Fukushima operator struggles to build ice wall to contain radioactive water Tepco says it is behind schedule with scheme 
because temperature of pipes sunk into ground is not low enough Agence France-Presse in Tokyo theguardian.com, Tuesday 17 June 2014 The operator of Japan‘s battered Fukushima nuclear power plant has said it is having trouble with the early stages of an ice wall being built under broken reactors to contain radioactive water.
Tokyo Electric Power (Tepco) has begun digging the trenches for a huge network of pipes under the plant through which it intends to pass refrigerant. This will freeze the soil and form a physical barrier that is intended to prevent clean groundwater flowing down mountainsides from mixing with contaminated water underneath the leaking reactors.
Tepco said on Tuesday that a smaller, inner ice wall whose pipes it sank earlier to contain the already-contaminated water was proving difficult. “We have yet to form the ice stopper because we can’t make the temperature low enough to freeze water,” a Tepco spokesman said.
“We are behind schedule but have already taken additional measures, including putting in more pipes, so that we can remove contaminated water from the trench starting next month.” The coolant being used in the operation is an aqueous solution of calcium chloride, which is cooled to -30C (-22F).
The idea of freezing a section of the ground, which was proposed for Fukushima last year, has previously been used in the construction of tunnels near watercourses.
However, scientists point out that it has not been done on this scale before, nor for the proposed length of time……http://www.theguardian.com/environment/2014/jun/17/fukushima-ice-wall-radioactive-water