Materials for storing radioactive waste degrade faster than previously thought
Nuclear waste warning: materials widely used to store radioactive waste degrade faster than previously thought and could cause dangerous leaks, scientists warn
- The scientists identified weaknesses in the current methods of storage of radioactive waste
- Waste is immobilized in glass or ceramic and then locked in metal cans.
- But these two materials interact over time, resulting in corrosion and leaks.
- The radioactive material is contained underground to avoid contact with humans
Current methods of nuclear waste storage are less stable than previously thought and could be filtering harmful radioactive material, the scientists warned.
The disposal of nuclear waste involves mixing them with other materials to form glass or ceramics, and then enclose those pieces of glass or ceramics, now radioactive, inside metal cans.
These containers are buried in the subsoil to isolate the radioactive material and prevent it from interacting with the environment.
However, the team found that glass and ceramic materials containing nuclear waste can interact with the stainless steel used to make the boats, accelerating corrosion.
This could affect the shelf life of nuclear waste storage and exacerbate radioactive contamination in the environment, which could contaminate water sources and endanger chronic diseases in humans.
Stainless steel containers used to store high level vitrified waste (HLW), which are generally stored underground for at least 50 years before disposal.
“In the real life scenario, glass or ceramic waste forms would be in close contact with stainless steel boats,” said Xiaolei Guo, lead author of the study and deputy director of the Center for Performance and Design of Nuclear Waste Forms Ohio State and Containers
‘Under specific conditions, corrosion of stainless steel will go crazy.
‘It creates a super aggressive environment that can corrode surrounding materials.’
Radioactive waste, by-products of nuclear power generation and nuclear fission, can remain dangerous to humans and the environment for hundreds of thousands of years.
As a result, this so-called high-level waste (HLW) is buried underground in mined deposits, at depths between 250 meters and 1,000 meters.
Radioactive waste is stored at such depths in stable geological formations to avoid any possibility of exposure to people’s radiation.
HLW generally arises in liquid form, generated as a byproduct during reprocessing of spent fuel from nuclear reactors.
In the United Kingdom, the treatment of HLW is carried out in Sellafield, a two-square-mile site near Seascale on the coast of Cumbria,
Aerial photograph of the Sellafield nuclear fuel processing site, Cumbira, which is the largest nuclear site in Europe
For the study, Dr. Gerald Frankel of the Ohio State University and his team pressed stainless steel, a so-called ‘barrier metal’, against the materials used to immobilize nuclear waste, a borosilicate glass and ceramic based titanate
They then studied the corrosion rate under simulated repository conditions and discovered that both materials corroded much faster in areas where they were in contact with stainless steel.
‘Severe’ corrosion was found between stainless steel and borosilicate glass and the ceramic waste form.
Accelerated corrosion can be attributed to chemical changes that occur within a confined space over time.
This investigation should be carefully considered when assessing the safety of nuclear waste disposal and when selecting barrier materials, according to the team.
“Corrosion that is accelerated by the interaction of the interface between different materials could profoundly affect the shelf life of nuclear waste packages, which, therefore, should be carefully considered when evaluating the performance of waste forms and their packages” said the team in their paper research, published in Natural materials.
“In addition, compatible barriers must be selected to further optimize the performance of the geological deposit system,” they add.
WHY IS RADIOACTIVE WASTE DANGEROUS?
Radioactivity is the process of an unstable atomic nucleus that loses energy through radiation.
It damages the cells of the human body, causing a mutation that can make them cancerous.
Radioactive waste, formed as a byproduct of nuclear processes, can take the form of different states of matter, including gases, solids and liquids.
Depending on the source of the waste, radioactivity can last from a few hours to hundreds of thousands of years.
If improperly disposed of, radioactive waste can devastate the environment, ruining the quality of air, water and soil.
These materials can have long-term negative effects on human health and can be fatal.
Source: Nuclear Energy Institute / How things work