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.