rhn, you are almost always correct (and incredibly helpful to all), however in this case I think a correction is needed. Using twisto's method (which I also proposed because I love how simple and easy it is), the reactor will NOT "raise the temperature of the reactor as high as it can". It's actually very simple. When the reactor power buffer (10,000,000 RF worth) is full (100%), then the control rods will be fully inserted, and the power output will be 0%. Conversely, when the power buffer is at 0 RF, that's the only time the reactor will power up to 100% of capacity. It's just an inverse relationship between the buffer storage and the control rod insertion percentage. If the reactor is 71% full, then the control rods will be inserted 100%-71%=29%. What I'm finding is that, for my base, the Reactor will settle into a more or less "steady state" power storage of around 2/3'rds full. Even if I place a huge power draw on the reactor, nothing will happen - it won't suddenly shoot up to highest temperature. In fact, nothing at all will happen... until the power level drops. As it drop, the reactor will correspondingly raise its output, but very slowly, to compensate.
This setup is so simple and so easy, it is a perfect way to avoid having to monitor the reactor constantly. A few days ago I didn't have the rednet ports installed and I forgot I had turned the reactor on... well I blew thru my entire stack of Yellorium in the reactor - I wasted it. Having the simple rednet ports hooked up like twisto suggests is the perfect "early-game" method of preventing such waste. Instead of a 3x3x3 reactor, I just build a 3x3x4 tall reactor, which gives me enough space to install the two rednet ports.