Fukushima is a triumph for nuke power: Build more reactors now!
Quake + tsunami = 1 minor radiation dose so far
Analysis Japan's nuclear powerplants have performed magnificently in the face of a disaster hugely greater than they were designed to withstand, remaining entirely safe throughout and sustaining only minor damage. The unfolding Fukushima story has enormously strengthened the case for advanced nations – including Japan – to build more nuclear powerplants, in the knowledge that no imaginable disaster can result in serious problems.
Let's recap on what's happened so far. The earthquake which hit on Friday was terrifically powerful, shaking the entire planet on its axis and jolting the whole of Japan several feet sideways. At 8.9 on the Richter scale, it was some five times stronger than the older Fukushima plants had been designed to cope with.
If nuclear powerplants were merely as safe as they are advertised to be, there should have been a major failure right then. As the hot cores ceased to be cooled by the water which is used to extract power from them, control rods would have remained withdrawn and a runaway chain reaction could have ensued – probably resulting in the worst thing that can happen to a properly designed nuclear reactor: a core meltdown in which the superhot fuel rods actually melt and slag down the whole core into a blob of molten metal. In this case the only thing to do is seal up the containment and wait: no radiation disaster will take place1, but the reactor is a total writeoff and cooling the core off will be difficult and take a long time. Eventual cleanup will be protracted and expensive.
In fact, though the quake was far beyond design limits, all the reactors went into automatic shutdown perfectly: triumph number one. Control rods slammed into the cores, absorbing the neutrons spitting from the fuel rods and pinching off the uranium-fission chain reactions powering the plant.
However, the cores were still producing heat and radiation at this point: intermediate radioactive isotopes of caesium and iodine are created during normal running. They have short half-lives and decay to insignificant levels within days of a shutdown, but for that time the reactor will still produce a few per cent of the heat it puts out in normal running – and this is still a lot of heat. If it is not dealt with, it can eventually melt down parts of the core, though the resulting mess will not be nearly as bad as a runaway meltdown.
Thus, even with the control rods in, the core still needs to be cooled for some days until the "residual" heating dies away and so power and water need to be supplied for this purpose. Backup cooling driven by diesels came on at all the plants without trouble, despite the way-beyond-spec hit from the quake: triumph number two.
For a few hours all was well. Then the tsunami – again, bigger than the plant had been built to cope with – struck, knocking out the diesel backups and the backup diesel backups.
Needless to say, this being a nuclear powerplant, there was another backup and this one worked despite having been through a beyond-spec quake and the tsunami. Battery power cut in and the cores continued to be cooled, giving the plant operators some hours of leeway to bring in mobile generators: triumph number three.
Unfortunately it appears that the devastation from the quake and tsunami was sufficient that mobile power wasn't online at all the sites before the temperatures inside the cores began to climb seriously. At this stage the cores are sitting immersed in cooling water inside their terrifically thick and strong airtight containment vessels. As the water is not being circulated and cooled any more, it is getting hotter, turning to steam, and pressure is building inside the vessel. Left alone the vessel interior will presently become hot enough to start melting the tough alloy casings of the fuel rods, at which stage the interior will fill with long-half-life radioactive materials – and will thus have to be buttoned up tightly and abandoned for a long time, creating a mess.
Next page: Letting off some steam
A well-reasoned Lewis Page article that I can agree with and recommend, I think hell must have just frozen over :)
While I have no axe to grind myself...
This article was premature in the same way that most men are their first time out. We are just over 72 hours from the quake and tsunami, with nothing yet contained, and someone is going off half-cocked about how this is a win for nuclear energy concerns the world over. However, let's toss a little (boric) acidified seawater on this reaction.
First, as of 6 AM Japanese local time on Tuesday, officials confirmed that a third explosion had indeed damaged and weakened the containment of Rector 2, making any build-up of pressure in the reactor core that much more dangerous. Additionally, after the explosion, the radiation level climbed to at 11,900 μSv/h, which is approaching dangerous territory for anyone at the plant.
Second, Reactor 4 was suffering from a runaway fission reaction and nuclear material was actually burning in a fire, releasing much larger amounts of radioactive materials into the air than any previous situation at the plant. While Reactor 4 wasn't running, it still contained spent rods, which seem to be having a grand old time right now. (Update: While I was writing this, Japanese officials indicated the fire had been extinguished for now.)
Third, due to the containment breach, threat of further explosions, the aforementioned fire, and rising radiation readings, Japan was considering an evacuation of all workers from the site. Let me repeat that. They are considering a wholesale evacuation of all technicians and support personnel from the site, effectively ceasing any and all recovery and containment activity. In essence, the plant is being given up for dead, and it's entirely possible that Reactor 2, at least, will suffer a containment-busting explosion and/or meltdown, resulting in the release of uranium and plutonium into the air, let alone their decay products.
Fourth, if this does occur, a little known problem could be the cooling pools used to store spent rods. As Rector 4 is demonstrating, they still have enough energy left in them to burn and release radioactive material. The problem is that they are in cooling pools are lightly protected and poorly contained, and only have enough water over top of them to remain unexposed to air for a week or two. Clearly, a full-scale meltdown would make any kind of mitigation impossible, and they would soon begin burning and releasing even more radioactive material into the air at a rate much greater than the relatively contained reactor cores.
So, while I don't personally find nuclear power abhorrent or otherwise unpalatable, it seems like this piece was exceedingly short-sighted and resulted in the tarnishing of a reputation that had to this point been decent. It's unfortunate that someone clearly let personal bias trump the facts on the ground and didn't even let the events settle down to a point that experienced people in nuclear physics would say the threat was contained. Poorly handled by Mr. Page.
A better article would have been something like this: While we don't know the extent of the damage and fallout (har) of the Fukushima nuclear incident, we know that nuclear power is safe most of the time, assuming we aren't dumb enough to build on the coast in a tsunami-prone area that is very near a large fault. Such self-evident things, sadly, only become apparent after calamity strikes.
Thank you - a lone voice of common sense in a sea of eco-hysteria
Thank you Lewis for a cogent, well-reasoned and above all rational (in the Enlightenment sense) defence of nuclear power. Already the greenies and watermelons in the media are seizing upon the tragedy in Japan as an argument AGAINST nuclear energy - as you've explained, this is 180 degrees out from the rational interpretation of events, but we all know how quickly lies can get around the world. A particularly impressive example of the "this is the final nail in the coffin of the nukular industry" genre from Geoffrey Lean in the Telegraph, here:
...although somewhat gratifyingly, the comments below his article show he hasn't convinced many readers!