First, start with a nice large lake, and build a moat 14 blocks wide.
A moat like this. There is a blueprint in the book to help you
Place the blueprint, make sure the pumps are green, ignore the red reactors etc.
Build the pumps, i usually build the next expansion-pumps as well to have more room
Fill in the moat, and build the blueprint. Final (right side of the) reactor, ready to receive an upgrade. To upgrade, remove the blue belt, and replace the blueprint. Don't forget to extend the pumps first
