Tokyo Electric Power Co. resumed operations of the problem-plagued radioactive water treatment system at its crippled Fukushima No. 1 nuclear plant.

But the multinuclide removal facility, called the advanced liquid processing system, or ALPS, is still in the test stage as its three treatment lines have been suspended intermittently due to filter gasket corrosion caused by radiation and other problems.

It is unclear when the test run will end so that full-fledged operations can begin, Tepco said.

The system is said to be capable of removing almost all types of radioactive materials except tritium from toxic water generated in the process of cooling the plant's reactors that suffered meltdowns in the 2011 nuclear crisis, triggered by a massive earthquake and tsunami.

Tokyo Electric is aiming to finish processing the toxic water building up at the complex by next March. To accelerate its efforts to tackle contaminated water, the utility is planning to build two more facilities, including one with enhanced performance.

As of Wednesday, around 360,000 tons of toxic water requiring processing by ALPS was stored in tanks at the complex. When in full operation, the facility will be able to process 750 tons of water per day, according to Tepco.