The secret of a passive thermostat lies in the small cylinder located on the reactor-side of the device. This cylinder is filled with a *metal alloy* that begins to melt at perhaps 500 degrees C (different thermostats open at different temperatures, ). A rod connected to the valve presses into this alloy. When the alloy melts, it expands significantly and pushes the rod out of the cylinder, opening the valve. If you have read How Thermometers Work <http://home.howstuffworks.com/therm.htm> and done the experiment with the bottle and the straw, you have seen the same process in action. The wax happens to expand a good bit more because it is changing from a solid to a liquid in addition to expanding from the heat.
On Sat, Jun 22, 2013 at 12:28 AM, James Bowery <[email protected]> wrote: > > Positive > Control<http://globalguerrillas.typepad.com/globalguerrillas/2013/06/positive-control-means-the-end-of-freedom.html> > > When something is very dangerous, like nuclear weapons, standard forms of > protections and control methodologies aren't sufficient. > > [image: > Hardtack_Umbrella_nuke]<http://globalguerrillas.typepad.com/.a/6a00d83451576d69e201901dadf09c970b-pi> > > Something that potentially dangerous needs something more aggressive. > > In the military, that's called *positive control*. > > Positive control is an active form of control where the dangerous item is > under 24x7x365 monitoring, checking, patrolling, testing, etc. > > ... read more at the link above > > They can't help themselves because they're too stupid to realize passive > control is the only form of control that is robustly stable. They probably > can't realize this because they can't even conceive of passive control > systems -- sort of like the idiots who gave us civilian nuclear reactors > derived from those designed for nuclear submarines can't conceive of why > they're responsible for the failure to achieve even a tiny fraction of of > atomic energy's peaceful potential. >
