Understanding how nuclear energy works

If you follow the news or the media, a lot of surveys are done about that thing or this thing. Nuclear is one of that. What to you really know about nuclear power plants ?

Inadequate critical thinking skills can hinder the ability to assess information critically and discern between accurate and inaccurate responses and the prevalence of misinformation and deliberate disinformation campaigns can lead to the spread of false information, making it difficult to distinguish truth from falsehood.

Don’t worry, we’re here to explain. Not judge, just explain.

A nuclear reactor, also known as a power plant, consists of a set of machines designed to harness nuclear fission to generate electricity. These reactors use small pellets made from the element uranium as fuel. Inside the reactor, uranium atoms are manipulated to split apart, and this splitting process releases tiny particles called fission products. These fission products, in turn, trigger more uranium atom splits, initiating a chain reaction. This chain reaction generates heat.

The heat produced by nuclear fission is used to heat a cooling substance within the reactor. Typically, water is used as the cooling substance, but some reactors employ liquid metal or molten salt. As the cooling substance absorbs heat from nuclear fission, it transforms into steam. This steam is then used to spin turbines, which are essentially wheels turned by the flow of steam. These turbines, in turn, drive generators, which are machines that produce electricity.

To control the amount of electricity generated, there are special rods made of a material known as nuclear poison. Nuclear poisons, like a certain type of the element xenon, absorb some of the fission products produced during nuclear fission. When more nuclear poison rods are inserted into the reactor during the chain reaction, it slows down and becomes more controlled. Conversely, removing these rods allows for a stronger chain reaction, leading to the generation of more electricity.

Uranium stands as the predominant fuel of choice for nuclear reactors primarily due to its distinct nuclear attributes that render it amenable to sustaining a controlled nuclear chain reaction. Herein lie several key rationales underlying the deployment of uranium as the primary fuel source for nuclear reactors:

Fissile Properties: Uranium-235 (U-235), an isotope of uranium, exhibits fissile characteristics, signifying its capacity to undergo nuclear fission upon neutron bombardment. In this process, the nucleus of a U-235 atom fragments into two smaller nuclei, liberating a substantial quantum of energy alongside additional neutrons. These liberated neutrons can subsequently induce fission in adjacent U-235 nuclei, instigating a self-perpetuating chain reaction.
Natural Abundance: Uranium, though relatively abundant in the natural milieu, harbors U-235 as a mere fraction, constituting approximately 0.7% of natural uranium. Notably, the more prevalent uranium isotope, uranium-238 (U-238), while not inherently fissile, possesses the propensity to capture neutrons and transmute into plutonium-239 (Pu-239), another fissile material. This characteristic permits the utilization of either natural uranium or mildly enriched uranium in specific reactor configurations.
Energy Density: Nuclear fission proffers an exorbitant energy yield in comparison to alternative energy sources. Even minute quantities of uranium can be leveraged to generate substantial energy outputs, endowing uranium with exceptional fuel efficiency.
Controlled Reaction: Nuclear reactors are meticulously engineered to govern the tempo of the nuclear chain reaction. Employing control rods and cooling systems, reactors orchestrate the precise modulation of the reaction, facilitating a measured and calibrated discharge of energy.
Low Greenhouse Gas Emissions: Nuclear reactors demonstrate a marked advantage in generating electricity with minimal greenhouse gas emissions vis-à-vis fossil fuels. This attribute positions nuclear power as an appealing recourse for mitigating climate change and curtailing carbon emissions.
Reliability: Nuclear reactors boast extended operational periods devoid of frequent refueling requisites, a characteristic that engenders a dependable and consistent electricity supply.
Base Load Power: Nuclear power exhibits commendable suitability for furnishing base load electricity, characterized by its capacity to furnish a continuous and uniform power output. This distinguishes nuclear power from certain intermittent renewable sources such as wind and solar energy.

In sum, the distinctive nuclear characteristics and favorable operational attributes of uranium collectively underpin its venerated status as the primary fuel for nuclear reactors, thereby contributing to the sustenance of a reliable and low-emission energy landscape. Note that other elements and materials, such as thorium and plutonium, can also serve as nuclear fuels in specialized reactor designs. Research and development continue to explore alternative fuels and reactor technologies to improve efficiency, safety, and sustainability in nuclear power generation.

The utilization of nuclear fuel, such as uranium or plutonium, carries significant geopolitical implications, owing to its dual potential for fostering both nuclear reactors and nuclear weaponry. Consequently, the international community has established mechanisms to govern the transfer of such materials, principally contingent upon a nation’s adherence to the Nuclear Non-Proliferation Treaty (NPT).

The Nuclear Non-Proliferation Treaty (NPT) serves as a foundational international agreement, delineating the parameters within which nations may engage in the importation and utilization of nuclear fuels. Underpinning the NPT is a twofold objective: first, to foster the peaceful and civilian application of nuclear fuel for purposes such as electricity generation through nuclear reactors; and second, to constrain the proliferation of nuclear weapons.
In the context of radioactive waste, we encounter two distinct categories:

Short-Lived Radioactive Waste:
- This category encompasses 1.8 kilograms of waste out of 2 KG of waste, characterized by a radioactivity level that diminishes by half in less than 30 years.
- Unlike chemical substances, whose toxicity remains constant over time, the radioactivity of this waste naturally decreases.
- Remarkably, after a span of 300 years, the radioactivity of this “short-lived” waste will reach a level comparable to that of natural radioactivity.
Long-Lived Radioactive Waste:
- Constituting 200 grams out of 2 KG of waste, this category is distinguished by its radioactivity, which reduces by half over more than 30 years.
- These materials can retain their radioactive properties for an extended duration, spanning several tens of thousands of years.
- The origin of this waste can be traced to spent nuclear fuel, a byproduct resulting from the utilization of nuclear power plants.
- To mitigate its environmental impact, this waste undergoes a comprehensive process of treatment and recycling aimed at diminishing both its volume and toxicity.
- Solution plans are still in a research phase.

These categorizations highlight the varying degrees of radioactivity and longevity associated with different types of radioactive waste, underscoring the importance of carefully managing and handling such materials to ensure the safety and security of both present and future generations.

Before you say that is better or not than a solar panel park, we will list some advantages and critical aspects comparing to renewables.

1. Energy Source:

Nuclear Energy: Derived from the fission (splitting) of uranium or plutonium atoms in nuclear reactors.
Renewable Energy: Generated from naturally occurring, replenishing sources like sunlight (solar), wind, water (hydroelectric), and geothermal heat. Directly dependent from those sources.

2. Greenhouse Gas Emissions:

Nuclear Energy: Low greenhouse gas emissions during electricity generation.
Renewable Energy: Virtually no direct greenhouse gas emissions during operation.

3. Energy Density:

Nuclear Energy: High energy density, producing a large amount of electricity from a small amount of fuel.
Renewable Energy: Variable energy density depending on the source. Still low efficiency (30%)

4. Fuel Availability:

Nuclear Energy: Availability depends on uranium and plutonium resources, with some limitations on long-term supply.
Renewable Energy: Reliant on naturally occurring resources, generally sustainable over the long term.

5. Energy Security:

Nuclear Energy: Enhances energy security by reducing dependence on fossil fuel imports.
Renewable Energy: Can reduce reliance on fossil fuels but may require energy storage solutions to ensure constant supply.

6. Reliability:

Nuclear Energy: Provides consistent, base load power, not affected by weather or time of day. Low risk of accidents.
Renewable Energy: Variable output due to weather conditions and sunlight availability (solar and wind). Very low risk of accidents.

7. Environmental Impact:

Nuclear Energy: Concerns about radioactive waste disposal, potential for accidents (e.g., Chernobyl, Fukushima), and habitat disruption during uranium mining.
Renewable Energy: Generally considered environmentally friendly, with minimal direct environmental impact they have an hidden cost :
- Silicon: Silicon is the primary semiconductor material used in the manufacturing of photovoltaic (PV) solar cells, which are the core components of solar panels. High-purity silicon is essential for efficient electricity generation in solar cells. While silicon is abundant in nature, the process of refining it to the required purity level can be energy-intensive and expensive.
- Iron: Iron is not a primary material used in solar cells, but it is a vital component in the infrastructure and support structures for solar panels. Iron is often used in the framing, racking, and mounting systems that hold solar panels in place, ensuring their stability and durability. Iron ore is mined from deposits in the Earth’s crust.

8. Land Use:

Nuclear Energy: Requires relatively small land area for power plants.
Renewable Energy: Wind and solar farms may require larger land areas.

9. Cost:

Nuclear Energy: High initial construction and decommissioning costs, with long project timelines.
Renewable Energy: Costs have been decreasing rapidly, with solar and wind becoming more competitive.

10. Waste Management:
Nuclear Energy: Involves challenges in managing and storing radioactive waste for thousands of years. – Renewable Energy: Produces no radioactive waste, but some components (e.g., solar panels, wind turbine blades) raise recycling and disposal concerns.

11. Proliferation Risks:
Nuclear Energy: Potential for the diversion of nuclear materials for weapons purposes.
Renewable Energy: No proliferation risks associated with energy generation.

In summary, both nuclear and renewable energy sources have their advantages and drawbacks. The choice between them often depends on factors such as energy security, environmental concerns, availability of resources, and cost considerations. Many regions are now exploring a mix of both to create a diverse and sustainable energy portfolio.