The underground temperature beside common fuel storage pool has not been decreased since the end of April from Tepco’s report released on 8/20/2015.
Tepco is testing the frozen underground wall to circulate the coolant material in the frozen duct.
They have been monitoring the temperature at 18 points around the crippled reactor buildings.
From their data, the temperature of the monitoring point “No.12″ is showing almost no decrease from the beginning.
This is located between Reactor 4 building and the common pool, where is stocking the fuel assemblies removed from SFP 4 (Spent Fuel Pool in Reactor 4). At the moment of 8/20/2015, it is still over 10 ℃.
For some reason, Tepco stopped sending the coolant material to 4 of the monitoring points.
Among the rest of the points, the temperature is still above 0 ℃ at 8 of 14 monitoring points.
Source: Fukushima Diary