What are the different kinds of radiation? What are the sources of them. Which are the most harmful to humans?
There are thee types of radiation we usually associate with nuclear power generation: 1) Alpha. This a particle comprising two protons bound to two neutrons, they are considered large, and will not penetrate far through air. Paper will stop it. It is dangerous if you get it in you or on your skin. 2)Beta particles are electrons or positrons. These penetrate slightly and ionise body tissues. 3)Gamma radiation. This is exremely penetrating, ionising photons. Very dangerous in large doses 4)x-rays as 3) above Gamma is the most dangerous traditionally, but nasty poisioning and skin burns can occur fro alpha and beta. Gamma is long lived usually whilst alpha and beta are less persistent.
To be honest I've just been clarifying this recently due to queries about radiological misuse. The wiki radiation entry covers a number of different types, and the difference between ionising and non-ionising radiation. What's interesting is the different measurements when dealing with exposure, for instance you have the depreciated Radian (Rad), you have the "Roentgen equivalent in man" (Rem) and the Gray (Gy). Then you have measurements like the Specific absorption rate (SAR) that's used in regards to non-ionising radiation (You'll find it listed on various products as to whether they are "Safe" for usage or not.) Microwave usage in the telecommunication's industry is "deemed safe" because it's non-ionising. Microwaves however do cause heat. While on the actual topic, but off this thread topic: I initially stated a while back that I believed Mobile phone usage could be proven to effect the overall weather, possibly global warming and causing things like the polar icecaps to retreat or the thawing of the Arctic Permafrost. I am pretty certain now by what I've learnt over the passed couple of days that my initial theory is accurate. It would require looking at the history of radiology and the increase in the number of antenna's and frequencies used. Initially early on the amount of "heat" wouldn't of upset the weather systems too greatly and the weather systems would have "normalised" by adapting to any temperature change. However in the last 20-25 years, mobile phones, antenna arrays, wireless networking and changes in our televisions has caused the effect that causes heat to increase. This means a change in the average temperature in degree's, which previously has just been pinned on Carbon Emissions (Obviously carbon's a concern in regards to Carbon Dioxide, it's what absorbs the radiology to generate the heat.) It however isn't just the planet at risk. While mobile phones might well not cause you cancer through the radiology (since it's posed that ionizing radiation would be require); they can potentially cause internal cavity pressure changes through "heat" in the ear or even potential the ventricles which in turn can cause various psychiatric issues they can also cause various dry skin conditions because the blood absorbs the heat and the heat attempts to escape through the skin causing the skin surface to cook (Don't get me wrong, it doesn't necessarily mean you completely fry, but it's enough to cause trauma to your skin), this in turn will likely cause an increase in respiratory conditions because all those flaky dead skin cells will be breathed in. In essence I really don't like mobile phones at all now lol
"Discussion" involves more than requests for basic facts. Perhaps you could add some context to your query, or describe what you already understand, or what you've heard but don't understand. Discussion is good!
Why do you care how I chose to discuss things? Perhaps we have different definitions of "discussion". But this is how I do it.
years ago I worked in RadCon in the Navy. There was this question on a test one time that I thought was interesting: You have an alpha emitter, a beta emitter, a gamma source and a neutron source. You have to hold one in your hand, you have to put one in your pocket you have to eat one and one you can throw one away. Which actions should go with which radiation source? I put the options in order of what you should do with the various sources.
Radiation includes such things as gravitational radiation and radio waves. Ionizing Radiation is the "dangerous" stuff that causes chemical changes, and typically includes UV, X-rays, and Gamma rays, but also such non-electromagnetic emissions from decaying nuclei such as alpha and beta rays. Some isotope decays produce neutrons. Neutrons are considered ionizing radiation because they can hit a nucleus so hard it dislodges the bound electrons, or transfer most of their momentum to a hydrogen atom's nucleus and cause proton radiation. Neutrons can also "activate" other materials turning them into radioactive isotopes. For more information about other types of radioactive decay, the Wikipedia page has a table. For more information about ionizing radiation including definition of the term "sievert", I recommend the wikipedia page as it seems much clearer than the pop science references of my youth. It turns out that there is a form of ionizing radiation not listed that you can't get away from: Muons. Muons come from cosmic ray collisions high in the atmosphere and reach sea level and into our homes. Humans have some capacity to absorb small doses ionizing radiation with a good chance of shrugging off the damage without immediate health effects. I for one used to live in Denver, which gets more cosmic-ray-generated neutrons than at sea level. -- I think you throw away the neutron source (activation fears), put the alpha source in your pocket (low penetrating power), eat the gamma source (lower the path length of exposure) and hold the beta source in your hand. Unless the beta source is a banana. http://en.wikipedia.org/wiki/Banana_equivalent_dose 1 BED = 0.1 μSv
A very minor correction, but Rad has nothing to do with the angular measure radian, but is rather the acronym "radiation accumulated dose" iirc.
How did they calculate that? The cited articles go from curies to sieverts, without explaining the details.
Any ingested potassium (from bananas or elsewhere) doesn't increase your body's potassium load for long, because the kidneys are great at maintaining a steady plasma concentration. And most of the potassium's time in your body is spent in your gut or your bladder, where most of the beta radiation will be absorbed by gut contents and urine, rather than tissue. But even assuming that the banana hangs around for 8 hours or so, and that all its radiation is absorbed in your tissues, that still seems to only deliver a nanosievert to a 70kg person.
Reference 1 for the Wikipedia article is equally unilluminating. 0.37 nCi is the decay rate = 14 Bq Potassium-40 Decays: 89.28% 1.31109 MeV betas 10.72% 1.5049 MeV gammas Potassium-40 means \(2.1339 \times 10^{-13}\) Joules/decay or for 14 Bq, \(2.9874 \times 10^{-12}\) Joules/sec .. say 3 pW http://en.wikipedia.org/wiki/File:Potassium-40-decay-scheme.svg For gammas, and beta particles 0.1 μSv = 0.1 μGy Connecting the two is a mass which absorbs the dose, m, and a time of exposure, t. t/m = 0.1 μGy/ 3 pW = 33,000 s/kg Say m = 70 kg, then t = 27 days, which seems like an unlikely lifetime for a banana in a human digestive tract. BUT, further research indicates that this is on the order of the biological average lifetime for potassium in the body. http://www.ncbi.nlm.nih.gov/pubmed/1181976
Sure, but the potassium in a banana is no more radioactive than the potassium in your cells, so the time that matters isn't the time that a particular potassium ion stays around, but rather the time that your body's total potassium is raised after a high potassium meal.
Well, I can't find a better reference for that. Assuming m = 70 kg, the lowest value of t that makes sense for the claim 1 BED = 0.1 μSv is about half an order of magnitude below the above value or about 8.5 days. http://www.google.com/search?q=what is 70 kg * sqrt(10) * 1e-8 Gy / 3e-12 Watts Normally, we are constantly ingesting and excreting potassium. A potassium-starved human would be expected to excrete potassium at a lower rate. And by some published standards, the US and German populations are on the average potassium-starved. But there is simply not enough information on common websites to justify any average lifetime in the body longer than about 3 days. Nor is there a source which justifies a much smaller average body mass absorbing the radiation dose. Still, the rough comparison indicates 0.1 μSv is a negligible extra dosage to take on, by a few orders of magnitude.
My rough calcs (8hrs, 11Bq, all absorbed by 70kg tissue) worked out to around 1 nSv. Two orders of magnitude is a lot in the contexts that BED is used. For example, if you were comparing 1mSv/yr (a common public dose limit for exposure around nuclear plants and uranium mines, according to Wiki) to bananas, then: 10000 bananas in a year (25 a day) is a lot of bananas, but is still within the bounds of reason. It doesn't feel like a lot of radiation, but... 1 million bananas a day (2500 a day) is obviously a different story, right?
