British Energy has taken its 555MW Dungeness B21 nuclear reactor out of service for scheduled maintenance.
The company said the 555MW unit in Southeast Britain has been taken out of service as part of mainetance which is carried out every three years.
British Energy is owned by EDF Energy.
British Energy has a current installed capacity of around 16.5GW.
The company supplies gas and electricity to over 5.5 million business and residential customers from its nuclear, coal and gas power stations as well as combined heat and power plants, and wind farms.