Prática de Shadowing: The Magic of Thorium Nuclear Reactors - Aprenda a falar inglês com o YouTube
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Thorium is a kind of miraculous element.
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Thorium is a kind of miraculous element.
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Thorium found in nature isn't fissile – the atom's nucleus won't split when it absorbs a neutron.
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And yet, if you put a chunk of this same thorium in a special nuclear reactor,
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after a while most of the thorium will be gone,
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a whole bunch of energy will have been generated,
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and you'll be left with typical byproducts of fission.
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It's as if thorium is fissile, even though it's not.
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This is the genius of thorium breeder reactors.
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Oh, and I should disclose here that this video is sponsored by Copenhagen Atomics,
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who are working to make thorium power a reality,
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but they didn't get any say in the video and didn't get to review it before posting.
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The standard oversimplified picture of a fission reactor is,
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a uranium nucleus splits apart,
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or fissions, releasing heat energy and two or three neutrons,
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and those neutrons go on to be captured by more uranium nuclei and cause them to fission,
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releasing more heat energy and more neutrons, and so on.
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The heat is used to generate electricity,
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the neutrons to maintain the fission chain reaction.
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However, the actual story is more complicated.
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When a nucleus splits, there are actually four things that can happen to the neutrons it emits.
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One, like we've already mentioned,
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they can be captured by a fissile atom like uranium-235,
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causing it to fission and release more neutrons,
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and this part has to happen on average at least once per fission to sustain the chain reaction.
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Two, neutrons can be captured by the nuclei of other atoms in the reactor,
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without causing fission, like maybe the metal case,
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or the moderator, or the control rods, or whatever.
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3 Neutrons can escape and leave the reactor entirely.
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Or 4 A neutron can be captured by an atom that's not fissile,
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and transmute it into an atom that is fissile.
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Because remember, these are atomic nuclei we're dealing with.
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Absorption of a neutron will turn uranium-238 into uranium-239,
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the number is just the total number of protons and neutrons.
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And uranium-239 can then radioactively decay into neptunium-239,
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which can then decay into plutonium-239, which is fissile.
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If the capture of a neutron transforms a non-fissile element into a fissile one,
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it's called a fertile capture.
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And fertile capture is what makes thorium useful.
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In fact, even in a normal uranium reactor,
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fertile capture accounts for over a third of the energy generated by the reactor.
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A normal nuclear reactor uses uranium-235,
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which is fissile, but naturally occurring uranium ore contains only 0.7% uranium-235.
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Almost all the rest is uranium-238,
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which is essentially non-fissile, but it is fertile.
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Even when using fuels with enriched levels of uranium-235 undergoing fission,
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there's so much non-fissile U-238 around that some of the chain reaction neutrons instead transform U-238 into plutonium-239,
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which can then fission.
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But U-235 doesn't make enough neutrons,
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and U-238 doesn't turn into plutonium easily enough
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that you can both sustain a fission chain reaction and continue to transform new fissile fuel.
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So at the end you're left with a big chunk of unfissioned but still full of radioactive waste, uranium-238.
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There's a different kind of reactor,
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called a fast breeder reactor,
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that uses plutonium as the primary fissile fuel,
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and uranium-238 as a fertile secondary source.
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This combination can both sustain the fission chain reaction and transform new fuel in a self-sustaining way.
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But fast breeder reactors are less researched,
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more expensive, and harder to run effectively.
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For now.
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This is where thorium comes in.
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The same route used in the transformation of uranium-238 to plutonium-239 can be replicated down here,
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starting instead with thorium-232.
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By adding a neutron, we get thorium-233,
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which decays to protactinium-233, which decays to uranium-233,
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which is fissile and can be used to generate energy.
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So if you load your reactor with thorium-232,
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which, remember, is not fissile,
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and you throw in some starter fissile fuel,
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then for each fission reaction,
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the number of new fissile atoms created is more than one on average,
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and the number of new atoms split is more than one on average,
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and remember those atoms give you more neutrons.
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So the transformation of thorium,
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and the fission of uranium,
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can keep going and going and going,
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until in principle, all of the thorium is gone.
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And crucially, thorium transformation can happen in a reactor that doesn't have the same challenges as a fast breeder reactor,
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and it gets rid of most of the long-lived radioactive waste.
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And thorium is more abundant than uranium,
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and doesn't need the expensive refining process to concentrate the fissile uranium-235,
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and so you can see why people get excited about thorium.
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There are, of course, challenges and downsides to making thorium reactors,
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which is why we don't have and so far have never had commercial energy generation from thorium.
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But that's fertile material for another time.
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Getting commercial power from thorium may soon be possible thanks to the work of organizations such as this video's sponsor, Copenhagen Atomics.
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Copenhagen Atomics is building compact,
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modular thorium reactors to produce cheap energy.
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Unlike traditional nuclear power stations,
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which are giant infrastructure projects,
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Copenhagen Atomics are designing a self-contained reactor unit that can fit inside a shipping container.
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The reactors are based on a design pioneered over 50 years ago that uses molten salt to carry the fuel,
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resulting in fewer lost neutrons and more complete combustion,
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so you get more energy for less waste.
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These reactors can also use plutonium waste from classic nuclear reactors as fuel,
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extracting ten times more energy out of spent nuclear fuel than the initial reactor did in the first place,
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and in doing so converting long-lived radioactive waste into short-lived radioactive waste.
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In theory, these reactors could run anything from grids to ships to moon bases.
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Check out Copenhagen Atomics website to learn more about their work.
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Contexto e Antecedentes
O vídeo intitulado "A Mágica dos Reatores Nucleares de Tório" apresenta uma explicação fascinante sobre como o elemento tório pode ser utilizado em reatores nucleares, mesmo não sendo fissível por natureza. O apresentador detalha o processo complexo por trás da fissão nuclear e como o tório se transforma em um combustível útil através da captura fértil. Essa informação é crucial para quem deseja entender não apenas a ciência por trás da energia nuclear, mas também a linguagem técnica envolvida. Para estudantes de inglês, esse vídeo oferece uma oportunidade valiosa de aprender vocabulário e expressões que podem ser aplicadas em contextos de conversação técnica e científica.
Top 5 Frases para Comunicação Diária
- "O tório é um elemento milagroso." - Essa frase destaca a importância e a singularidade do tório.
- "Quando um núcleo se divide, quatro coisas podem acontecer." - Uma introdução sobre os resultados da fissão nuclear.
- "Os nêutrons podem ser capturados por átomos não fissíveis." - Refere-se ao processo de captura fértil, essencial para a compreensão do tema.
- "A captura fértil é o que torna o tório útil." - Essencial para destacar a funcionalidade do tório em reatores.
- "Um reator nuclear normal utiliza urânio-235." - Informativo sobre os tipos de combustível usados na fissão.
Guia Passo a Passo para Shadowing
Para quem deseja melhorar a pronúncia em inglês e dominar o conteúdo apresentado no vídeo, a técnica de shadow speak (ou shadow speech) pode ser extremamente eficaz. Aqui está um guia passo a passo:
- 1. Escute o vídeo com atenção: Antes de começar a repetir, assista ao vídeo e familiarize-se com o conteúdo e as ideias principais.
- 2. Divida o vídeo em partes: Escolha pequenas seções de duas a três frases para facilitar a repetição.
- 3. Reproduza a fala: Ouça uma frase e pause o vídeo. Tente repetir exatamente como o apresentador fez, focando na intonação e no ritmo.
- 4. Grave-se: Ouça suas próprias gravações e compare com o original. Preste atenção às diferenças na pronúncia.
- 5. Pratique regularmente: A prática constante é fundamental. Experimente incorporar essas frases em sua prática de conversação em inglês diária.
Com esse guia, você pode melhorar seu domínio do inglês técnico e se sentir mais confiante ao discutir temas complexos, como os reatores nucleares de tório.
O que é a Técnica de Shadowing?
Shadowing é uma técnica de aprendizado de idiomas com base científica, originalmente desenvolvida para o treinamento de intérpretes profissionais. O método é simples, mas poderoso: você ouve áudio em inglês nativo e repete imediatamente em voz alta — como uma sombra seguindo o falante com 1-2 segundos de atraso. Pesquisas mostram melhora significativa na precisão da pronúncia, entonação, ritmo, sons conectados, compreensão auditiva e fluência na fala.
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