I wrote: "The uranium does not have to melt to form a new geometry.
At three mile island the fuel did not melt - it rubblized. This
involves a change in geometry."
That should say: "The uranium does not have to melt to form a new
geometry. At three mile island the fuel did not *initially* melt -
it rubblized. This involves a change in geometry."
Also relevant from several aspects and viewpoints of the issue, as
well as to both the reactor problems and storage pool problems:
http://en.wikipedia.org/wiki/Corium_(nuclear_reactor)
"During a meltdown, the temperature of the fuel rods increases and
they begin deforming, in case of Zircaloy above 700–900°C. If the
reactor pressure is low, the pressure inside the fuel rods ruptures
their cladding. High-pressure conditions push the cladding onto the
fuel pellets, promoting formation of uranium dioxide–zirconium
eutectic with a melting point of 1200–1400°C. An exothermic reaction
occurs between steam and zirconium, which may produce enough heat to
be self-sustaining even without the contribution of decay heat."
Best regards,
Horace Heffner
http://www.mtaonline.net/~hheffner/
