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Friday, July 8, 2011
Water treatment, cooling systems finally working
Tepco able to patch leaks in 4 km of hose, for now
After suffering numerous problems, the newly installed treatment system for decontaminating radioactive water at the Fukushima No. 1 power plant and another system designed to recirculate that water to cool the reactors are finally working.
Leaks at couplings and various other parts of a 4-km-long stretch of hoses between the water treatment system and the circulation cooling system have been a major headache for Tokyo Electric Power Co. workers, who have been forced to shut down the systems several times.
Experts say, however, that Tepco is out of options.
The circulation cooling system "is crucial. Without this, the contaminated water would only keep increasing," said Kenji Takeshita, a professor at the Research Laboratory for Nuclear Reactors at Tokyo Institute of Technology and an expert on nuclear waste disposal.
Takeshita said the initial troubles were expected as the jury-rigged system was built in a rush with different technologies from three countries — Japan, the United States and France.
The water treatment system was installed to address the problems triggered by contaminated water leaking from holes, cracks or other breaches in the containment vessels and filling reactor buildings, turbine buildings and outside trenches connected with those facilities.
Before the decontamination effort started, massive amounts of radioactive water managed to find its way to the sea.
As of Tuesday, there was an estimated 97,610 tons of contaminated water in reactor buildings 1 through 4 and their turbine buildings. The water is transferred to two other storage facilities and then enters the treatment system.
In addition, another 21,850 tons of water were being kept in the two storage facilities as of Tuesday.
Tepco started full operation of the water treatment system on June 17 and began the circulation cooling system on June 27. Both suffered setbacks, including repeated leaks that brought the operation to a halt until they were sealed.
However, the system is now running smoother, which has allowed Tepco's workers to cool reactors 1, 2 and 3 with only decontaminated water since Saturday. Until then, the three reactors were also receiving water from a nearby reservoir.
The water treatment system had processed 13,610 tons of contaminated water as of Tuesday.
For now, Tepco's main task is to keep the operations stable, since more leaks could occur from the couplings connecting the hose sections.
"Maintaining an operation with such a long hose itself is a risk," said Tepco spokesman Junichi Matsumoto.
The leaks at the connections show that they need to be reinforced, he added.
Goshi Hosono, state minister in charge of the Fukushima crisis, played down the troubles.
"Problems may persistently crop up, but the circulation cooling system's operation rate is gradually progressing. By the end of the first phase, I think it will be more stable," Hosono said when he visited the plant last weekend.
But Tepco still has many hurdles to overcome before disposing of the thousands of tons of highly radioactive water accumulating in the compound, which is preventing workers from achieving the ultimate goal of getting control of the radiation-spewing reactors.
Tepco on April 17 revealed its road map to end the crisis and announced that the first phase, including installing the self-contained cooling system, was expected to take about three months.
While the utility appears headed toward stabilizing the cooling system, it is still unsure when it will be able to clear out all the water.
Last month, the government's Nuclear and Industrial Safety Agency ordered Tepco to report changes in the amount of contamination on a weekly basis.
As of Tuesday, the water accumulating in the reactor and turbine buildings had dropped 1,830 tons compared with a week earlier, according to Tepco.
The utility expects to reduce the total by another 1,130 tons by next Tuesday.
The utility aims to process 200,000 tons of the contaminated water by the end of the year, and Matsumoto said the water flooding the four reactor buildings and turbine buildings will be pretty much removed by then, but it is unclear how much will be left in other storage facilities.
The work may continue for a year or longer.
Matsumoto said that while the estimated service life of the water treatment system is one year, Tepco hopes to use it longer through effective maintenance, though this could cause unforeseen problems.
Another task will be the disposal of large amounts of radioactive waste, such as sludge created by processing the contaminated water.
Matsumoto said Tepco has not yet come up with specific plans to dispose of such waste.
"I think the disposal of the radioactive waste will be a critical issue," said Takeshita of Tokyo Institute of Technology, adding, "ways to solve that issue need to be discussed among experts as soon as possible."
No Ehime reactor restart
MATSUYAMA, Ehime Pref. — Shikoku Electric Power Co.'s chances of restarting a nuclear reactor in Ehime Prefecture on Sunday are pretty slim, Gov. Tokihiro Nakamura said.
"The conditions will never be met by Sunday," he said Wednesday of the No. 3 reactor at the Ikata nuclear plant in west Shikoku. The reactor has been shut down for a regular inspection.
Speaking in Ehime's capital of Matsuyama, Nakamura said he will never approve restarting the reactor unless three conditions are met — the central government gives a presentation of safety standards, sufficient safety-enhancing measures are taken by Shikoku Electric, and local communities give their consent.
Shikoku Electric began regular checkups on the reactor April 29 and expected to restart it Sunday before completing the checkups and resuming commercial operations Aug. 9.
Since the March 11 earthquake and tsunami in Tohoku triggered the Fukushima nuclear crisis, however, no reactor undergoing regular checkups has been allowed to resume operation.