One of the main problems with nuclear power is how to store and dispose of nuclear waste produced by develop and manufacture of nuclear weapons. Currently, vitrification is used for permanent long-term storage of nuclear waste in underground geological repositories. Nuclear waste is mixed with other materials that form glass or ceramics when heated and then enclosed in metallic cylinders. Unfortunately, scientists have now found that the glass and ceramic materials used in vitrification can interact with the stainless steel of the cylinders. This can result in an acceleration of corrosion of the cylinders.
This accelerated corrosion will definitely affect the estimated service life nuclear waste storage. This, in turn, could increase the risk of the release of radioactive materials into the environment. Pollution of drinking and irrigation water as well as injury to public health would be a probable result.
Xiaolei Guo is the lead author of the sturdy. He is the director of Ohio State’s Center for Performance and Design of Nuclear Waste Forms and Containers. He says, “Under specific conditions, the corrosion of stainless steel will go crazy. It creates a super-aggressive environment that can corrode surrounding materials.” Nuclear waste can remain radioactive and dangerous to human beings and the natural environment for hundreds of thousands of years.
In response to this longevity of risk, countries that possess nuclear waste related to nuclear weapons have created plans to store this high-level waste up to three thousand and two hundred feet below the ground in a deep geological repository. This deep storage should prevent contamination of ground water and a threat of the release of radioactive materials into the environment. High level waste is created in liquid form during nuclear weapons production. Guo said, “In the current disposal plan for many countries, the high-level nuclear waste will be primarily mixed with other materials to form glass or ceramic waste forms.”
Dr. Gerald Frankel at Ohio State University and his team carried out experiments for this study. They pressed pieces of stainless steel against vitrification materials such as a borosilicate glass and titanate-based ceramics. They studied the rate of corrosion in the stainless steel and found that the degree of corrosion was much faster in areas where the vitrification materials were in contact with the stainless steel.
Guo said, “'Severe' corrosion was found between stainless steel and both borosilicate glass and the ceramic waste form. Our study showed that the release rate could be enhanced due to the corrosion interactions between different materials used to isolate these wastes. Specifically, the corrosion of metallic canisters creates a highly aggressive environment that can corrode the surrounding materials faster than what was predicted.”
The accelerate corrosion could be the result of chemical changes that take place in a confined space over time. This research should be carefully reviewed when assessing the safety of nuclear waste disposal and materials when selecting the material that will be used to enclose the waste.
Guo says, “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. Moreover, compatible barriers should be selected to further optimize the performance of the geological repository system.”
In the United Kingdom, HLW treatment is carried out at Sellafield which is a two square mile site that is near Seascale on the coast of Cumbria. The site does not have a deep geological repository. Sellafield spokesmen say that the U.K. government is searching for a site for a deep geological repository but they are storing HLW for the time being on site.
In the U.S., there are over ninety thousand metric tons of nuclear waste that await disposal. For the moment, the waste is stored onsite near the reactors in temporary canisters. A permanent deep geological repository has been proposed for Yucca Mountain in Nevada but work was halted in 2009.
Only Finland has begun construction on a deep geological repository for HLW. Guo said, “At this stage, it is still a plan for most countries, but there have been continuous research and risk assessment efforts on this topic. Eventually, it is very likely to occur.”