Reactor Inlet is the only block that lets a fluid line cross the sealed shell of an Ala Industrial reactor: the room scanner counts Reactor Inlet as wall, so a pipe connects outside, another inside, and the controller still sees a formed room. Throughput is 50 mB per tick (1/20 of a second) in both directions — water in, steam out — and the same figure is the whole buffer: one tank of exactly one tick of flow, a hole in the wall rather than a reservoir. All six faces accept and give up any fluid, and the block never ticks by itself: the pipes on both sides do the moving. EU never crosses Reactor Inlet: a cable pressed to it stops at the wall as at Reactor Casing, because power leaves through the Reactor Outlet and the controller's five faces.
The buffer holds a single fluid at a time, so one inlet serves one direction: the water line and the steam line go through separate inlets. A room with one Reactor Column needs one inlet in and one out; a room pushed to the HV ceiling of 512 EU per tick needs six of each, twelve total, because no reactor room drinks more than 273 mB of water per tick. Every working room needs that water: while the reaction runs the shell sheds no heat, and a dry room climbs its heat gauge to an accident even on one column. Reactor Inlet is crafted on a vanilla crafting table from four Rubber, two Fluid Pipes, two Shielding Plates and one Reactor Casing, and a pickaxe is required for the drop. Hardness 5.0 and blast resistance 30.0 match the rest of the shell, and the mod runs on Fabric and NeoForge in Minecraft 26.2 Java Edition.