Hot Particles and Measurement of Radioactivity From Fukushima Daiichi

Hot Particles and Measurement of Radioactivity from Fairewinds Energy Education on Vimeo.

Fairewinds' Chief Engineer Arnie Gundersen and Boston Chemical Data Corporation’s Founder Marco Kaltofen have an in-depth conversation regarding the challenges of measuring radiation exposures to people around the globe. Kaltofen explains the scientific methodology involved in accurately analyzing and measuring radioactive releases from Fukushima Daiichi, including the impact of hot particles on human physiology.

Associated Material

Laboratory Test Results: Tokyo Soil Samples

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Arnie Gundersen: Hi, I am Arnie Gundersen from Fairewinds. This is the first video on the new Fairewinds site. We worked really hard to make it user friendly and searchable and we hope you like it. If you have any questions, please send us a comment.

You recall Marco Kaltofen. He presented at the American Public Health Association a couple of months ago and we heard his presentation. Today, I had a longer conversation with Mr. Kaltofen. Mr. Kaltofen runs the Boston Chemical Data Corporation and he is a professional engineer. He talks about radiation in the environment and especially radiation from the Fukushima accident. I hope you enjoy the conversation between Mr. Kaltofen and me.

(Begin Discussion Between Arnie and Marco Kaltofen)

Marco Kaltofen: Yes, but the one on the right is the fascinating one.

Arnie Gundersen: And these are the isotopes that I picked up in the soil in Tokyo.

Marco Kaltofen: Oh yes, exactly the same.

Arnie Gundersen: So the isotopes you are finding in indoor air filters are the exactly what I am picking up in the soil.

Marco Kaltofen: That is why those soil samples you sent, are completely non-controversial, because what is in them is exactly the same as what is in every other sample we have gotten from the same area. So the 100+ samples, every one of them has cesium 134, 137, some low, some not so low.

Arnie Gundersen: But we had cobalt too, and this has got cobalt . . .

Marco Kaltofen: Yes, cobalt 60, another common thing that we see. When we did the air filters from the car engines, a few things that were interesting about it, a lot of these are from commercial or fleet vehicles, so we actually have a log about where they were driven, when they were used. The car filters, the way people drive in Japan, the number of miles that people do, the size of these vehicles, stoichiometrically, a car engine filter processes about as much, air in a day, as a hard working adult would process. So 10-30 cubic meters of air a day for a filter or for a person. So it is a nice qualitative model. So what you are seeing in some of these filters is what you would expect to see for a person exposed to the same air.

So the idea of using the car filters was to take a large number of car filters and try and get a feel for whether or not we were getting radioactively hot particles outside the evacuation zone. This is one of about 4 different methods that we have used for looking at air and dust in Japan and the US and Canada. And this method was meant to give us that kind of a birds-eye view about what is happening. And what you immediately see when you look at this is Fukushima City, Tokyo, Seattle.

I like this graphic because it is a fast easy way to show, look, Fukushima, City, even though you are 65 kilometers away, we pick up an enormous number of hot particles in these engineer filters. In Tokyo, we are still getting those hot particles. We are not at the levels where people are evacuating, but we are at the levels where people need to think about how they are going to reduce dust exposure overall. That is just a good public health practice. And then in Seattle, I call this my stop whining graphic because really there is not much happening in Seattle. West Coast of the United States, lower the stress level, we are fortunately not seeing it there. If anybody is going to see radioactive transport outside of Japan, I would think at this point, we are going to see it in the marine environment, not in the air. We are going to see a lot more of it coming through the ocean, maybe through food coming from the ocean than we are going to see it in these airborne particles.

This sample for Seattle was collected during the time of maximum exposure which was mid-April. That is when we had the highest rise, almost doubling, of background levels that lasted for about 2 weeks in the middle of April.

The human lung is very good at picking up certain size dust particles. The range of dust particles that the lung is good at retaining is from about .5 to 5 microns and if you are not familiar with that unit, it is really a millionth of a meter or or a thousandth of a millimeter. These are microscopic sizes. Things that are bigger never make it down into the deep lung. Things that are smaller tend to come in and then they get exhaled out again without sticking. So the particles that are in that size range are the important ones.

That is what my research project is about: How many of the dust particles are in the size range that is actually important to human lung exposure. If they are too big or too small, they are less of a problem for human health. But I need to know, not the type of radiation so much, but I need to know how big the dust particles are that carry and what they are made out of. When you know how big the dust particle is and what it is made out of, you can learn a lot about where it is going to end up in the environment and how people will be exposed. So all that stuff about you are exposed to radiation in an airplane from cosmic rays or from eating bananas, or whatever, it is just nonsense when you are thinking about trying to measure radiation exposure that is important for human health. That is a completely different ball game. And that is what the dust research is all about.

We have our filter that is placed up on this X-ray plate. So because we can see the dark spotting from the radioactive particle, we can actually cut this piece out of the filter and it goes on a little piece of, it is essentially expensive double stick tape. It is this high carbon double stick tape that we use that goes straight into the scanning electron microscope. And you can actually look at the microscopic particle. You can take its picture and we hit it with an x-ray beam and that will tell us the composition of that particle. So if there is uranium in it or if there is americium or cesium, we will see that. Now you cannot tell the difference between radioactive cesium and non-radioactive cesium. But there is no non-radioactive form of americium. So those compounds we can be certain.

Kids were tracking in radioactive material on their shoes from being in contact with the outdoor soil. This is also being done with gamma spectrometry. The nice thing about children's shoes is children obviously get outdoors and they play in the dirt more than adults. Children's shoes are smaller, they fit in my detector belt. So we get better results working with kid's shoes. Gives us an idea of what we are looking at. We have never detected radioactive material from Fukushima in children's shoes in the United States. None of the samples were positive. All of our shoes from Japan show that there is cesium 134 and cesium 137 present.

Arnie Gundersen: So this is total in both of them.

Marco Kaltofen: That is the 2 combined.

Arnie Gundersen: When I was in that park in Tokyo and I took the sample by the tree, that was decontaminated, and still we had high cesium, both cesiums. And kids were running by throwing stones at each other, like kids always do. So I am thinking, grab the stone on the ground, they threw it, and here I am measuring the ground, so if it is on their shoes, it is on their hands. It is sad.

Marco Kaltofen: Well, it was on the shoelaces, for instance. We found that the radiation was also on the shoelaces. And when we do this X-ray autoradiograph, we actually take the shoe and put it on a piece of x-ray film, you can see the spotting from the radioactive particles stuck to the soles of the shoes.

One of the things you get from looking at the individual particles, the individual hot radioactive particles, is you can tell the difference between radioactivity that comes from a natural source or from an industrial source. You can tell the difference between a particle that comes from Chernobyl or one that comes from Fukushima. They look different, they have different chemical compositions. In the example of Fukushima and Chernobyl, Chernobyl particles have cesium 137. Fukushima particles have cesium 137 and cesium 134. So it is a signature, it is a fingerprint for the radiation coming out of Fukushima.

So if you find a particle that has about the same amount of cesium 134 and 137 and it is less than say, 20 microns or so and you found it on the west coast of the United States, that is telling you that you found a particle of radioactivity from Fukushima.

Arnie Gundersen: But if there is no more 134, it is from bomb-testing or from Chernobyl.

Marco Kaltofen: It could be bomb-testing, it could be Chernobyl, it could be old radioactive wastes, it could be from a research reactor, but it would not be from Fukushima. So one of the things that we will be able to do is tell you whether the radioactivity we are detecting is natural or not. We get that all the time with folks who use the geiger counter to test something in their back yard or something that rained out, now that people are a little bit more aware of radiation in the environment. The nice thing is to be able to say, well, while it is radioactive, it has nothing to do with Fukushima.

Maggie Gundersen: I have a question. Last night we were at a panel discussion in Massachusetts and one of the panelists who is a nuclear engineer for the industry said that it is all radiation. Radiation is natural in the background, there is nothing to be worried about. We do not have to worry about any radiation. Things that are coming off of Pilgrim as the nuclear plant do not matter, because radiation is ubiquitous and it is part of our natural background. Can you differentiate that for the viewers?

Marco Kaltofen: Sure, and I think that is an interesting attitude, because we will go back to the radon issue. We have got . . . The US Environmental Protection Agency has made a major push to try and get people to test for, and where necessary, reduce their exposure to radon because it is a significant health hazard. It is part of the radiation background. Background is not the same thing as safe. It is a public health problem that has been accepted, there is a government protocol for doing the testing and there are some simple remedial steps that you can take and they do not break the bank. So I do not know why one agency of the government would say, the agency that this is most concerned with environmental health, why are they saying this is a serious health problem that we need to work on, and someone else says, well, it is background and it's OK. Background is not OK. We all have natural ailments, things that harm our bodies. I don't care if they are natural. We would rather stay healthy. So I am a little confused about that one.

Arnie Gundersen: The one that gets me and it came up in the meeting last night was the radioactive banana. You know we all have potassium and our body is in equilibrium with that potassium. Some of it is radioactive, some of it is not radioactive. So if you take potassium in, you are going to excrete potassium out because you are already in equilibrium with that potassium. And I cannot understand how we can compare the dose of a banana to flying on a plane or working at Fukushima.

Marco Kaltofen: What it comes down to is radiation comes in different flavors. Some radiation does less damage than others. We have what is called a quality factor for radiation, where we say flat out, the amount of health damage that you do, is related to the form of the radiation. So that this type of radiation might be 20 times more hazardous than that type of radiation. That is something that is happening with the banana. All radiation is not alike and to imply that it is, is probably oversimplifying, oversimplifying to the point where people fail to take steps they could to improve their health.

Arnie Gundersen: But the quality factor . . . an internal alpha is worse than an external alpha, neutrons are worse than all, and things like that. But that is for a ray or a burst of energy, most of that research. But the hot particle issue where you are imbibing it, it is either coming in through your mouth or coming in through your lung, that quality factor, it has got to be greater than an external exposure from a gamma ray for instance.

Marco Kaltofen: You know the best argument that I hear from folks when they talk about the difference between rays and hot particles, goes something like this: It is complicated. And that is exactly right. It is very hard to measure exactly what the health damage will be from a hot particle compared to an energy ray, like a photon from a gamma ray or an X-ray. It is not saying that the hot particle is worse or better. But remember that the hot particle can be trapped in your body for a long time. The ray passes through you at light speed. It comes, it does its damage, it is gone. The hot particle, on the other hand, can stay in your body and continuously expose different cells in your body to radiation. So there is a qualitative difference in what happens because of the hot particle.

Some researchers have said hot particles are actually better for you. Here is the reason. If you have a hot particle inside your body, there are parts of your body that are not exposed to that hot particle. That hot particle that is in your lung is not exposing your foot because it is shielded by the distance and by the intervening tissues. Which I think is a terrible use of tissue, by the way, to use it as a radiation shield. But nevertheless, I understand. What they mean is, it depends on where in your body that hot particle winds up.

Does it dissolve in your body once you inhale it and then pass into the bloodstream to other parts of your tissues?

Does this stay stuck in the lung where it might cause, well in the case of plutonium oxide, a hot plutonium oxide particle would cause a fibrotic nodule in the lung. It would actually damage some of the surrounding lung tissue. Some of that tissue might even be killed, those cells will actually die, but the surviving cells potentially are tumor-genic sites, cancer causing cells. These are all complicated processes that do not happen with rays.

Arnie Gundersen: Now you had a picture of the plutonium oxide particle in the lung, right?

Marco Kaltofen: So this is from an older health journal and what you see here is, this particle is about a 100 micron size plutonium oxide particle and you can see that there is a fibrotic nodule, if you are a pathologist or histologist, in the healthy animal lung tissue that is actually closest to the particle. So it has done some physical damage to the cells that are closest to it where they have been directly exposed to alpha radiation.

Arnie Gundersen: So this white stuff is what a normal lung would look like.

Marco Kaltofen: So we have got the normal healthy cells and we have got the fibrotic nodule that has formed because of the hot particle here. And again, that is about 100 microns across. Make it a little bit more. This is half a millimeter, 500 microns. Most of the hot particles we have been looking at are a lot smaller than that. For them to travel a significant distance, they really have to be more on the order of 10 microns, not a 100. At that size they can go global distances.

Arnie Gundersen: What we saw in Seattle in April was some really small, a couple of microns kind of particle.

Marco Kaltofen: We are seeing very small particles that are coming here to the US. As opposed to larger particles that would have been deposited immediately around the plant. It is probably why they saw so much plutonium right around the plant, because a lot of those big particles dropped off closer.

Arnie Gundersen: They picked it up as far as 50 kilometers away so there must have been a lot in really close.

Marco Kaltofen: I have not seen the data, but I would just assume that on average, the particles that are found further away tend to be smaller.

Arnie Gundersen: Right.