Fukushima meltdown: worst case scenario?

UK government Chief Scientific Officer Professor John Beddington comments on the developments at Fukushima nuclear plant. I hope he is correct.

If the Japanese fail to keep the reactors cool and fail to keep the pressure in the containment vessels at an appropriate level, you can get this, you know, the dramatic word "meltdown." But what does that actually mean? What a meltdown involves is the basic reactor core melts, and as it melts, nuclear material will fall through to the floor of the container. There it will react with concrete and other materials that is likely.

Remember this is the reasonable worst case, we don't think anything worse is going to happen. In this reasonable worst case you get an explosion. You get some radioactive material going up to about 500 meters up into the air. Now, that's really serious, but it's serious again for the local area. It's not serious for elsewhere, even if you get a combination of that explosion it would only have nuclear material going in to the air up to about 500 meters.

If you then couple that with the worst possible weather situation, i.e. prevailing weather taking radioactive material in the direction of Greater Tokyo and you had maybe rainfall which would bring the radioactive material down, do we have a problem? The answer is unequivocally no. Absolutely no issue.

The problems are within 30 km of the reactor. And to give you a flavor for that, when Chernobyl had a massive fire at the graphite core, material was going up not just 500 meters but to 30,000 feet; it was lasting not for the odd hour or so but lasted months, and that was putting nuclear radioactive material up into the upper atmosphere for a very long period of time. But even in the case of Chernobyl, the exclusion zone that they had was about 30 kilometers. And in that exclusion zone, outside that, there is no evidence whatsoever to indicate people had problems from the radiation.

The problems with Chernobyl were people were continuing to drink the water, continuing to eat vegetables and so on and that was where the problems came from. That's not going to be the case here. So what I would really reemphasize is that this is very problematic for the area and the immediate vicinity and one has to have concerns for the people working there. Beyond that 20 or 30 kilometers, it's really not an issue for health.