Technically, this reactor setup should have 48 Heat Exchangers, but because it is circuited and buffered, the temp never goes over 900 anyways. This setup buffers 500K steam and fuel is inserted when that gets below 80K. On a single tick, the steam tanks will fill and the temperature will go from 500 to somewhere around 800 - 850 depending on power usage. A small base would be powered for an hour or two before needing more fuel, plenty of time to get more U-235.