Nandu News Reporter Sun Xiaopeng Intern Liang Yingyi Correspondent Chen Pengchen Nandu reporter learned today that the Japanese government held a relevant cabinet meeting on the 13th to formally decide to filter and dilute million tons of nuclear sewage from the Fukushima Daiichi Nuclear Power Plant and discharge it into the sea, and the discharge will begin in about 2 years. This news caused an uproar in the world, and security issues became the most concerned topic.
So, is it really safe and reliable to discharge nuclear wastewater into the ocean? What are the implications for humans and marine life, among others? To this end, Nandu reporter interviewed Wang Xun, associate professor of the College of Oceanography of South China Agricultural University, which focuses on marine ecological toxicology and heavy metal pollution ecology research. He said, "The impact on the ecological environment is actually difficult to estimate."
Wang Xun, Associate Professor, College of Oceanography, South China Agricultural University. Courtesy of respondents
point of view
Emissions are "purely economic considerations" and ignore environmental protection issues
Wang Xun told reporters that the nuclear wastewater of the Fukushima nuclear power plant is different from the nuclear waste of other nuclear power plants. In general, under normal circumstances, the nuclear waste generated in nuclear power plants is mostly solid or liquid, small and closed, and not easy to leak. The more internationally accepted treatment method is to directly solidify the nuclear waste and then bury it deeply, usually in the deep sea below 4000 meters;
However, the Fukushima nuclear power plant was affected by earthquakes and tsunamis, and the reactor group was damaged, and radioactive materials inside leaked. At that time, in order to prevent the reactor core from exploding at too high a temperature, the Fukushima nuclear power plant injected seawater into the reactor group to cool down. In Wang Xun's view, radioactive materials mixed with seawater form a large amount of nuclear wastewater, which is huge in volume and complex in composition.
Wang Xun said that if the nuclear wastewater is cured and transported to the deep sea for burial, it is theoretically the safest, but the volume of nuclear wastewater generated so far is too large (it has reached 1.25 million tons), the cost and requirements are particularly high, and it is "economically unbearable". The current behavior of the Japanese government is actually "purely economic considerations" and ignores environmental protection and other issues.
It is understood that according to the resolution of Suga's cabinet, nuclear wastewater will be diluted more than 100 times, and the concentration of tritium will be reduced to one-fortieth of the Japanese national standard and one-seventh of the drinking water quality standard set by the World Health Organization (WHO) before it will be officially discharged into the Pacific Ocean.
Wang Xun said that according to the information currently disclosed, the nuclear wastewater of the Fukushima Daiichi Nuclear Power Plant contains a variety of radioactive substances such as cesium, strontium and tritium. However, "after Japan's long-term treatment, the concentration of more than 60 radioactive substances such as strontium and cesium in nuclear wastewater has been reduced to a certain standard value, and the two substances that are potential threats to human health are tritium and carbon-14." According to Xinhua News Agency, data from Japan's Ministry of Economy, Trade and Industry shows that as of June 2020, the total activity of tritium in nuclear sewage at the Fukushima Daiichi Nuclear Power Plant was about 860 trillion becquerels, with an average of about 730,000 becquerels per liter of water.
worry
Food chain enrichment increases the amount of radioactive substances in fish
Wang Xun mentioned that there are strict restrictions on the amount of nuclear radiation that the human body can withstand, and when the nuclear radiation exceeds a certain dose, it will cause harm to the human body, such as "three causes" (carcinogenic, teratogenic, mutagenic), and if the dose is larger, it will directly cause death, "whether it is a person or other organisms."
According to the Japanese government's plan, if nuclear wastewater is diluted more than 100 times, the radioactive tritium element in it will not cause harm to the human body. However, he is concerned that other radioactive elements in nuclear wastewater (such as carbon-14, with a half-life of more than 5,000 years) are likely to be transmitted and accumulated along the food chain, and enriched in organisms with higher trophic levels (such as fish, seabirds, etc.) to a level of risk. "If people eat these marine fish, they are very likely to cause harm to their health, including the risk of 'three causes'."
According to reports, the phenomenon of biomagnification refers to the phenomenon that organisms accumulate certain elements or compounds that are difficult to decompose from the surrounding environment, and gradually enrich in the organism with the increase of nutrient levels, and the concentration becomes larger and larger. Wang Xun said: "Radioactive materials are transmitted up the food chain by one level, the concentration may increase by more than 10 times, reaching the level of fish, its concentration may be tens of thousands of times higher than the concentration in seawater, at this time the content of radioactive substances in the fish exceeds the safe range, and the possibility of harm caused by people eating fish is also increased." ”
"My personal biggest concern right now is how to emit it." Wang Xun said that the best way is to bury in the deep sea, but if it is only discharged into the bay like the usual ordinary wastewater discharge, on the one hand, it will soon spread to the global sea through ocean currents, and the world will be at risk; on the other hand, due to the impact of food chain transmission, the entire marine fishery resources will be seriously endangered. "In general, the marine surface (within 200m) has the largest number and richest variety of organisms, and if radioactive materials are directly discharged into this range, they can not only endanger humans through food chain enrichment, but also cause unpredictable harm to local ecosystems."
So, is there a better way to deal with the problem of nuclear wastewater discharge? Wang Xun believes that the volume of nuclear wastewater can be concentrated as much as possible, and then cured in storage tanks made of special materials and buried in the deep sea. But in doing so, the cost will indeed be very high.
"The biggest uncertainty about the discharge of Fukushima nuclear wastewater is whether the Japanese government is credible. If nuclear wastewater is not properly treated and directly discharged into shallow seas, the impact on the ecological environment and all mankind is difficult to estimate. At the end of the interview, Wang Xun added.