It was supposed to be 8 minutes. There was a minimum of 250 seconds if the test had to be cut short for some reason that didn't invalidate the test,...
It might, or might not. It might also require temperatures near absolute zero, or pressures high enough to make it of no practical use. There aren't...
1600 K is a hair under the melting point of inconel, and well above the boiling point of sodium. You're talking about a system that could use liquid...