Controlled areas are areas in which persons may receive an effective dose of more than 6 millisievert or higher organ doses than 45 millisievert for the eye lens or 150 millisievert for the skin, the hands, the forearms, the feet and ankles in a calendar year. In this context, the external and internal radiation exposure is to be considered. A period of 40 hours per week and 50 weeks per calendar year for remaining in a certain area is decisive for the determination of the limit for controlled area or monitoring area, if no other reliable data on time of staying is available. Controlled areas must be fenced off and identified. Access is permissible only with observation of special radiation protection regulations.