Tokyo Electric Power Co. said Saturday it has halted a trial run of its much-vaunted water treatment system at the Fukushima No. 1 plant just a day after it resumed operations.

At around 10:40 p.m. Friday, Tepco detected technical problems with line C of the advanced liquid processing system (ALPS), which was restarted after midnight Thursday and had processed around 100 tons of toxic water before its suspension. Tepco is investigating the cause.

ALPS extracts most radioactive materials from contaminated water and is seen as crucial in the utility’s efforts to process the vast amount of toxic water that continues to accumulate at the crippled No. 1 nuclear plant. The system operates via three separate lines.

While Tepco’s existing water treatment facility at Fukushima No. 1 can only remove cesium, ALPS can extract 62 different types of radioactive materials, with the exception of tritium.

Tepco and the government had trumpeted the ability of ALPS to process tainted water faster than it builds up at the wrecked complex, which suffered three meltdowns in March 2011. They planned to expand the system and to enhance its performance in the future.

The utility initially started a trial run of lines A and B in March, but halted all operations in June after the tank of line A was found to be leaking water because of internal corrosion. While Tepco worked to repair the tank and investigate the problem, it sped up efforts on line C, which at the time was still waiting to be tried out.