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| Fig. 1: Dry storage areas of SONGS. [3] |
The San Onofre Nuclear Generating Station (SONGS), located in San Diego County, California, was a key source of electricity for millions of residents. In addition, it is recognized as a landmark to many Southern California residents due to the distinctive dome shape of the reactor containment buildings and proximity to the I-5 freeway. Following its permanent shutdown in 2013 due to safety concerns with its steam generators, the plant entered the decommissioning phase. [1] This report examines the complexities of the decommissioning process, focusing on radioactive material removal, waste management, environmental considerations, and the financial and quantitative implications.
SONGS consisted of three units, two of which were operational at the time of its shutdown. Units 2 and 3, commissioned in the 1980s, faced significant operational issues, leading to the decision to decommission. Unit 1 was previously decommissioned in 1992. The plant's closure marked the beginning of a lengthy and intricate dismantling process, governed by stringent federal and state regulations. [2]
The decommissioning involves the safe dismantling and removal of radioactive components, including reactor vessels, steam generators, and spent fuel. Spent fuel is being transferred to dry cask storage onsite, a temporary solution pending the availability of a permanent federal repository, as seen pictured in Fig. 1. [2]
One of the most significant challenges in the decommissioning process is managing nuclear waste. Approximately 1,631 metric tons of spent nuclear fuel must be processed, stored, or transported from the site. [2] The current strategy includes interim onsite storage of spent nuclear fuel, reinforced with steel rebar and concrete. However, on-site storage holds the risk of fissile nuclear material falling into the hands of nefarious actors, as well as the host of environmental risks that remain due to proximity with high-traffic areas. Long-term solutions currently remain uncertain as the U.S. lacks a centralized repository for high-level nuclear waste, after funding was cut for the Yucca Mountain nuclear storage site shortly before it was scheduled to open. [3]
The decommissioning of SONGS has significant environmental implications, especially given its coastal location. One key focus is the protection of marine ecosystems, as the plant's ocean water intake systems historically impacted marine life. Decommissioning eliminates these operations, providing an opportunity to restore affected habitats. Offshore structures, such as intake and discharge conduits, are being removed or mitigated to minimize disruption and support marine recovery. [4]
Groundwater and soil contamination are closely monitored to prevent the spread of radioactive materials. Spent nuclear fuel is stored in the reinforced dry cask systems designed to safely contain waste and withstand seismic activity, reducing risks to the environment. [5] Air quality impacts from dismantling and transportation are mitigated through dust control and emissions management Land restoration is another critical aspect, aiming to repurpose the site while addressing residual contamination. Coastal erosion and the sites seismic resilience are also managed to ensure long-term environmental safety. [4] Overall, SONGS decommissioning provides an opportunity to address historical environmental impacts while preventing future risks.
The decommissioning of SONGS is projected to cost approximately $4.4 billion. Funding is sourced from a trust established during the plant's operational years, financed by ratepayers. Cost oversight is provided by the California Public Utilities Commission to ensure financial accountability and transparency. [6] To contextualize the impact SONGS decommissioning, consider the following calculations:
Nuclear Waste Volume: SONGS decommissioning will result in approximately 1,630,000 kg of spent nuclear fuel and other waste needing storage, of which some is stored in 50 horizontal and 73 dry casks onsite. [3]
Decommissioning Costs: At $4.4 billion, the decommissioning cost represents a significant expense, with $3.2 billion allocated for waste management and disposal alone. [6] The decommissioning is expected to be completed by 2040, with major dismantling work finished by the mid-2030s. [6] Using this timeline, with a period of 27 years, this results in an average of roughly $163 million per year in spending. Relating cost per kilogram of material through the cost associated with waste management and disposal, the decommissioning process amounts to approximately $2000 per kg of material.
The decommissioning of SONGS highlights the complexities and challenges of retiring nuclear power plants, exposing critical gaps in current methods. While progress has been made in dismantling and storing radioactive components, the lack of a long-term solution for nuclear waste storage remains a significant concern, with interim on-site storage posing ongoing risks to safety and the environment. The financial burden, largely shouldered by ratepayers, raises questions about the fairness and sustainability of funding mechanisms, particularly given the escalating costs of waste management. Additionally, while regulatory frameworks aim to ensure safety and environmental protection, they fall short in addressing long-term uncertainties, especially in coastal and high-traffic areas like SONGS. As aging nuclear facilities across the U.S. face similar challenges, the SONGS experience underscores the urgent need for more innovative and secure decommissioning strategies to address the intertwined issues of safety, cost, and environmental stewardship.
© Garrett Brown. 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] B. Bonanni, '"San Onofre Nuclear Generating Station," Physics 240, Stanford University, Fall 2016.
[2] R. Alvarez, "Reducing the Hazards of High-Level Radioactive Waste in Southern California: Storage of Nuclear Waste from Spent Fuel at San Onofre," Friends of the Earth, June 2013
[3] R. Nikolewski, "Report Looks at What to Do with the Nuclear Waste at San Onofre," The San Diego Union-Tribune, 16 Mar 21.
[4] T. J. Palmisano, "Docket Nos. 50-36 and 50-362, San Onofre Nuclear Generating Station Units 2 and 3: Post-Shutdown Decommissioning Activities Report," Southern California Edison, September 2014.
[5] A. Chun, "Nuclear Waste at San Onofre," Physics 240, Stanford University, Fall 2020.
[6] "2014 Decommissioning Cost Analysis of the San Onofre Nuclear Generating Station Units 2 and 3," Energy Solutions, 164001-DCE-001, September 2014.