The Extraction Steam System uses steam discharged from different points of the steam turbine to heat condensate and feedwater prior to the steam generator. Non-return valves are installed on the lines close to the turbine to support operation during transient conditions. The OPEN100 design, because of its size, relies far less on regenerative heating and as a result has a much simpler design and layout with extraction steam used only for preheating the feedwater in a deaerator and a single feedwater heater.