also
"The word “spent†is a euphemized word meaning “extremely dangerous waste†or the milder form; “irradiated fuel“ "
No, I think spent fuel rod means the fuel is spent- in that the rods when together with other rods no longer make enough energy to be valuable enough to continue to remain in the reactor. And so they are removed and unspent rods are put in their place in the reactor and then the spent rods are stored somewhere.
But the spent rods are extremely dangerous waste and I would say much more dangerous than compared to unspent rods. But they aren't dangerous because of high temperature, but rather they radioactively "hot". "Hot" is the euphemized word.