What is Radioactive Waste?
Radioactive waste, also regarded as nuclear waste is basically such unwanted material or substance that has a high concentration of radionuclides. The nuclear substances over here can occur either naturally or can be the outcome of various man-made activities.
The term radionuclide corresponds to the nuclide that has a large amount of nuclear energy, this unstabalizes the element.
It is a very well-known fact that radioactive waste is basically a byproduct of activities such as nuclear reactions, fuel processing, various research-related activities, hospitals, etc. These wastes are mainly classified as high-level or low-level waste.
It can be said that the classification of radioactive waste is dependent on the activity level along with the half-life of the radionuclide present in the radioactive element. If the half-life is around 31 years then it is said that radioactive waste is short-lived.
The SNF from power reactors is radioactive waste. Generally, universally it is known that SNF is needed to be stored for some time before transportation and disposal so that radioactivity can take place and decay heat to be reduced. Due to this storage the cost of transportation and disposal, as well as the risks associated, get reduced.
The radioactive level of SNF is so high that it is required to be kept within pools underwater at the site as it generates excessive heat. The water acts as a radiation shield that provides protection against gamma radiation thereby providing cooling effects to SNF. Its storage time exists between 2 to 5 years.
A noteworthy point over here is that after a point of time the SNF is shifted to dry storage systems such as concrete vaults or steel casks.
Nature of Radioactive Wastes
Nuclear industries provide radioactive wastes in excessive amounts. Due to the fundamental characteristics of radioactive materials these exhibit hazardous behaviour.
Until and unless the radiation is in massive doses, the radiation remains undetected and exhibits cumulative effects. However, the nature of radioactivity helps in detecting the presence certainly with quite accuracy.
The various radioactive wastes are very much different from one another in terms of physical and chemical form, volume, radioactivity, and half-life of radioactive elements.
Let us now proceed to understand the management solutions of radioactive wastes.
The various management solutions include
- Sorting: Here the separation of the waste is done according to their properties or we can say the half-lives of the radionuclides present in it. After separation, the waste is compacted and, melted down so as to decrease its volume.
- Treatment and Conditioning: Different wastes are treated in a different manner such as incineration, calcination, melting, compacting, cementation, vitrification, etc. Further, the wastes are sealed within the container and a radioactive waste package is formed.
- Storage and Disposal: In storage facilities, the wastes packages are stored for a specific duration. Finally, in waste management disposing of wastes is performed in which the packages are diverted to their final point. This helps in protecting the people as well as the environment for a very long period of time.
Disposal Methods of Radioactive Wastes
As we have recently discussed that disposing of the waste is the final as well as the most crucial stage so let us see in brief the methods for disposing of the radioactive wastes.
Dilute and Disperse Method: It is a simple approach where the wastes are disposed off by diluting it with inert materials. Here the wastes are diluted upto an acceptable level and then is further discharged into the atmosphere. In case of liquid wastes, water bodies like rivers are used where disposal is performed. This technique is suitable only for low or intermediate level of radioactive wastes.
Concrete and Contain Method: This techniques is the one that suits the radioactive wastes that are very dangerous for the biosphere. In this approach, the radiowastes are locked within crystalline structure of special rock formed by scientists. This rock exhibit insolubility in water and kept within water for years. However, the method is not suitable for long-lived high-level wastes.
Delay and Decay Method: These are used when there is medium-level wastes where the wastes are decayed within slow soil movement. But this leads to deterioration of the soil system as radioactive contamination takes place. However, sometimes underground tanks are used to lessen the harmful effects towards the environment. The tanks are made up of concrete or steel that is corrosion free and the decaying takes around 250 to 400 years.
This is all about radioactive wastes and its disposal techniques.