OKUMA, Japan (AP) — At a small section of the Fukushima Daiichi nuclear plant’s central control room, the treated water transfer switch is on. A graph on a computer monitor nearby shows a steady decrease of water levels as treated radioactive wastewater is diluted and released into the Pacific Ocean.

In the coastal area of the plant, two seawater pumps are in action, gushing torrents of seawater through sky blue pipes into the big header where the treated water, which comes down through a much thinner black pipe from the hilltop tanks, is diluted hundreds of times before the release. 

The sound of the treated and diluted radioactive water flowing into an underground secondary pool was heard from beneath the ground as media, including The Associated Press, toured the plant in northeastern Japan for the first time since the water release began.