WE ALL GONNA DIE
Well, not really.
Naturally, however, you're probably worried about the growing nuclear crisis at Japan's Fukushima Nuclear Plant. And while there is cause for concern, there's also a lot of FUD being spread around, and as someone who considers himself a scientist (even if only in the armchair capacity), that doesn't resonate well with me.
Let's get some things out of the way first:
EXPLOSIONS at the facility are not nuclear events. They are an unfortunate side-effect of trying to cool superheated nuclear materials with water, something you often have to risk doing during an accident. The problem is that the conditions involved (intense heat and ionizing radiation) tend to break apart water into it's components: hydrogen and oxygen. This, as you might imagine, creates a highly flammable gaseous environment, which can inevitably lead to explosions. These explosions are lethal and damaging to facilities and equipment, but frightening as they are, they're probably the least of your worries.
RADIATION is not exactly what YOU have to worry about. If something, like the melting plutonium-uranium core of a nuclear reactor, is emitting a lot of radiation, just get far enough away from it and/or behind something thick enough that will block the radiation. This is something workers at the plant and anyone immediately nearby will have to worry about, not you, especially if you live on a different continent.
PARTICULATE MATTER is much more worrysome when events conspire to create large amounts of it, such as smoke from a fire. These particles, which are radioactive, are then lofted high into the atmosphere by the heat, and then dispersed over large areas. This can contain very fine plutonium and uranium compounds, which are very radioactive. Essentially, the concentrated nuclear fuel from the reactor is being ejected from containment.
Naturally, to get a handle on how bad things could be, we need to start making comparisons to the Chernobyl accident, and the lessons learned there. But for all the errors committed in the design and operation of the plant, the intense environmental damage caused by Chernobyl can be blamed on one element: NO CONTAINMENT BUILDING. In the United States, federal regulations require that a nuclear reactor must have a containment building strong enough to withstand the impact of a fully-loaded passenger jetliner.
Chernobyl's reactor was in an ordinary industrial building. When it overheated, it suffered a steam explosion, which blew the reactor apart as well as the building containing it. Graphite control rods, intensely hot, and exposed to the open air, ignited. And so an incredibly hot fire was able to burn and loft all sorts of nuclear materials up, up, and away. It took several days to extinguish the reactor fire.
Now, all of that said, here's the problem:
The buildings used in Fukushima's plant are not strict containment vessels in the sense I've defined above. All of them have been through a major earthquake and several powerful aftershocks. Three have been damaged by hydrogen explosions, and reports say that at least one has been damaged to the point where reactor elements are exposed to the atmosphere.
Currently, workers are attempting to keep the reactors, and their spent fuel, submerged under water. This keeps the fuel cool and prevents it from getting to the point where it could melt completely, which is where things get problematic and even more difficult to control. This is becoming increasingly difficult, as local radiation (the stuff mentioned up above) is getting too intense for anyone to work for extended periods in or near the plant without getting a potentially lethal dose of radiation. Naturally, this creates big personnel complications.
Dr. Michael Allen, dean of graduate studies at Middle Tennessee State University, spent much of his early career at Sandia National Labs studying and simulating nuclear accidents with real materials under controlled conditions. It's his job to know what to expect when nuclear reactors break. In a recent interview, Allen explained what a "worst case" scenario for Fukushima could look like. You should probably read the article yourself, but I'm going to paraphrase:
It is possible that local radiation levels around Fukushima will become too high for anyone to work around. If that happens, the nuclear fuel will eventually just boil away all the cooling water, and start heating up the floor of the reactor. The risk then is that, in a total meltdown scenario, molten nuclear fuel will find its way through the floor to a reservoir of water underneath, leftover from cooling efforts.
This was also a concern during the Chernobyl accident, before drastic measures were taken to cool the molten fuel. The problem is that if you drop a blob of molten metal into a pool of water, you get a pretty violent reaction: a steam explosion.
That would, in turn, create a cloud of radioactive particulate matter. In such a scenario, you might be surprised to learn that the best case scenario would be a prevailing easterly wind. The Pacific Ocean is a very big place, and there's plenty of room for the radioactivity to become diluted to the point where it would become harmless background radiation.
However, if the winds were light and headed southwest, the fallout would occur over most of Japan's most heavily populated areas. That would be a disastrous outcome, and could result in a near-total loss of the entire country.
I doubt that anyone is going to let that happen. Even Chernobyl, as bad an accident as it was, could have been much, MUCH worse, were it not for firefighters, divers, and other accident workers who gave their lives and exposed themselves to lethal doses of radiation to bring the meltdown under control. I fear that's what this will come down to.
I have a number of other sciency friends, and I'm eager to hear their thoughts, feelings, fact-checking, correction, science, etcetera on this matter.
I would also like to encourage everyone to donate generously to the Red Cross Japan Relief Effort, because God knows Japan has their hands full with Fukushima.
Good luck, Japan. And Godspeed.
Posted on March 17, 2011 06:17 PM
Very good explanation Jesse. You should send a copy to the Vancouver Sun.Posted on March 18, 2011 09:28 AM
Thanks Mom, but I am no expert, and imagine that my exposition contains at least some logical errors. Like I said, I'm eager to hear others' opinions.Posted on March 18, 2011 09:40 AM