Nuclear Fission Flashcards
What is nuclear fission, and how does it differ for heavy elements compared to lighter ones?
Nuclear fission is the process of splitting heavy atomic nuclei into smaller elements. It differs from lighter elements as the binding energy per nucleon reaches a maximum for A ≃ 60, making it possible to achieve an increase in binding energy by splitting heavier elements.
How was nuclear fission discovered, and what particles can induce it?
Nuclear fission was discovered while firing neutrons at heavy element targets.
Other particles that can induce fission include deuterons, alpha particles, and protons.
What are the main components of the liquid drop model used to explain nuclear fission?
The liquid drop model explains nuclear fission by considering the deformation of a nucleus. It involves surface tension, Coulomb repulsion, volume, asymmetry, and pairing terms.
How is the energy released calculated in nuclear fission, and what determines the height of the Coulomb barrier?
The energy released in nuclear fission is calculated by subtracting the total mass of the fission products from the initial mass of the parent nucleus, multiplied by the speed of light squared. The height of the Coulomb barrier is determined by the repulsive force between protons in the nucleus.
What role does excitation energy play in inducing fission, and how does it affect the cross-section for neutron-induced fission?
: Excitation energy contributes to inducing fission by elevating the energy state of the nucleus. It affects the cross-section for neutron-induced fission by influencing the probability of fission, with higher excitation energies leading to larger cross-sections.
What factors determine whether a nuclear pile is supercritical, critical, or subcritical, according to the four-factor formula?
The reproduction factor
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k depends on factors including the effective number of neutrons (
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η), fast fission factor (
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ϵ), resonance escape probability (
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p), and thermal utilization factor (
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f).
What type of reactor is commonly used for power generation, and how does it operate?
The pressurized water reactor (PWR) is commonly used for power generation. It circulates water to extract heat for steam generation and moderates neutrons. Control rods, usually made of cadmium, are used to control the reactor.
