The operator of the Fukushima Daiichi nuclear plant will attach makeshift hoses to its wastewater filtering system to help improve the water flow.
Tokyo Electric Power Company has been filtering highly contaminated wastewater to remove radioactive material and salt, and then pumping the water back into the reactors as coolant.
But the filters have been working at about 35 percent below capacity, likely because metal piping connecting the tanks has been narrowed by mud.
The utility therefore plans to stop the system for nearly 12 hours on Thursday and attach bypass hoses at 2 locations.
TEPCO has also installed a new device to remove radioactive cesium, in addition to the one currently in use.
It plans to start test-running the device on Saturday, and begin full operation next Monday.
TEPCO aims to improve the efficiency of its water filtering system to lower wastewater pooled in facility basements to safe levels as soon as possible.
The utility says it plans to achieve this for the No.1 and No. 2 reactors in early September.