Japan began Thursday August 24 to discharge water from the damaged Fukushima nuclear power plant, despite strong opposition from China and the concern of Japanese fishermen.

The process, which includes pumps, valves and a complex network of pipes, was initiated shortly after 1 p.m. Japanese time (6 a.m. French time) after a brief countdown, according to a live video broadcast by Tepco, the plant operator.

This first spill is expected to last about 17 days and involve some 7,800 m3 of plant water containing tritium, a radioactive substance that is only dangerous in highly concentrated doses. Tepco plans three other spills by the end of March, for volumes equivalent to the first.

In total, Japan plans to evacuate into the Pacific Ocean more than 1.3 million m3 of wastewater stored until now on the site of the Fukushima Daiichi power plant, from rainwater, groundwater underground and injections needed to cool the cores of reactors that went into meltdown after the March 2011 tsunami that devastated the northeast coast of the country.

Many precautions taken

This process will be very gradual – it should last until the 2050s – and the tritiated water content in daily discharges into the sea will not exceed 500 m3. The water has been filtered beforehand to remove most of its radioactive substances, with the exception of tritium.

Japan plans to discharge this water with significant dilution beforehand, so its level of radioactivity does not exceed 1,500 becquerels (Bq) per litre.

This level is 40 times lower than the Japanese national standard for tritiated water aligned with the international standard (60,000 Bq/litre), and it is also about seven times lower than the limit established by the World Health Organization ( WHO) for drinking water (10,000 Bq/litre).

The International Atomic Energy Agency (IAEA), which oversees the dumping operation, gave the green light in July, saying the project met “international safety standards” and will have a radiological impact “negligible on population and environment”.

Beijing slams ‘selfish and irresponsible’ action

But many see things differently. Japanese fishermen first fear an impact on the image of their products. This impact is already being felt at the level of their exports, China having banned imports of foodstuffs from ten Japanese departments, including that of Fukushima, in July. Hong Kong and Macau took similar action this week.

“The ocean is the common good of humanity. Forcibly dumping the contaminated water from the Fukushima nuclear power plant into the sea is an extremely selfish and irresponsible action that disregards the international public interest,” the Chinese foreign ministry said in a statement. communicated.

Analysts say Beijing’s hardline stance on Fukushima water is most likely also linked to already strained Sino-Japanese relations over many economic and geopolitical issues.

Discharging tritiated water into the sea is a common practice in the nuclear industry worldwide, and the annual level of radioactivity from such discharges from Chinese nuclear power plants is far higher than expected at Fukushima Daiichi, Tokyo noted.

“This is a classic case where the perception of the risk associated with tritium is radically higher than the real risk it represents”, commented this week Tom Scott, an expert from the University of Bristol (England), recalling by elsewhere that tritium is naturally present in the Earth’s upper atmosphere and in the oceans.

“Do nothing that is potentially dangerous”

Other Asia-Pacific states with better relations with Japan, such as South Korea, Taiwan, Australia and even Fiji and the Cook Islands, have thus expressed their confidence in the safety of the rejection process. controlled by the IAEA.

Japan must “transparently publish” data on the impact of water discharges from Fukushima “over the next 30 years”, South Korean Prime Minister Han Duck-soo has said, while denouncing “false information” and demagogy about Japan’s decision that Seoul has publicly supported.

Protests against dumping at sea have taken place in South Korea. Ten people have been arrested for attempting to enter the Japanese Embassy in Seoul. But in Japan, a sign of a certain resignation of the population, a protest rally Thursday morning near the Fukushima Daiichi power plant brought together only nine people.

“A good policy would be not to do anything that is potentially dangerous, under the precautionary principle,” protester Ruiko Muto, 70, who lives in Fukushima prefecture, told Agence France-Presse reporter. “The sea is already very polluted, I think it is really unacceptable to intentionally allow this to continue. »