I'm building a nuclear reactor with IC2 in the Direwolf20v1.023 modpack. I built the reactor, put in a uranium fuel rod with a heat vent below it, and it ran fine with an output of 5EU/t. I then decided to see what would happen if I put another uranium cell in. I put it next to the original cell but did not insert any extra heat vents. As you might expect, the reactor heated up. It triggered my redstone safety system at 150 temperature units (found using a thermal monitor). I promptly removed all the fuel cells in an attempt to cool it down. However, the hull temperture remains at just over 150 units and is not cooling down. How do I make it cool down?
I worked it out. The normal heat vents only cool the fuel rods, not the reactor itself. In order to cool the reactor down I put in a Reactor Heat Vent along with the fuel rods and other normal heat vents. This cooled the reactor down to a safe temperature and it now runs fine.