Hon, Yes, that is a possibility. Hydrogen which has less windage than air and has the capability to dissipate heat faster. It is used in just about every large generator for cooling that I know of. The turbine building is isolated and protected pretty well by fire protection devices in Nuclear plants but H2 is dangerous and an explosion there is possible.

My experience has been that fire usually starts because of the hydrogen and not an explosion but of course that is possible. About 8 years or so ago I was one of the lead engineers on an investigation of a generator hydrogen and lube oil fire that caused, I think $ 50 mil. in damages. This happened in South Boston, MA at the L St. Plant. There was an incident in which the turbine suffered major damage as did the H2 seal on the turbine end of the generator. In addition the fire was fueled by a 10,000 gal. Lube oil system that was spraying oil in the area when the bearing cap lifted. It took quite a while before they could enter the closed up building and shut down the Lube oil pumps. It happened during cold weather and the building almost immediately filled with smoke. The unit never ran again and the whole plant was decommissioned a few years later. This was a fossil fuel gas burning plant at the time of the incident. We have had a couple of other less damaging H2 fires in my career. The point is there was a lot of fire in that incident for quite a long time but luckily no explosion.

There could be many sources of an explosion in the secondary part of a Nuclear plant and some could be of the hydrogen system, generator, gas bottles, and many other types of pressure vessels. It is safe to say though that the source will not be the reactor vessel, reactor fuel, or anything like that.

This is going to take a while to sort out. I'm retired now or I would pick up the phone and see what the scuttlebutt is although it is even way too early for that.

The Japan Earthquakes are continuing.
http://earthquake.usgs.gov/earthquakes/recenteqsww/Maps/10/140_40.php

Red are within the last hour. Many of those are ranging from 5.0 to 7.0

Hon, The latest out is that the explosion was caused by H2 but not the H2 used to cool the generator. From what I can gather some of the fuel rods may have overheated and gave off some H2 gas which had to be vented into the reactor building. This is a different scenario which is much more serious than a generator fire or explosion. Information is hard to come by and this on going event is not going to be fully explained for some time.



PS This whole castastrophe is not going to be good for Japan, I guess that goes with saying but I wonder what effect this will have on the world economy? Not good I'll bet. Our prayers should be with these people this is just terrible. Huge loss of life and a huge loss to their economy.

The New York Times has published stunning before-and-after satellite photos of areas affected by the earthquake and tsunami.

For ragman... http://cnsc.gc.ca/eng/pdfs/japan-earthqu...etary-Japan.pdf

Marty, those pictures are stunning indeed.

Environmentalists have long been fond of saying that the sun is the only safe nuclear reactor, situated as it is some ninety-three million miles away.

environmentalists are fond of saying a lot of things

http://news.yahoo.com/s/space/20110226/sc_space/monstersolarflareeruptsfromthesun

From Japan.....

What I said about it tailing off? Forget it! We had 18 here yesterday and we’ve had 9 so far today and it’s not 10 a.m. yet! One of the ones yesterday is shown in your picture as a big one off Sendai. That was M7.1 and it shook my house quite violently. I live just south of the arrow-shaped lake north-east of Tokyo. My hanging lights were clinking together uncontrollably, and I got as far as the front door thinking that evacuation was on the cards. That’s when it started to subside. Today we have had a M6.3 but it was just off the coast near here so the effect here was the same as the M7.1 last night. Strictly, last night’s was assessed as intensity 5 on the local scale and today’s as intensity 5-. The local scale goes from 1 to 7. The M7.1 quake was intensity 6+ in Sendai. It still staggers me to think that, in the M9.0 quake, which was centred I believe on Kesennuma – 350km from here – caused the ground beneath my feet to heave, and therefore all the ground for at least a 350km radius must also have been heaving. That’s an extraordinary amount of land waving about like a sea. Astounding.

One thing that always concerned me was that the stresses in the crust caused by the M9.0 quake would create other stresses farther along the fault line, perhaps to the south nearer us. It’s the spur of land to the east of Tokyo that is the marker for us. That’s where this morning’s M6.3 was, and it certainly appears that the seismic activity is picking up again, presumably for those reasons of increased stresses. I just hope there isn’t a really big one again. The M9.0 was the 4th biggest in history so I think (and hope) that it’s reasonable to assume that anything like that is unlikely to happen again in my lifetime.

from a friend in Japan...

The table below shows the incidence and average magnitude of earthquakes since the 11th March. I should point out that these are only the earthquakes that have affected me!

Week No of Earthquakes Av. Magnitude

1 131 5.4
2 31 5.2
3 16 4.9
4 20 4.6
5 50 4.8
6 24 4.5
7 12 4.9
8 14 4.7
9 13 4.3

It seems to show that there was a progressive quietening over the first month, then another major spate of activity followed by another quietening. If there’s going to be another increase in activity after another month, it should start about now. I hope not, as we’re still averaging about 2 earthquakes per day which is about 20 times the norm that we had over the whole of last year. In other words there’s still a lot of activity going on but it does seem to be diminishing in both frequency and magnitude – as one would expect.

FYI as I was typing, I had to adjust the week 9 figures from 12 to 13 and 4.4 to 4.3!