How should Japan deal with nuclear waste water? Give us some ideas

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How should Japan deal with nuclear waste water? Give us some ideas [Copy link]

April 13, Japanese Government

Official decision to discharge Fukushima nuclear wastewater into the sea

Once nuclear wastewater is discharged into the sea

Radioactive Materials

Will spread to most of the Pacific Ocean within 57 days

10 years later, it will spread to all seas around the world

What are the hazards of nuclear waste water? See the figure below

Source: CCTV News

It has been 10 years since the Fukushima nuclear power plant accident. Why did the Japanese government choose to discharge nuclear wastewater at this time?

One of the important factors is that there are not enough reservoirs to store nuclear wastewater, and Tokyo Electric Power Company does not have extra land to build more reservoirs. The existing reservoirs can only be used until 2022 at most.

Secondly, due to Japan's geographical factors, earthquakes and tsunamis occur frequently. There are more than 1,000 existing containers for storing nuclear wastewater. Once a natural disaster occurs in the area, the nuclear wastewater will flow out, which will cause great harm to the country's land and residents. In addition, Japanese Prime Minister Yoshihide Suga promised the Japanese people in 2020 that he would properly handle the nuclear wastewater issue.

The Japanese government decided to discharge wastewater generated by cooling the nuclear power plant and the groundwater contaminated in the process. This is not the first time that the Japanese government has discharged nuclear wastewater. In the year when the Fukushima nuclear power plant accident happened, Tokyo Electric Power Company of Japan discharged low-concentration radioactive wastewater into the sea, weighing 11,500 tons. But the then Chief Cabinet Secretary said: We have no choice.

Although Japan has already discharged nuclear wastewater before, why is this discharge so controversial? Although Japan has always claimed that the discharged nuclear wastewater has been diluted and purified. What's funny is that during a previous inspection of the Fukushima nuclear power plant, Japanese Prime Minister Yoshihide Suga asked relevant personnel whether the purified wastewater could be drunk by residents. The staff said it was drinkable, but Suga did not drink it in the end.

The American magazine Science claims that even after treatment, the levels of various radioactive isotopes in the wastewater are still too high. It may be difficult to see its adverse effects in the short term, but the long-term harm cannot be ignored. So is there no other way except to discharge the nuclear wastewater into the ocean?

Of course there are other ways! The Japanese government has previously proposed five options: discharge into the sea, discharge into the atmosphere as water vapor, discharge deep underground through underground pipes, electrolysis, and solidify and bury underground. In fact, there are other ways to deal with nuclear waste water, so let's talk about the correct way to dispose of nuclear waste water.

A chemical precipitation method

The chemical sedimentation method is to inject a certain amount of chemical flocculants such as iron sulfate, sodium sulfate, and iron chloride into the water to make the colloids in the water lose stability and condense into fine precipitable particles, which can be combined with the original suspended matter in the water to form loose fluffy particles. The fluff particles have a strong adsorption capacity for radioactive elements in the water and can purify radioactive substances in the water. Although this method is simple to operate and low in cost, its removal efficiency is low. The sludge produced by chemical sedimentation needs to be treated by processes such as concentration, dehydration, and solidification, otherwise it is easy to cause secondary pollution.

Second, evaporation concentration

Because most of the radioactive elements in nuclear wastewater do not volatilize, this property can be used to heat the wastewater to evaporate them, and then concentrate the remaining radioactive substances that cannot evaporate. One reason is that nuclear power plants generate a lot of useless waste heat during operation, so heating wastewater will not cause too much energy consumption; the other reason is that the evaporation method basically does not require the use of other substances, and will not produce other forms of pollutants due to the transfer of pollutants like other methods.

The third is ion exchange filtration technology

The principle is similar to the water purifiers we use in daily life. A resin specially used to absorb radioactive substances is placed in the pipe where sewage flows. In this way, water will flow out and radioactive substances will remain in the resin. After the resin is absorbed, it will be replaced with new resin. In addition, the resin that absorbs radioactive substances can be compressed to reduce its volume, collected and sealed with cement. If the radioactivity of the resin is not high, it can be placed in an iron barrel and sealed.

Fourth, membrane separation method

Membrane separation is a method in which only water and small molecules can pass through the membrane surface when the stock solution flows through the membrane surface under a certain pressure. The membrane surface is a very tight micropore. In the stock solution, large-particle substances such as radioactive ions are cut off on the liquid inlet side of the membrane and become concentrated liquid, thereby achieving the purpose of separating liquid and radioactive substances. Membrane separation has the advantages of no phase change, low energy consumption, simple operation, safety and reliability. However, when the content of radioactive substances in the pollutants is low, or there are small molecular radioactive substances, it is usually difficult to handle, and the core "membrane" material of the membrane separation method itself is not resistant to high temperature and is easy to corrode, which also limits the large-scale application of this method.

Fifth, adsorption method

The absorption method is to use porous solid adsorbents to treat radioactive wastewater, adsorb radioactive substances to the surface of the adsorbent, and achieve the purpose of removing radioactive substances. Adsorption is one of the important methods for wastewater treatment, and has also been widely used in wastewater treatment, especially radioactive wastewater treatment. Adsorbent materials with large specific surface area and high surface energy are selected to adhere pollutants to the surface of the adsorbent, separate the wastewater, and achieve the purpose of purification. The adsorbent has a large specific surface area, and the reaction process between the adsorbate and the adsorbate is very fast. This process has the characteristics of high efficiency and fast speed in treating wastewater.

Sixth, electrolysis

This is best for the environment, but it consumes a lot of electricity and the government needs to spend a lot of money to buy electricity.

The surrounding area of the underground landfill of the Fukushima nuclear power plant has been designated by the Japanese government as a "temporary uninhabitable area", which means that there is enough available space to build more than 5,000 storage tanks. With so many different methods, the Japanese government only intends to "go with the flow" and rely on seawater to dilute and degrade. Although this is a method, it cannot properly eliminate the various isotopes and radioactive substances in the nuclear wastewater. The large amount of water discharged into the natural environment will exist in nature for a long time. It is a slow and uncontrollable process. (Author: Yisibei Industrial Wastewater Treatment)

How should Japan deal with nuclear wastewater? Which method is best? Give us your suggestions

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According to Guancha.com, on April 13, the Japanese government officially decided to discharge the Fukushima nuclear wastewater into the sea. In response to this decision, the International Atomic Energy Agency (IAEA) issued a statement saying that the agency welcomes Japan's decision to deal with the Fukushima nuclear wastewater and is ready to provide technical support to Japan and supervise and review the safety and transparent implementation of the relevant plan.

Agency Director-General Rafael Grossi said that the nuclear wastewater treatment method chosen by Japan is "technically feasible" and "in line with international practice"; but due to the huge amount of nuclear wastewater at the Fukushima nuclear power plant, it is a "unique and complex case."

Grossi also described the Japanese government's decision as a "milestone", claiming that it would help "pave the way for the decommissioning of the Fukushima Daiichi Nuclear Power Plant." He also said that with the participation of all stakeholders, handling nuclear wastewater in a safe and transparent manner is crucial to the decommissioning of nuclear power plants.

"Nuclear safety is a national responsibility, and it is the responsibility of the Japanese government to resolve the key issue of nuclear wastewater management. I believe that the Japanese government will continue to interact with all parties in a transparent and open manner to implement today's decision," Grossi said.

Previously, Japan had asked the IAEA to help with the treatment of nuclear wastewater, and the agency would send a special mission of international experts to review the relevant plans according to its safety standards and provide support for environmental monitoring activities. In response to this request, Grossi said, "The agency will continue to work closely with Japan before, during and after the discharge of wastewater."

One day earlier (12th), Grossi met with Wang Qun, China's permanent representative to the United Nations in Vienna, and expressed his willingness to actively promote the agency's assessment and supervision work in a fair, objective and scientific manner. In this process, the agency is willing to strengthen communication with all stakeholders. At present, efforts should be made to prevent this matter from further endangering the marine environment, food safety and human health.

After the Fukushima Daiichi nuclear power plant accident, the IAEA carried out extensive cooperation with the Japanese government on the follow-up handling of the accident, covering important areas such as radiation monitoring, wastewater management, and nuclear power plant decommissioning.

On the morning of April 13th local time, the Japanese government held a relevant cabinet meeting and formally decided to discharge nuclear wastewater from the Fukushima Daiichi Nuclear Power Plant, which is harmful to the marine environment, into the sea, with the discharge scheduled to begin in two years.

The Japan Broadcasting Corporation (NHK) stated that before discharge, Japan will dilute the nuclear waste water to one-fortieth of Japan's national radiation concentration benchmark value, which is equivalent to one-seventh of the drinking water radiation safety standard set by the World Health Organization (WHO).

After the Japanese government made this decision, the US State Department quickly issued a statement supporting Japan's decision, saying that Japan "appears to have adopted an approach 'consistent with globally recognized nuclear safety standards'" and that the US expects the Japanese government to continue to coordinate and communicate with the outside world when monitoring the effectiveness of the method. US Secretary of State Blinken also tweeted "thanks" for Japan's decision.