otb-portfolio/nuke.tex

\section{The science of nuclear energy}

\begin{frame}{Nuclear energy, the way to go ?}
    If, as suggested before, the use of heat pumps increases, power plants are needed to back up
    this electricity consumption.

    From the perspective of reducing carbon emissions to match the objectives of the Paris Agreement, it is unimaginable to produce
    with carbon-emitting fossil fuel. One of the very efficient ways of producing a low-carbon electricity is the nuclear power plant.  
\end{frame}


\begin{frame}{Deep into the fundamentals}
    To fully understand nuclear power, one must focus on the deep functioning of matter, its description, its structure, its mechanisms.

    First, there will be a focus on the matter itself, the atoms and radioactivity. Then, we will describe the functioning of a power plant, and more specifically a nuclear power plant, the challenges and the risks they raise.

    Finally, a small depiction of the possible future of nuclear energy will be given.
\end{frame}

\begin{frame}{Atoms}
    Atoms are an elementary brick of the matter that compose the universe. They are the smallest components of matter the unique chemical properties.
    Those chemical properties are determined by the number of protons (a subatomic positively charged particle) that lays in the nucleus, along with neutrons at the center of the atom.
    The number of protons is called the atomic number and defines an element, and the number of particles in the nucleus (proton + neutrons) account for the mass number.

    \begin{figure}
        \centering
        \includegraphics[width=.25\linewidth]{images/nuke/carbon.png}
        \caption{Carbon's atomic number is 6}
    \end{figure}
\end{frame}

\begin{frame}{Elements}
        Known elements are all sorted in the periodic table of the elements, introduced by Dmitri Ivanovitch Mendeleïev in 1869.

    \begin{figure}
        \centering
        \includegraphics[width=.5\linewidth]{images/nuke/periodic-table.png}
        \caption{Current state of the periodic table of the elements.}
    \end{figure}
\end{frame}

\begin{frame}{Isotopes}
But there is more, if an element corresponds to one and only one atomic number, it may exists several versions of this element with different mass numbers, with the only difference of the neutron count. They are called isotopes.

Isotopes are everywhere in nature, in different proportions, they are referred as Element-Number of mass. For instance, the most widespread 
isotope of carbon is called Carbon-12, but another isotope: Carbon-14 is well-known and used in carbon dating.
    
\end{frame}

\begin{frame}{Radioactivty}

Isotopes can be unstable and thus randomly disintegrate into different elements with different mechanisms. That fact is called radioactivity.\\
Isotopes disintegrate at different rates, a classical metric to designate this disintegration rate is the half-life. It is the time period for an unstable element batch to lose half of its components. For instance, Carbon-14 has an half-life of 5730 years.
Which means that a fossil containing 1000 atoms of Carbon-14, will roughly have only 500 atoms of Carbon-14 left by the year 7754.
    
\end{frame}

\begin{frame}{Nuclear fission}
    
Some of the isotopes of heavy elements (like uranium and plutonium) undergo nuclear fission they are unstable isotopes which split into two smaller atoms when disintegrating. They also emit several neutrons
that can be captured by other atoms nearby and then make those unstable which will also undergo nuclear fission and so on, starting a chain reaction.

\begin{figure}
    \centering
    \includegraphics[width=.5\linewidth]{images/nuke/fission.jpg}
    \caption{The example of the fission of Uranium-235}
\end{figure}


\end{frame}
\begin{frame}[allowframebreaks]{How does a nuclear power-plant work ?}

In the process of fission, an atom loses mass, which is turned into huge amounts of thermal energy, described by the famous Einstein equation:
\begin{equation*}
    E = mc^2
\end{equation*}

If uncontrolled, the chain reaction basically turns the fissile combustible into a nuclear bomb.
In a nuclear reactor, one can control the chain reaction, making it self-sustained but not explosive, to take advantage of the released energy. \\

A nuclear power plant basically works as any heat powered power plant (like coal or gas-powered). The combustible heats water, which will go through a turbine with high pressure, thus creating rotation: i.e kinetic energy for an alternator producing electric current.
\begin{figure}
    \centering
    \includegraphics[width=.66\linewidth]{images/nuke/nuclearplant.jpg}
    \caption{Simplified diagram of a nuclear power plant.}
\end{figure}

\end{frame}

\begin{frame}{Famous nuclear acccients}
    Nuclear plants obviously brings the famous nuclear accidents in mind, which are undoubtedly Chernobyl and Fukushima-Daiichi.
    There are common misconceptions about those accidents. In the case of Chernobyl, only 30 persons died directly from radiation (mostly the firefighters that fought the open-core fire at the beginning of the catastrophe) and 4000 were exposed to substantial radiation doses. 
    In the case Fukushima, 6 people have been exposed to substantial doses of radiation, and the average dose received by a Fukushima-Daiichi nuclear worker during the accident was equivalent to th dose delivered by an abdominal X-ray scanner. No significant increases in cancer numbers have been observed in 10 years in the surroundings.
    
    As a matter of fact, in Europe, coal-fueled power plants alone are estimated to have caused around 23 000 premature deaths during 2013.
\end{frame}

\begin{frame}{Nuclear energy safety}
Chernobyl and Fukushima accidents are considered as the worst nuclear accidents that ever happens and rated level 7 on the INES scale.
\begin{figure}
    \centering
    \includegraphics[width=.66\linewidth]{images/nuke/level.png}
    \caption{International Nuclear and Radiological Event Scale (INES)}
\end{figure}
\end{frame}

\begin{frame}{What about nuclear waste ?}
    The question of nuclear energy safety undoubtedly raises the question of nuclear waste.

    Nuclear fuel, once used, lays behind radioactive components, some of them can be recycled and transmuted into new fuel to use in other types of reactors. Once the nuclear fuel potential of an element has been fully depleted
    it remains nuclear waste, that stay radioactive for thousands of years and is potentially dangerous for human health if people are exposed. Nowadays, the best solution found is geological storage, which involves vitrification of the high-energy nuclear waste and 
    burying in geologically stable sites.  

\end{frame}

\begin{frame}[allowframebreaks]{Is it still relevant ?}
    One can ask if nuclear energy, a 70-year old technology is still relevant to take up the climate change and energy
    transition challenge.

    Nuclear energy fits the low-carbon electricity challenge as the only carbon emitted during the life cycle of a nuclear plant is the carbon energy needed to build concrete buildings, which makes nuclear electricity virtually zero-carbon.  
    
    \begin{figure}
        \centering
        \includegraphics[width=.5\linewidth]{images/nuke/ecarbon.png}
        \caption{Carbon equivalent emissions per kWh of electricity for different production means}
    \end{figure}

\end{frame}

\begin{frame}[allowframebreaks]{Nuclear fusion}
    Another future perspective for nuclear energy is nuclear fusion. Although it is far from being accomplished yet. 
    The idea is quite the inverse of nuclear fission. In this case, isotopes of light elements, deuterium and tritium (hydrogen isotopes) are fused to make heavier elements, that are lighter than the sum of the masses of fused elements, which means some mass has been converted to energy.

    The energy released by fusion of light elements is substantially greater than the energy released by fission which makes nuclear fusion very interesting along with the fact it does not produce long-lived nuclear waste, but mostly helium, an inert gas. 
    
    \begin{figure}
        \centering
        \includegraphics[width=.6\linewidth]{images/nuke/fusion.jpg}
        \caption{Energy released by fusion or fission of elements}
    \end{figure}
    
\end{frame}
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