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Welcome to my blog, which was once a mailing list of the same name and is still generated by mail. Please reply via the "comment" links.

Always interested in offers/projects/new ideas. Eclectic experience in fields like: numerical computing; Python web; Java enterprise; functional languages; GPGPU; SQL databases; etc. Based in Santiago, Chile; telecommute worldwide. CV; email.

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© 2006-2013 Andrew Cooke (site) / post authors (content).

Some Points Related to the Fukushima No. 1 Reactor

From: andrew cooke <andrew@...>

Date: Sat, 12 Mar 2011 18:29:37 -0300

First, a quick summary of what I understand has happened:

 - The reactor is water cooled, but the cooling is not
   passive/convective, so it's critical that there is electrical power
   for valves and pumps.  It cannot "fail safe" when there is no
   power.

 - Power is automatically cut on earthquakes, and the core shuts down.
   But heating continues for many hours.

 - There are two backup power systems - diesel generators and
   batteries.  At least the first of these failed, possibly due to
   flooding.

 - Lack of power meant that it was not possible to cool the reactor as
   normal, so the water in the core started to boil, raising pressure.

 - To avoid damaging the core, some steam was vented into the
   surrounding concrete container (the core is in a smaller steel
   container, inside).

 - Unfortunately, some kind of damage occurred inside the core.  I do
   not understand this completely, but the result was that hydrogen
   was generated.  This escaped with the vented steam.

 - The hydrogen ignited/exploded, destroying the outer concrete
   container, but apparently not the steel container around the core.

 - To cool the core it is now being flooded with seawater and boric
   acid.  The boric acid is a damper (it helps kill the nuclear
   reaction).

 - As I type this, there is also a problem with reactor 3.  The above
   is for reactor 1.

So, given the above, there are at least three obvious questions:

 1 Nuclear reactors that do not fail safe?  What the fuck?

 2 How much worse could this have been?  The diesel backup was running
   for the first few hours, when the core was hottest.  If the tsunami
   had been sooner (ie if the plant was nearer the epicentre) then the
   cooling would have failed at a more critical moment.  Would
   meltdown have been possible?

 3 What was the process that created the Hydrogen?  Not just the
   physical/chemical process (it seemed to be something standard, as
   commentators quickly identified "a hydrogen explosion"), but also
   the engineering damage that caused this.  Details here will affect
   the amount of radiation leaked.

Andrew

Re: your excellent blog

From: andrew cooke <andrew@...>

Date: Sat, 12 Mar 2011 20:05:00 -0300

Hi - thanks for these (my dumb old blog software was confused by your modern
email that included HTML so I am forwarding your comment as quoted text).
Andrew.

From: Gerry Newby <gerrynewby@...>
To: "compute+SomePoints0@..." <compute+SomePoints0@...>
Subject: Re your excellent blog

http://www.tepco.co.jp/en/press/corp-com/release/11031233-e.html

http://www.world-nuclear-news.org/RS_Battle_to_stabilise_earthquake_reactors_1203111.html

Hydrogen Source

From: andrew cooke <andrew@...>

Date: Sat, 12 Mar 2011 21:32:46 -0300

The Guardian says that "At 1,200C (2,200F), the zirconium casings of the fuel
rods can react with the cooling water and create hydrogen" which suggests that
was the source of the gas that exploded.  So this is more serious than initial
reports suggested and the word "desperate" is now being used to describe the
use of sea water for cooling.

Andrew

Good Article on Explosions

From: andrew cooke <andrew@...>

Date: Tue, 15 Mar 2011 17:52:59 -0300

http://mitnse.com/2011/03/15/explanation-of-hydrogen-explosions-at-units-1-and-3/

Andrew

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