Radiation levelsWorkers are now pumping out a large puddle of the contaminated water and will transfer it to other tanks. However, their work is under pressure from forecasts of heavy rain in the area later on Wednesday.
The water's radiation level, measured two feet above the puddle, was about 100 millisieverts per hour, the same as the maximum cumulative exposure allowed for plant workers over five years, TEPCO spokesman Masayuki Ono said.
The massive amount of radioactive water at Fukushima is among the most pressing issues affecting the cleanup process, which is expected to take decades.
Around one thousand tanks have been built to contain the water from three reactors, as well as underground water that is contaminated when it runs into reactor and turbine basements.
However, 350 of these tanks, holding 300,000 tonnes of water, are less durable than others, with rubber seams.
"We have no choice but keep building tanks, or there is no place to store the contaminated water," Mr Ono said.
Pacific threatTEPCO has been unable to prevent some of the radioactive water reaching the ocean - hundreds of tonnes of the water runs into the Pacific Ocean each day, it is understood, and is largely made up of ground surface water mixed with untreated radioactive water.
However, the current leak is the worst of its kind in terms of volume to hit the clean-up operation, TEPCO said. There have been four previous cases of leaks, but each one was only up to ten litres of water, Mr Ono said.
Fukushima suffered multiple meltdowns following a massive earthquake and tsunami in March 2011.
*China – Fulkushima contamination reaches the 20 degrees north latitude = IAEA are still silent on lack of monitoring http://nuclear-news.net/2013/08/25/china-fukushima-contamination-reaches-the-20-degrees-north-latitude-iaea-are-still-silent-on-lack-of-monitoring/