The UK Government's Chief Scientific Adviser, Professor Sir John Beddington, is in Tokyo trying to dampen expat fears that the Fukushima nuclear reactors could possibly ruin their lives.

I had actually received snippets of this meeting by email and was tempted to publish them yesterday. Luckily, Sir John's wisdom is now online for all to see. I just wish to copy some excerpts.

Let me now talk about what would be a reasonable worst case scenario.  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 metres 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 metres.  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 [my bold... unequivocally, of course].  The problems are within 30 km of the reactor.  And to give you a flavour for that, when Chernobyl had a massive fire at the graphite core, material was going up not just 500 metres but to 30,000 feet [10,000 metres, slightly tactless change of units].  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 kilometres.   And in that exclusion zone, outside that, there is no evidence whatsoever to indicate people had problems from the radiation [really?!!!! Too short a space here to list all the problems with that statement. The 30km Zone of Alienation is still in place today, 25 years after Chernobyl].  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 [The Japanese don't eat or drink?].  So what I would really re-emphasise 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 kilometres, it’s really not an issue for health.

I feel mightily reassured by this. However, Sir John's reputation seems to have a half-life measurable in seconds:

[Q] Yes, I’d just like to ask, there are reports as you say of higher than normal radiation levels in Tokyo.  I think I saw one report of eight times normal.   What kind of multiple of normal should we be worried about?

[JB]  I’ll pass that to Hilary or to Lesley.

[HW] Well to begin with it would have to be many multiple times a background level to really be an issue.  Orders of a hundred or so.

[JB]  Yes, I agree.
Yes, ok so I don’t know whether that came through but basically eight times, don’t worry at all, eight times is really nothing.  It’s the, it’s when it get to a hundred, two hundred, three hundred times that we really have to be concerned and the question if there is eight times in Tokyo tomorrow it’s normal, it’s nothing…

[DF]  I think also Sir John, this is David Fitton again, there is a point too isn’t there in the distinction between times normal and times what is permissible is that the right word?

[JB] Absolutely, Hilary, what is seen as the permissible dose?

[HW] Much higher than what we’re seeing as background, you’re talking almost a hundred times that.

[JB] Yes.
Yes. Ok so permissible would be a hundred times the background. [all bold typefaces are mine]

[DF] OK thank you very much.  I’ll move quickly on.  We’ve got one more question in this room. Kevin?

I think Kevin must have left the room by then! "HW" is Hilary Walker from the Department of Health and Lesley Proctor from Health Protection Agency was also present but was wisely silent on this particular issue.

And we science writers wonder why people are confused, sceptical and scared?