The treatment of nuclear waste

　　The nuclear waste produced by the use of nuclear energy will produce dangerous radiation, and the impact will last for thousands of years. Scientists around the world are studying how to deal with nuclear waste. As long as this problem is dealt with, the benefits of nuclear energy outweigh the disadvantages, and it stands at the forefront of emission reduction. From a certain perspective, the use of nuclear energy can undoubtedly reduce greenhouse gas emissions to a great extent.

　　Regarding the issue of nuclear waste, low- and medium-radiation nuclear waste can now be safely disposed of through landfill and other methods; for the treatment of high-radiation nuclear waste, some countries such as Sweden and Finland have achieved some research results, such as through Isolation, circulation, combustion and other methods reduce its radiation performance so that it can reach safety standards after treatment.

　　Approach

　　At present, nuclear waste treatment is generally divided into two methods: marine treatment and land treatment. Most countries adopt a marine disposal method, which is to put nuclear waste barrels into the seabed below 4,000 meters in selected sea areas. Experiments have proven that these nuclear waste barrels will not break or leak even if they are dropped to the seabed below 6,000 meters. Even if the iron barrel breaks down on the seabed, the dose it will emit to the sea surface will only be one ten millionth of the human body's allowable intake (100 millirem per year), and generally will not cause harm to people. Moreover, in order to ensure safe handling, countries must also be subject to international supervision when releasing. Terrestrial nuclear waste disposal has its relatively rational side. Low-level radioactive waste is buried in the shallow surface of the earth, while high-level radioactive waste is buried in the deep crust thousands of meters below. Generally, there is no risk of contamination. Moreover, some of the nuclear waste buried on land is not suitable for ocean treatment, but if necessary, the waste buried on land can be recycled.

　　research and development

　　Physicists from Germany's Ruhr University said they have developed a new technology that can shorten the time it takes to turn nuclear waste into harmless substances. According to the Alpha Galileo website hosted by the British Association for the Advancement of Science, the principle of this new technology is to place nuclear waste in a metal container and cool it to ultra-low temperatures, so that the radioactive material decays faster and its half-life is shortened. . Physicists involved in the study say the technology could render nuclear waste harmless in decades rather than thousands of years. This method can greatly shorten the half-life of radioactive particles, so that nuclear waste does not need to be buried deep in underground storage. This research is still in its preliminary stages. Researchers are studying radium-226, a harmful component of nuclear waste, to verify the practicality of this new technology.

　　New nuclear reactors that can convert nuclear waste into inert and useful products will provide new hope for the expanded application of nuclear energy. Scientists from the Russian and Israeli Environmental Energy Resources (EER) companies announced in late March 2008 that they could convert radioactive and hazardous nuclear waste into inert and useful by-products such as glass and clean energy. A medium-sized waste treatment reactor has been commissioned at the northern facility near Karmiel. Using a system called Plasma Gas Melting Technology (PGM) developed by the research center of Russia's Kurchatov Institute, Russia's Radon Institute and the Israel Institute of Technology, EER combines high temperatures with low radiant energy to melt waste. change. The waste treatment reactor is said to be environmentally friendly. The reactor combines three processes: cracking the waste using plasma moments, regasifying the carbon waste, and finally converting the inorganic components into solid waste. The remaining material is inert and can be used to produce ceramic tiles, porcelain plates, etc. for the construction industry. Karmiel's facility has a capacity of converting 500-1000kg of waste per hour.

　　Radioactive waste is a major problem facing the United States and the world. After 20 years of research, Chien Wai, a professor of chemistry at Edward University in the United States, announced on September 1, 2008 that he had developed a technology for recovering uranium from radioactive nuclear waste ashes. This new recycling device can use efficient and environmentally friendly technology to The development of this technology, which reuses nuclear waste as nuclear fuel, was inspired by the process of removing coffee. This technology is expected to become a key breakthrough in the recycling of the most dangerous radioactive waste in the future. The principle of this technical process is to use supercritical fluid to dissolve toxic metals. Chien Wai collaborated with Edwards University's Sydney Koegler, a member of Nuclear Industry AREVA, to develop the purification process that recovers enriched uranium from the ash of contaminated material. Supercritical fluids (in this case carbon dioxide) are substances that can assume both gaseous and liquid states at certain temperatures and pressures. In the supercritical state, some substances can directly become solids and soluble compounds like liquids. For example, supercritical carbon dioxide can directly dissolve and remove bacteria from coffee. When the carbon dioxide pressure returns to normal, it becomes a gas and evaporates, leaving only the extracted metal. No solvents are required, no acids are used, and no organic waste is left behind. Because the technology is simple, low-cost and environmentally friendly, AREVA has conducted the first large-scale trial using 32 tons of incineration ash in Richland, Washington. Tests have shown that nearly 10% of the ash weight can be used to obtain enriched uranium, with a spot market value of approximately $900/lb. This means that the value of using this technology to recover from nuclear waste can now reach about $5 million. The new recycling facility is expected to be operational in 2009.

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