Hydrogen-air explosion inside the containment building? Not just at the top? Prevailing winds & weather charts
Robin Whittle
think this at first, since I didn't then understand how zirconium could
oxidise in steam and so produce hydrogen) I guessed that the hydrogen
must have built up in the upper part of the building, which is now just
a bunch of wall girders. However, this didn't make complete sense,
since that would be well ventilated - see photos below. Also, if that
was the volume of gas which exploded, the shock-wave would have gone in
all directions. Instead, we saw in the video that the shock-wave went
primarily upwards, with a dispersion of about 20 to 30 degrees or so,
with a much slower sideways blast of grey debris from the walls of that
top part of the building.
I now think that this explosion was probably due to hydrogen and air
inside the steel-concrete containment building (and therefore outside
the reactor pressure vessel). This means not in the top section of
which there are photos below, but inside the solid concrete containment
structure, the top of which is the floor of the area in these photos.
I guess this would have blown off the shallow conical looking cover:
http://www.nucleartourist.com/imagemaps/rx-bldg1.jpg
which is shown above as a semicircle of concrete, with a slight wedge
shape, above the yellow dome. I guess the dome would have blown off
too, and that the gas explosion came from the inner part of the concrete
containment building, and outside the dark brown body of the reactor
vessel itself.
The yellow dome can be seen here:
http://www.nucleartourist.com/images/headlift.jpg
I guess the explosion blew that away, but would this have been seen in
the videos? It is big, but the video was from a great distance, and the
dome would have been travelling very fast, so its image would be smeared
over a large part of the video frame (assuming the camera CCD was
capturing light for most of the frame time). What of the concrete layer
above it? Maybe that is the octagonal section of floor here:
http://www.nucleartourist.com/images/rflg-fl1.jpg
So I think the labelling of this diagram:
http://www.nei.org/filefolder/BoilingWaterReactorDesign_3.jpg
is incorrect. That depicts the gas explosion happening above the
concrete section. The lower red dot labels the concrete containment
building itself, but refers to it as "primary containment", whereas I
would call it the secondary containment, with the primary containment
being the reactor vessel itself.
Looking at images of the Unit 3 explosion, my guess is that the same
thing happened, but with more force, and that the explosion knocked out
some of the concrete sides of the containment building.
If so, then in both Units 1 and 3, I think that the outside of the
reactor pressure vessel is open to the atmosphere. To what extent is
the reactor pressure vessel leaking? To what extent can the controllers
avoid releasing radioactive steam etc. straight to the atmosphere due to
heat boiling the water in the reactor and exceeding a safe pressure?
Fortunately, the heat generation dies down over days and weeks (sorry, I
can't find the reference now).
*Fortunately* the prevailing winds are out to sea:
http://www.wunderground.com/global/Region/i_JP/2xWindSpeed.html
and have been since I looked yesterday.
The weather maps:
http://www.prh.noaa.gov/hnl/graphics/npac.gif
http://www.jma.go.jp/en/g3/
show the reactor area with a Low (anticlockwise) to the north and a High
(clockwise) to the south. So the wind is to the east-north-east and has
been, I think, since the earthquake.
If the wind was blowing in the opposite direction, my guess is that
significant and potentially disastrous levels of radiation would have
been blown to highly populated areas, including Tokyo.
Te above diagram and photos are for a General Electric reactor, I guess
in the USA, presumably like Unit 1. I understand that Unit 3 is
designed by Toshiba, but I guess that it is reasonable to assume a
similar structure and similar principles, although somewhat larger.
The reactor pressure vessel is connected by pipes to the turbine
building. This has presumably not been so much damaged by the
explosions. If the gas explosion was inside the concrete containment
building (not just the top area) I guess that there is virtually no
chance of anything mechanical or electrical functioning in the reactor
buildings themselves, and that no-one would go into those buildings
unless they were prepared to be exposed to very high levels of radiation.
To what extent are people able to access and work with equipment in the
turbine buildings?
AFAIK, the government hasn't even released a diagram of the reactor or
its buildings, much less provided information about where workers are
able to access the site, and at what personal danger.
They have a responsibility not to incite panic, but I think they also
have a responsibility to provide much better information than they have.
- Robin