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| Fig. 1: Radioactivity of long-lived fission products. The vertical axis is Curies per metric ton of initial heavy metal. [2] (Courtesy of the DOE) |
Unlike coal or natural gas, nuclear energy has long been prized for its sustainable, high energy density characteristics contributing to global efforts to reduce greenhouse gas emissions and ensure energy security. However, one of the main obstacles associated with nuclear energy is the formation of radioactive waste. For instance, as of 2022, the cumulative global spent nuclear fuel (SNF) production has exceeded 300,000 tonnes, in addition to substantial volumes of intermediate-level waste (ILW) and low-level waste (LLW). [1] These figures reflect the growing scale of nuclear waste management challenges as nuclear energy continues to expand worldwide.
Assessing these in terms of volume and radioactive intensity, while SNF represents a small proportion of the radioactive waste produced globally by different industries, it is the most hazardous waste product. This is due to its high radioactivity, presence of long-living radionuclides, continued heat release, and the requirement to confine SNF for a long time period, on the order of one million years for some isotopes although the most acutely dangerous fission products (Cs-137, Sr-90) decay to comparatively low levels within approximately 1,000 years (Fig. 1). [1,2] However, while technologies exist and are well developed and employed for treatment and disposal of LLWs, for SNF, no final disposal facilities are yet operational worldwide, with even the most advanced programs still in development or regulatory review. The lack of experience in deep geological repository deployment, extensive time involved in implementation of back-end solutions, and high costs have created mounting uncertainties about the viability of fully managing SNF.
As such, as nuclear energy continues to expand, with nuclear reactor revival and Small Modular Reactor (SMR) building plans, the need for countries to understand SNF volumes and disposal costs continue to grow.
According to the International Atomic Energy Agency (IAEA), at the end of 2024, 417 nuclear power reactors were operational, providing 377 GW of global capacity across 31 Member States. [3] Nuclear reactors generate thermal energy, which drives a steam turbine to produce electricity, operating at around 33% efficiency on average. [4] The thermal power generated from nuclear reactors is thus 377 GW / 0.33 = 1143 GW. The total mass of fuel in the reactor generally stays constant. Thus, to determine the mass of SNF generated annually, we calculate the mass of fresh fuel rods required to maintain this capacity. Assuming that the fission energy present per unit mass of fresh fuel rod at 4% enrichment is 45 GWd/tonne, we find a waste generation rate annually in current conditions. [5]
| 1143 GW × 365 d y-1 45 Gw d tonne-1 |
= | 9271 tonnes y-1 |
This matches the reported number of an estimated collective discharge of 7,000-11,000 tonnes annually in the form of SNF as of 2022. [1]
Looking ahead, as several countries have called for a tripling of global nuclear energy by 2050 with nuclear programmes expected to expand and deployment of Generation IV designs beginning, the need to find efficient and cost-effective solutions to managing SNF become urgent. [6]
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| Fig. 2: Nuclear Fuel Cycle (Courtesy of the NRC. Source: Wikipedia Commons) |
At the present time, the global infrastructure for permanent SNF disposal remains nascent. Of the handful of deep geological repository (DGR) programs worldwide, only Finland's Onkalo facility represents the world's most advanced DGR to this date, albeit still undergoing regulatory review. [7] The United States Yucca Mountain repository in Nevada remained indefinitely stalled due to political opposition, while France and Sweden are building repositories that are not yet operational. [7,8] Thus, the overwhelming majority of the world's accumulated SNF remains in interim surface storage with no confirmed permanent disposal. Understanding SNF management costs is thus becoming increasingly important, especially amidst a landscape of Nuclear Power Plant decommissioning and compounding of an already substantial SNF inventory.
Generally, used nuclear fuel is kept in either wet or dry storage facilities, before being recycled or disposed of. In 2024, about 30% of spent fuel had been reprocessed and recycled back into uranium and plutonium. [9] The remaining 70% of the fuel discharged from nuclear reactors went through a once-through pathway where used fuel is disposed directly into a geological repository after a 25-year period of interim storage (Fig. 2). These estimates will be utilized as general proportions for SNF direct disposal and reprocessing ratios.
In terms of costs, given the variability of cost model estimates across studies due to differences in plant scale, technological assumptions, and uncertainties in repository costs, the OECD/NEA has aggregated studies across cost approximations for once-through and reprocessing costs. [10] Table 1 illustrates a summary of cost estimates across studies, and we thus utilize these values to estimate the weighted cost of SNF management.
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| Table 1: Cost of once-through and reprocessing costs across studies stated by OECD/NEA, where cost of once-through pathway is sum of interim storage and geological disposal of UOX and reprocessing pathway cost is sum of recycled U/TRU product storage, UOX reprocessing, and geological disposal of reprocessed waste. [10] |
Scaling to the annual waste generation of 9271 tonnes/year we we obtain the results in Table 2.
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| Table 2: Annual SNF management cost estimates for 9,271 tonnes/year. |
From our analysis, based on the literature cost values obtained, we can see that the annual SNF management cost for 9,271 tonnes/year ranges between US $7.23-15.47 billion. While these costs might not be complete representations of all costs associated with reprocessing and once-through cycles, they provide a general order-of-magnitude baseline for understanding the backlogged annual financial liability involved in global SNF management, sufficient to illustrate the scale of the challenge facing the nuclear industry as production continues to grow.
Thus, without fully operational permanent disposal pathways, the backlog from continued accumulation of SNF could continue generating detrimental mounting liabilities through prolonged interim storage, transport, and eventual disposal costs.
Beyond annual management costs, prolonged interim storage create long-term liabilities that are rarely captured in standard cost accounting. SNF stays lethal for about 1,000 years, implying that much of the true cost of SNF is heavily backloaded. This means that any scenario in which no permanent repository is ever agreed upon would require waste on site needs to be kept in perpetuity in dry casks.
Consider the cost of maintaining dry-cask storage in perpetuity, on-site at existing nuclear power plants. Such scenario would require, over that 1,000 year horizon, continuous armed security to prevent theft or terrorist access to plutonium-bearing waste, maintenance crews to repair cask degradation due to corrosion and seal failure as storage timeline extend far beyond originally designed periods, sustained institutional oversight across political regimes, and remediation of animal incursions or other environmental factors, which involves even larger variable costs across the storage years. Thus, the true costs of perpetual storage is very difficult to estimate, but any credible estimate would agree that unlike most infrastructure, where costs are front-loaded into construction, radioactivity risks cause SNF management costs to continue accumulating and compounding over centuries.
In addition to its cost implications, prolonged storage of spent nuclear fuel extends to safety challenges associated with nuclear waste management.
First are safety and national security risks. The indefinite accumulation of SNF in dry casks present significant national security vulnerabilities. For one, SNF represents a potential target for nuclear proliferation where, unlike a deep geological repository which would consolidate and bury waste further beyond accessible reach, interim dry casks require continuous physical security, monitoring, and maintenance, each compounding potential failure points. [11] For two, while dry casks are engineered with multiple barriers, extended storage over decades increases possibility of degradation in seals and supporting infrastructure, increasing risks of radioactive materials released into surrounding environments and consequent groundwater contamination and radiation exposure. Thus, the longer permanent disposal is deferred, the wider the attack surface and the greater the cumulative risk exposure for surrounding environments and the public becomes.
Second are social and political limitations. While the need for permanent disposal grows, so does the deeply entrenched public opposition to hosting these nuclear waste facilities. For instance, in the case of the Yucca Mountain repository in Nevada, despite decades of scientific study and billions of dollars in site characterization, the project was effectively abandoned following sustained opposition from Nevada residents and state officials. [8] Thus, this results in a political gridlock where, in general, no jurisdiction willingly accepts nuclear waste, focusing continued reliance on interim storage and delaying permanent disposal solutions that would reduce other forms of long-term risks.
Overall, this analysis shows that global nuclear energy currently produces ~9271 tonnes of SNF per year, consistent with reported estimates of ~7-11,000 tonnes annually as of > 2022. Applying OECD/NEA back-end cost figures suggest that managing this annual flow of SNF carries recurring backlog of SNF global liability of ~US $7.23-15.47 billion per year, in addition to safety and national security concerns. These findings thus suggest that, if nuclear energy continues growing in this current infrastructural environmental, the growing global backlog of SNF could become a major constraint on the long-term scalability and sustainability of nuclear power unless significant advances are made in fuel cycles, storage systems, and permanent disposal infrastructure.
© Amber Kwok. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
[1] A. F. Holdsworthet al., "Spent Nuclear Fuel-Waste or Resource? The Potential of Strategic Materials Recovery During Recycle for Sustainability and Advanced Waste Management," Waste 1, 249 (2023).
[2] A. G. Croff et al., "Graphical and Tabular Summaries of Decay Characteristics for Once-Through PWR, LMFBR and FFTF Fuel Cycle Materials," Oak Ridge National Laboratory, ORNL/TM-8061, January 1982.
[3] "Energy, Electricity and Nuclear Power Estimates for the Period up to 2050," International Atomic Energy Agency, IAEA-RDS-1/45, September 2025.
[4] Md. W. Rahman, M. Z. Abedin, and Md. S. Chowdhury, Efficiency Analysis of Nuclear Power Plants: A Comprehensive Review," World J. Adv. Res. Rev. 19, 527 (2023).
[5] "A Review Report on High Burnup Spent Nuclear Fuel," Center for Nuclear Waste Regulatory Analyses, CNWRA 2004-06, September 2004.
[6] I. M. Rodrguez et al., "Assessing the Nuclear Fuel Cycle Under Global Capacity Expansion Scenarios toward 2050," Ann. Nucl. Energy 230, 112175 (2026).
[7] M. Larson et al., "Geology and Design of Major Spent Fuel Repositories." Oak Ridge National Laboratory, ORNL/SPR-2020-1804, November 2020.
[8] G. Rothwell, "Spent Nuclear Fuel Storage: What Are the Relationships Between Size and Cost of the Alternatives?," Energy Policy 150, 112126 (2021).
[9] K. Kiegiel, T. Smoliński, and I. Herdzik-Koniecko, Advanced Nuclear Reactors - Challenges Related to the Reprocessing of Spent Nuclear Fuel," Energies 18, 4080 (2025).
[10] "The Economics of the Back End of the Nuclear Fuel Cycle," Nuclear Energy Agency, NEA No. 7061, 2013.
[11] "Issues in Radioactive Waste Disposal." International Atomic Energy Agency, IAEA-TECDOC-909, October 1996.
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