So as I wandered around Vault 101, slaughtering people that even looked at me wrong, The strangest question came to mind.
During all the many years of operation, when people died due to old age or disease, what happened to their corpses?

Quite a few, probably about one or two generations worth of people, over two hundred years, assuming one person lived to be on average idk, 85, so that means the vault would be about two and half generations in. The deceased are incinerated.

Well that leaves little to the imagination. I was hoping for something cooler than incineration

Nope. It's confirmed in game from the poem that mystic women gives you. What did you expect, that they processed them into food, a la soylent green?