TEPCO said the Advanced Liquid Processing System was stopped after workers found higher than normal levels of calcium in water in one of the three lines, according to The Hindu. The other two lines had already been stopped for not sufficiently removing radioactive material from the water.
The same system was stopped in March after it was found that one of the three lines was not eliminating radioactive material properly. The system was restarted about five days later.
TEPCO said if all three lines worked, the system could treat 750 tons of radioactive water a day. It is used to treat water that is being used to keep the nuclear reactors cool at the plant after it was hit by an earthquake and tsunami in March 2011.