Water is crucial to the continued safety and stability of the Fukushima Daiichi plant.  TEPCO is still injecting hundreds of thousands of gallons into the reactors every day to keep them from overheating again. Contaminated water is currently estimated to be leaking out of the reactors at a rate of 10,000 tons a month, cleaning it up and storing the excess is a constant challenge.

After being used to cool the reactors, the water goes through a processing facility so that radioactive substances are removed to a certain extent. Some of the water is then recycled as a coolant and the remaining portion is placed in tanks at the site.  But the storage capacity could eventually run short, raising the possibility that TEPCO may resort to dumping low—-level radioactive water in the Pacific Ocean, a plan the utility said it was considering in December but gave up due to opposition from the fishing industry.

Since mid-June it is estimated that the cesium activity has increased by about 15 percent due to fuel decay products.

One facility for removing cesium was created by the California-based Kurion Inc, whose equipment us so big it could only be transported by a special Russian aircraft. The Kurion equipment has had issues with pumps, and leaks, which have caused the entire water treatment system to shutdown.  Another was made by France’s AREVA, which came up with an intricate system of pipes and valves that took 50 welders more than a month to put together, TEPCO said. The AREVA system isn’t being used now.

TEPCO shut down the Kurion and AREVA systems in September, after water that had been processed by the Kurion system, was found more radioactive after being run through the AREVA system. It is possible that highly radioactive sludge in AREVA’s system leaked. TEPCO has placed most of it’s hope in Toshiba Corp.’s SARRY system, Toshiba and support companies deploy 140 workers to operate and monitor the water-processing system, and another 20 to oversee pumping and circulation, through a 2.5-mile line of pressure-resistant hoses.

Tepco has the capacity to store 165,000 tons of contaminated water, said Katsuhiko Iwaki, deputy manager of the Fukushima Daiichi stabilization center. About 125,000 tons of water already is being stored. The company plans to expand capacity to about 205,000 tons, he said.

Kurion, the US  nuclear cleanup technology corporation, reported progress of its cleanup efforts at the Fukushima Daiichi disaster. The firm said that since it began processing the highly contaminated water at the plant, it has processed more than 137,340 Metric Tons (MT)(36 million gallons) of waste water and was responsible for removal of approximately 3.5 x 10(17) Becquerel (9.4 million curies) of cesium. The system started operation June 17, and Kurion said that the figure is approximately 70 percent of the radioactivity removed from the doomed nuclear plant.

Internet site reference: http://enformable.com/2012/03/contaminated-water-accumulating-at-fukushima-daiichi-still-poses-problems-for-tepco/