Fukushima water purifying system plagued by failures

July 16, 2011

By NAOYA KON / Staff Writer

Problems stemming from complicated procedures, as well as dumb human errors, have plagued Tokyo Electric Power Co.'s key weapon in ending the crisis at its Fukushima No. 1 nuclear power plant.

In less than a month of operations, the cyclic water injection and cooling system, which purifies accumulated radioactive water and recycles it to cool down fuel rods, has experienced more than 10 suspensions and water leakages.

The system contains 4 kilometers of piping that connects the nuclear reactor buildings, a radioactive water purifying plant and storage tanks. Most of the failures have occurred at the purifying plant.

Water leakages were reported on July 10 and 12 at a purifying unit manufactured by France's Areva SA.

A polyvinyl chloride pipe junction found damaged was replaced by a metal part. But a similar failure occurred at another junction on July 13.

Workers had to fix the problem quickly amid high radiation levels within the site.

A number of failures also hit a unit manufactured by Kurion Inc. of the United States that uses zeolite to absorb and eliminate radioactive substances.

The unit stopped immediately after entering full operations on June 17.

This was the first time for both Areva and Kurion units to be used in such a complicated system to treat saline radioactive water.

Many failures revealed poor preparations.

On June 22, after the performance of Kurion's purifying unit was unusually low, workers found that a valve that should have been closed was actually open in part of the piping. That allowed radioactive water to pass through freely without being purified.

The "open" and "closed" symbols were mixed up near the valve.

On June 29, the equipment stopped and an alarm sounded because a valve that should have been set on "automatic" was erroneously set on "manual."

The following day, Areva's purifying unit stopped automatically because a wrong figure had been set for the water level in a tank.

In the face of these failures, TEPCO has only reiterated: "The system is of an unprecedented large scale. We hope to arrive at stable operations after reviewing the initial glitches."

But the problems do not end there.

Water is still not flowing smoothly within the purifying unit, with the hourly flux only about 70 percent of the original projection.

The cause has not been specified, although TEPCO suspects a flaw in the piping structure.

The water for the entire system is flowing at only 73 percent of capacity. If the utilization rate does not improve, it may compromise TEPCO's goal of removing all accumulated contaminated water in the reactor building basements and elsewhere by the end of this year.

By NAOYA KON / Staff Writer
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