The operator of the Fukushima nuclear plant says seawater samples taken around the facility are safe.
Tepco’s test results come a day after the treated contaminated water was released from the plant in Japan, which was devastated by a tsunami in 2011.
The discharge into the Pacific sparked protests in the region and retaliation from Beijing.
Japan asked its citizens living in China to keep a low profile on Friday, including speaking quietly in public.
“When going out, try to be careful, such as not speaking Japanese unnecessarily loudly,” the country’s embassy in Beijing said. It also warned citizens to “pay close attention to the embassy’s surroundings” if they were planning to visit.
The Japanese consulate in Chinese-ruled Hong Kong also issued a notice warning of protests there over the drainage, after 100 people took to the streets on Thursday to protest the drainage.
Chinese officials called Japan’s decision to release the water “extremely selfish and irresponsible,” despite the plan’s approval by the UN’s International Atomic Energy Agency.
Beijing, the largest buyer of seafood from Japan, imposed a ban on all such imports after the waters began to drain.
It also saw panic buying of sea salt amid fears that future supplies could be contaminated.
China’s largest salt producer, the state-run National Salt Industry Group, said it was increasing supplies as people in some parts of the country rushed to stock up after the water was released.
But TEPCO said seawater samples taken Thursday afternoon showed that levels of radioactivity were within safe limits.
“We have confirmed that the analyzed value is equal to the calculated concentration and that the analyzed value is less than 1,500 Bq/L,” TEPCO spokesman Keisuke Matsuo said at a press conference.
Becquerel per liter – or bq/L – is a measure of radioactivity. The national safety standard is 60,000.
Matsuo added that the results were “similar to our previous simulations and sufficiently lower” than the safety limit.
He said TEPCO will continue to run the analysis every day for the next month and “even after that, it will continue our analytical efforts.”
Japan’s Environment Ministry said it also collected seawater samples from 11 different locations on Friday and will announce the results on Sunday.
More than 1 million tons of water stored in Fukushima will be discharged over the next 30 years.
Since 2011, TEPCO has been pumping water to cool the remains of three reactors. The resulting polluted water is treated and stored in more than 1,000 huge tanks.
The plant’s operator says the water has been filtered of all radioactive elements except tritium and is safe.
The International Atomic Energy Agency said on Thursday that samples taken from the first batch of softened water destined for discharge showed that tritium levels were within safe limits.
Most scientists agree, but environmental lobby Greenpeace said the filtering process, known as ALPS, was not working and that a huge amount of radioactivity would be released into the ocean.