I thought I'd share the plans I have for a reactor chain.
It currently has 6 reactors, two of which are on at a time while the other 4 cool down. so there is almost a constant 400 eu/t without having to use casuc style ice/water bucket cooling.
of course this is easily expanded. by adding more reactors you can reduce the 30 second timer the longer the chain is. or keep the timer the same and increase the output. the only thing you need to remember is that the timer must be set to the time it takes a reactor to cool, divided by the amount of reactors. in this case a reactor takes 180 seconds to cool, there are 6 of them, so i have the timer set to 30 seconds.
i've set the temperature cut off to 200 as the cooldown isn't an exact science and is affected by tick rates.
anyway this is a very expensive way to run your reactors, but i thought i'd share.
attached is a link to my tekkit single player save for you to peruse
http://www.mediafire.com/?96724m7x7eb9sv2