Tokyo: A huge floating structure to hold radioactive water has been berthed at the quay of Japan`s disaster-hit Fukushima Daiichi nuclear power plant.
The plant`s operator, Tokyo Electric Power Company (TEPCO), said the pontoon-type structure would be used to contain part of nearly 90,000 tonnes of contaminated water which has been stored at the facility.
The so-called "mega-float", which is 136 metres long, 46 metres wide and three metres high can hold 10,000 tonnes of water, TEPCO spokesman Hajime Motojuku said.
It was provided by the city of Shizuoka, which had used it as floating park for anglers, he said.
"The mega-float is one of the options to contain radioactive water from the plant. We have also built tanks to store waste water."
A massive 9.0-magnitude earthquake and massive tsunami knocked out cooling systems at the Fukushima plant on the Pacific coast on March 11.
In a stop-gap measure to contain the emergency at the plant, workers have been pouring massive amounts of water onto reactors where fuel rods are reported to have melted, and topped up pools for spent fuel rods.
Meanwhile, a water leak from the crippled nuclear power station earlier this month resulted in about 100 times the permitted level of radioactive material flowing into the sea, TEPCO said.
The operator said the leak discovered on May 11 at a storage pit outside the No 3 reactor of the plant had started in the early hours of the previous day and lasted for 41 hours, releasing 250 cubic metres of contaminated water into the sea.
An estimated 20 terabecquerels of radioactive material escaped as a result, a company spokesman told a news conference.
In April, the plant`s No 2 reactor developed similar leaks, which the operator managed to seal with liquid glass and other substances.
TEPCO later intentionally released low-level radioactive water into the sea after it ran out of storage capacity for more highly contaminated water.
The latest study on the April leak from the No 2 reactor showed it included a total 4,700 terabecquerels of radioactive material in 500 cubic metres of water.
The company reported these new findings to the government`s safety agency late on Friday.