Why will Fukushima radioactive water be dumped into the sea, what is in it, and what are the risks?

Why will Fukushima radioactive water be dumped into the sea, what is in it, and what are the risks?

Tomorrow Japan will start Dumping of water polluted by the Fukushima nuclear disaster into the Pacific Ocean March 11, 2011, the worst atomic accident in history after Chernobyl. Prime Minister Fumio Kishida gave the go-ahead for the operation to start by Tokyo Electric Power Holdings Corporation (TEPCO), the operator of the Fukushima Daiichi nuclear plant. It will last at least thirty years.

The selection has been approved byInternational Atomic Energy Agency (the International Atomic Energy Agency), according to which the launch, if carried out as planned, would have minimal impact on the environment and human health, while it prompted protests from China, which recalled the Japanese ambassador, and from various Pacific nations. South Korea, which initially opposed this, said it had encountered “no scientific or technical problems” with the launch, but would ask Tokyo to halt the operation immediately if concentrations of radioactive material above international standards were detected in the waters. For many scholars, scheduled release, though unprecedented in this dimension, is the safest option.

Where does Fukushima’s polluted water come from?

the Undersea earthquake of magnitude 9.1 on March 11, 2011 (strongest on record in Japan and fourth most intense on record) Next tsunami Destruction of the cooling systems at the Fukushima Daiichi plant, causing the destruction of the cooling systems at the Fukushima Daiichi plant Three reactor fusion, by liquefying fuel rods containing uranium. In order to avoid further overheating of the highly radioactive liquefied fuel, and thus possible explosions with the release of radioactive materials, TEPCO technicians began pumping seawater over the molten cores, which were thus contaminated with radioactive materials, and are still working. Keep pumping it, because the three reactor cores are still molten.

“After more than 12 years, the continuous cooling process still produces more than 130 tons of polluted water per dayNational Geographic writes. This water floods the tunnels of the station and penetrates into the foundations, as well as seeping into the basic groundwater. The same applies to rainwater that comes into contact with molten reactors. TEPCO technicians collect it, and also take contaminated water from the groundwater, and filter it with a process called an “advanced fluid handling system,” or “advanced fluid handling system.”Alps») and stored in tanks of a capacity of one thousand cubic meters each. Since the day of the accident, twelve years ago, 1,073 or 1.34 million tons filled – the equivalent of 500 Olympic swimming pools. According to the Japanese government, the storage space will run out early next year, and it will have no choice but to start pouring water into the Pacific Ocean.

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What is polluted water in Fukushima?

Molten reactors are produced at the Fukushima plant 64 radioactive elements, also known as radionuclides or radioisotopes. “The most worrying – explains The Conversation – are those that can pose a threat to human health: Carbon-14, iodine-131, cesium-137, strontium-90, cobalt-60 and hydrogen-3also known as tritium. Some of these radionuclides have short half-lives (i.e. decay time) and have already decayed in the 12 years since the disaster. But others take longer to break down. Carbon-14, for example, has a half-life of more than 5,000 years.”

According to Tepco, the Alpine Filtration System manages this Eliminate 62 of these 64 radioactive elements And – writes Nature – to “reduce its concentration below the 2022 Japanese regulatory limits for the discharge of water into the environment” (limits based on IRC indicators). However, there is currently no technology that can effectively filter carbon-14 and tritium. TEPCO says the resulting concentration of tritium is about 1,500 becquerels (a measure of a substance’s radioactivity) per liter. About seven WHO guidelines for tritium in drinking waterNature explains again (the WHO recommended drinking water limit is 10,000 becquerels per liter). The Conversation estimates that the expected release of only 0.06 grams (22 terabecquerels) of tritium per year is a “real decrease in the ocean” compared to the amount of the isotope naturally found in the Pacific Ocean.

The same is true of the carbon-14 in the tanks, which according to Tepco – as Nature writes again – “currently has a concentration of about 2% of the maximum set by regulations, which will decrease further with carbon mitigation”. sea ​​water”.

An alternative to release would be to continue storing the tritium in the plant area or other designated locations for at least a period of time 100 years is the period of decay of this isotope. But according to many experts and observers, the matter is not a feasible hypothesis: “It is not realistic to store water for such a long period, because the quantities are very large. Prolonged storage also increases the risk of accidental and uncontrolled release,” writes The Conversation, for example.

Where and how did the radioactive isotopes from Fukushima spread?

Radioactive isotopes found in marine waters can be transported through currentspiling on phytoplankton and inanimal being They feed on them and their predators and bind to microplastics found in the sea. The main stream bordering Japan is Kuroshio or “Black Stream”. It is the second largest ocean current in the world, and it moves in a clockwise direction from Japan towards North America Then it descends towards the south along its coast.

– Kuroshio Current (Source: National Oceanic Service)

A study conducted by Stanford University marine biologist Daniel Madigan and published in the scientific journal Pnas, found Fukushima isotopes. In tuna caught near San Diego, California, five months after the accident. According to Ken Boesler, a marine radiochemist and Pacific Islands Forum advisor, the radioactivity detected off the west coast of North America was “millions of times lower than the peak levels off Japan, which were dangerously high in early 2011”. Absolutely non-lethal levels have been detected in the US, Boesler told National Geographic, but that “doesn’t mean we shouldn’t be concerned.”

What do ecologists say and what does the scientific community say

Greenpeace Japan He criticized the decision to proceed with the release of radioactive water into the sea. According to the environmental association, “This decision ignores scientific evidence, violates the human rights of communities living in Japan and the Pacific region, and is inconsistent with international maritime law. Finally, it also ignores people’s concerns, including those of fishermen.” Greenpeace argues that filtration does not really work and condemns the “failure of Alpine processing technology” stating that “approx And 70% of this water will have to be treated again». Boesler, an advisor to the Pacific Islands Forum, voiced similar concerns, saying that filtered water still contains radioactive isotopes in different proportions depending on the reservoirs analyzed. “It is incorrect to say that they were successfully removed,” he told National Geographic.

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Azbi Brown, principal investigator for environmental watchdog group Safecast, criticized the phenomenon The New York Times Non-transparency of the Japanese government and TEPCO: “The Japanese government and TEPCO made the decision to release the water after a process that was neither fully transparent nor sufficiently inclusive of important stakeholders, both in Japan and abroad.” This sows the seeds of what could be decades of mistrust and conflict. More worryingly, Japan is setting a precedent for other governments that may be less transparent. This is particularly serious in Asia, where more than 140 nuclear reactors are already in operation and, thanks to the growth of China and India, dozens more are under construction, in the planning stages or proposed. If Japan, a world-respected cultural and economic powerhouse, can get away with dumping radioactive water, what’s to stop other countries? Brown asks in his editorial.

However, the scientific community and the International Atomic Energy Agency believe that releasing filtered water into the sea is necessary The safest choice out of the already possible options. “The amount of radioactive material has reached levels that will not have any impact on the environment. There are no risks, the levels of radioactivity are very low and the scientific community is unanimous in confirming this,” Alessandro Dodaro, director of the Department of Fusion and Technology for Nuclear Safety at INEA, told ANSA news agency.

What will happen now

The launches will not begin on Thursday unless weather and sea conditions permit. TEPCO plans to put it into the sea 7,800 tons of water were treated in the first 17-day cycle. By the end of March 2024, 31,200 tons of treated water will be released, thus emptying around 30 tanks on site. The pace will pick up later. Sea water and marine life will be tested and the results will be published on government and Tepco websites.

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