Each reactor had a service machine for carrying out maintenance operations on the control rods and control rod mechanisms while the reactor was still on load on under pressure.

The machine traveled above the reactor and like the charge machine used closed circuit television (CCTV) to monitor the various operations.

As an additional facility the service machines could have been used for charging and discharging fuel from the top of the reactors if for any reason this was necessary.
Part of the Virtual Hunterston Group of Websites