The generation of tritium in sufficient quantities is an absolute requirement for a next step fusion device such as DEMO due to the scarcity of tritium sources. A number of methods have been proposed in order to meet this requirement, however a lithium-based tritium breeding blanket that surrounds the fusion plasma is widely considered to be the most suitable solution. Although the production of sufficient quantities of tritium will be one of the main challenges for DEMO, within an energy economy featuring several fusion power plants the active control of tritium production may be required in order to manage surplus tritium inventories at power plant sites. The primary reason for controlling the tritium inventory in such an economy would therefore be to minimise the risk and storage costs associated with large quantities of surplus tritium. The composition of liquid breeding materials could be potentially be adjusted on-line in order to control the amount of impurities and the amount of tritium being produced, however the composition of solid breeders could not be easily changed with a short replacement time. In order to ensure that enough tritium will be produced in a reactor which contains a solid tritium breeder, over the reactor’s lifetime, the tritium breeding rate at the beginning of its lifetime is relatively high and reduces over time. This causes a large surplus tritium inventory to build up until approximately halfway through the lifetime of the blanket, when the inventory begins to decrease. This surplus tritium inventory could exceed several tens of kilograms of tritium, impacting on possible safety and licensing conditions that may exist. This paper describes a possible solution to the surplus tritium inventory problem that includes neutron poison injection, which is managed with a tritium breeding controller. A PID controller is used to inject neutron absorbing compounds into the water coolant, depending on the difference between the required tritium excess inventory and the measured tritium excess inventory. The compounds effectively reduce the amount of low energy neutrons available to react with lithium compounds, thus reducing the tritium breeding ratio. This controller reduces the amount of tritium being produced at the start of the reactor’s lifetime and increases the rate of tritium production towards the end of it lifetime. Thus, a relatively stable tritium production level may be maintained, allowing the control system to minimize the stored tritium with obvious safety benefits. Previous tritium breeding studies have shown that coupled neutron-transport and burn-up is required in order to accurately predict the tritium self-sufficiency. Hence, the FATI code (Fusion Activation and Transport Interface) will be used to perform the tritium breeding and controller calculations. FATI couples MCNP and FISPACT-II in a cyclic manner and implements controller mechanisms between transport and burn-up steps. Results are presented from the FATI code applied to a simplified HCCB DEMO conceptual model.