Lethal Levels of Radiation at Fukushima: What Are the Implications?

Fairewinds Energy - Lethal levels of radiation at Fukushima Daiichi


About This Video

TEPCO has discovered locations on the Fukushima plant site with lethal levels of external gamma radiation. Fairewinds takes a close look at how this radiation might have been deposited and how similar radioactive material would have been released offsite.

Video Transcript

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Arnie Gundersen: Hi, I'm Arnie Gundersen from Fairewinds and it is Thursday, August 4th.

Two days ago, Tokyo Electric announced some really high radiation levels on the Fukushima site and I wanted to put that into perspective and let you know what I think is happening.

First, Tokyo Electric discovered very, very high radiation in a stack which is used to vent radiation out of the plant and up into the air. The quantity of that radiation was really, really high exposure. It was 10 Sieverts and to convert that over to rems, which I am used to, is a thousand rem. Now, what does that mean?

A thousand rem or more, because the instrument went off scale, a thousand rems, if you were there for less than half an hour, would mean death within a couple of days. Those kinds of exposures cause extensive neurological breakdowns that cannot be reversed medically. So basically, to be near that for any amount of time beyond a couple of minutes, would be a death sentence. What that means is really interesting. This site has been extensively mapped. There is a map that is current that shows many, many hot spots. This hot spot was not discovered until just a couple of days ago. Now that could mean a couple of things. It could mean really poor health physics in that this was missed for 100 days.

I do not think that is the case, but earlier site maps do not show this high concentration of radioactivity in that area. More likely is that this event happened over time, this radiation built up over time, and that is my theory about how the material was deposited. The key is that it occurred in a vent. Now that vent was venting the containment for weeks and months before the radiation was detected.

When you start your car up in the morning, you will see water dripping out of the end of the exhaust pipe. I think that is what happened at Fukushima. The hot humid gasses from inside the containment were going up this stack and where the gasses touched the outside of the stack, they were condensing. It was not just water and hot air, but it also contained lots of cesium. So the cesium and the hot water ran down the outside of the pipe and collected at the bottom. So over a period of time, that concentration got higher and higher and higher. It is likely that the first surveys missed it, because it just was not as high a radioactive source in comparison to all the other radioactive sources that were there.

But over time the concentration went up and up and up as more and more and more water containing cesium came down. It is important to remember that this lethal amount of radiation was found on site, not off site. So that is good. The other piece of that is, it was found in the stack, air was being pulled over that, and up and exhausted into the air for a long time. I think it really speaks to how much radiation was released over the last 140 days. And that this is just a small portion of what was released to the environment.

There is another competing theory: some people think it was blown into that location during the explosion in the first week.

Again, either the health physics practices of measuring that on site were really, really poor, or it was not there in the first week and has gradually built up over time.

Tokyo Electric has found high radiation in the ground in that vicinity and all around the plant.

And in fact has bulldozed some of it under, so that workers could access some of these areas. What that means is that we are going to continue to see over the next 10 years, spikes in radiation on site. First, as pieces that were bulldozed actually come to the surface in the excavations, there will continue to be these enormous radioactive sources that are in the dirt.

And second, when they get into these buildings to actually try to dismantle the plant, they are going to find even higher radiation levels than this one. Remember, at the bottom of the nuclear reactor, the nuclear core has leaked out and is now lying like a pancake on the concrete floor, working it's way down, but probably not through the concrete. That is even much more radioactive than this.

That is why it is going to take Tokyo Electric 10 or 20 years to clean up. This is not something you send somebody in with shovels to shovel the floor. This is going to have to be done robotically and it is going to take a long, long time.

I will keep you informed as more develops.

One last thing, I wanted to say that I made a mistake in the last video at the University of Vermont. It is Finland that has the waste repository. In my presentation, I said Sweden. My apologies to the Finns for mistaking your country.

Thank you very much.

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重要なのはこれが排気塔で見つかったことです。今回の高レベル放射線が検出されるまで、この排気塔は 何週間も何ヶ月ものあいだ格納容器内のガスを逃がしてきました。朝、車のエンジンをかけると、排気管から水が滴り落ちることがあるのはご存知でしょう。福 島で起きたのはそういうことだと思います。格納容器から出るガスは高温で多量の水分を含んでいます。ガスは排気塔を上へとのぼっていきますが、排気管の外 側にガスが触れると、気体が凝縮して液体になります。



覚えておいていただきたいのですが、この致命的なレベルの放射線が見つかったのは敷地外ではなく敷地内です。これは喜ぶべきことです。ですが、その排気塔からは長期にわたって排気が行なわれていました。実際に過去140日間でどれだ け高レベルの放射線が放出されてきたのかを今回の発見が物語っています。しかもそれは、環境中に放出された全体量のごく一部でしかないのです。



もうひとつは、実際に原子炉を解体するために人が建屋のなかに入るときです。今回以上に高い放射線量 に直面することになるでしょう。思い出していただきたいのは、炉心が今や原子炉を突き抜けて、パンケーキのようにコンクリートに張り付き、下へ下へと落ち ていっていることです。まだコンクリートを突き破ってはいないと思いますが。その炉心の放射線量は今回発見されたレベルの比ではありません。だから東電は 原子炉をきれいにするまでに10年から20年かかると発表しているわけです。



最後にひとつお詫びがあります。前回のバーモント大学からのビデオに一箇所間違いがありました。最終 処理施設が建設中なのは「フィンランド」です。プレゼンテーションのなかで私は間違ってスウェーデンと言ってしまいました。フィンランドの皆さん、皆さん の国を間違えてしまって申し訳ありません。