This might save you some heartache:
http://www.youtube.com/watch?v=9Drg2TmDYEk
Yes, I am from the south.
And yes, i am congested. shush and watch.
actually, i am using a system now that uses the redstone pipes(in the technic pack) that detects if a block is passing through it, hooked it up to the ice overflow that picks up the excess ice from the reactor.
So if no ice is passing through the overflow loop, it means that my primary cooling system is not sufficent, so it shuts down the reactor, letting the primary system fill it up and start the overflow cycle, and thus starting the reactor again.
should the primary cooling system be completely broken, this will prevent it from starting up at all =P
also tested having it start a backup cooling system, using a bunch of chests filled with ice and some engines to pump it into the loop, a fun extra feature but probably not needed.