Japan's release of over one million tonnes of treated nuclear wastewater into the Pacific is officially underway.
Tokyo Electric Power Company Holdings has confirmed that the disposal started at 1pm local time on Thursday.
"This is a big step and punctuating moment in the process of decommissioning," TEPCO spokesperson Junichi Matsumoto told media on Thursday.
"We will have 30 years or so [to release the water], we will ensure safety and quality.
"We will accomplish this discharge, we have to buckle down ourselves and we have to do it with an intense attitude," he said.
TEPCO said it was an important step towards decommissioning the destroyed Fukushima power plant after it was hit by a tsunami 12 years ago.
"Per day 460 tonnes is the amount of discharge. So if there are no troubles in about 17 days, 7800 cubic metres of water will be successfully discharged," Matsumoto said.
Assurances were given in TEPCO's latest media briefing that if unsafe levels of Tritium were detected, the operation would stop until the water has been re-treated through its ALPS processing system and was safe.
Daily monitoring has begun and the International Atomic Energy Agency (IAEA) is also independently monitoring the process on site.
"So, after a sea water pump is operated regarding the vertical shaft, the monitoring will become in service," Junichi Matsumoto said.
The treated water is being discharged "continuously", he added.
Holding Japan 'fully accountable'
Pacific leaders are committed to holding Japan accountable should anything go wrong, the Secretary General of the Pacific Islands Forum, Henry Puna said.
"We've done our best to get Japan not to commence the discharge, until there is full agreement that it's verifiably safe to do so. But Japan has taken a sovereign decision.
"And you know, that point is now past. What we need to focus on now is to hold Japan to account," he said.
He said Japan has made a guarantee that it will comply with international standards and the Pacific will be watching keenly to make sure it stays that way.
"Since the announcement of the discharge in April 2021, our leaders have been busy engaging with Japan.
"The statements are very clear. Their collective statements expressing our concerns given our nuclear legacy issues and that position has never changed," Puna said.
Pacific leaders are to discuss the issue face-to-face in Rarotonga in November at the Pacific Islands Forum leaders' meeting.