Because countries around the world experience revival in nuclear energy projects, questions where and how to remove nuclear waste remain just as politically full. For example, the United States has stuck in a deadlift of the only long -term underground nuclear waste repository. Scientists utilize both modeling and experimental methods of researching the impact of underground nuclear waste removal, and ultimately hope that they build public trust in the decision -making process.
Modern research of scientists from MIT, Lawrence Berkeley National Lab and the University of Orléans are progressing in this direction. The study shows that simulations of underground interactions with nuclear waste, generated by novel, high -performance computer software, well adapted to experimental results from the research facility in Switzerland.
A study that was co -authored by Mit Dauren Sarsenbayev and assistant professor Haruko Wainwright, together with Christophe Toussat and Carl Steefel, appears in the journal .
“These new new computing tools, combined with real experiments, such as those in Mont Terri Research Site in Switzerland, will help us understand how radionuclides will migrate in combined underground systems,” says Sarsenbayev, which is the first author of the novel study.
The authors hope that research will improve trust among decision -makers and societies in the field of long -term underground security of nuclear waste.
“This is research – combining both calculations and experiments – is important to improve our trust in waste removal safety assessments,” says Wainwright. “When nuclear energy appears again, as a key source to fight climate change and ensuring energy security, confirmation of removal paths is key.”
Comparison of simulation with experiments
The removal of nuclear waste in deep underground geological formations is currently considered the safest long -term solution for high -level radioactive waste management. Therefore, a lot of effort was put into studying the migration behavior of radionuclides from nuclear waste in various natural and designed geological materials.
Since the foundation in 1996, Mont Terri Research Site in northern Switzerland served as an crucial test bed for the international consortium of scientists interested in studying materials such as Opalinus Clay-Grubian, waterproof clay bountiful in tunnelad areas of the mountains.
“He is widely considered one of the most valuable real places of experiments, because it provides us with decades of data sets around cement and clay interaction, and these are key materials proposed by countries around the world for designed barrier systems and geological repositories for nuclear waste,” explains Sarsenbayev.
For their research, Sarsenbayev and Wainwright collaborated with co -authors of Tournassat and Steefel, who developed high -performance computing software to improve the modeling of interaction between nuclear waste and both engineering and natural materials.
Until now, several challenges have a restricted understanding of scientists how nuclear waste react with cement barriers. First of all, barriers consist of irregularly mixed materials deep underground. In addition, the existing class of models commonly used to simulate radionuclide interactions with cement clay does not include electrostatic effects associated with negatively charged clay minerals in barriers.
The novel TOURT and SETEFEL software includes electrostatic effects, which makes it the only one that can simulate these interactions in three -dimensional space. The software, called Crunchoditi, has been developed from a fixed software known as Crunchflow and has recently been updated this year. It has been designed to run on many computers with high performance simultaneously in parallel.
In the study, scientists looked at the 13-year experiment, with initial emphasis on the interaction of the rock with cement. Over the past few years, a mixture of both negative and positively charged ions has been added to the well. Scientists focused on a 1 -centimeter broad zone between radionuclids and a cement group called “leather”. They compared their experimental results to software simulation, stating that two sets of data are even.
“The results are quite significant because these models do not fit very well before,” says Sarsenbayev. “It is interesting how minor phenomena on” skin “between cement and clay, physical and chemical properties that change over time, can be used to reconcile experimental and simulation data.”
Experimental results have shown that the model successfully took into account the electrostatic effects related to the creation of clay affluent and interaction between materials in Mont Terri over time.
“All this is powered by decades of work to understand what is happening on these interfaces,” says Sarsenbayev. “There was a hypothesis that this interface has mineral precipitation and porosity, and our results strongly suggest this.”
“This application requires millions of degrees of freedom, because these multi -barrillary systems require high resolution and high computing power,” says Sarsenbayev. “This software is really perfect for the Mont Terri experiment.”
Assessment of waste removal plans
The novel model can now replace older models that have been used to carry out safety assessments and performance of underground geological repositories.
“If the United States finally decides to get rid of nuclear waste in a geological repository, these models can dictate the most suitable materials for use,” says Sarsenbayev. “For example, at the moment, clay is considered the right storage material, but salt formations are another potential medium that can be used. These models allow us to see the fate of radionuclids in millennia. We can use them to understand the interaction in times that differ from months to years to many years.”
Sarsenbayev claims that the model is quite accessible to other researchers and that future efforts can focus on using machine learning to develop less calculations of steep replacement models.
Further data from the experiment will be available this month. The team plans to compare this data with additional simulations.
“Our colleagues will generally get this block of cement and clay, and will be able to carry out experiments to determine the exact thickness of the skin along with all minerals and processes present at this interface” Sarsenbayev says. “This is a huge project and requires time, but we wanted to share the initial data and the software as soon as possible.”
For now, scientists hope that their study leads to a long -term solution for storing nuclear waste, which decision -makers and society can support.
“This is an interdisciplinary study that includes experiments from the real world showing that we are able to predict the fate of radionuclids in the sub -subjects,” says Sarsenbayev. “Motto MIT Department of Nuclear Science and Engineering to” Science. Systems. Society “. I think it connects all three domains. “