The idea would totally work, but i don't know how to automatically remove any component of the reactor. You're using another mod than industrial craft?
I don't get either your "start timer".
As i got the pistons only pushing blocs & letting lava go on when the uranium cell is gone, you can guess i know a bit about redstone and detector cable 
But i'm not using any mod permitting me to automatically remove a component from the reactor. I'd be glad to know one.
The idea would totally work, but i don't know how to automatically remove any component of the reactor. You're using another mod than industrial craft?
I don't get either your "start timer".
As i got the pistons only pushing blocs & letting lava go on when the uranium cell is gone, you can guess i know a bit about redstone and detector cable
But i'm not using any mod permitting me to automatically remove a component from the reactor. I'd be glad to know one.
Redpower 2. One of the greatest mods available. www.eloraam.com
Again, thank you a lot for your help. Now i have a choice to make; be dependent on another mod or not...
It's all clear to me now.
"External lava" should be explained in the wiki, by the way.
And i have no idea if fire is doing anything (just stopping the "air bloc" to be counted?), but it never happens with me.
And i have no idea if fire is doing anything
It provides 1 heat/tick per 2 fires. Single lava provides 3. Again it only applies to external cooling down to 0.
