A unique feature of the Hunterston reactor design was its method of charging and discharging fuel. This was done not from above the reactor as in other stations but from underneath where the working temperatures were lower.
The charge machine, mounted on a travelling carriage on a turntable made a sealed connection with the bottom of the reactor - closing over the ends of the various standpipes carrying the fuel channels - and made fuel changes by remote control while the reactor was still on load and under full gas pressure. It was able to invert fuel channels and change position of elements to ensure that the available heat from each element was used to its full extent.
Three charge machines were provided to the station so that one could be undergoing planned maintenance while the other two were in operation below the reactors.