At the cabinet meeting on April 13, the Japanese government officially decided to discharge nuclear sewage from the Fukushima Daiichi Nuclear Power Plant into the ocean that pollutes the marine ecological environment.
Agence France-Presse said that Japanese Prime Minister Yoshihide Suga stated that the Japanese government has approved a plan to discharge treated nuclear sewage into the Pacific, but the discharge is unlikely to be implemented within two years.
“This is not a responsible approach. As early as a year or so after the Fukushima nuclear accident, Japan had discharged about 30,000 tons of nuclear sewage into the sea, causing protests from neighboring countries. The Japanese statement at the time was to store high Radioactive sewage makes room. It’s been 9 years since the accident happened today. The measures that should be done should have been done long ago, and such a decision should not be made now.” Chinese Academy of Engineering academician Ye Qizhen said on April 13 to minimize waste. Environmental discharge is the principle, and the discharge of nuclear sewage to the outside is in principle inappropriate.
What is the impact on China’s waters? It’s related to the location of nuclear sewage discharge!
“What is certain is that whether it is discharged outside Fukushima or on the high seas, nuclear sewage will have an impact on China’s waters.” On April 13, an unnamed expert said in an interview with a reporter from the Science and Technology Daily.
The expert said that if the discharge location is selected outside Fukushima, under the continuous action of the Kuroshio Extension and Oyashio Current in the North Pacific, the main body of nuclear material contained in the nuclear sewage will spread eastward, and the west coasts of Canada and the United States will be the main affected areas. . At the same time, a part of nuclear sewage affects China’s waters through the submergence process of the Western Pacific, and the specific quantified impact results need to be further studied. From the perspective of the oceanic cycle, North America is located upstream of the radionuclide transport channel, and its environmental radiation level monitoring and assessment results are of warning and reference significance for China. If the location of nuclear sewage discharge is on the high seas, the impact on China’s waters needs further assessment.
In the 12th issue of “Science Bulletin” in 2011, the results of a paper published by former researcher Qiao Fangli of the First Institute of Oceanography of the State Oceanic Administration and his colleagues showed that there are three types of natural channels for the migration of nuclear leaked materials, namely, random channels in the atmosphere. The fast transport channel of airflow, the slow transport channel of the ocean surface with the ocean current, and the very slow transport channel of the middle and lower oceans. In addition, human activities such as ships and aircraft, as well as marine swimming organisms, will produce unnatural transport processes of nuclear sewage.
An article published in the journal “Acta Oceanica” in 2015, “Numerical Study of Long-term Behavior of Fukushima Cesium 137 in the Ocean” mentioned that, according to the results of numerical simulations, nuclear-leaked material is mainly transported eastward along the ocean surface channel, and its main body It will reach the west coast of the United States within two to four years, and then head south along the California coast of the United States, and then turn west. After such a large cycle, it will return to the western Pacific. At the same time, part of the nuclear material will enter the middle and lower oceans in the western Pacific.
How long is the impact of the accident? Will be long-lived and more complex!
In the history of the peaceful use of nuclear energy by mankind, there have been three relatively serious nuclear accidents.
Unlike the Chernobyl nuclear accident in the Soviet Union and the Three Mile Island nuclear accident in the United States, the Fukushima nuclear power plant is located on the northeastern coast of Japan, on the edge of the Pacific Northwest. Therefore, the artificial radionuclides produced by the Fukushima nuclear accident have a wide range of oceanographic effects. The ecological environment has directly produced nuclear pollution.
How the discharge of nuclear sewage will affect the marine ecological environment and human health and safety is a matter of great concern to society.
Relevant experts believe that the degree of impact of nuclear sewage discharge on the marine environment depends on the type, concentration, total amount, location and time of discharge of radionuclides, as well as specific radionuclides and sediments, marine organisms and other key elements of the marine environment. Complex processes such as interactions.
China and Japan are separated by a narrow strip of water. As early as the end of 2013, pollutants from the Fukushima nuclear accident have been monitored to enter the waters under China’s jurisdiction.
Experts explained that the impact time of nuclear sewage is related to the half-life of artificial radionuclides. The so-called half-life refers to the time required for the radioactivity to reach half of its original value.
Take cesium 134 with a half-life of about two years as an example. After five half-lives, the radioactive intensity drops to 1/32 of the initial value. This means that after about 10 years, cesium 134 has decayed to a negligible level in the environment. . The half-life of cesium-137 is as long as 30 years, and it takes 30 years for the radioactivity to be reduced to half of its original value. In other words, even if 32 years have passed since the Chernobyl nuclear accident, caesium-137 may still exist in the environment.
In 2012, the monitoring results of Japan’s Ministry of Agriculture, Forestry and Fisheries (MAFF) showed that 40% of fish caught in the waters around Fukushima still exceeded radiation standards. Almost at the same time, American scientists published an article in the Proceedings of the National Academy of Sciences that radioactive materials released into the ocean by the Fukushima nuclear accident were detected in bluefin tuna caught off the coast of California.
Relevant experts said that at present, mankind still lacks the technology to effectively dispose of artificial radioactive pollutants entering the ocean, and can only reduce the pollution concentration through the attenuation of radioactive substances and the dilution and diffusion of ocean waters.
Although the total amount of iodine and cesium leaked from the Fukushima nuclear power plant is equivalent to about 10% of the accidental leakage of the Chernobyl nuclear power plant, it is the most serious nuclear source that has directly polluted the marine ecological environment since the peaceful use of nuclear technology by mankind. Some artificial radionuclides with long half-lives can be enriched in marine organisms and transferred through the food chain. For example, strontium 90 is an osteophilic radionuclide and is easy to accumulate on bones, while cesium 137 is easier to concentrate in muscles and liver. Enriched in parts, these nuclides are passed along with food to the top of the biological chain, thereby posing a potential threat to human survival and safety. Because of this, the impact of the Fukushima nuclear accident will exist for a long time, and the transmission process is very complicated.
Are there legal restrictions on nuclear sewage discharge? Japan takes advantage of the fuzzy zone!
Why has there been a large number of voices opposing the direct discharge of nuclear sewage into the ocean? The Japanese government still approves the plan to discharge the preliminarily treated sewage into the Pacific Ocean. Are there any relevant laws and regulations that can restrict this?
In this regard, some experts in the law of the sea believe that the 1972 London Dumping Treaty prohibits dumping in principle, and the 1982 United Nations Convention on the Law of the Sea entrusts the contracting parties with the obligation to protect the marine environment, but the provisions are more principled and vague. In addition, there are scientific doubts about whether low-radiation or high-radiation, low-pollution or high-pollution substances, in fact, Japan has also used legal ambiguities, exception clauses, and scientific disputes.
Source: Science and Technology Daily