But the Korea Institute of Nuclear Safety said that although small levels of radioactive iodine and caesium particles had been found in rain falling in part of the country, they were not enough to cause concern over public health.
In Vermont, legislators voted in February to prevent Vermont Yankee from continuing to operate because of safety fears and recent leaks of tritium, a radioactive isotope of hydrogen.
China froze all new nuclear power plant approvals on Wednesday so that safety standards can be reviewed following the explosions that leaked radioactive steam from Fukushima.
None of the Daiichi accidents were considered major safety hazards, and none caused any injuries or led to the release of any radioactive material outside the plant, until this month's accident.