The radiation symbol was originally developed at the University of California in 1946 with a blue symbol on a magenta background. The symbol is now internationally recognised as being black on a yellow background. The symbol is actually specific to ionizing radiation and there is a different symbol for non-ionizing radiation. This symbol has a red background with a skull and crossbones and a person running away both sat below a radiation symbol.
For something to radiate, it means it emits something, either waves or particles. So things emitting light radiate. Ionising radiation is the category that includes all high energy waves and particles, such as X rays, gamma rays, some ultraviolet light as well as alpha and beta particles and any other sub-atomic particles. Non-ionising radiation includes visible light, infra red, lasers, microwaves and radio waves. So things that are radioactive radiate and are classed as ionising radiation.
Radioactivity is something that happens at the atomic level. Some atoms are just so big and ungainly, that they are unstable. They fall apart. Different substances have different numbers of protons, neutrons and electrons. When an atom is unstable, it loses bits until it become more stable. It can lose pure energy, which is gamma rays; an alpha particle which is two protons and two neutrons or a beta particle which is a single electron (or if it has a positive charge, a positron).
I think radioactivity is a very scary thing and one of the things that makes it so scary is that it is invisible and the scale of the disasters caused by it. One atom decaying is not to much of an issue but there are a lot of atoms in a tiny amount of material. When a particularly unstable radioactive material is concentrated and allowed to be in contact, as each atom decays or falls apart, it causes the atoms next to it to also decay. Imagine a bunch of jenga towers next to each other, one falls and it knocks two of the others, each of which knock two more and so on, until most of them fall. This is what happens when there is a radioactive explosion. The bombs used in Japan, the disasters of Chernobyl, Three Mile Island and Fukushima... all runaway radioactive decay. Uranium and Plutonium are the most dangerous of elements.
Uranium occurs naturally and is present in the granite where I live. When I was at college we took a geiger counter out one time and found some very radioactive rocks. A cave on a beach created when they used to mine and this mine produced Uranium amongst other metals. A stone in a wall by a busy path, at the perfect height to sit on. Down near St Just, children are told not to play with the black rocks. The Uranium is spread out so it isn't going to cause a runaway event leading to an explosion.
It isn't actually the Uranium that is the most dangerous though, one of the things it decays into is a radioactive gas called Radon. Radon is able to travel upwards, out of the ground and into peoples homes. Some homes in Cornwall have very high levels of Radon and have to have alterations made to ventilate the gas away. Basements are also particularly susceptible. People breathe the gas in and it is one of the biggest causes of Lung Cancer along with Asbestos following Smoking. One particular issue is that people that smoke and also live with high levels of Radon are at even higher risk because the Radon atoms tend to be attracted to the smoke particles which remain in the lungs.
Radioactivity is not all bad. When managed extremely carefully it is very useful. It is the cleanest source of electricity after renewable sources. It is also used in medicine to treat people with Cancer and for sterilizing things to ensure they are completely clean and not contaminated with any microbes. That's not to say it's nice, even when used in these ways.... It's a harsh treatment.
When I was growing up, they wanted to bury radioactive waste nearby at Elstow. I remember seeing protests on the local news and I remember a family friend being amongst those protesting. It was such an important story locally that a monument was built, although it had to be relocated and repaired a few years back. The site that would have been used for nuclear waste has been redeveloped for housing and what was a quiet backwater in the 80s is now a vital part of the local road network and part of huge redevelopment. I don't think any of that would have been possible if they had used it for nuclear waste.
Nuclear has laid waste to land, made it unsafe to inhabit... Fukushima and Chernobyl have both resulted in ghost towns with haunting photos of what happens when people just leave. The fear of this happening haunted us all during the Cold War. Nowhere would have been safe. I don't think people realise the scale of nuclear preparations. I know of several basement nuclear bunkers now used as storage and often full of files. The irony is now the ventilation has been turned off, in Cornwall at least, these rooms are sometimes more radioactive than those above ground, full of Radon gas.
You can see my pinterest board for Radiation here!
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