Minecraft Nether Reactor?

No only on pocket edition

No you can't - a Nether Reactor was the way they created for the PE version to make Nether materials available, as it was not implemented as a separate world (not sure if it ever did get added).
This is not necessary on the PC version since the player can access the Nether normally.

If you like getting into Reactors, you need to get into Feed The Beast. This is a modded version of minecraft, which is free to download if you have purchased regular minecraft.

They include Modpacks that will grant you the ability to build reactors, machines, run electricity, etc. They make the game 10x larger than what it already is.

Go to Youtube and look up "Direwolf20" he has some awesome videos and features his own modpack on FTB.