Physics · Science General

Nuclear Physics and Energy

1,324 Questions

Access a comprehensive set of questions on nuclear physics, reactor mechanisms, and atomic energy. Topics include nuclear fission, plasma generation, and radiation control. These physics questions form a core part of the syllabus for various engineering and civil service exams.

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Nuclear Physics and Energy Questions

Multiple choice chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

The fission of $U^{238}$ is possible by 

  1. only fast neutrons

  2. only slow neutrons

  3. fast as well as slow neutrons

  4. fast protons
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Uranium-23, do not usually undergo fission when struck by slow neutrons, but do split when struck with neutrons of high enough energy. The fast neutrons produced in a hydrogen bomb by fusion of deuterium and tritium have even higher energy than the fast neutrons produced in a nuclear reactor. This makes it possible to increase the yield of any given fusion weapon by the simple expedient of adding layers of cheap natural (or even depleted) uranium. Fast fission of uranium-238 provides a large part of the explosive yield, and fallout, in many designs of hydrogen bomb.

Multiple choice chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

State two safety measures to be taken while establishing a nuclear power plant.

  1. Use uranium rod and inside environment is not shielded

  2. Use uranium rod and inside environment should be shielded

  3. Use copper rod and inside environment is not shielded

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
$\rightarrow$ The nuclear energy can turn into the strong blast due to exponential growth in its reaction process. We use Uranium rods to control the reaction.
$\rightarrow$ The inside environment must be shielded from outside because its reaction with water & air causes potential health hazard.

Multiple choice chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

Fast neutrons can easily be slowed down by

  1. the use of lead shielding

  2. passing them through water

  3. elastic collision with heavy nuclei

  4. applying a strong electric field
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
A neutron moderator is a medium that reduces the speed of fast neutrons, thereby turning them into thermal neutrons capable of sustaining a nuclear chain reaction.
Commonly used moderators include regular (light) water (roughly $75$% of the world's reactors), solid graphite ($20$% of reactors) and heavy water.
Multiple choice chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

What is the purpose of Boron rods in a nuclear reactor ?

  1. Absorb excess neutrons

  2. Absorb alpha particles

  3. Slow down the speed of neutrons

  4. Speed up the reaction
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Boron rods are used as control rods in nuclear reactors to control the fission rate of uranium and plutonium. These are capable of absorbing many neutrons without fissioning themselves. Composition of control rods is designed for the neutron spectrum of the reactor.

Multiple choice chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

Control rods in a nuclear power plant is to

  1. Slow the neutrons thereby controlling the fission reaction.

  2. Shut down the reactor.
  3. Both $(1)$ and $(2)$

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Slow the neutrons thereby controlling the fission reaction.


Control rods are used in nuclear reaction to control the fission rate of uranium and plertorium. They are composed of chemical elements such as boron, silver, indium and cadmium that are capable of absorbing many neutrons without themselves fissioning.

Multiple choice chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

Scientists are working hard to develop nuclear fusion reactor. Nuclei of heavy, $ _{ 1 }^{ 2 }{ H }$, known as deuteron and denoted by D, can be thought of as a candidate for fusion reactor. The D-D reaction is  $ _{ 1 }^{ 2 }{H }+ _{ 1 }^{ 2 }{ H }\rightarrow _{ 2 }^{ 3 }{ He+n+energy }$. In the core of fusion reactor, a gas of heavy hydrogen is fully ionized into deuteron nuclei and electrons.This collection of $ _{ 1 }^{ 2 }{ H }$ nuclei and electron is known as plasma. The nuclei move randomly in the reactor core and occasionally come close enough for nuclear fusion to take place. Usually, the temperatures in the reactor core plasma. Special techniques are used which confine the plasma for a time $\displaystyle { t } _{ 0 }$ before the particles fly away from the core. If $n$ is the density (number/volume) of deuterons, the product ${ nt } _{ 0 }$  is called Lawson number, In one of the criteria, a reactor is termed successful if Lawson number is greater than $5 \times { 10 }^{ 14}s/{ cm }^{3 }$. It may be helpful to use the following: Boltzmann constant 

$k=8.6\times { 10 }^{ -5 }eV/K$; $\displaystyle \frac { { e }^{ 2 } }{ 4\pi { \epsilon } _{ 0 } } =1.44\times { 10 }^{ -9 }eVm$. In the core of nuclear fusion reactor. the gas becomes plasma because of :

  1. strong nuclear force acting between the deuterons

  2. coulomb force acting between the deuterons

  3. coulomb force acting between deuteron-electron pairs

  4. the high temperature maintained inside the reactor core
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The temperature inside the core of nuclear reactor is so high that the gas of heavy hydrogen used becomes the fourth state of matter which we call as plasma.

Multiple choice chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

Introduction of which rod in a nuclear reactor controls  chain reaction ?

  1. Iron rods

  2. Silicon rods

  3. Cadmium rods

  4. Platinum rods
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Cadmium rods are used as control rods in nuclear reactors to control the fission rate of uranium and plutonium. These are capable of absorbing many neutrons without fissioning themselves. Composition of control rods is designed for the neutron spectrum of the reactor. Rods are composed of boron,silver,indium and cadmium which can absorb excess neutrons.

Multiple choice chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

Nuclear reactors are normally refuelled ___________.

  1. when they are decommissioned

  2. when the gauge indicates fuel low
  3. in every $12$ to $18$ months
  4. in every $2$ to $4$ weeks
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Nuclear power plants rum almost all the time and refuel only once every two years or so. Outages typically occur in the spring or autumn when electricity demand is lowest and there is little winter heating or summer air conditioning.

Multiple choice chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

The functions of the reflectors in nuclear power plant is that:

  1. It reflects the neutrons that are escaping from the case.

  2. It reflects the radiation escaping the case of the reactor.
  3. Both $(1)$ and $(2)$

  4. It accelerates the reaction.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Both (1) and (2)

A reflector is a region of unfueled material surrounding the core . Its function is to scatter neutrons that leak from the core, thereby returning some of them back into the core. This design feature allows for a smaller core size. In addition, reflectors "smooth out" the power density by utilizing neutrons that would otherwise leak out through fissioning within fuel material located near the core's outer region.

Multiple choice chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

Nuclear power plants always operates as ___________.

  1. peak load plants

  2. base load plants

  3. can be used as both; the load and peak load plants depends on the requirements

  4. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Base load power plants operate at maximum output. They shut down or reduce power only to perform maintainance or repair. Base load power plants include coal, fuel oil, almost all nuclear, geothermal, hydroelectric, biomass and combined cycle matural gas plants.

Multiple choice chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

Which of the reactors are highly stable?

  1. Pressurised water reactors

  2. Boiling water reactors

  3. Pressurised heavy water reactors

  4. Fast breeder reactors
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Boiling Water Reactors (BWR) are generally considered highly stable due to the negative void coefficient, where increased steam production reduces reactivity, providing an inherent safety mechanism.