Treated water from the Fukushima No. 1 nuclear plant is safe to be released under controlled circumstances into the Pacific Ocean, according to an independent Tepco adviser.

"It is much better to do a controlled release in my view than to have an accidental release," Dale Klein, a former chairman of the U.S. Nuclear Regulatory Commission, said in an interview in Tokyo. "I get nervous about just storing all that water when you have about 1,000 tanks. You have all the piping, all the valves, everything that can break."

More than five years after the meltdowns at Fukushima No. 1, Tokyo Electric Power Company Holdings Inc. continues to struggle to contain the radiation-contaminated water that inundates the plant.