6/26/2011 TEPCO ready to try again with water decontamination system

Source: Japan Today
Date: Jun. 27, 2011 - 05:29AM JST

TOKYO — Tokyo Electric Power Co (TEPCO) said Sunday that it plans to start full-scale operations of its system to decontaminate highly radioactive water at its stricken Fukushima Daiichi nuclear power complex on Monday.

The system has been experiencing a number of glitches since last week. TEPCO said it had replaced the chemicals in the absorption equipment and made the necessary repairs.

Goshi Hosono, director of the government’s nuclear crisis task force, said the system has met operational requirements and had decontaminated nearly 5,000 tons of tainted water in test runs on Saturday.

Workers have cooled the reactors and spent fuel by pumping in fresh water, which becomes contaminated with radiation. About 110,000 tons of tainted water have accumulated, and it could start overflowing in early July unless workers get a trouble-plagued water treatment system working properly. 

The system became fully operational a week ago but shut down after a few hours when one of the radiation absorbing cartridges reached its limit much more quickly than expected.

Hosono told NHK that one problem is that heavy rain due to the rainy season might increase the amount of contaminated water.

6/22/2011 | TEPCO restarts Fukushima Daiichi water treatment but tests show underperformance

TEPCO has continued tested it's radioactive water treatment system at Fukushima Daiichi but discovered that the subsystems were not performing up to expectations. Per the EX-SKF blog expectations were for a 1/1,000,000 reduction in radioactive materials overall after filtering, but only a 1/18,400 decrease was actually achieved. The under-performance was noticed in the Kurion treatment subsystem, as well as the Areva (French) subsystem which both did not perform up to expectations.

The latest estimate for the amount of water pooled at the Fukushima Daiichi complex is estimated at more than 110,000 tons. Per TEPCO spokesman Junichi Matsumoto 1700 tons of water have been treated so far. The processing rate at which TEPCO wants to run the water treatment system is 50 tons/hour. Assuming 24 hour nonstop operation, 1200 tons/day of radioactive water could be theoretically processed at this rate.  Approximately 500 tons a day of water is injected in to Fukushima Daiichi per the JAIF (Japan Atomic Industry Forum, Inc.) Earthquake Report for June 22, 2011.

In order to decrease the rate at which the radioactive water is building up TEPCO has reduced the amount of water being poured in to reactors 1 (-.5 tons/hr), 2 (-.5 tons/hr) and 3 (-1 tons/hour) while carefully monitoring the heat level of the reactors. The #3 reactor did experience a heat rise per TEPCO who are monitoring closely without increasing the water poured in to the reactor. The water flow in the #1 and #2 reactors will be reduced by another -.5 tons/hr.

The right sidebar of the EX-SKF blog shows the number of millimeters left to the top of the water ditches for reactors 2 and 3 if you are interested in imminent overflow.