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Back in the day when I taught basic science at a small college part time, I would walk into class the day of the lecture on radiation holding a “device” in one hand and announcing that radiation had been detected. I would then reveal the device to be a radio, and use that as the launching point for the lesson. Today, were I to do that I would probably be met with absolute panic instead of eye rolls.
The fact is, we are surrounded by radiation pretty much every moment of every day. Light, radio waves, and other beneficial delights enrich our lives. Radiation, in and of itself, is not a bad thing. I’m going to skip the part of the lesson on the electromagnetic spectrum and get to the meat of today’s lesson.
The type of radiation you really need to be concerned about is ionizing radiation. That’s the nasty stuff that can damage the body and/or kill you. As always, this is a 201-level course and not a 500 or higher physics course.
Ionizing radiation gets its name because the subatomic particle or electromagnetic wave in question can strip electrons from a stable bond or state. By doing so, it converts items into ions (an atom or atoms that have gained or lost electrons), hence the name ionizing radiation. As with other portions of the electromagnetic spectrum, some types of ionizing radiation can have beneficial uses (X-rays for example) when applied in a controlled/limited amount. It’s when the dosage and type of ionizing radiation is not controlled that things get interesting.
Most texts, especially lower-level texts, break ionizing radiation down into three types: Alpha, Beta, and Gamma. Gamma is in many ways a “catch all” as neutrons, X-rays, and even cosmic radiation fall into that category.
Alpha is the easiest to deal with. Basically, two neutrons and two protons bound together, though that’s really not critical info for this lesson. The fact is, a piece of paper can stop alpha radiation. Most clothing blocks it, and the skin has as one of its functions stopping alpha radiation. It is, however, strongly ionizing.
Beta radiation is basically an electron or positron moving at high speed. It is actually less ionizing that Alpha, though more than Gamma. A thin sheet of aluminum (note, not foil) will stop beta radiation, though it is not a good idea to use it. Fact is, some forms of beta radiation can have enough energy to create gamma radiation when they hit such a shield.
Gamma radiation is not just gamma, but also pretty much the rest of the electromagnetic spectrum. To protect against it (that which you can protect against — there are some subatomic particles out there that pass through the entire Earth basically undiminished and are a bear to detect and study) takes serious shielding, such as concrete, lead, or special materials that combine layers of shielding.
Keep in mind that we are naturally exposed to some ionizing radiation every day. The atmosphere protects us from a good bit, but if you spend a lot of time in airplanes you are getting a higher exposure than you would if you stayed on the ground. It is also in the ground and otherwise around us. That’s one reason it’s a good idea to have your basement, or even crawl space, checked in certain parts of the country. The key is limiting the exposure.
To wrap up for the day, let’s talk radioactive materials. Radioactive materials are ones that are unstable in terms of their atomic structure, and as such give off energy (heat, ionizing radiation, etc.) as they “decay” into more stable materials. Yeah, yeah, there’s a lot more to it than that, again, this is a 201-level course. Don’t tell me your primary school introductory science course included bond types, valences, and other delights, especially since you were lucky to get baking soda and vinegar right…
Radioactive elements have what is called a half-life: the amount of time it takes for one half of the material in question to go away (change into a different form). For example, tritium (critical for nuclear weapons) has a half life of 12.3 years, while cobalt-60 (used in radiotheraphy/radiation treatments) has a half life of 5.26 years. Others, however, have half lives that can be measured in thousands if not millions of years, or, in fractions of a second.
This is important for our purposes as a nuclear bomb exploding is going to interact with the atmosphere, structures, and the ground in such a way that it will effectively convert non-radioactive materials into radioactive materials. Some of these materials will have a blessedly short (though energetic) half-life. Some are going to be around for a long time to come. In addition to radioactive contamination of the blast site, the nuclear explosion (and fires that follow) are going to send this radioactive material up into the air where it will eventually fall back to Earth. This is known as fallout, and it will be a significant part of survival after a nuclear explosion.
Tomorrow I think we will get into survival, preparedness, and some of the realities of radiation exposure.
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SOME PREVIOUS POSTS:
Nuclear 201 Posts In Order
Nuclear 201: Will You Be My PAL?
Nuclear 201: Additional Thoughts On Coms
Nuclear 201: Targeting, Take 2
Nuclear 201: Policy, SIOP, and Escalation
Nuclear 101 Posts In Order:
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