The brief suspension of spent fuel cooling at unit 5, delayed efforts to block contaminated water in a tunnel, and a typhoon highlighted the news from Fukushima Daiichi this week.
Developments related to the Japanese nuclear plant severely damaged in 2011 include:
SFP Cooling Interrupted at Unit 5
On Sunday, a leaking pipe forced TEPCO to suspend the spent fuel cooling system at unit 5, which is one of two units that did not experience core damage or a hydrogen explosion following the 2011 tsunami. A 3mm hole was found leaking salt water Sunday from a flow control valve on the auxiliary sea water system, TEPCO reported in a release. SFP cooling was stopped during initial repairs. It resumed Tuesday afternoon using the reactor's residual heat removal system.
Tunnel Freezing Process Delayed
On Monday, Japanese regulators ordered TEPCO to improve a process meant to block highly contaminated water in a tunnel between the turbine buildings of units 2 and 3. The structure must be drained and filled with cement before a larger project to block groundwater at the plant using frozen soil can be completed. TEPCO has tried unsuccessfully since April to prevent water from entering the tunnel using ducts installed in the ground meant to create a plug of ice, the Yomiuri Shimbun reported. Nuclear Regulation Authority officials instructed TEPCO to double or triple the number of ducts if necessary to stop the flow.
Plant Prepares for Typhoon
A typhoon expected to be one of the strongest in decades made landfall in southern Japan this week, killing at least three people and subjecting parts of the country to flooding and landslides. At Fukushima Daiichi, TEPCO said in a release that reactor buildings were strong enough to withstand winds expected from the storm. Crews secured smaller temporary structures and built up dams around tank farms that have flooded and leaked contaminated rainwater in the past. The storm was not expected to hit the site directly.