The Japanese government originally planned to make a decision to discharge sewage into the sea in 2022 on October 27.
After the news broke,
pressure from home and abroad
made the plan have to be postponed again.
The 2011 earthquake and tsunami severely damaged the Fukushima Daiichi Nuclear Power Plant in Japan, causing 3 of the 6 reactors to melt down. Now, nearly 10 years later, the tide of the tsunami has long since subsided, but nuclear power plant managers are still struggling to cope with another dangerous flood: large amounts of radioactive waste water produced by damaged nuclear power plants every day.
More than 1.2 million tons of water contaminated by radioactive materials are currently stored in an expanding forest-there are currently 1,044 huge steel containers stacked there. Every day, 170 tons of sewage need to be stored, and so far, There is no final plan to deal with them.
Major Japanese news organizations recently revealed that the new Japanese government has made a decision that the Fukushima nuclear power plant will discharge the treated sewage into the neighboring Pacific Ocean. The operation will start as early as 2022 and will take decades to complete.
The Japanese government originally planned to make a decision to discharge sewage into the sea on October 27. After the news broke, pressure from home and abroad caused the plan to be postponed again.
’s water storage tank is almost full
Follow-up cleanup and withdrawal of the leakage from the Fukushima Nuclear Power Plant , Has spent US$200 billion on the holder of this nuclear power plant-Japanese power giant Tokyo Electric Power Company. But now, the clean-up is still not complete, which involves a large amount of seawater used to cool the reactor, groundwater flowing into the facility, and contaminated rainwater after the accident. As of September this year, the accumulated sewage from nuclear power plants has reached 1.23 million tons. According to the Japanese Ministry of Environment, at this rate, the existing water storage tanks will reach their capacity limit in 2022.
Lake Barrett, who once served as the head of the Office of Civil Nuclear Waste Management of the U.S. Department of Energy, is also one of Tokyo Electric Power’s consultants on this issue. He said in an email reply to the interview that Tokyo Electric Power has been purifying the water , But there is always a low level of radioactivity.
Specifically, Tokyo Electric Power Company will pump out the polluted water and let it pass through a huge filtration system. Inside the system are rows of stainless steel pipes filled with sand-like particles. These particles grab cesium ions, strontium ions and other dangerous isotopes in the water and release sodium. After being filtered through multiple water treatment systems, the water removed most of the radioactive contaminants-but not including a radioactive substance called “tritium.” Tritium is also the main reason why the fate of these waters has not been determined.
”Tepco has proven that it can adequately treat this water to meet all water treatment standards. At present, except for the inability to remove tritium, most of the sewage has been treated to an appropriate level, and the remaining part is undergoing final cleaning.” Lake · Barrett said that any type of radioactive material release restrictions are very strict. Even if it meets international safety and environmental standards, the water can only be stored at the production site, and the existing storage scale is rapidly approaching the maximum water level.
The internal committees of the Ministry of Economy, Trade and Industry of Japan have conducted many discussions on the treatment of Fukushima nuclear sewage, and proposed five options including evaporative release, electrolytic discharge, dilution into the sea, underground burial, and injection into the ground. Some of them have no precedent and cannot assess risks, and some have many obstacles in technology and time, so there has been no conclusion. The Japanese government has never made a decision, so discussions on the disposal of Fukushima’s radioactive sewage will appear in media reports from time to time and cause controversy.
But recently, discussions on this issue have accelerated. On December 23, 2019, the department decided to focus on the treatment methods: release after evaporation and discharge into the sea after dilution. According to the official website of the United Nations, due to the postponement of the 2020 Tokyo Olympics, the Japanese government was able to free up its hands and make the latest decision on the disposal of nuclear waste.
On September 26 this year, the new Japanese Prime Minister Yoshihide Suga personally inspected the Fukushima nuclear power plant. Three weeks later, on October 16, many Japanese media reported that the government would formally decide whether to discharge Fukushima nuclear sewage into the Pacific as soon as this month. Just as there is an uproar every time Japan involves the disposal of nuclear-contaminated wastewater, the latest developments in this round are also widely circulated on social media and arouse concerns about the environment and safety of the international community.
an international practice to release into the sea
Lake Barrett said that although TEPCO’s water treatment system technology It is among the most advanced in the world, but many existing studies have shown that there is still no practical method to filter and clean a large amount of low-concentration tritium in Fukushima nuclear sewage.
Tritium, also known as superheavy hydrogen, is one of the isotopes of hydrogen. Unlike general pollutants that exist in water in suspended or dissolved form, tritiated water is a change in the structure of water molecules themselves. Therefore, it has the same physical and chemical properties as water, and it is difficult to separate it with conventional technology.
Lake Barrett further explained that traditional water treatment systems cannot remove tritium. However, due to the relatively low content of tritium and its low impact on organisms, the planned dilution of the existing tritium in Fukushima sewage can meet all international and Japanese standards.
Professor Idemitsu Kazuya of the Department of Applied Quantum Physics and Nuclear Engineering at Kyushu University in Japan studies radioactive waste disposal. He told reporters that there are two ways to dilute the concentration of tritium below the emission level: the liquid is diluted and released into the ocean or evaporated into the air. in. From a cost and safety point of view, if only low concentrations of tritium are contained, then discharging it into the ocean will be the “best solution.” In fact, operating nuclear power plants all over the world are discharging diluted tritium-containing water into the ocean.
Lake Barrett explained that discharging in the form of water vapor is also an option, but there is no precedent for such a huge amount of sewage in Fukushima, because so much water contains a lot of salt residues that need to be treated. In this case, it is more common and cheaper to dilute to the discharge standard and choose to discharge to sea water.
Similar to the opinions of scholars such as Lake Barrett, Dale Klein, the former chairman of the US Nuclear Energy Safety Regulatory Commission, also believes that at present, the concentration of tritium in Fukushima sewage is low enough to safely discharge water into the sea. In an interview with the media, he said, “Controlled emissions are better than accidental leaks.” When the Director General of the International Atomic Energy Agency visited Japan for the first time in February this year, he also stated that the discharge into the sea is in line with international practice and that support will be provided for discharge.
Not only a scientific problem
However, whether such a plan can be adopted is not so much a science and technology The problem is more of a social or emotional problem. The Three Mile Island nuclear reactor accident in Pennsylvania, USA in 1979 is an example.
There, after about 10 years of purification work, only 9,000 tons of tritium-containing water remained, which had been stored for 14 years. Although tritiated water is within the limits of safety and environment, the local public has a strong emotional reaction to the water being discharged into the Suskhana River, because people living downstream depend on the river.
Therefore, the owner of the nuclear power plant, the water company and other public utilities, decided that forcibly evaporating tritiated water is the best way out-the amount of 9,000 tons is relatively small, so the evaporation method is feasible. “If Three Mile Island is a nuclear power plant near the sea, there is no direct drinking water supply problem downstream, then the plan to discharge to sea water may be adopted.” Lake Barrett pointed out.
Every time the idea of dumping tritiated water is mentioned, the fishery in Japan, especially the local fishery in Fukushima, causes commotion. The industry was hit hard after the Fukushima accident, and it still faces many countries’ restrictions on the import of its seafood, and this move will further damage the reputation of Japan’s fishing industry. “If water is discharged into the ocean, the price of seafood products may drop, or consumers simply don’t want to buy them.” Shuji Okuda, director of sewage treatment and polluted water management at the Ministry of Economy, Trade and Industry of Japan pointed out, so even if there is no scientific evidence to show that after treatment The waste water is harmful, and we are still worried about its impact.
On the other hand, the trust of TEPCO among the people in the world, including Japan, was hit in the first few years after the meltdown of the nuclear power plant.
Peng Guangxiong, a post researcher at the Institute of High Energy Physics of the Chinese Academy of Sciences and a professor at the National University of Science and Technology of China, said that because TEPCO had “previous history” and some data had been falsified before, everyone did not believe it very much. For example, in 2018, TEPCO once stated that most of the water, except for tritium, has been cleaned below the safety standards of the Japanese government. But by the summer of 2019, the company admitted that only about one-fifth of the stored water was effectively treated.
In view of the current pandemic of the new crown pneumonia epidemic and effective domestic and international consultations cannot be fully carried out, on June 9th, UN human rights experts called on Japan not to rush to discharge Fukushima nuclear sewage into the sea, because how nuclear waste will be treated will affect mankind and the planet. The profound impact lasting for generations is related to the livelihoods of local fishermen and the human rights of people in other countries. They believe that the Fukushima nuclear power plant has sufficient space to build more water storage tanks to increase the storage capacity of nuclear sewage, and that public consultation on this issue was originally scheduled to start after the end of the 2020 Tokyo Olympics, and the government does not need to make a hasty decision.
Peng Guangxiong said that compared with other nuclear waste pollution, tritium, the radioactive isotope of hydrogen, has a much lighter impact on biologically active substances in living organisms, but this aspect is particularly lacking in in-depth quantitative research. Intuitively, it takes a long time for organisms to adapt to the ingredients in the environment. Therefore, a sudden change in a component of the natural environment will break this balance and cause unnatural damage to the environment. Moreover, simply discharging nuclear sewage into the sea will make Japan feel guilty for a long time, and will suffer great moral and economic losses.
”I think Japan must take this matter very, very carefully. It should be responsible for the future of mankind and make a decision that can withstand the test of history.” Peng Guangxiong believes that with the development of science and technology, there may be no need to wait in the future. Too long there will be a solution to the sewage. Compared with other radioactive substances such as cesium, the half-life of tritium is much shorter, about 10 years. He also suggested that Japan can go to some uninhabited islands to build more storage tanks, and it is not yet at the point where it must be treated. Perhaps before the completion of the previously planned seaside park, the tritium in these sewage will naturally be reduced to no problem.