The utility initially planned to begin the tests for the system, intended to decontaminate highly radioactive water that is accumulating at the site and hampering work to restore the damaged plant, last Friday, but postponed it because water leaks were found in the equipment that day.
Repairs to fix the water leaks were completed by Sunday and the firm, also known as TEPCO, was getting ready to conduct the tests.
But the fresh problem is likely to cause a delay in the company's plan to put the system in full operation from mid-June, as the trial run using low-level radioactive water is expected to last about a week.
The firm said the quantity of water that was run through the system during the preparations decreased while it was going through an adsorption device designed to remove radioactive substances, indicating the possibility that the piping or other parts may be clogged, the officials said.
The operation of the system is seen as crucial to containing the three-month-old nuclear crisis, as the decontaminated water is expected to eventually be recycled as a coolant for the reactors, which lost their cooling functions as a result of the March 11 earthquake and ensuing tsunami.
