The makers of an underground “ice wall” meant to prevent groundwater seeping into the ruined Fukushima nuclear plant and becoming irradiated before it seeped out again have admitted that the system is failing.

(Article by Richard Lloyd Parry)

Tokyo Electric Power Co (Tepco) inserted 1,568 metal pipes filled with coolant 30m (100ft) into the earth, surrounding the plant at one-metre intervals, freezing the earth and supposedly forming an impenetrable curtain. It was switched on in March.

However, the wall appears to have had only a minor impact on the volume of water entering the plant: last month an average of 321 tonnes a day was…