Sizewell B has begun generating again following the completion of an £80 million upgrade. The Suffolk nuclear plant has been offline since the middle of February. In that time, the plant has undergone refuelling and a series of maintenance works. This included replacing one of the two rotors that are responsible for turning the turbine that makes the power, replacement of one of the four reactor coolant pumps inside the plant’s dome and routine servicing of valves and motors.