You can negate that risk by getting a UPS. You should get a UPS in any case imo since even a shitty one lets you at least save your work and shutdown properly if your electricity drops.
I updated mine a couple of weeks ago. I was actually really anxious as It went through the process, but it worked fine, at first...
Then I found out Microsoft considered it a new computer and deactivated windows. (And that's when I found out they deleted upgrade licences from windows 7 & 8 back in September)