Japan expects to stop pumping radioactive water into the sea from a crippled nuclear plant on Saturday.
Engineers have been pumping low-level radioactive seawater, used to cool overheated fuel rods, back into the sea for the past five days due to a lack of storage capacity at the Fukushima plant.
The Tokyo Electric Power Company said on Friday the work was expected to finish "tomorrow" (Saturday).
However, no time frame has been given for when the crisis will end.
Officials say it could take months to bring the reactors under control and years to clear up the toxic mess left behind.
Meanwhile, China has expressed concern about the discharge. It is demanding that Tokyo provide swift and accurate information on the crisis.
China said it had detected 10 cases of ships, aircraft or cargo arriving from Japan with higher than normal levels of radiation since mid-March.
It said traces of radioactivity had been found in spinach in three provinces. The Xinhua state news agency reported trace levels of radioactivity had been detected in 22 provinces.
A magnitude 8.9 earthquake and tsunami on 11 March left 12,787 people dead and 14,991 missing according to the latest figures issued on Friday.
Six nuclear reactors north of Tokyo were also damaged.
An aftershock measured at 7.1 occurred on Thursday close to the epicentre of the earlier quake, at a depth of 49 km.
TEPCO said there had been no damage to its plant from the latest quake.
Japan is facing a damages bill as high as $US300 billion.
The Bank of Japan warned on Friday that power shortages and supply disruptions will leave the economy weak for some time.