Highly contaminated water leaked from a large storage tank is seen at the H6 zone of Tepco's tsunami-crippled Fukushima Daiichi nuclear power plant. File picture: Tokyo Electric Power Company, via Reuters

Tokyo -

The operator of a stricken Japanese nuclear plant has not been able to create a “frozen wall” to stop radiation-contaminated water from flowing to the sea, a news report said on Tuesday.

The project to freeze radiation-contaminated water underground at reactor 2 has not gone as scheduled, broadcaster NHK reported, citing plant workers at the Fukushima Daiichi Nuclear Power Station.

Tokyo Electric Power Co has been struggling with massive amounts of toxic water as the operator continues to pump water into three reactors to keep them cool.

The plant suffered meltdowns at three of its six reactors after a tsunami swept through the facilities in March 2011. The operator started to pour coolant into tunnels at reactor 2, hoping to freeze the water.

Tests show the water remains above freezing temperature, NHK reported.

Tokyo Electric spokesman Keisuke Murakami confirmed the report. The problem is attributed to objects in the tunnels, which have prevented the chemicals spreading evenly, NHK said.

The operator may not be able to complete the frozen wall by the end of June, and dry up the tunnel in June, as scheduled, the report said.

The latest trouble does not bode well for the construction of a separate 1.5-kilometre underground ice wall around four nuclear reactor buildings.

The unprecedented project started early June and the operator hopes the wall will help prevent groundwater from becoming contaminated by flowing into the facilities. - Sapa-dpa