How to Cool a Create Nuclear Reactor and Prevent Meltdown

Place Coolers Strategically

Reactor Cooler blocks are what keep your core from overheating. Place them directly adjacent to the Reactor Core where possible — coolers that are not touching the core or the hot casing do much less work. If your reactor is large, ring the core with coolers on multiple sides rather than clustering them in one spot. More coolers means more heat shed per tick, but they also take up interior space you might want for fuel rods.

Supply Coolant Continuously

Coolers need coolant to function. Pipe Cooled Nitrogen Concentrate or your chosen coolant into the Reactor Fluid Input and make sure the supply never runs dry. Use a tank buffer between your production line and the reactor so a brief hiccup upstream does not starve the core. Monitor the fluid input with a gauge or comparator so you can see when it is running low.

Watch the Controller and Alarm

Attach a Reactor Alarm to the casing and keep an eye on the Reactor Controller's readouts. If temperature climbs steadily even with coolers running, you are either under-cooled or over-fueled — reduce fuel input via the Reactor Rod Input or add more coolers. If the alarm triggers, shut the reactor down immediately and let it cool before restarting. Never ignore a rising temperature; the Nuclear Explosion that follows will destroy your base and irradiate the chunk.