Tokyo Electric Power Co. attempted Monday to circulate decontaminated water to cool three damaged reactors at the Fukushima No. 1 power plant but was forced to stop just 1 1/2 hours later by a leak.
The water was found leaking from a hose linking the reactor cores to a temporary water tank.
The start of the “circulating injection cooling” is seen as key in getting a handle on reactors 1, 2 and 3, which are being cooled from outside in an emergency measure that is causing thousands of tons of highly radioactive water to flood the premises.
Tepco, meanwhile, continued decontaminating coolant water from the reactors Monday using a new water treatment system.
Tepco tried injecting 16 tons of water per hour into the reactors and aimed to replace 13 tons of it with water decontaminated by the new system, which removes cesium and iodine.
The new system has been failed in trial runs because of leaks. Still, about 1,850 tons of clean water has been produced so far, and Tepco started injecting that water Monday, the Nuclear and Industrial Safety Agency said.
Some 110,000 tons of highly contaminated water — enough to fill about 40 Olympic-size swimming pools — plus coolant from the leaking reactors is flooding the reactors’ turbine buildings and adjacent areas, raising the risk that it might overflow and enter the Pacific Ocean.
NISA spokesman Hidehiko Nishiyama said the main focus of the circulating injection cooling will first be on reducing the amount of polluted water to address the overflow danger.
The cores of units 1, 2 and 3 are assumed to have melted and sunk to the bottoms of their pressure vessels, where the deformed fuel pellets are being cooled by perpetual water injections.
Reactor lids in works
A combination of traditional post-and-beam construction methods and cutting-edge dome stadium technologies will be used in building giant covers for three damaged reactor buildings at the Fukushima No. 1 nuclear power complex, it was learned Monday.
Major general contractors Kajima Corp., Shimizu Corp. and Takenaka Corp. will begin work as early as Tuesday, with an eye to completing the first cover around the fall, industry sources said.
The construction orders for blanketing the buildings of reactors 1, 3 and 4 to contain the release of radioactive substances are expected to cost ¥15 billion to ¥20 billion each, the sources said.