Q31. Which of the following fusion reactions is considered the “holy grail” of nuclear fusion research due to its potential for producing abundant energy with minimal radioactive byproducts?
a) Deuterium-tritium fusion
b) Deuterium-deuterium fusion
c) Tritium-tritium fusion
d) Proton-proton fusion
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Correct Answer: a) Deuterium-tritium fusion
Explanation: Deuterium-tritium fusion is often referred to as the “holy grail” of nuclear fusion research because it has the highest probability of achieving sustained fusion reactions with net energy gain in the near term. This reaction releases abundant energy and produces helium as a byproduct, minimizing radioactive waste compared to other fusion reactions.
Q32. Which of the following phenomena is responsible for confining the high-temperature plasma in a magnetic confinement fusion device?
a) Gravitational forces
b) Electromagnetic forces
c) Nuclear forces
d) Electrostatic forces
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Correct Answer: b) Electromagnetic forces
Explanation: Magnetic confinement fusion devices, such as tokamaks and stellarators, utilize electromagnetic forces to confine and stabilize the high-temperature plasma where fusion reactions occur. Strong magnetic fields generated by superconducting magnets shape and control the plasma, preventing it from contacting the walls of the fusion reactor and losing heat.
Q33. What is the term for the condition in which the energy released by nuclear fusion reactions exceeds the energy input required to sustain the reactions?
a) Breakeven
b) Criticality
c) Ignition
d) Supercriticality
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Correct Answer: c) Ignition
Explanation: In nuclear fusion research, ignition refers to the condition in which the energy released by fusion reactions exceeds the energy input required to sustain the reactions. Achieving ignition is a key milestone in fusion research and represents the point at which a fusion reactor becomes self-sustaining and capable of producing net energy gain.
Q34. Which of the following elements is used as a neutron moderator in some fusion reactor designs?
a) Carbon
b) Lead
c) Boron
d) Lithium
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Correct Answer: a) Carbon
Explanation: Carbon is used as a neutron moderator in some fusion reactor designs to slow down fast neutrons produced by fusion reactions. Slowing down neutrons increases their probability of causing further fusion reactions, enhancing the efficiency of the fusion process. Other materials, such as beryllium and water, can also serve as neutron moderators.
Q35. What is the primary objective of the experimental fusion reactor known as the National Ignition Facility (NIF)?
a) To achieve controlled nuclear fusion for practical energy production
b) To study nuclear fission reactions in a controlled environment
c) To investigate the feasibility of inertial confinement fusion
d) To demonstrate sustained nuclear fusion using magnetic confinement
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Correct Answer: c) To investigate the feasibility of inertial confinement fusion
Explanation: The National Ignition Facility (NIF) is an experimental fusion research facility located at Lawrence Livermore National Laboratory in the United States. Its primary objective is to investigate the feasibility of inertial confinement fusion (ICF) by compressing and heating small targets containing fusion fuel using powerful laser beams.
Q36. Which of the following fusion reactions is considered an advanced concept for achieving fusion power without the use of radioactive fuels?
a) Deuterium-tritium fusion
b) Deuterium-deuterium fusion
c) Tritium-tritium fusion
d) Proton-boron fusion
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Correct Answer: d) Proton-boron fusion
Explanation: Proton-boron fusion, also known as p-B fusion or aneutronic fusion, is considered an advanced concept for achieving fusion power without the use of radioactive fuels. This reaction uses abundant and non-radioactive fuel sources—protons and boron-11—and produces primarily charged particles, reducing the generation of radioactive byproducts.
Q37. Which of the following is a potential application of nuclear fusion other than energy production?
a) Radioisotope production for medical imaging
b) Generation of radioactive waste for disposal
c) Production of fissile material for nuclear weapons
d) Propulsion for spacecraft
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Correct Answer: d) Propulsion for spacecraft
Explanation: Nuclear fusion has the potential to revolutionize space exploration by providing a highly efficient and sustainable propulsion system for spacecraft. Fusion-powered propulsion systems could enable faster travel within and beyond the solar system, significantly reducing transit times and opening up new possibilities for human exploration of space.
Q38. Which of the following fusion reactor designs uses a toroidal magnetic field configuration to confine the plasma?
a) Tokamak
b) Stellarator
c) Inertial confinement reactor
d) Z-pinch device
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Correct Answer: a) Tokamak
Explanation: Tokamak is a fusion reactor design that uses a toroidal (doughnut-shaped) magnetic field configuration to confine and stabilize the high-temperature plasma where fusion reactions occur. Tokamaks are among the most widely studied magnetic confinement fusion devices and are considered a promising approach for achieving sustained fusion energy.
Q39. What is the primary advantage of inertial confinement fusion (ICF) compared to magnetic confinement fusion (MCF)?
a) Lower energy requirements
b) Simplicity of reactor design
c) Ability to use solid fuel pellets
d) Longer plasma confinement times
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Correct Answer: b) Simplicity of reactor design
Explanation: Inertial confinement fusion (ICF) offers the advantage of simplicity in reactor design compared to magnetic confinement fusion (MCF) approaches. ICF devices, such as laser-driven fusion reactors, rely on compressing and heating small targets containing fusion fuel using intense laser or particle beams, potentially leading to simpler and more compact reactor configurations.
Q40. Which of the following fusion reactions is considered to be inherently safer due to its low production of neutrons?
a) Deuterium-tritium fusion
b) Deuterium-deuterium fusion
c) Tritium-tritium fusion
d) Proton-boron fusion
Show Answer
Correct Answer: d) Proton-boron fusion
Explanation: Proton-boron fusion, also known as p-B fusion or aneutronic fusion, is considered to be inherently safer than reactions involving tritium, such as deuterium-tritium fusion. Proton-boron fusion produces primarily charged particles, including alpha particles, with minimal neutron production, reducing the risks associated with neutron activation and radioactive waste generation.