Nuclear power is not just a low-carbon energy source but a low-resource energy source, with a total environmental impact per kilowatt hour similar to that of renewables, according to a new study.
Past life cycle analyzes of nuclear power have mostly focused on the energy consumption and greenhouse gas emissions associated with building, operating, and decommissioning nuclear power plants. But this isn’t a total picture of environmental impacts or sustainability. What was missing was a more comprehensive look at all the resources extracted from the Earth throughout the life cycle of nuclear power plants.
In the new study, researchers calculated the Total Material Requirement (TMR) coefficient, a measure of the mining intensity of a process, associated with the entire life cycle of nuclear power. This includes uranium mining, milling, and enrichment, fuel production, reactor construction, reactor operation, fuel reprocessing, reactor decommissioning, and nuclear waste disposal, transport, and storage.
“One of the particularly noteworthy aspects of TMR is that it considers mine waste,” the researchers write in the Journal of Cleaner Production. “This mine waste is a major driver in the damage incurred by the ecosystems surrounding mining sites, and is a major contributor to the environmental impacts caused by the extraction of natural resources.”
In addition, the researchers treated land used for underground nuclear waste storage facilities as mine waste, enabling a rigorous accounting for this phase of the nuclear power life cycle.
The researchers assembled information from existing databases to calculate how the TMR coefficient per kilowatt hour of nuclear power varies depending on mining method, nuclear reactor type, fuel cycle type, and grade of uranium ore.
Mining, uranium processing, and plant construction and operation make the biggest contributions to the total environmental impact of nuclear power, the researchers found.
Open-pit mining, which generates large amounts of mine waste, is not surprisingly the mining method with the largest environmental impact, especially when mining low-grade ore. A method known as in-situ leaching, in which an acid solution is injected into boreholes and the resulting uranium-containing solution is pumped out, has the smallest impact, although it is not suitable for every location.
Mining method has a big impact on total resources used but a much smaller impact on greenhouse gas emissions. Interestingly, of the three mining methods open-pit mining has the lowest greenhouse gas impact – the reverse of its material impact.
In the ‘open’ fuel cycle of conventional nuclear plant operation, spent fuel is simply disposed of. But some reactors have a ‘closed’ fuel cycle, in which spent fuel is recycled to produce new fuel. A closed fuel cycle with reprocessing of uranium fuel uses 26% less resources than an open cycle, the researchers calculated, demonstrating that even in nuclear power plants recycling is important.
The researchers calculated a representative TMR coefficient of nuclear power generation and then compared it to that of fossil fuel power generation. Nuclear’s impact is 20% that of coal, 23% that of oil, and 35% that of liquified natural gas power. It’s comparable to that of renewables such as solar, making nuclear power not just a low-carbon energy source but a low-resource energy source.
Still, nuclear power is mining-intensive; the fact that the resulting fuel is energy dense is what makes its per-kilowatt-hour impact fairly low. The findings highlight that the environmental impact of nuclear power doesn’t just boil down to greenhouse gas emissions, the researchers say: “The heavy reliance on greenhouse technologies gas emissions and global warming potential when evaluating the environmental impact of power generation comes at significant risk ,” they write. “Despite the undeniable importance of these factors, this conventional approach for evaluating the environmental performance of power generation may lead to hidden factors associated with natural resource use being completely overlooked.”
Source: Nakagawa N. et al. “Life cycle resource use of nuclear power generation considering total material requirement.” Journal of Cleaner Production 2022.
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