CNN's John King interviews Arnie Gundersen about the Hot Particles discovered in Japan and the US.

CNN's John King and Arnie Gundersen discuss "hot particles" detected in Seattle and Japan, the cozy relationship between Japanese regulator NISA (Nuclear and Industrial Safety Agency) and plant owner TEPCO, and changes at the Fukushima accident site since March. John King and Arnie Gundersen also discuss how TEPCO's acknowledgement today of another error in calculating radiation dose more than doubles the amount of radioactivity to which people in the Northern Hemisphere have been exposed.


KING: And Arnie Gundersen is with us now live.

Arnie, you were with us very early and throughout this crisis. And you long argued it was worse than they were telling us. What do you make of this news now? How could they have not known?


You know, they're saying now, these are all calculations. All of the instruments were blown to smithereens. So, they're calculating what these exposures were.

How could they not know?

I think there's some confusion and there's some cultural issues, too, with the Japanese. But the biggest problem is this combination of being a regulator and a promoter of nuclear power. There's a revolving chair situation in the Japanese structure where executives go to work for the regulator and the regulator goes to work for Tokyo Electric. And that makes it hard to really see how serious the accident is while you're in it.

KING: And as we try to judge the fallout, not only in Japan, we'll see what the government report says, but we've talked about some radiation, relatively low amounts, very low amounts, make its way across the Pacific. You've seen evidence of what's called hot particles showing up on the U.S. West Coast, in Seattle, for example.

What are we talking about? And how worried should people be?

GUNDERSEN: Well, the radiation initially comes out as a big cloud of gases. And that's what you can measure with a Geiger counter. But now what we're finding are these things called "hot particles," and in the industry we call them "fuel fleas" because they're incredibly small. They're smaller than the thickness of your hair.

In Tokyo, in April, measurements indicate that there's about 10 hot particles per day in what a normal person would breathe. And it's interesting, because in Seattle, it didn't go down that much. It was about five hot particles a day. Because most of the time, as we talked about back in April, the wind was blowing toward the West Coast. Now, that's why we were warning to wash your lettuce and things like that.

Now, what that means is that it's -- these hot particles can lodge in your lung or in your digestive tract or your bone, and over time cause a cancer. But they're way too small to be picked up on a large radiation detector.

KING: And so, do you believe there are enough of them that people in the West Coast of the United States need to be worried? Or is it a very minor concern?

GUNDERSEN: Well, the average person breathes in about 10 cubic meters a day. And the filters out there for April show that they were breathing in -- per day, about five particles. Now, these are charged, which is why we call them fuel fleas, too, and they latch on to lung tissue.

You know, I'm still advising my friends to wash all of your vegetables to make sure you can get it off. But short of that, we're at a point now where you just can't run from the particles that are still in the air.

KING: We'll keep watching that. I want to show our viewers some satellite images that we have now, satellite images of the Fukushima nuclear plant on March 14th compared to May 25th.

When you look at this, three months since, do you get the sense -- looking at the new photos -- number one, first and foremost, do things appear to be under control right now?

GUNDERSEN: No. The units are still leaking.

The difference in the picture, though, it was cold in March so you could see steam, sort of like breathing on a cold day. Now, it's hot, so you don't see the steam coming out of the plant. But there's still emitting radioactive gases, and an enormous amount of radioactive liquid.

So, the only thing that's going to make this go away is time. They're going to need another year or so before this radioactive material cools down to the point where it doesn't boil anymore. And until it stops boiling, you're going to be cranking out steam and you're going to be cranking out radioactive liquids.

KING: And if you look closely at the newer photo, you see what appears to be blue, I would call it spray paint, a blue covering of some sort. What's that?

GUNDERSEN: They started a program where they sprayed down a resin on the site to keep down these hot particles we were talking about. After the explosions, there's a lot of radiation on the soil. And you'll recall that guys are all in these white suits with the respirators on.

That blue stuff is a resin and it's designed to keep the dust down, because if the dust comes up, it will make even more hot particles, which is really difficult to work in.

KING: And we have some video -- this is from TEPCO, the Tokyo Electric Power Company and it is of unit one. And I want to show this video and I want to ask you, Arnie Gundersen, when you look at this video -- as someone who understands the design, the engineering in here -- what are you seeing?

GUNDERSEN: It frightened me. What it's showing is that the nuclear reactor core has melted, and it's somewhere down below the floor. And you can just see boiling water and boiling steam coming out of that hole in the floor. It's the closest yet they've come to approaching that radioactive core. So, that was the first thing.

The second thing is that the robot -- these were taken with a robot -- measured a dose in that room of 400 rem per hour. We call that LD 50/50. And what that means is that it's a 50 percent chance you'll get a lethal exposure in one hour.

KING: So, if somebody was in that room for an hour or more, they're likely dead or seriously --

GUNDERSEN: Yes. If they're in that room for an hour, it's a quick death. It's not 10 years out. It's a 50/50 chance you'll die within a week.

KING: And so, let's take everything we've talked about in this conversation over the last several minutes, and take us back to the beginning, when we had conversations and you were critical about the size of the expansion zone, how far out people were when they were evacuated. Is it -- do you have proof now to say they should have done this and what is "this"?

GUNDERSEN: Well, there's a lot of proof coming in, largely because of the Internet. We're not getting it from the Japanese government or from the U.S. government. But we're finding in trenches along the sides of roads, roadside ditches -- exposures on the order of 200 times normal. They found plutonium off site about a mile away from the gate.

So, this accident is severe. And the cost of cleaning it up is going to be astronomical. I'm betting that it's going to exceed $200 billion with a B dollars.

KING: Remarkable.

Arnie Gundersen, we appreciate you coming back to share your insights tonight. And we'll continue to track this story in the months ahead. It's important not only for the people of Japan but for nuclear industry here in the United States and around the world.

Mr. Gundersen, thanks again you for your help and your insights.