C[omp]ute

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