🚀 go-pugleaf

In article <1992Apr3.194448.21075@cs.rochester.edu>,
dietz@cs.rochester.edu (Paul Dietz) writes:
|>In article <69672@ut-emx.uucp> johncobb@ut-emx.cc.utexas.edu (John W.
Cobb) writes:
|>
|>>|>and I said to that:
|>>|>it would be impossible because the temperature that is needed is to
sustain
|>>|>the reaction is so high that if a "mass" did escape the chamber, it would
|>>|>dissipate and with the momentum it had (if any)  the most damage that
|>>|>would be caused is a hole in the chamber and some nearby jogger
complaining 
|>>|>that someone from the plant is throwing bowling balls at her. 
|>>|>
|>>|>who is right?
|>>|>
|>>
|>>You are.
|>
|>
|>No.  You can compute the "time to meltdown" for a fusion reactor,
|>assuming the first wall is made of a given material, there is a given
|>neutron wall loading during operation, and assuming that when the
|>fusion reaction is terminated, cooling of the first wall is lost.  For
|>bad choices of materials, like aluminum, the first wall melts within
|>minutes due to heat from induced radioactivity.
|>
Correct.

|>Even a little cooling helps, though, and some materials, like silicon
|>carbide, cannot melt even if they are never subsequently cooled.  But,
|>in principle, it is possible to get meltdowns in an improperly
|>designed fusion reactor.
|>
|>	Paul F. Dietz
|>	dietz@cs.rochester.edu
                             
2 notes. 

1) the first attribution (the original question) should be that of the 
   original poster, Francis Godfrey and not me.

2) In the rest of my answer which you did not include in your reply,
   I went on to say, in effect, that you could "screw up the machine"
   in minor ways via controllable or uncontrollable disruptions and 
   you could even screw up in big ways and breach the first wall. One
   way to do it is by melting the first wall as you detailed above (there
   are also others). However, my first point was that this was not a 
   likely occurance (but not impossible). My second and more important
   point was that if it did occur you would not get a Chernobyl-like
   Megacurie radioactivity release. This is what the original poster
   indicated, and if I read between the lines in what you are saying,
   perhaps this is your feeling as well. So it seems we're all pretty
   much in agreement on facts.

Since you are at Rochester, perhaps you could comment on ICF accident
scenarios. Since ICF is pulsed at a few hertz while MFE is continous,
perhaps there is more (or less) problems with thermo-mechanical stresses
on the frist wall, support strucuture, etc.

John W. Cobb
jwc@fusion.ph.utexas.edu