Catastrophic failure is not a failure mode for a modern reactor past its service life.

Catastrophic failure is an engineering term, and also general language term, to describe when a device that breaks down completely, or breaks down in such a way that it's completely unusable.

You're assuming I use that word just to explain a huge explosion and loss of life, which is possible as a side effect of catastrophic failure, but not necessarily, like 3 Mile island.