Sorting Out the Alphas, Betas and Gammas of Radiation
IRA FLATOW, host:
This is SCIENCE FRIDAY. I'm Ira Flatow.
Detectors have picked up faint traces of radioactivity in rainwater falling in the U.S., a result of the ongoing nuclear crisis in Japan. We're talking very faint traces. Experts say that people in the U.S. have nothing to be concerned about. The fact that these signs of radioactive materials are being picked up is more a testament to the sensitivity of our detectors.
But when people talk about radioactive rain or radioactive milk or spinach or whatever, what are we actually talking about? What's in those consumables that we call them radioactive? What's the difference between radioactive and radiation? A cloud of radiation, what's that?
Well, this hour, first up, we're going to talk about some of the explanations of nuclear lingo and terms. Just what do all these things mean - alpha, beta, gamma, neutrons, things like that - what are we talking about? It's been in the news so much, we thought we'd stop and catch our breath and see what these terms actually mean.
If you'd like to talk about that, our number is 1-800-989-8255. You can also tweet us @scifri, @-S-C-I-F-R-I, or ask your question on Facebook @/scifri.
Let me introduce my guest. Steve Sugarman is a certified health physicist and is health physics project manager for the Radiation Emergency Assistance Center Training Site. That's a DOE project managed by the Oak Ridge Associated Universities in Oak Ridge, Tennessee. Welcome to SCIENCE FRIDAY.
Mr. STEVE SUGARMAN (Radiation Emergency Assistance Center): Hey, thank you very much. How are you today?
FLATOW: Fine, thank you. Do you find the public is just, you know, doesn't understand all these different terminology items and things in there and...
Mr. SUGARMAN: Well, you know, there sure is a lot of terminology to wrap your hand around, that's for sure, and there's been a little bit of confusion about what different words mean, that type of thing. So I think this is a great opportunity to maybe learn and expand our vocabulary a little bit.
FLATOW: All right. Let's start with item number one: the difference between radioactive and radiation.
Mr. SUGARMAN: Well, that's a very, you know, common misconception, really, when people think about that. And really what we're talking about is the difference between being contaminated and being exposed. And when you're contaminated with a material, what that really means is that you have the material physically on you. And being exposed to it simply means you're in the presence of a radioactive material.
So if you can imagine holding a sweetener packet, for instance, and that sweetener is radioactive, I can hold the outside of that packet and not get any of the material on my hands. So I'm simply being exposed. But when I open that packet and I get some on my hands, or I put it in my coffee and swallow it, I'm now contaminated. So that's the real difference between those two words.
FLATOW: So there are actual particles of radioactive material on you when you get contaminated?
Mr. SUGARMAN: What you have is actually the material itself. And the radioactive material emits various types of radiation: alpha particles, beta particles or gamma rays, for instance. But you're not contaminated with the alpha particle. You're contaminated with the material that emits the alpha particle.
FLATOW: Okay, and what different kinds of materials are there being emitted from the reactor?
Mr. SUGARMAN: Well, with regards to nuclear reactors, there can be various things that occur, materials that emit alpha particles, beta particles and gamma rays. All three are found in reactors.
FLATOW: And are they all equally as threatening to us, or are some more threatening than others?
Mr. SUGARMAN: Well, I would not use the word threatening as far as how radioactive materials go. Different emissions do have different biological effects associated with them. And basically what that comes down to is how efficient they are at creating ionization, which is simply the removing of an electron.
And if you sort of think about it in terms of magnetism - and this isn't, this is obviously not a magnet - but if you can imagine if you had a lot of south-poled BBs on the desk in front of you and a big north-poled magnet, as you got fairly close there would be some interaction.
And that would be something like what an alpha particle is. It's fairly big, fairly strong charge. Or we can have a beta particle, which would be a much smaller, weaker magnet. Therefore you would have to be much closer for it to interact. And common sense sort of dictates that that would not be as efficient at interacting.
FLATOW: And let's say you had all three close to your skin or on your skin, these particles. How would they affect your skin or penetration of your body differently?
Mr. SUGARMAN: Well, alpha particles, as a general rule, don't penetrate the outer layer of skin. So if I'm holding an alpha-emitting source in my hand, I'm not terribly concerned with that because the outer layer of skin is already dead. It's not, you know, going to get any worse. So I don't worry about that.
Beta particles will penetrate a millimeter or so into tissue, which is getting past that dead layer of skin. So if I hold a beta-emitting source in my hand, I do have to have some concern about that living, you know, tissue underneath.
And gamma rays act a lot like when you go to the hospital and get a chest X-ray. Much of what comes in the front side goes out the back. Obviously in the hospital you have to get to the film. So gamma rays are very penetrating and many of them go straight through without interacting.
FLATOW: Now, we've heard different kinds of radionuclides involved in nuclear reactors. We've heard of uranium, plutonium, cesium, iodine. Can you walk us through what those are?
Mr. SUGARMAN: Well, all of these are various radioactive materials that are generated in a nuclear power plant. Cesium, iodine, these types of isotopes are what we call fission products. And they simply occur when the uranium atom is split. It's just what the fission is, is the splitting of the atom, and when that splits, two other atoms are created.
And cesium-137, for instance, is one of those things that's created, as is iodine. And there are hundreds of others. So there are many other things. And there are some that we have more of a - I don't want to use the concern the word concern - but I'll use that - they're on our radar a little bit more because they're more predominately produced.
FLATOW: We've heard people talk about radioactive plumes and radiation clouds. Do they mean really anything, or is the correct technology there - correct terminology there?
Mr. SUGARMAN: Well, for me, I prefer not to use the word radioactive, you know, a leak of radiation or radiation plume or anything like that. Really, all that is, is this radioactive material that has been released, and you can - radioactive materials can be released, you know, in a variety of things. But that's really all it is, is the material itself that is now airborne.
FLATOW: Let's see if we can get a call or two in here. Peter in Palisade, hi, welcome to SCIENCE FRIDAY.
PETER (Caller): Hi, thanks for taking my call. I was wondering about how radiation behaves in the atmosphere and if it has mass. Does it want to fall to the ground? And will it gravitate toward other masses in the air, like streams of smog and those kinds of things? How does it tend to behave? Does it concentrate along certain lines?
FLATOW: See, now, Peter, you're using the word radiation.
PETER: Oh, I'm sorry.
(Soundbite of laughter)
FLATOW: See, now, that's exactly what I'm talking about. How does radiation flow in the atmosphere? And that's exactly what we're talking about, Steven, aren't we, different terminologies?
Mr. SUGARMAN: Yeah, it is. It's some different terminologies. And I think that if folks would really understand what the radioactive materials are - they're really no different than any other materials. It just so happens that that particular atom gives off some energy, such as radiation.
So the way things act, whether they're up in the air or wherever they may be, is really just like they would act if they weren't radioactive.
So take, for instance, calcium. Calcium would act, if it were put up in the air in a certain way, and if it were a radioactive isotope of calcium, it would act the same way, because it's calcium.
FLATOW: Well, that's until you ingest it.
Mr. SUGARMAN: Well, even then, even if it's ingested or taken into the body, it's a chemical issue, and the body processes calcium, whether it's radioactive or not, the same way.
FLATOW: But it's not going to - it may pose a greater threat if it's radioactive than if it's not radioactive. Aren't they telling people not to drink milk that had radiation or radioactive particles on the grass the cows ate?
Mr. SUGARMAN: Well, I think that there are some public health issues and some public health advisories that the government is providing, and I don't have all the information about how those came about and all the numbers right in front of me. So I'd really rather not, you know, speak too much about what the public health advisories are.
But I will say that when something is taken into the body biokinetically, or metabolically, it acts the same. And it does stand to reason that if you take a substance that's radioactive into the body, that there are issues that would have to be addressed, and there may be ways to rid the body of these materials and this type thing.
But I think the key thing to think about is that it behaves chemically in the body the same as its non-radioactive counterpart, and therefore physicians can address it in such a way.
FLATOW: Is there a good website to learn about all the differences between them?
Mr. SUGARMAN: There are some really nice websites out there that do that. Our website, for instance, ORISE.ORAU.gov/reacts, we have some frequently asked questions that are on there that address the various drugs that could be used to treat internalizations. The Food and Drug Administration has a nice website, really nice one, that deals with potassium iodide. The CDC has some other nice websites as well.
But our website links to all of those other places. So you can go there, look at the frequently asked questions, and maybe learn a little bit and link to some other places.
FLATOW: Yeah, I also found the Center for Biosecurity has an interesting definition site of all these different terminologies that people use. And you know, in the old days we used to call stuff, radioactive particles that fell out of the sky, fallout. Why do we not use that term anymore?
Mr. SUGARMAN: Well, to be honest with you, I don't know why that term's not used anymore. Really, all they were talking about when they talked about fallout was the particles were put up in the sky, the materials put up in the air, and it fell back down. And so they just said, well, it fell out of the air and that's where the word basically came from.
FLATOW: Maybe because it was so closely associated with atomic bombs and things.
Mr. SUGARMAN: Well, there is that association that's there. That's very true. And I think that sometimes if you can avoid those negative associations, sometimes that it would really help with the, you know, the public's understanding of radiation, and probably affects the acceptance of that sometimes as well.
FLATOW: One quick question: Does material exposed to radiation become radioactive?
Mr. SUGARMAN: As a general rule, the answer to that is no. Alpha particles, beta particles and gamma rays do not make other things radioactive.
There is a process called neutron activation. And what happens in neutron activation is the nucleus of a non-radioactive atom absorbs a neutron and is made to be radioactive.
FLATOW: All right, we're going to have to stop it right there, Steve. Thank you very much for being with us.
Mr. SUGARMAN: Yes, sir, thank you.
FLATOW: Steve Sugarman is a certified health physicist. We're going to take a break, and when we come back, switching gears and talk about global warming. So stay with us. Right after this break. I'm Ira Flatow. This is SCIENCE FRIDAY from NPR.
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