More than 10,000 tons of water with low levels of radioactivity have been poured into the ocean from the Fukushima No. 1 nuclear power plant to make room for highly radioactive water, officials said.
More than 10,000 tons of water with low levels of radioactivity have been poured into the ocean from the Fukushima No. 1 nuclear power plant to make room for highly radioactive water, officials said.
Officials at Tokyo Electric Power Co. and the Nuclear and Industrial Safety Agency said Friday the total discharge was less than expected.
TEPCO discharged 10,393 tons of radioactive water, less than the projected 11,500 tons, between April 4 and 10, to free up storage space for water contaminated with much higher levels of radioactivity near the No. 2 reactor.
The radioactivity in the discharged water was 150 billion becquerels, compared with a projected 170 billion becquerels, the officials said.
TEPCO said the figures were provided to diplomatic missions of neighboring countries in Tokyo, the Fukushima prefectural government and four municipal governments and fishing cooperatives.
The utility had been accused of not providing sufficient information to fishery officials and neighboring countries when it started discharging the water.
The water, which contained iodine-131, cesium-137 and other radioactive materials, was stored at a central waste processing facility and groundwater pits around the No. 5 and No. 6 reactors.
The discharged water's radioactivity measured about 100 times the legal concentration standard for seawater.
If an individual ate fish or seaweed harvested at least 1 kilometer from the Fukushima plant on a daily basis for a year, the amount of radiation ingested would be 0.6 millisieverts, one-quarter of the person's natural radiation exposure over the course of a year.
TEPCO, meanwhile, is having difficulty preventing the highly radioactive water in the turbine building and a trench for the No. 2 reactor from leaking into the ocean.
The company transported 660 tons of contaminated water from the trench to a condenser in the turbine building on Tuesday and Wednesday.
The water levels in a shaft of the trench initially fell 8 centimeters, but rose 10.5 cm by Saturday morning, suggesting the possibility that contaminated water is still flowing in from the No. 2 reactor building or elsewhere.
On Thursday, it was discovered that radioactivity levels in groundwater at the No. 2 reactor had risen 17-fold from levels a week earlier. TEPCO officials said radioactive materials may have spread via the ground.
TEPCO is planning to install temporary tanks to store the contaminated water.
The company is also designing a facility to treat the contaminated water by filtering or sedimentation to reduce radioactivity, officials said Friday.
Seawater taken on April 6 near the No. 2 reactor contained about 5.6 million becquerels of iodine-131 per liter, or 140,000 times the standard, and about 3.2 million becquerels of cesium-137, or 36,000 times the standard.
Seawater samples taken April 11 about 30 kilometers east of the Fukushima plant contained 88.5 becquerels of iodine-131 per liter, or more than double the standard, and 71 becquerels of cesium-137, close to the standard 90 becquerels.
Highly radioactive water leaking from around the No. 2 reactor is believed to be the main source of contamination.