Nuclear Reactor Overview

OVERVIEW OF NUCLEAR REACTOR AND REACTOR ENERGY Nuclear reactors are complex systems designed to initiate and control a fission nuclear chain reaction, primarily for electricity generation. This overview will detail the fundamental principles of nuclear reactors, their components, types,...

OVERVIEW OF NUCLEAR REACTOR AND REACTOR ENERGY Nuclear reactors are complex systems designed to initiate and control a fission nuclear chain reaction, primarily for electricity generation. This overview will detail the fundamental principles of nuclear reactors, their components, types, and the energy they produce. Nuclear Reactor: A nuclear reactor is a device that initiates and controls a self- sustaining series of nuclear fission reactions. In this process, heavy atomic nuclei (typically uranium or plutonium) split into smaller nuclei, releasing energy in the form of heat. PURPOSE Energy Production: Nuclear reactors are primarily used to generate electricity by converting the heat produced from nuclear fission into electrical power. Research: They are utilized in scientific research to study nuclear physics and materials science. Generation of Radioactive Isotopes: Reactors produce isotopes used in medicine, industry, and agriculture. FUNDAMENTAL PRINCIPLES OF NUCLEAR REACTOR Nuclear reactors operate on the principle of nuclear fission, where heavy atomic nuclei, such as uranium-235 or plutonium-239, absorb a neutron and split into lighter nuclei, releasing a significant amount of energy, gamma radiation, and additional neutrons. These emitted neutrons can then induce further fission, creating a self- sustaining chain reaction. The energy released during fission is harnessed to produce heat, which is then used to generate steam that drives turbines to produce electricity.  KEY COMPONENTS OF A NUCLEAR REACTOR Fuel Coolant Turbine and Generator Moderator Containment Structure Steam Generators Control Rods (in PWRs)  Key Components of a Nuclear Reactor FUEL The primary fuel used in most reactors is uranium, typically in the form of uranium oxide (UO₂) pellets. These pellets are arranged in fuel rods, which are grouped into assemblies within the reactor core. A typical 1000 MWe pressurized water reactor (PWR) may contain around 51,000 fuel rods. Key Components of a Nuclear Reactor MODERATOR This material slows down the neutrons released during fission, increasing the likelihood of further fission events. Common moderators include water (light water), heavy water, and graphite.  Key Components of a Nuclear Reactor CONTROL RODS Made from neutron-absorbing materials like cadmium or boron, control rods are inserted or withdrawn from the reactor core to regulate the fission reaction rate. Their position directly affects the reactor's power output. Key Components of a Nuclear Reactor COOLANT This fluid, often water, circulates through the reactor to remove heat from the core and transfer it to a steam generator or directly to turbines. The coolant must remain under high pressure to prevent boiling in many reactor types.  Key Components of a Nuclear Reactor CONTAINMENT STRUCTURE A robust containment structure, typically made of steel and reinforced concrete, surrounds the reactor to prevent the release of radioactive materials in the event of an accident.  Key Components of a Nuclear Reactor STEAM GENERATORS (IN PWRS) In pressurized water reactors (PWRs), steam generators transfer heat from the primary coolant loop to a secondary loop, producing steam without allowing the coolant to boil.  Key Components of a Nuclear Reactor TURBINE AND GENERATOR The steam produced drives turbines connected to generators that convert mechanical energy into electricity.  TYPES OF NUCLEAR REACTORS Pressurized Water Reactor Heavy Water Reactor Fast Breeder Reactor (PWR) Boiling Water Reactor Small Modular Reactors Gas-Cooled Reactor (BWR) (SMRs)  Types of Nuclear Reactors PRESSURIZED WATER REACTOR (PWR) The most common type, where water is kept under pressure to prevent boiling and is used to transfer heat from the reactor core to a secondary circuit, generating steam.  Types of Nuclear Reactors BOILING WATER REACTOR (BWR) In this type, water boils directly in the reactor core, producing steam that drives the turbines.  Types of Nuclear Reactors HEAVY WATER REACTOR Uses heavy water (deuterium oxide) as a moderator and coolant, allowing the use of natural uranium as fuel.  Types of Nuclear Reactors GAS-COOLED REACTOR Utilizes gas (often carbon dioxide) as a coolant, with graphite as the moderator.  Types of Nuclear Reactors FAST BREEDER REACTOR Designed to convert fertile material into fissile material while generating energy, these reactors do not use a moderator and rely on fast neutrons.  Types of Nuclear Reactors SMALL MODULAR REACTORS (SMRS) A newer design that is smaller in size and can be manufactured off-site, offering flexibility and reduced initial capital costs. ENERGY PRODUCTION AND EFFICIENCY Nuclear reactors are highly efficient in energy production. A single kilogram of uranium-235 can produce millions of times more energy than an equivalent mass of fossil fuels. This efficiency is due to the nature of nuclear fission, where a small amount of fuel can sustain a large energy output over extended periods. The heat generated from fission is transferred to a working fluid (usually water), which is then converted into steam to drive turbines connected to electrical generators. Additionally, the heat can be utilized for district heating, industrial processes, and even desalination. LIGHT WATER REACTORS Light Water Reactors (LWRs) are a type of nuclear reactor that use ordinary water (H₂O) as both a coolant and a neutron moderator. Water in the reactor acts as a coolant, which means it absorbs the heat generated by the nuclear fission process inside the reactor core. Water also functions as a neutron moderator. In the nuclear fission process, when uranium atoms split, they release neutrons. These neutrons are initially very fast and need to be slowed down to make them more likely to cause further fission in other uranium atoms (specifically, Uranium-235). Water does this by "moderating" or slowing down the neutrons as they collide with water molecules, primarily with the hydrogen atoms. LWRs are the most common type of nuclear reactor worldwide, found in countries like the United States, France, Russia, and China. They are used primarily for electricity generation, though they can also have applications in research and naval propulsion. Light Water Reactors (LWRs) are the backbone of the global nuclear energy industry, accounting for around 80% of all nuclear reactors worldwide.  Coolant and Moderator: Ordinary KEY FEATURES water serves two roles: it removes heat from the reactor core (coolant) and slows down neutrons to sustain the nuclear chain reaction (moderator). Fuel: LWRs typically use enriched uranium as fuel, where the concentration of Uranium-235 is increased to around 3-5%. Thermal Neutrons: LWRs rely on slow (thermal) neutrons to maintain the nuclear chain reaction, meaning water is essential in moderating neutron speed. TYPES OF LIGHT WATER REACTORS The two main types of LWRs, Pressurized Water Reactors (PWRs) and Boiling Water Reactors (BWRs), have distinct operational characteristics: Read More  PRESSURIZED WATER REACTOR (PWR) Design: In a PWR, the reactor core and coolant are kept at high pressure, preventing the water from boiling even at temperatures above 300°C (572°F). Primary and Secondary Loops: The PWR uses a primary water loop (the water in direct contact with the reactor core) to transfer heat to a secondary loop, where the water boils and turns into steam. This design reduces the risk of radioactive contamination in the steam. Safety: The separation of the primary and secondary loops enhances safety by isolating the reactor coolant from the turbine and steam generator. Application: PWRs are the most common reactor type globally, used in countries like the United States, Russia, and France.  BOILING WATER REACTOR (BWR) Design: In a BWR, water in the reactor core is allowed to boil. The steam generated directly drives the turbine. Simpler Design: Since BWRs do not need a secondary loop, they are simpler and potentially cheaper to build than PWRs. However, the steam may carry radioactive particles, necessitating careful containment and shielding. Application: BWRs are less common than PWRs but are still widely used, particularly in the United States and Japan. ADVANTAGES OF LIGHT WATER REACTORS LWRs offer several benefits that have made them the dominant technology in nuclear power generation: 1. Proven Technology: LWRs have been used for over 60 years, with thousands of reactor-years of operational experience. Their reliability and scalability are well- established. 2. High Efficiency: LWRs have thermal efficiencies of around 33%, meaning that a significant portion of the heat generated by nuclear fission is converted into electricity. 3. Safety Systems: Modern LWRs are designed with multiple layers of safety, including containment structures, emergency core cooling systems, and automatic shutdown mechanisms to prevent accidents. 4. Standardization: The widespread use of LWRs has led to significant standardization in reactor designs, which helps to reduce costs and streamline maintenance and operational procedures. 5. Flexibility: LWRs can be scaled to produce different amounts of power, making them adaptable to various grid sizes and energy demands. DISADVANTAGES AND CHALLENGES Despite their advantages, LWRs face several challenges: 1. Radioactive Waste: LWRs generate large amounts of spent fuel, which remains highly radioactive for thousands of years. The long-term storage and management of this waste are significant concerns. 2. Limited Fuel Utilization: LWRs only use a small fraction (about 3-5%) of the energy content in uranium fuel, meaning the rest is discarded as waste. Other reactor types, such as fast breeder reactors, can utilize more of the fuel. 3. Safety Risks: Although LWRs are designed with robust safety features, the potential for severe accidents (such as the Fukushima or Chernobyl disasters) exists, especially in older designs. These accidents can result in widespread radioactive contamination and long-term environmental damage. 4. Water Requirements: LWRs require large amounts of water for cooling, which can limit their deployment in arid regions or during droughts. Additionally, they are usually located near large bodies of water (oceans, rivers, or lakes), raising environmental concerns. 5. Proliferation Risks: Enrichment of uranium, necessary for LWR fuel, also increases the risk of nuclear proliferation, as the same technologies used to enrich uranium for reactors can be adapted for weapons-grade materials. RECENT INNOVATIONS AND FUTURE OUTLOOK The future of LWRs lies in the development of more advanced designs, which aim to improve safety, efficiency, and sustainability. Some key developments include: 1. Small Modular Reactors (SMRs): SMRs are compact versions of LWRs that are designed for smaller power grids and decentralized energy production. They offer greater flexibility, enhanced safety features, and can be built in factory settings, potentially reducing costs and construction times. 2. Generation III+ and IV Reactors: These advanced reactors incorporate passive safety systems that can operate without human intervention, reducing the risk of accidents. Some designs also aim to use fuel more efficiently and reduce the amount of nuclear waste generated. 3. Reprocessing and Recycling: Technologies for reprocessing spent nuclear fuel are being developed to extract usable materials from spent fuel and reduce the amount of waste that needs to be stored. However, these technologies come with their own set of technical and political challenges. 4. Accident-Tolerant Fuels (ATF): ATF is a new class of fuel designed to withstand higher temperatures and resist melting during accidents, offering an additional layer of safety. REFERENCES World Nuclear Association. (n.d.). Nuclear Power Reactors. https://world- nuclear.org/information-library/nuclear-fuel-cycle/nuclear-power- reactors/nuclear-power-reactors Wikipedia. (2023). Nuclear reactor. https://en.wikipedia.org/wiki/Nuclear_reactor CEA. (n.d.). Nuclear reactors. Retrieved from https://www.cea.fr/english/Documents/thematic-publications/cea- nuclear-reactors.pdf Britannica. (2024). Nuclear reactor | Definition, History, & Components. https://www.britannica.com/technology/nuclear-reactor U.S. Energy Information Administration. (n.d.). Nuclear power plants. https://www.eia.gov/energyexplained/nuclear/nuclear-power-plants.php THANK YOU! presented by: group 3 bsme 3a alexander john naje rob ribaya Myla joy huera arianne de la torre