for just 1% of the total absorbed radiation dose[1]).

An interesting note about neutron radiation is that it is the driving factor in how most conventional Uranium based nuclear weapons work as released neutrons from one decay go on to collide with other Uranium atoms causing them to decay too.

Gamma Radiation

Gamma radiation is an electromagnetic wave, the same type of wave we use to see. It is just a higher energy photon than visible light. It has a large penetrating power, being able to go through meters of concrete but also has a low ionising capability compared to the others. Bunker walls are so thick to protect you from this.

As gamma radiation can never be fully stopped, the effectiveness of a material at blocking it is measured in halving thicknesses. The halving thickness of a material is the thickness of it required to half the amount of radiation from one side to the other. Another similar measure of a materials ability to stop gamma radiation is the protection factor (PF). A protection factor of 10 would mean that the walls of your bunker have reduced the radiation level inside to 1/10th of the radiation level outside. It is worth noting that the minimum level of protection for public fallout shelters is PF 40 [2].

Beta Radiation

These are high energy electrons or positrons. They have a high ionising power and medium penetrative power. They can pass through paper and skin but not much else. It poses a high threat for inhalation, ingestion, and wound contamination as well as external contamination. This is due to its high ionising potential. If it gets inside your body it will deal high amounts of damage to any tissue up to about 3cm away.

A common use for beta radiation is actually food preservation. It is used to irradiate food and kill of bacteria that may cause it to go bad. Irradiation is completely safe as the food item you are eating does not become radioactive in any way.

Alpha Radiation

These are heavy particles consisting of two protons and two neutrons. They are the most ionising of all the radiation types (i.e. they do the most damage) but the least penetrative. It can be stopped by a sheet of paper or 3cm of air. Because of this it poses a large threat for inhalation, ingestion, and wound contamination but not much else.

Demonstration of penetration power of different types of radiation.

How Does Radiation Damage You?

Radiation does most of its damage by disrupting atomic bonds. It breaks bonds or changes the structure of chemicals in DNA leading to either the cell dying or the cell not reproducing correctly. This can be damaging in two ways; too many cells can die leading to tissues dying and ultimately you dying, or the cells can reproduce incorrectly leading to cancerous cells occurring.

It is able to break and disrupt bonds due to the electromagnetic forces between the radioactive particles and the electrons in the bond. The radioactive particles attract electrons from the bond to themselves leaving the bond electron deficient.


Radiation is an invisible killer. You can’t see it or the damage it does so you need to know how to protect against it. Your shelter should be air tight to stop alpha and beta radiation and have thick walls to reduce gamma exposure. You should never underestimate the dangers of radiation.

Learn about how you can build a kit to protect yourself from radiation here.

If you liked this article and want to read more have a look at our other articles or the sources below:


[1] D. Preston et al., “Effect of recent changes in atomic bomb survivor dosimetry on cancer mortality risk estimates,” Oct. 2004.

[2] FEMA TR-87 “Standards for Fallout Shelters” Sept. 1979.

Leave a Comment

Your email address will not be published. Required fields are marked *