Materials for storing radioactive waste degrade faster than thought

Nuclear waste warning: Materials widely used to store radioactive waste degrade faster than previously thought and could lead to dangerous leaks, scientists warn

  • Scientists identified weakness in current storage methods of radioactive waste  
  • Waste is immobilised in glass or ceramics and then enclosed in metal canisters 
  • But these two materials cause corrosion over time, affecting their service life 
  • Radioactive material is contained underground to prevent contact with humans

Current nuclear waste storage methods are less stable than previously thought and could be leaking harmful radioactive material, scientists have warned.

Disposal of nuclear waste involves mixing it with other materials to form glass or ceramics, and then encasing those pieces of glass or ceramics — now radioactive — inside metallic canisters.  

These canisters are then buried deep underground in a repository to isolate the radioactive material and prevent it from interacting with the environment.  

However, the team found that the glass and ceramic materials holding nuclear waste can interact with the stainless steel used to make the cannisters, accelerating corrosion.

This could affect the service life of nuclear waste storage and exacerbate radioactive contamination into the environment – potentially polluting water sources and risking chronic disease in humans.

Stainless steel canisters used to store vitrified high-level waste (HLW), which is usually stored deep underground for at least 50 years before disposal

‘The corrosion that is accelerated by the interface interaction between dissimilar materials could profoundly impact the service life of the nuclear waste packages, which, therefore should be carefully considered when evaluating the performance of waste forms and their packages,’ the team said in their research paper, published in Nature Materials.  

Radioactive waste – by-products of nuclear power generation and nuclear fission – can remain hazardous to humans and the environment for hundreds of thousands of years.

As a result, this so-called high level waste (HLW) is buried deep underground in mined repositories, at depths of between 250 metres and 1,000 metres.

Radioactive waste is stored at such depths in stable geological formations so to prevent any chance of radiation exposure to people. 

HLW typically arises in liquid form, generated as a by-product during the reprocessing of spent fuel from nuclear reactors. 

In the UK, HLW treatment takes place at Sellafield, a two-square-mile site close to Seascale on the coast of Cumbria, 

Aerial photograph of the nuclear fuel processing site of Sellafield, Cumbira, which 

For the study, Dr Gerald Frankel at Ohio State University and his team pressed stainless steel  – a so called ‘barrier metal’ – against materials used to immobilise nuclear waste – a borosilicate glass and titanate-based ceramics.

They then studied the rate of corrosion under simulated repository conditions, and found that both materials corroded much faster in the areas where they were in contact with the stainless steel.

‘Severe’ corrosion was found between stainless steel and both borosilicate glass and the ceramic waste form.

The accelerated corrosion can be attributed to chemical changes that occur within a confined space over time. 

This research should be carefully considered when assessing the safety of nuclear waste disposal and when selecting barrier materials, the team say. 

‘Moreover, compatible barriers should be selected to further optimise the performance of the geological repository system,’ the ream say.  

WHY IS RADIOACTIVE WASTE DANGEROUS?

Radioactivity is the process of an unstable atomic nuclei loses energy through radiation.

It damages the cells of the human body, causing a mutation, which can make them cancerous.

Radioactive waste, formed as a by-product of nuclear processes, can take the form of different states of matter, including gas, solids and liquids. 

Depending on the waste’s source, the radioactivity can last from a few hours to hundreds of thousands of years. 

If disposed of improperly, radioactive waste can devastate the environment, ruining air, water and soil quality. 

These materials can have long-term negative effects on human health, and can be fatal. 

Source: Nuclear Energy Institute/How Stuff Works 

 

 

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