The Nuclear Regulation Authority proposed stricter criteria Thursday for evacuation and other protective actions against radiation exposure as part of efforts to flesh out atomic disaster mitigation guidelines.

According to a draft of revised guidelines, the NRA said people living outside a 5-km radius from a nuclear power plant should expect to evacuate immediately if a radiation dose of 500 microsieverts per hour is detected, while people living within the 5-km radius will be instructed to evacuate much earlier.

The radiation level is tougher than the international standard. The Vienna-based International Atomic Energy Agency sets the benchmark at 1,000 microsieverts.