TEPCO said it halted the Advanced Liquid Processing System (ALPS)—the only one of three that was in operation—early Friday following “an alert suggesting abnormality in the process”.
The firm said the cause of the problem remained unknown, but no leaks of radioactive water from the system had been detected.
The stoppage came just four days after TEPCO got the system back up and running following a breakdown when a piece of plastic clogged the machine.
ALPS is the great hope for TEPCO, which is badly struggling to cope with a huge—and growing—volume of liquids at the plant, where reactors had to be cooled with thousands of tonnes of water after a tsunami hit in March 2011.
The glitch is the latest of several mishaps in less than a month, and prompted the Nuclear Regulation Authority (NRA) to summon the utility president and reprimand him in public on Friday.
Katsuhiko Ikeda, administrative head of the agency, ordered TEPCO President Naomi Hirose to ensure better on-site management and prevent human error, and submit improvement plans in a report.
“It is unacceptable that contaminated water leaked because of human error,” Ikeda said. “We must conclude that on-site management is extremely poor.”
Tetsuro Tsutsui, an engineer and expert of industrial tanks, said the latest problem was emblematic of how TEPCO runs the precarious plant. He said it was “unthinkable” to fill tanks up to the top, or build them on a tilted ground without building a level foundation.
Read more at NRA publicly reprimands TEPCO chief over latest problems at Fukushima