The cost increase due to load following operation is related to several factors: (a) additional and more stringent requirements for the plant design, the monitoring system and the fuel element design, (b) increased operation and maintenance expenses since the plant’s components need more frequent inspections and repairs, and (c) income losses due to the reduction of the plant’s load and availability factor. The load following option is therefore already “built-in” in the reactor design and it does not causes additional investment costs. Also, a number of older nuclear units have already been designed for significant manoeuvring capabilities or have already been upgraded to improve their operating flexibility, no investment or limited investment are thus required to exploit those units in a load following mode.