nuclear-news

The Nuclear Regulation Authority said plant operator Tokyo Electric Power Co. has yet to submit documents demonstrating the safety and efficacy of the project, which is unprecedented in scale.

Announced in May 2013, the frozen walls are intended to stem the flow of groundwater into the nuclear complex.

“Once the project is started, it will be difficult to turn back,” said Toyoshi Fuketa, an NRA commissioner who is screening the project planned by TEPCO and the central government. “We have to thoroughly examine every aspect of this project because it is such a drastic measure.” TEPCO has been grappling with ways to staunch the daily flow of 400 tons of groundwater into the plant complex. The groundwater mixes with melted nuclear fuel debris and has significantly raised the volume of contaminated water that TEPCO has to deal with, in addition to tons of highly radioactive water used to cool the reactors.

The technique to build the walls of frozen soil is similar to a method used in the construction of tunnels.

A series of steel pipes that contain a liquid at minus 30 degrees spaced at 1-meter intervals will be placed around the buildings housing the four reactors, as well as the turbine buildings.

Stretching 1,500 meters, the frozen walls are expected to cut the inflow of groundwater to 130 tons from the current 400 tons a day.

TEPCO and the government plan to begin the actual freezing of soil in March 2015, with the expectation the walls could last for seven years.

The government has provided 32 billion yen ($313 million) in funding for the project…….

Fuketa pointed out at a review meeting that the document fell far short of providing the necessary safety assurances to pass screening.

The NRA told the utility to provide answers to 24 items that the watchdog is concerned about, such as the possibility of land sinking, leaks of contaminated water and countermeasures in the event the frozen soil thaws.

The NRA is also demanding that TEPCO explain how the construction of the walls of frozen soil will be able to cut the volume of contaminated water…….http://ajw.asahi.com/article/0311disaster/fukushima/AJ201405170031