Extreme Reactors reactor simulator

Draw your reactor's interior from above: fuel rod columns, and the blocks or fluids that fill the space between them. The simulator runs the reactor for 40,000 ticks the way the mod does and reports the power or steam it settles at, how much fuel it burns and how hot it runs. The link in your address bar keeps the design.

How a reactor makes power

Each tick one fuel rod fires radiation in the four horizontal directions, up to four blocks each way. Its strength grows with the total fuel in the reactor, a little faster than linearly, which is why big reactors are more efficient than small ones. Whatever the radiation passes through absorbs part of it: other fuel rods turn it into fuel heat (and more fission, the fertility number), moderator blocks and fluids turn it into casing heat and soften it so the next fuel rod catches more. The casing walls stop it.

Heat flows from the fuel to the casing through whatever touches the rods, so conductive moderators like graphite, gold or diamond keep the fuel cooler. In passive mode the casing's heat above 20 °C is turned into RF (a Basic reactor keeps 80% of it). In active mode it boils water into steam at 4 units of heat per mB, for a turbine to turn into power, and the casing settles above water's boiling point.

Radiation that one fuel rod catches from another builds fertility, and fertility cuts the fuel each fission uses (to a third or less in a dense core). Control rods cut the radiation a rod emits and make neighbouring rods absorb more of it without breeding fertility.