Nuclear power plants are used to generate electrical energy in various countries. Owing to operational restrictions, a nuclear power plant's life is about 35-45 years. After completing their life cycle, nuclear power plants are decommissioned. As simple as it may seem, it is a complex process involving years of planning and execution.
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A Brief Introduction to Nuclear Decommissioning
The International Atomic Energy Agency defines the process of nuclear decommissioning as the combination of two operational tasks performed simultaneously, i.e., administrative and technical activities. As a result of these activities, a thorough clean-up of radioactive resources and waste from the nuclear power plant occurs. This is done for the repurposing of the site to be utilized for any other purpose.
The complete process of nuclear decommissioning involves meticulous planning of shutting operations, the physical and radiological characterization of materials by experts, the development of an efficient decontamination strategy for the nuclear site, the safe dismantling of the facility structures, and the management of waste materials as per rules and regulations. This comprehensive approach ensures the safe and effective transition of the facility for future use.
Nuclear Decommissioning: A Strategic Process
In the field of nuclear sciences, the safe decommissioning of facilities is considered an essential part of the lifecycle management of nuclear sites. Field experts are hired to devise relevant strategies for the shutting down and clean-up of the nuclear sites.
The complex decommissioning process incorporates years of data gathering, and the plan for the nuclear decommissioning of any facility is initiated along with the operational authorization of the facility. The plan must be economically and functionally viable and cover all the associated financial costs. This early planning ensures that the nuclear waste is managed safely without causing any harm to the ecosystem.
A detailed decommissioning plan is formulated upon final shutdown, outlining the strategy for safely dismantling the facility. It describes the steps to ensure radiation protection for workers and the public, addresses environmental impacts, outlines the management of radioactive and non-radioactive materials, and details the termination process for regulatory authorization regarding the facility and its site.
Challenges Associated with Nuclear Decommissioning
Various technical, environmental, and social challenges threaten the decommissioning of existing nuclear facilities and future energy infrastructures. It is necessary to efficiently understand these major challenges and devise sustainable solutions.
A research article published in Energy Policy has highlighted several challenges faced during the decommissioning of nuclear facilities. The statistics reveal that after mid-2020, only 3% of nuclear reactors have been fully decommissioned.
Decommissioning existing nuclear energy infrastructures encounters technical challenges in safely managing radioactive, toxic, and hazardous materials. Proper handling, transporting, reusing, recycling, and disposing of large components also pose difficulties. A general absence of standardized recycling policies and regulations for end-of-life waste management amplifies these challenges.
The economic implications of nuclear decommissioning are expected to be substantial and will rise as more assets approach the end of their operational life. Public funds often finance most nuclear decommissioning in Europe, and inadequate reserves by operators mean that taxpayers will likely bear the future decommissioning costs.
Globally, decommissioning costs for nuclear plants range from US$ 1 billion to US$ 1.5 billion per 1000-megawatt plant. The cost of dismantling facilities associated with the fuel cycle, research reactors, and laboratories needs consideration.
Furthermore, environmental challenges emerge when it is planned to either restore decommissioned infrastructure sites to their original state or prepare them for future use. There is a considerable risk of the release of harmful pollutants in the event of any minor mishap. The ecological response must be assessed carefully and balanced with the imperative to maintain the site's functionality and manage risks, including the potential for catastrophic collapse.
Robotics: An Innovative Solution for Nuclear Decommissioning
With the progress of robotic technologies and artificial intelligence, experts are increasingly focused on extending the autonomous operations of robots into more intricate yet harsh environments. As per a recent article in Robotics, special robots are now being developed to perform complex tasks during nuclear decommissioning.
Handling objects in nuclear environments poses two primary challenges: dealing with unknown objects and ensuring their safe manipulation (i.e., without breaking or dropping them). Incorporating haptic intelligence and leveraging tactile sensing in contemporary robotics has greatly enhanced the safety of grasping before and during object manipulation.
Recently, a novel approach employing fiber-optic tactile sensors for detecting surface cracks has been introduced. This technique offers distinct advantages, designed with nuclear decommissioning in mind and intended for use with remotely operated robots. Fiber optics is advantageous as it remains unaffected by gamma radiation, providing a potential alternative to electrical cables in nuclear power plant applications.
Novel Technology to Significantly Reduce the Cost of Decommissioning
A company registered in the UK, C-Tech Innovation, has been performing research studies for the past 10 years to develop an innovative electrochemical nuclear decontamination system that is much cheaper than traditional methods.
The first technological innovation presented by the company was its advanced electrolytically assisted surface decontamination (EASD) system. This technology offers a controlled, rapid, and cost-effective method for dissolving surfaces using nitric acid as the medium.
It facilitates the removal of radioactivity from contaminated metal by leveraging accelerated electrolytic dissolution of the contaminated metal surface. The resulting radioactive dissolved metal is transferred into the nitric acid effluent, which is processed downstream using conventional methods.
Electrochemical Nuclear Decontamination (ELENDES) technology, poised to revolutionize the removal of contaminated organic matter from aqueous effluent before downstream processing, has also been tested.
ELENDES involves electrochemically oxidating insoluble organic waste material at nuclear sites, effectively eliminating the organic matter that contains radioactive content from the waste material. This advanced electrochemical nuclear decontamination solution provides a safe and efficient means of removing contaminated organic matter at the end of its life cycle.
Several challenges still surround the process of nuclear decommissioning. The complex planning and safe execution of the process, along with ensuring its environmental sustainability, is a major hurdle. The recent technological advancements in robotics and industrial equipment ensure that nuclear decommissioning will become safer and cheaper as time progresses.
References and Further Reading
C-Tech Innovation, (2022). Two Step Change Technologies that Offer a Significant Reduction in the Cost of Nuclear Decommissioning. [Online]
Available at: https://www.ctechinnovation.com/technologies-that-reduce-the-cost-of-nuclear-decommissioning/ [Accessed 29 November 2023].
International Atomic Energy Agency, (2023). Decommissioning of nuclear installations. [Online] Available at: https://www.iaea.org/topics/decommissioning [Accessed 29 November 2023].
Nuclear Energy Agency, (2019). The Regulatory Challenges of Decommissioning Nuclear Reactors. [Online]
Available at: https://www.oecd-nea.org/jcms/pl_13760/the-regulatory-challenges-of-decommissioning-nuclear-reactors?details=true [Accessed 28 November 2023].
Invernizzi, D. et. al. (2020). Developing policies for the end-of-life of energy infrastructure: Coming to terms with the challenges of decommissioning. Energy Policy, 144, 111677. Available at: https://doi.org/10.1016/j.enpol.2020.111677
Vitanov I. et al. (2021) A Suite of Robotic Solutions for Nuclear Waste Decommissioning. Robotics. 10(4):112. Available at: https://doi.org/10.3390/robotics10040112
World Nuclear Association, (2022). Decommissioning Nuclear Facilities. [Online]
Available at: https://world-nuclear.org/information-library/nuclear-fuel-cycle/nuclear-wastes/decommissioning-nuclear-facilities.aspx [Accessed 27 November 2023]
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