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Nuclear Energy Fuel removal progress at Fukushima reactor unit #4 (TEPCO)

Published on August 20th, 2014 | by Sandy Dechert


TEPCO Concedes Failure of Fukushima Ice Wall

August 20th, 2014 by  

Fukushima ice wall and other TEPCO contaminant isolation schemes (TEPCO)

Less than a week ago, Naohiro Masuda, the Tokyo Electric Power Company’s Chief Decommissioning Officer, spoke about development of the “ice wall” around the four ruined  reactor units at the Fukushima I power station. In the company’s regular “prompt report,” the decommission head said that along with other measures, the $0.3 billion Fukushima ice wall would continue to “contribute to further improving water management at the site.”

Different story on Tuesday, August 19. TEPCO officials told Japanese nuclear regulators that the section of ice wall between the unit #2 turbine building and the cable tunnel—-estimated to hold 5-6,000 tons of highly radioactive water—-was not working. As we reported on June 6, workers from a TEPCO subcontractor, Kajioma Corp., had been tasked to install 1,500 thin tubes of refrigerant at -30° C a meter (3 ft) apart and up to 30 meters (100 ft) underground. The soil thus frozen would create an impervious wall about two meters thick (over 6 ft) around the wrecked reactors.

TEPCO administrators said Tuesday that although they had injected more than 400 tons of ice and dry ice to freeze radioactive water in this section of the Fukushima ice wall, the temperature did not fall low enough and the strategy did not work. The company now plans to start using filler in mid-September to slow the flow of water in the unfrozen section. They expect that doing so will enable it to freeze.

The Japan Times and Japan News (Yomiuri Shimbun) each reported yesterday that “at Tuesday’s meeting, NRA members and experts questioned or even expressed doubt about the effectiveness of the measure.” Nonetheless, TEPCO concluded that it would continue applying the ice in hopes of isolating the contaminants.

Also this summer:

  • Reactor unit #5, previously thought safe, developed a leak that threatened overheating within two weeks.
  • The groundwater bypass operation for contaminant isolation did not significantly reduce the amount of highly radioactive water at three wells examined. TEPCO attributed some of the problem to rain and announced plans to cover soil near the wells with asphalt by the end of next March.
  • Full-scale operation of the advanced liquid processing system (ALPS) for contaminant removal will now not begin until December.
  • Ancillary water treatment facilities, including tritium removal, will not come online until at least September and October.
  • Questions continued about the unskilled, disadvantaged labor pool and its reported connections to Japanese organized crime.
  • Available tank water storage capacity continued to diminish.

Fuel removal progress at Fukushima reactor unit #4 (TEPCO)At the exposed secondary containment pool of unit #4, fuel has been about 75% cleared. 1166 of 1,331 spent fuel assemblies have been moved to safer storage, and 22 of 202 new assemblies have been transferred. The cask has been transported 54 times. However, removal has had to halt for several months to do an annual check on the overhead crane. It is expected to be completed later this year.

A seaside impermeable wall and a subdrain system are reportedly ready for approval from the regulator and the other important stakeholders.

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About the Author

covers environmental, health, renewable and conventional energy, and climate change news. She's currently on the climate beat for Important Media, having attended last year's COP20 in Lima Peru. Sandy has also worked for groundbreaking environmental consultants and a Fortune 100 health care firm. She writes for several weblogs and attributes her modest success to an "indelible habit of poking around to satisfy my own curiosity."

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