Monday, March 14, 2011

Japan disaster

I've been away for a long weekend, and haven't been keeping up with the news. Other people have, though.
Highly Allochthonous has a roundup on the Earthquake.

See links therein for details.

Jeff, the Arms Control Wonk, was in japan visiting the reprocessing facility at the time of the quake, and has decent information on the state of the reactors.

Geoblogger Evy's dad is a nuclear engineer, so she has posted two explanatory interviews.

An commentary on various things I heard on the radio while driving:

1. The hydrogen explosions at the nuclear plants are not the same as little hydrogen bombs.

Hydrogen bombs release nuclear energy bu fusing hydrogen into helium; basically the same reaction that makes the sun shine.

The hydrogen explosions at the Japanese nuclear plants are a chemical explosion caused by hydrogen gas igniting in air.

The hydrogen is released by the reaction of water (or possibly an acid) with a metal (M):

xH2O + M -> xH2 + MOx

Where x is one half the valence state of the oxidized metal.

The reaction can take place at low temperature in the presence of an acid or catalyst, or at high temperature in the presence of pure water. The most likely scenario is that the zirconium metal in the fuel rods are reacting. One kilogram of Zr metal will release about 44 grams, of ~500 liters, of H2 gas, so you don't need much metal to get a decent bang.

It may be possible that the seawater they have been using as an emergency coolant is boiling to produce a hot, highly saline brine that might be able to catalyze oxidation of other metal components. But you'd have to talk to an aqueous chemist and a nuclear engineer to see what metals are present and whether they could be corroded in this manner. The boric acid that they have been adding to absorb neutrons is a weak acid, and should not be able to react with anything in the reactor to produce hydrogen. There was a confirmation of exposed fuel rods this morning.

2. The earthquake in New Zealand did not cause the Japan Earthquake. They are related only in that they involve the western edge of the Pacific tectonic plate, which is sliding past the Australian plate in New Zealand, and under the Eurasian plate in Japan.

3. The uranium in the reactor may well have been mined in Australia. Japan imports uranium from Australia. It also imports natural gas and coal from Australia. It also imports uranium from Canada. I don't know how much of the non-nuclear generating capacity has been damaged, but there have been images of burning natural gas facilities in the papers.

4. I don't buy the suggestions that this quake is a foreshock for a bigger quake. This is about as big as they get, and none of the other 8.5+ quakes that I know of have been followed by similar sized quakes on the same system. On the other hand, aftershocks are likely, and some may be as big or bigger than the NZ quake.

I don't know if this makes a large quake on Japan's southern subduction zone more or less likely. That would not be a significantly bigger quake (it might even be smaller), but it would effect a more densely populated part of the island, so that could be what people mean by 'the big one'.

3 comments:

Anne Jefferson said...

Minor correction: The Japanese quake actually occurred where the Pacific plate is subducting under the North American plate. The Northern half of Japan is actually on the North American plate, as shown in Callan's post: http://blogs.agu.org/mountainbeltway/2011/03/11/japan-m8-9-quake-tsunami/

Chuck said...

What fault defines the boundary?

Chris Phoenix said...

Out of 16 "world's largest" earthquakes happening since 1900 (from http://en.wikipedia.org/wiki/Lists_of_earthquakes)

Five of them have happened in the last 7 years.

Three of those were in or near Sumatra; the others were Chile and Japan. All somewhat near a coastline.

Adding water to a large reservoir can cause earthquakes. Also, tides have been correlated with increased vulcanism.

As we warm and expand the ocean, we're not adding water, but we are pushing the water up on the shore. That's a whole lot of weight per km of coastline. Is it possible that this could be causing increased earthquake activity?