 Its generation (or upstream) activities were transferred to three generating companies – 'PowerGen', 'National Power', and 'Nuclear Electric' (later 'British Energy', eventually 'EDF Energy'); and its transmission (or downstream) activities to – the National Grid Company.When the CEGB split up was announced, its power stations were decided to be divided between PowerGen and National Power.The nuclear stations, Magnox, AGR and the then under construction Sizewell B (PWR), were allocated to National Power in their nuclear division.