Broomstick wrote:
Nations have a bad habit of refusing help, and if anything the more industrialized/developed nations are the worst offenders (aside from a few cases like Myanmar). I think it has something to do with not wanting to be perceived as weak, possibly also not wanting intrusion on bureaucratic territory, but it's getting to be so typical of these huge disasters I think it's just another factor that, like it or not, has to be accounted for during planning.
I think another good recent example, almost a year to the day, is the Macondo blowout diaster in the Gulf of Mexico last year. I recall the Dutch offering oil scooping equipped ships, but being declined on the offer.
The risk of hydrogen explosion was known, but maybe the fact it didn't happen at Three Mile Island lead to some complacency? After all, TMI was the only comparable reactor that had had a serious cooling problem. Perhaps they relied overmuch on just that one example.
It's hard to draw direct comparisons with any previous event, given TMI had a meltdown with corium remaining intact within the containment vessel for the most part, while Chernobyl involved a single reactor burn and explosion during fission, like Windscale, but on a far larger release thanks to the explosion and lack of containment partition. Fukushima is another scenario entirely. Unlike all the previous examples, the reactors would've survived with nary a scratch, had it not been for the coolant systems having their generators flooded, diesel tanks washed away and batteries having sub-par performance for the duration of the blackout (Daiini was able to get power from the grid, unlike Daiichi).
There are multiple reactors in critical condition with damage that we can't really see directly, only by proxy. If you look at the recent picture of the control room which the technicians have managed to get back into, you'll see most all of the instruments are dead or reading incorrectly. It is only in the last few days they've managed to get main lights working, even.
A lot of what has gone on could've been prevented. While the GE Mk. I reactor design has many flaws, the major problems were down to TEPCO's organisation, or lack of, along with them copying a design from the continental United States and placing it exactly as designed in a totally different environment. Simply relocating the diesel generators and having the far larger storage battery systems now used throughout most of the EU and US, would've saved the plant.
Do they know what istopess are causing much of the seawater contamination? It's nothing good, of course, but if most of it is short-lived stuff it won't be as bad long term as if it were long half life isotopes spreading farther before decaying and hanging around longer. In some case a LOT longer.
As far as I'm aware, the main contaminants are iodine and cæsium, with the former being a smoking gun for any potential reactor faults that could lead to further fissionable material being released. I have read of other trace radionuclides being released, but of far smaller quantities and posing no real risk (that comes with the caveat, that any heavy metal contamination can potentially be magnified as it travels up the trophic levels of the marine food chain towards man).
It was my very limited understanding that in the case of criticality the heat generated usually (or at least typically) expands the fissioning material to the point things are no longer critical... but perhaps that is more a feature of criticality with small masses. After all, there is not much precedent for such a thing happening in a melted reactor core lacking controls.
I'm sure many new things are being learned.
This is likely sub-criticality as I mentioned some pages back. It's not technically full blown out-of-control fission, but it does produce neutrons to an extent that it would pose a danger, and can transmute some elements within the core which could leak out, either in coolant or as gas. It does not, however, lead to a steady state of fission which prolongs a reaction. Another fear is that the dislodged fuel in Reactor 4's spent fuel pool could have shifted from the quake and moved into the sub-optimal configuration that is avoided when the rods are loaded into the pool, so as to avoid any criticality accidents. Reactor 4 is the one which had a hot load moved into the pool prior to the tsunami.
I viewed it as inevitable that at some point the airborne radiation would be carried to Europe, just as it has been to North America. So far the amounts reported have been minuscule and, aside from media hysteria, nothing to worry about. That's the good news. The bad news, of course, would be if it continues long enough or if the contamination spikes or we get some of the more toxic stuff traveling around the world.
Right now, the bigger problem is media coverage, since I have seen the CNN show (I forget the presenter's name) with some woman trying to tell a weatherman on the show that the cloud poses a significant risk to public health on the western US coast. The weatherman, at least I think he was one, was quite adamant that this was not the case, which concurs with all assessments so far. Even with the clouds produced equalling Chernobyl's by measure of activities, the Japanese are fortunate that the westerly wind has kept it from the mainland and allowed it to disperse harmlessly over the Pacific before hitting land again. Similar feats of luck happened in the Ukraine, where a particularly potent cloud from the erupting reactor was blown to a higher level and dissipated harmlessly, rather than hitting Kiev and causing potentially many deaths within a short time.
Your posts are quite clear and authoritative - do you have some sort of background or profession that gives you greater than average insight into this matter? Or are you "just" an extremely well-informed layperson who posts more coherently than the average person?
I'm just a chemist by profession. I'll make the disclaimer now that I'm not pro- or anti-nuclear power, simply pro-information.
