As an important form of energy, nuclear energy has brought many conveniences to human society, but also produced a serious problem - nuclear waste.
With the continuous development of global nuclear energy utilization, the amount of nuclear waste is increasing day by day, and how to properly dispose of nuclear waste has become a difficult problem facing mankind.
In the process of using nuclear energy, a certain amount of nuclear waste will inevitably be generated. According to the difference in radioactivity levels, nuclear waste can be divided into high-radioactive waste, medium-radioactive waste, and low-radioactive waste.
Highly radioactive waste is mainly the fuel that has been replaced in the reactor core, i.e. spent fuel; Low- and medium-level radioactive waste mainly comes from the decommissioning of nuclear power plants and the production of nuclear fuel.
For low- to medium-level radioactive waste, compression and solidification are usually used. It is compressed and solidified, then packed into containers and transported to disposal sites in shallow formations for safe storage.
In this process, the radioactive elements in the nuclear waste gradually decay over time, reducing the harm to humans and the environment. Over the course of several decades, its radioactivity levels decrease significantly.
The process of disposing of spent fuel is more complex. When spent fuel is removed from the reactor, its temperature and radioactivity are at extremely high levels.
At this point, it needs to be cooled in a pool of water for 5 to 8 years to reduce the radiation intensity. Once the cooling is complete, it is inspected for the presence of available components, such as unreacted uranium-235 and plutonium-239, and separated for recovery.
The remaining residue is packed into a container that can effectively insulate nuclear radiation and is eventually buried at a depth of 500-1000 meters. The location of nuclear waste repositories is a crucial issue that needs to meet extremely stringent requirements. It is important to ensure that the location is geographically stable and able to withstand natural disasters such as earthquakes, volcanoes and explosions.
This is because the radioactive half-life of nuclear waste can be tens or even hundreds of thousands of years, and a suitable repository location can minimize the potential threat of nuclear waste to the environment and people. In practice, it is not easy to find such an ideal site for the disposal site, and it is necessary to comprehensively consider various factors such as geological structure, hydrological conditions, and seismic activity.
For example, the geological structure of the site selection area should be stable, and there should be no geological defects such as faults and karst caves; Hydrological conditions should be appropriate to prevent the erosion and dispersal of nuclear waste by groundwater; At the same time, there is relatively little seismic activity in the area to reduce the impact of earthquakes on the repository. On a global scale, the disposal of nuclear waste is an extremely complex and serious issue, which imposes a heavy economic burden on countries. In the United States, for example, Yucca Mountain was selected as the site for a deep-ground repository of high-level radioactive nuclear waste, with a project budget of tens of billions of dollars.
However, in the end, the project was shelved, resulting in a lot of investment coming to naught.
Faced with the difficult problem of nuclear waste disposal, the practice of storing nuclear waste to the seabed has been proposed. Rather than simply throwing the waste directly into the sea, this method requires a series of complex treatment processes.
First, the nuclear waste is cooled and stored dry, then loaded into metal tanks and finally released to the seabed below 400 meters in a specific sea area. However, there are a number of problems with this approach.
Historically, the United States, the United Kingdom, France and other countries have dumped more than 200,000 tons of solid nuclear waste into the ocean, which has put the ocean under tremendous pressure and become a "potential threat" of nuclear waste. With the passage of time, it will be difficult for the iron bucket to resist the corrosion of seawater forever, and nuclear waste may leak, causing serious damage to the marine ecological environment. In addition to storing nuclear waste to the bottom of the sea, there are also ideas of sending nuclear waste into space by rockets. Back in the 70s of the 20th century, the National Aeronautics and Space Administration (NASA) conducted research on this idea, and it was planned to implement it in 1990.
However, the explosion of the space shuttle Challenger in 1986 forced the project to be terminated. Even if space technology could ensure absolute security, the issue of cost would remain a huge obstacle.
In France, for example, there are hundreds of tons of nuclear waste that need to be disposed of every year, and the limited carrying capacity of a rocket means that the launch cost per ton of nuclear waste is extremely high. In contrast, the cost of storing nuclear waste underground is much lower. At present, the safest and most feasible method of nuclear waste disposal is still recognized as deep underground. While this approach can reduce the direct impact of nuclear waste on people and the environment to some extent, it is not perfect.
To a certain extent, this is equivalent to leaving the problem to future generations, and whether it is truly reasonable is worthy of our in-depth consideration.
In the process of solving the difficult problem of nuclear waste disposal, nuclear fusion technology has been pinned on high hopes and is regarded as the hope of human civilization. Nuclear fusion has the advantages of huge energy release, abundant raw materials, and less radioactive waste.
If the commercial application of nuclear fusion can be realized, it will not only provide us with more ideal energy solutions, but also bring new ways and methods for nuclear waste disposal. However, there are still many challenges in nuclear fusion technology, which require continuous research and exploration.
It is believed that in the future, with the continuous progress of science and technology, we can find more perfect nuclear waste disposal methods, achieve the sustainable development of nuclear energy, and at the same time make nuclear fusion, the light of hope for human civilization, shine more brightly.