A Nuclear Regulation Authority panel introduced new criteria Thursday for issuing atomic crisis evacuation orders that are twice as stringent as current international benchmarks.
The new standards will be reflected in a government guideline for nuclear disaster steps.
Under the new standards, in the event of a fallout crisis involving a nuclear plant, residents outside a 5-km radius of the facility will be told to evacuate within several hours if the radiation level reaches 500 microsieverts per hour. This compares with the figure set by the Vienna-based International Atomic Energy Agency: 1,000 microsieverts.
A restriction on the consumption of food produced near a disaster-hit power plant must be issued within a few days if radiation levels hit 0.5 microsievert per hour, compared with 1 microsievert set by the IAEA.
New criteria also call for issuing temporary evacuation orders to residents in areas where the radiation level reaches 20 microsieverts per hour. The figure is lower than the international standard of 100 microsieverts.
The government will begin collecting information to gauge the effects of a powerful earthquake — intensity of lower 6 or stronger on the Japanese scale to 7 — on municipalities where nuclear plants are located.
Residents within a 5-km radius of a nuclear plant will be asked to prepare to evacuate if all power at the plant goes out for more than five minutes or if the reactor cooling system cannot be run from the control room.
The panel calls for immediate evacuation of residents when a plant operator loses the ability to shut down reactors or when pressure in reactor containers reaches the maximum allowable limit.
The NRA debuted in September as a highly independent body to replace the Nuclear and Industrial Safety Agency and Nuclear Safety Commission. NISA was hit for failing to improve the defenses of Tokyo Electric Power Co.’s Fukushima No. 1 nuclear plant, which suffered three meltdowns last year after being overrun by tsunami.