/ Waste in a temporary storage facility. A number of countries, including the United States, have been planning for long-term storage of nuclear wastes. While many of these nations plan to keep the waste isolated from water, that’s not something that can be guaranteed over the extremely long lifespans of the waste. If water reaches the radioactive isotopes, there’s the chance that the isotopes could contaminate the groundwater in the area and spread well beyond the site of the storage repository. To prevent that, plans are to have multiple layers of defense. The waste itself will be incorporated into a chemically inert, insoluble glass. And the glass itself will be placed in a stainless steel flask that will keep it from mixing with the surroundings. At the interface
In this case, water getting inside of the stainless steel container would percolate into the narrow space between the glass and the steel. And here, there’s the possibility of what’s apparently termed “crevice corrosion.” In the narrow interface between the two materials, the chemistry can be very different than in a bulk solution. Local concentrations of dissolved material can be much higher, material that dissolves on one surface can immediately react with the other, and the chemistry can create feedback loops, greatly increasing the rate of otherwise rare reactions.
In the case of the crevice between the stainless steel and the glass, a lot happens when some of the metals present dissolve. They can drop the local pH, which will then increase the rate at which the stainless steel corrodes. Meanwhile, some of the dissolved metal ions will include some of the radioactive material. To balance the chemistry, the environment outside the crevice will become more basic, which could trigger additional chemical reactions. Real-world data That’s what can
happen. What actually does? To find out, the researchers used a standard (non-radioactive) glass material and stainless steel. These were pressed up against each other, and a solution of sodium chloride was added. The mixture was kept at (° C for) days. The water had dissolved oxygen in it, which would be relevant to the conditions that might take place at the Yucca Mountain repository in the United States; Other nations are planning repositories that would have anoxic conditions. At the end of 0579 days, the team did some spectroscopic imaging to figure out where various materials ended up.