Referring to my Sunday post about the events in Japan, a friend in the US has asked me “Are you still this non-apocalyptic after the latest explosion?”. And given what has been reported about the situation at the Fukushima reactors since Sunday I feel I should update my opinions.

So where are we? Well it’s really difficult to tell. There have now been three explosions, and a further significant release of radioactivity. Albeit the radioactivity appears to be relatively short-lived nucleotides. But we now really don’t know enough about what is actually happening in Fukushima. In fact nobody knows exactly what’s happening apart from the engineers on the ground. All we are getting is the third- or fourth-hand account which the Japanese government are putting out and which is then being spun every which way by the media.

Do I trust what we’re being told? Again it is hard to say. All nuclear authorities (and governments) have a poor track record of owning up to bad news; the Japanese are no better or worse that anyone else. That means I am very skeptical about what’s being admitted to. What is being said may be true, but it may not be the whole truth and nothing but the truth. But as I say, we really don’t know, and cannot know.

However as I understand it, and despite the latest reports, the worst case scenario still cannot be as bad as Chernobyl due to the design of the reactors. Of course that doesn’t mean it couldn’t still be really very nasty. Remember that these nuclear plants have three or four levels of containment between the fuel rods and the open air. A full meltdown and fire, as happened at Chernobyl, would require all the levels of containment to be breached, all the cooling to have failed and at least some of the control rods to not be in place between the fuel rods. Given that we are told the reactors shutdown correctly, all the control rods should be inserted amongst the fuel rods which, if I have understood correctly, makes the worst case Chernobyl scenario highly unlikely.

Let’s also be clear. This situation has not obviously been caused by the earthquake – the facility appears to have withstood a quake some 5 times more severe than its design limit. (I have read that the design limit was to withstand a quake of magnitude 8.2, so this 9.0 quake is way above that design threshold; remember the Richter Scale is logarithmic.) It was the subsequent tsunami taking out the nuclear plant’s backup power generators which triggered the problems, and that clearly was not designed for. One has to question the wisdom of building nuclear facilities so close to such an active geological fault, especially one know to trigger tsunamis.

It’s undoubtedly a nasty situation, and extremely scary for the local population. But as far as one can tell the Japanese authorities are probably handling this as well as anyone could. We just have to hope that the authorities and the engineers are doing enough.

But we just don’t know (and may never know) enough about what’s really happening inside those reactors – no-one does except the engineers on site.

if you want to know more technical details there are good posts here, here and here, and regular technical updates here.

No, I’m not going to write in any detail about, what I suspect we all agree are, the horrors of the recent events in Japan; I’m not going to indulge in ghoulish voyeurism. However I find these events fascinating from a forensic viewpoint: what happened; how and why did it happen; how did it unfold. So I will content myself to comment on one or two things which have stuck me, as a scientist, over the last few days.

First of all the size of the quake. Initially assessed at Richter 8.9 it has now been upgraded to 9.0. This is normal as further seismic data becomes available. According to Wikipedia this makes the Sendai quake equal fourth largest in the last 150 years. This should not be surprising given the geology of the area.

There were some fore-shocks; but that is only known with hindsight. This brings home to me just how impossible it is for even the best experts to predict earthquakes. A lot of progress has been made in recent years on predicting volcanic eruptions, if only in the short term. But earthquakes are a totally different problem. Predicting when a geological fault is going to move is next to impossible. Japan has regular (almost daily) relatively small earthquakes because of where it sits on the fault lines. The scientists had predicted a big quake “sometime in the next 30 years”, which is about as precise as earthquake prediction appears possible at present. Is the Sendai Earthquake this big event? Well who knows. It isn’t impossible that a larger quake might happen, although my guess is that it is now much less likely.

Earthquakes impossible to predict with accuracy; so are tsunamis. As I understand it whether a quake generates a tsunami depends on many factors: the way the fault moves, the size of the movement, the seabed topography. The area around Japan is at high risk of tsunamis because of the type of faults in the nearby seabed and they have had tsunami monitoring and warning systems in place for some 40 or more years – but all they can do is send out alerts once a tsunami has been created and detected. And then tsunamis travel so fast (up to 500 miles an hour, apparently) that for nearby coasts any warning is almost too late.

It is in the nature of Japan that they are one of the most naturally controlled of societies. They are not people to leave things to chance if they can have a process to ensure it works properly. And they are world leaders in earthquake-proof design. In consequence they are possibly the best prepared of nations for earthquakes: they have very strict building codes, everyone is taught the drills almost from birth, there are excellent communication channels and warning systems. That is fine as far as quakes go, and as we have seen on the TV footage the majority of buildings (at least the more modern buildings) remained intact following the quake.

What is infinitely harder is to defend against a tsunami. Tsunami can be so large and generate such power that protecting against them is almost beyond our engineering (and almost certainly financial) capabilities. As protection one would have to build enormously high (50 feet?), thick and strong sea defences along every inch of low-lying coast. Sure it could be done, but probably no country on earth could afford to do it, especially for such relatively rare events. Physically preparedness is hugely hard; preparing the people, as is done for earthquakes, is almost impossible.

What is clear is that in much of the affected coastal areas it is the tsunami which has caused the vast majority of the damage. Again the TV footage shows buildings remaining intact after the quake but being simply washed away like matchsticks by the tsunami. Avoiding even that would be a huge engineering problem, but one I suspect Japan may now try to address.

This brings me to thinking about the situation at the Fukushima nuclear facility. As a scientist what has impressed me here is that all the fail-safe systems in the nuclear plants have worked as designed. Notwithstanding there do appear to have been issues. Fukushima 1, which blew the lid off it’s “shed” on Saturday, was working as designed until the backup generators were swamped by the tsunami (again it is the tsunami which has caused the problems!) and even then backup batteries were available. Even the venting of steam (and thus small amounts of short half-life radio-isotopes) is a planned and controlled event. And the “shed” is designed to fall apart (outwards, as it did) in the event of an explosion, so that explosion (however spectacular) wasn’t a majorly significant event.

Let’s be clear that, from what we’re being told, there is no nuclear meltdown at these plants; the reactors were automatically closed down when the quake struck, just as designed – this itself ensures that there can be no meltdown. (If meltdown were going to happen it would almost certainly have done so by now with far more major consequences than we’ve seen.) However there could well be some damage to the casings of a small number of fuel rods (as I understand it, it is this which caused the explosive hydrogen to be created). The reactors, having been shut down, do still generate heat which needs to be removed but this reduces quite quickly over a matter of days and (notwithstanding the problem at Fukushima 3) the worst of the heating problems should now be past.

What is of concern is whether the Japanese authorities are being truly open and honest about the situation at the nuclear plants; like most nuclear authorities they do not have a track record of transparency.

What I suspect will also happen is that Japan (indeed all the nuclear industry) will question the advisability of putting nuclear plant in areas most open to tsunami – like maybe not on Japan’s east coast?!

Of course those in the anti-nuclear lobby will use this same information to draw totally the opposite conclusions. As scientists we need to remain clear about what is designed for and whether it worked. I shall be most interested to see the reports from independent international inspections.

Finally a comment about the planet we live on. Many things in these events have stunned me, not the least being the awesome power of the tsunami. But perhaps the most staggering of all I found on the Scientific American website where there are many good reports:

Italy’s National Institute of Geophysics and Volcanology said the earth’s axis shifted 25 cm as a result of the earthquake, and the US Geological Survey said the main island of Japan had shifted 2.4 metres.

That doesn’t sound a lot, but they are incredibly large effects for the planet!

Our thoughts and hopes are, of course, with all the people of Japan.

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