A possible solution to the increasing amount of radioactive water inside the crisis-hit Fukushima No. 1 nuclear power plant could be to pump groundwater into the sea before it flows into the reactor buildings, as planned by the plant operator, the head of international inspectors has said.

“It will be very nice if they really get to bypass the main (buildings) through these systems — through this direct pumping of the water to the sea or whatever it is. Because it is clean water,” said Juan Carlos Lentijo, head of a 13-member team of the International Atomic Energy Agency that inspected the plant last month.

Tokyo Electric Power Co. has created a system to direct part of the groundwater into the sea before it flows and seeps into the reactor buildings and mixes with highly radioactive water accumulating inside, increasing the amount by 400 tons a day, but has yet to win approval from local fishermen to discharge the water.

Lentijo, who is an expert on nuclear fuel cycles and waste technology, called the ongoing accumulation of water the biggest remaining problem at the site, given that it is possible a relatively stable condition at the reactors and spent-fuel pools could be achieved.

He also said decontamination of the accumulated water is a key factor for the future development and stability of the site.

If such water is removed, “maybe they can go to the building and try to see what the problems are and try to repair these problems,” he said.

As the central government and Tepco review their road map for decommissioning four reactors there, Lentijo called for a decision soon on the plant’s “end-state,” terming it a “very strategic decision” that will have a significant impact on the process as options range from the site’s complete cleanup to its use for long-term storage or disposal of radioactive materials.

Asked about the necessary time to clean up the plant, he called a 30- to 40-year period “realistic from the current knowledge,” which results mainly from decommissioning efforts at previous incidents, while noting that the situation in Fukushima is unique.

But there still is “potentiality for future developments that could enhance the situation,” he said, referring to a recently imposed research program that he said could help in speeding up the process by developing new efficient tools, instruments or methods for enhanced decommissioning.

His view will be included in a final report the team will deliver to the government on May 22, he added.