The short answer is yes. This has been done to death EXTENSIVELY. Just because you aren't aware of it doesn't mean that it hasn't happened.
"Or was it simply destruction by way of a thermal reaction or controlled burn."
And the simple answer is no. Not enough space available to hold a sufficient amount of reactive chemical to account for the total heat produced.
I said that it was obvious to me that a reaction took place.
I'm not a chemist, but I do have some experience with catalysts and catalytic reaction behavior. When working, they react evenly and always the same unless you screw it up or change it. They can run for days with very little fuel or catalyst.
It's getting the reaction stable that requires a lot of testing attempts but once you have it....you can repeat it endlessly. But I don't have experience in heat storage chemistry....As I said, I am a electrician...a retired one at that..and I'm too old to have had much experience with thermal imaging. I don't therefore know it well and I don't have a trust relationship with the tech as to what weaknesses it has or how cameras can misread and therefore be used to come to the wrong scientific conclusions. But it appears to me that 500C of the total temp was produced by the reaction and it continued for some 4 days...
Not getting into the weeds on what should be expected because we don't know what went into it and until you can get down to heating a volume of water in a controlled environment to count BTUs, I can't say if the estimates they derived from thermal imaging is correct or not. That painted coating put on the vessel is there for some reason...but I guess that's a secret as well.
Not saying the coating is to significantly change the thermal measurements. I think it's used to shield the optics from seeing a thermal image inside the vessel. A heat signature....if you will that might cause speculation. So you paint the windows ......
To be frank, if they were not hiding so much, I would not be commenting about it.
I doubt I'll ever be commenting on it again since I don't generally keep up with stuff in this category. I am busy enough playing in the stock markets...