Well ignoring the issue of chunks disappearing when power surges happen, how about the question of "where or how can I get some info about how to backup worlds?" (I know, Google, but since we're already talking about it...)
Go into this folder: (or whatever your exact file path will look like)
C:\Users\Adam\Desktop\FTB123\Unleashed\minecraft\saves
Copy the world folder from in there.
Put it somewhere else.