26 September 2023

Misleading: Beige sea surface near Fukushima nuclear plant is unrelated to treated wastewater

Tritiated water is colorless. The shoreline discoloration is likely caused by stirred-up sediment that was observed even before the discharge.

On Aug. 24, the day Japan began releasing treated wastewater at Fukushima Daiichi Nuclear Power Station, a Japanese tweet implied that the ocean was already polluted, pointing out that the seawater nearby had “out-of-ordinary” colors.

The post included an image showing beige-toned seawater marked as “after release” in Japanese. This was contrasted with the turquoise-blue water within the breakwaters marked as “without released [water]”.

The tweet gained over 1,600 engagements at the time of writing and went viral on Weibo (for example, here and here) and other Chinese websites, garnering more than 22,000 engagements in total.

Japan’s 30-year discharge plan has raised political, environmental, and societal concerns from its neighboring countries, especially China.

However, the claim is misleading.

The seawater with traces of beige was regularly spotted even before the wastewater discharge began.

On that day, the nuclear wastewater discharge was live broadcasted by many news organizations, including TV Asahi (ANN News). The recorded live stream on YouTube shows the same pattern of water discoloration repeatedly before the discharge (for example, 22 minutes and 12 minutes before the release).

The same pattern of water discoloration surrounding the breakwaters can be seen in the ANN News livestream 22 minutes before the discharge.

Annie Lab also found a number of historical satellite images through Google Earth Pro, showing various levels of sandy-toned sea surface discoloration outside the plant’s breakwaters over the years, including those that were taken in March 2011 and March 2019.

Google Earth Pro satellite images captured in March 2019 (left) and March 2011 (right) both show various levels of sea surface discoloration

Other stock images such as the Alamy photo captured by Kyodo News in November 2016 shown below and another one captured by the Yomiuri Shimbun in October 2021, also feature a similar pattern of discoloration.

Kyodo News photo on Alamy showing the discoloration in 2016 and Yomiuri Shimbun in 2021.

Dr Christelle Not, a geochemist and assistant professor at the University of Hong Kong’s Department of Earth Sciences, said the discoloration could be caused by sediment in water, such as the soil in the runoff after rainfall, or a bloom of plankton, tiny organisms that live in water.

“Both [causes] are natural and carry no impact on the marine fauna. The [waste]water discharged should not trigger any of these causes,” Not said.

She noted that with the exception of the contaminated water containing sediments on its own, “the released water shouldn’t cause discoloration.”

Annie Lab looked into a 2022 implementation plan by Tokyo Electric Power Company, the operator of the Fukushima Daiichi nuclear power station.

The document includes information about the geological composition near the shoreline. The plants’ breakwaters and their adjacent seabed appear to be surrounded by sand, rock, and debris of different sizes.

A 2022 TEPCO report shows the shoreline is surrounded by coarse sand and debris, marked in orange.

The graphic in the document also shows the position of the one kilometer-long treated wastewater undersea discharge tunnel (marked in blue), which appears to be far from the majority of the sea surface discoloration.

According to the International Atomic Energy Agency’s safety review report on Fukushima, contaminated wastewater is treated with the Advanced Liquid Processing System (ALPS), a closely monitored pumping and filtration system that uses a series of chemical reactions to remove 62 radionuclides from the contaminated water apart from tritium.

It states that tritium is released predominantly as tritiated water (HTO) from nuclear installations. Tritiated water is colorless and odorless, according to the Canadian Nuclear Safety Commission.

Explanation of the ALPS treatment process. Source: IAEA

The wastewater with tritium would be further diluted with seawater of more than 100 times its volume, to 1/40 (2.5%) of the tritium concentration permitted under Japanese safety standards before being discharged.

According to IAEA, tritium also exists naturally and is produced in the atmosphere by cosmic rays, energetic particles originating from solar coronal mass ejections, as well as direct accretion from the sun.

IAEA estimates there are two million terabecquerels, the unit measuring radioactivity, of tritium on earth. The limit of the tritium in the treated water to be released a year at Fukushima is 22 terabecquerels.

The IAEA’s review concluded that the discharged water would have a negligible radiological impact on people and the environment, mentioning that nuclear power plants around the world regularly release treated contaminated water with low concentrations of tritium and radionuclides into the environment.

In March 2011, the Great East Japan Earthquake with a magnitude of 9.0 caused a tsunami that wrecked a wide area of coastal Japan. The Fukushima Daiichi Nuclear Power Station endured substantial damage, which resulted in the loss of the cooling function at three of its operating reactor units and fuel pools.

Japan Fact-check Center also debunked the same claim.