High Radiation Levels Recorded At Japanese Plant

The problems at the nuclear power plant in Fukushima, Japan, are growing more ominous. There was a third explosion and a fire. High levels of radiation have been detected.

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RENEE MONTAGNE, host:

As we've just heard, the problems at the nuclear power plant in Fukushima, Japan are growing more ominous. There was a third explosion and a fire. And there are more reports of high radiation levels.

NPR's Jon Hamilton joins us now to help sort out what's going on there.

Good morning.

JON HAMILTON: Good morning.

MONTAGNE: First, where was this latest explosion? And also while you're at it, please, give us a sense of the geography of the plant.

HAMILTON: Okay. All this is happening at a power plant that's called Fukushima Daiichi, or Fukushima One. It's in Fukushima Prefecture, which is about 150 miles north of Tokyo. And by the way, that's pretty close to the epicenter of the earthquake. It's also a place that got hit very hard by the tsunami.

In fact, the power plant there, as I understand it, is one of the few things that's still standing. So Fukushima Daiichi is a power plant. It has six different nuclear reactors as part of this plant. Three of them were operating when the earthquake hit, and all three of those have been overheating because of problems with their cooling systems.

They need to keep water circulating through the core or it will overheat, and the systems that do that, it seems, have been failing. And I should say, that's still true, even though the nuclear reaction was stopped five days ago.

MONTAGNE: And what about that fire?

HAMILTON: So the fire there had already been, you know, some explosions. The fire was in reactor number four. And that's actually kind of strange, because this is one of the reactors that was not even operating when the earthquake hit. It was actually down for maintenance, which means there wasn't any nuclear reaction that was going on. And the core actually should have been cold. But what officials are saying is that the trouble seems to have come from something known as the cooling pond. And that's actually this sort of tank where you put nuclear fuel after its been spent and it can't power the reactor anymore.

So you put it in there and this fuel is still radioactive, it's still hot. And it can stay hot for years, so it needs to be kept underwater. And it appears what happens is the water in the cooling pond may have dropped or boiled away and this allowed the nuclear fuel to heat up and it heated up enough to cause a fire.

MONTAGNE: And just, I mean briefly, people keep worrying a meltdown. Where are we at at this moment in time?

HAMILTON: Well, so far we've gotten really different information about whether there has about the degree of meltdown. People talk a lot about this partial meltdown phenomenon. And that's been true in both reactors one and three. It's a little less clear with number two. But what they think has happened is that the fuel rods got hot enough that they were actually damaged by the heat. They're encased in this zirconium alloy metal, and if it gets hot enough, that will actually start to interact with steam and produce hydrogen. If it gets hotter than that, it will actually start to melt, and that can release these fuel pellets that are inside. It can let them sort of drop out and you can end up with this kind of radioactive molten puddle at the bottom of your reactor.

The thing is, we don't how much meltdown has occurred.

MONTAGNE: What about radiation? What has has been released? How bad it is? Where is it going?

HAMILTON: Again, the information is all over the place. And I think to this point it's safe to say that most of the radiation releases have not been enough to cause any health problems. However, there has been one reading that is troubling. They talked about seeing 400 millisieverts per hour in one reading. And that's enough radiation to cause radiation sickness in just a few hours. So that's pretty worrisome. However, really it's worrisome for people who work at the plant. We're not talking about something where the general public would be endangered by that.

MONTAGNE: Still and all, it all sounds quite bad. Scary even. Could this this has come up for the last several days. Could this be at any point possibly another Chernobyl?

HAMILTON: You know, I spent a lot of yesterday asking a bunch of experts exactly that question, and what they said to me was essentially no. And there's some important reasons for that. You know, for one thing, the explosion in Chernobyl occurred when that nuclear reactor was going full out. It was actually out of control. And that heat caused a massive explosion that put huge amounts of radioactive material into the atmosphere.

In Fukushima, you know, it's possible that the cores could melt, but and in a worst case they might even melt through the containment structure and into the ground but we're not talking about a huge explosion that would put stuff into the air.

MONTAGNE: So not a Chernobyl. It will end up being a Fukushima. Whatever that will end up being.

HAMILTON: Not good but not as bad as Chernobyl.

MONTAGNE: Jon, thanks very much.

HAMILTON: You're welcome.

MONTAGNE: NPR's science correspondent Jon Hamilton.

Japan's troubles are having an impact elsewhere. German leader Angela Merkel today announced that Germany's seven oldest nuclear power plants would be provisionally shut down.

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