20 Août 2013
August 20, 2013
Tread carefully: Water that had apparently leaked from the drainpipe near a water tank (top right) is seen Monday morning at the Fukushima No. 1 nuclear power plant. | TEPCO/KYODO
Puddles of water with extremely high radiation levels have been found near water storage tanks on the premises of the crippled Fukushima No. 1 nuclear power plant, nuclear regulators and plant operator Tokyo Electric Power Co. said Monday.
The radiation level, measured around 50 cm above the toxic water, stood at about 100 millisieverts per hour, Tepco said, while acknowledging that the water likely came from the tanks. It is possible that around 120 liters of water has so far leaked out.
Tepco denied that toxic water had flowed into the Pacific Ocean, but the Nuclear Regulation Authority ordered the utility to study the possibility that the toxic water had escaped into the sea through nearby drains.
The NRA released a preliminary assessment of a level 1 incident on an eight-point international scale, defined as an “anomaly.”
A low barrier around the tanks is meant to block water from escaping when a leak occurs, but drain valves attached to the barrier may have been left open, allowing water to flow outside the barrier.
A Tepco employee found water leaking from a valve at about 10 a.m. Monday while patrolling the site. One of the puddles outside the barrier was around 3 square meters in size and about 1 cm deep.
A massive amount of radioactive water is accumulating at the plant as a result of continuing water injections into the Nos. 1, 2 and 3 reactors that suffered meltdowns in the midst of the March 11, 2011, nuclear crisis, which was triggered by a huge earthquake and tsunami.
Tepco also said the same day that it had found two workers contaminated with up to 13 becquerels per 1 sq. cm of radioactive material when they were waiting for a bus to leave the site. The contamination was detected on their heads.
Airborne radioactive substances where the workers were waiting were around eight times the alert level. The two workers did not suffer internal exposure.
A similar incident, involving 10 people waiting for a bus, occurred a week earlier. Their contamination was up to 19 becquerels per square cm, lower than the state limit of 40 becquerels.
TOKYO, Japan (Kyodo) -- An estimated 300 tons of highly radioactive water have leaked from one of the water storage tanks at the crippled Fukushima Daiichi power plant, making it the worst leakage incident from such containers, plant operator Tokyo Electric Power Co. said Tuesday.
TEPCO detected in the leaked water 80 million becquerels per liter of radioactive substances emitting beta rays, such as strontium-90, and admitted that it has not yet identified from which area of the tank the polluted water is escaping.
"We think the leakage is continuing," TEPCO spokesman Masayuki Ono told a press conference, but denied that toxic water is flowing into the adjacent Pacific Ocean on the grounds that the radiation level of the water in a nearby gutter was not high.
TEPCO calculated the amount of leakage based on the water level within the tank, which was about 2.9 meters lower than it should have been. The tank originally contained about 1,000 tons of contaminated water.
TEPCO has collected around 4 tons of the leaked water. Admitting that the toxic water has most likely flowed into the soil, TEPCO said it is currently working to prevent the spread of contamination.
The latest revelation came a day after TEPCO said puddles with extremely high radiation levels had been found near the tanks.
A massive volume of radioactive water has been accumulating at the Fukushima plant as a result of continuing water injections into the Nos. 1 to 3 reactors that suffered meltdowns during the nuclear crisis triggered by a huge earthquake and tsunami on March 11, 2011.
TEPCO estimates leak at 300 tons
The operator of the disabled Fukushima Daiichi nuclear plant says about 300 tons of highly radioactive water appears to have leaked from a storage tank. It says some of the water could have seeped into the ground.
The tank is one of 26 installed on the inland side of the No.4 reactor. The tanks are surrounded by a low barrier.
Tokyo Electric Power Company initially found water forming a puddle near the barrier on Monday morning. The water had apparently leaked through the barrier's rainwater drainage pipe.
TEPCO officials say an inspection showed a drop in the water level inside one of the 26 tanks. They estimate that the tank has lost about 300 out of the roughly 1,000 tons of water it held.
Officials say water inside the tanks has been treated to reduce radioactive cesium. But a test of the leaked water found it contained up to 80-million becquerels per liter of beta-ray emitting substances, including strontium.
The utility plans to remove soil near the tank. It will also measure radiation levels in the area to determine the scale of the latest water leakage at the troubled nuclear plant.