How is Nuclear Waste Generated?

India recently initiated the core loading of its much-awaited Prototype Fast Breeder Reactor (PFBR), marking a significant step towards the second phase of its three-tier nuclear strategy, which utilizes uranium and plutonium. The ultimate goal, stage III, envisions leveraging India’s extensive thorium reserves for nuclear energy production, enhancing energy autonomy. However, the expansion of nuclear power brings with it the challenging issue of managing nuclear waste.

Relevance: GS III (Science & Tech)

Stages of India’s Nuclear Energy Development

• Stage I: Involves the use of natural uranium in pressurized heavy-water reactors.
• Stage II: Advances to utilizing fast breeder reactors, employing a mix of uranium and plutonium.
• Stage III: Targets the harnessing of thorium, abundant in India, to foster energy self-sufficiency.

What is Prototype Fast Breeder Reactor (PFBR)?

Overview of the Prototype Fast Breeder Reactor (PFBR)

• The PFBR is designed to generate more nuclear fuel than it consumes, effectively creating a self-sustaining cycle.
• In Pressurized Heavy Water Reactors (PHWRs), deuterium oxide (heavy water) is used to slow down neutrons from fission reactions, allowing them to interact with uranium-238 (U-238) and uranium-235 (U-235) nuclei, leading to further fission events.
• The heavy water is kept under high pressure to prevent it from boiling, facilitating the production of plutonium-239 (Pu-239) and energy.
• PHWRs operate with natural or slightly enriched U-238, yielding Pu-239 as a secondary product. This Pu-239, mixed with more U-238 into a mixed oxide, is then used in the core of a new reactor along with a blanket material that, when interacted with by fission products, generates additional Pu-239.

Understanding Nuclear Waste Management

• Nuclear waste originates from the fission process in reactors, where neutrons collide with the nuclei of certain atoms.
• When a nucleus captures a neutron, it becomes unstable and splits, releasing energy and creating different atomic nuclei.
• For instance, when U-235 captures a neutron, it may split into barium-144, krypton-89, and additional neutrons. The resulting elements, like barium-144 and krypton-89, which cannot undergo further fission, are classified as nuclear waste.
• Once nuclear fuel is utilized in a reactor, it becomes irradiated and must eventually be removed, at which point it is referred to as spent fuel.
• Due to its high radioactivity, nuclear waste requires secure storage in specially designed facilities to prevent any leakage or environmental contamination.

Managing Nuclear Waste

• Nuclear waste, which is highly radioactive and generates heat, requires initial storage in water to cool for several decades.
• After sufficient cooling, the waste is then moved to dry casks for more secure, long-term storage.
• Countries with established nuclear programs have significant amounts of spent fuel. For instance, as of 2015, the U.S. reported having 69,682 tonnes, Canada 54,000 tonnes in 2016, and Russia 21,362 tonnes in 2014.
• Facilities for treating liquid nuclear waste are integral to nuclear power plants. The International Agency for Atomic Energy notes that it’s permissible to release minor amounts of treated water with short-lived radionuclides into the environment. An example is the ongoing release of treated water from Fukushima’s nuclear plant into the Pacific Ocean by Japan.
• The process known as vitrification is used to manage high-level liquid waste, turning it into a glass-like substance for safer storage, as it encompasses nearly all fission products created within the fuel.

How is Nuclear Waste Dealt with?

• After cooling in a spent fuel pool for a minimum of one year, spent fuel is eligible for transfer to dry-cask storage, where it’s encased in robust steel cylinders and insulated with an inert gas.
• These cylinders are then securely enclosed in larger steel or concrete containers for added protection.
• For long-term disposal, the waste is encapsulated in specially designed containers and buried deep within stable geological formations like granite or clay, known as geological disposal.
• However, concerns exist about the potential exposure of radioactive materials to humans if these underground containers are inadvertently disturbed, for example, by excavation activities.
• Reprocessing technology, which chemically processes spent fuel to separate reusable fissile materials from waste, offers an alternative waste management solution.
• Given the hazardous nature of spent fuel, reprocessing plants are equipped with advanced safety measures and skilled personnel, despite the higher operational costs and efficiency benefits.
• The Waste Isolation Pilot Plant (WIPP) in the U.S. serves as a cautionary example, highlighting the unpredictable challenges (“unknown unknowns”) of long-term waste storage. Despite its status as a benchmark for radioactive waste management, a 2014 incident at WIPP involved a release of radioactive material, underscoring significant maintenance lapses.
• The difficulty in establishing successful waste repositories is a common challenge globally, with many attempts facing setbacks.

Exporting nuclear waste is an environmental injustice

• The management of waste from power plant operation accounts for about 24% of the costs and 15% ids due to power plant decommissioning. The remaining 50% of costs is associated with the back end of the fuel cycle.
• Waste management imposed a cost of $1.6- 7.1 per MWh of nuclear energy.

How does India handle Nuclear Waste?

• India utilizes reprocessing facilities located in Trombay, Tarapur, and Kalpakkam to manage its nuclear waste, as highlighted in a 2015 report by the International Panel on Fissile Materials. The nuclear waste produced during the operational phase of nuclear power plants is categorized as low and intermediate in terms of radioactive activity and is handled directly at the plant sites. This waste undergoes treatment and is stored in designated facilities within the power plant premises. Every nuclear power station in India is equipped with such facilities, and the areas surrounding these plants are routinely monitored to ensure there is no radioactive leakage.
• The report from the International Panel on Fissile Materials also noted that the delays experienced by the Prototype Fast Breeder Reactor (PFBR) could indicate operational inefficiencies at the Tarapur and Kalpakkam reprocessing sites, with an observed combined average capacity factor of about 15%.

Conclusion

• Innovative Reactor Designs: India’s PFBR represents a significant advancement in nuclear technology, offering the potential for a more sustainable and efficient use of nuclear fuel by breeding more fuel than it consumes.
• Challenges in Waste Management: The management of nuclear waste, particularly in terms of safe, long-term disposal, remains a complex challenge that necessitates innovative solutions and stringent safety measures to protect the environment and human health.
• Strategic Reprocessing Efforts: India’s approach to reprocessing spent fuel, especially in facilities like Trombay, Tarapur, and Kalpakkam, underscores the country’s commitment to recycling and minimizing nuclear waste, albeit with operational challenges that need addressing.
• Environmental and Economic Considerations: The handling and disposal of nuclear waste not only have significant environmental implications but also entail considerable costs, highlighting the need for a balanced approach that considers both sustainability and economic viability in the context of nuclear energy development.

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