Which of the following is more appropriate for a moderator? One which
Does not absorb neutrons
Absorbs neutrons
Accelerates neutrons
Eats up neutrons
Correct Answer :
A. Does not absorb neutrons
Related Questions
The energy produced by a thermal reactor of same size as a breeder reactor is
Almost same
Slightly more
Slightly less
Much less
A moderator generally used in nuclear power plants is
Graphite
Heavy water
Concrete
Graphite and concrete
Where reactor operation is designed with fast neutrons such as in reactors using highly enriched fuel, the moderator used is
Heavy water
Graphite
Carbon dioxide
No moderator is needed
U238 will undergo fission by
High energy (fast) neutrons alone
Low energy (slow) neutrons alone
Either fast or slow neutrons
Medium energy neutrons
The energy required to be applied to a radioactive nucleus for the emission of a neutron is
1 MeV
2.4 MeV
4.3 MeV
7.8 MeV
The efficiency of a nuclear power plant in comparison to conventional and nuclear consideration is
Higher cost of nuclear fuel
High initial cost
High heat rejection in condenser
Lower temperature and pressure conditions
A fast breeder reactor
Uses graphite rods as moderator
Has powerful moderator
Has no moderator
Uses ferrite material as moderator
Pressurised water reactor is designed
For boiling pi water in the core
To use liquid sodium metal as coolant
To use intermediate coolant
To prevent the water coolant from boiling in the core
A moderator, in nuclear power plants, is a medium introduced into the fuel mass in order to
Slow down the speed of fast moving neutrons
Control the reaction
Reduce the temperature
Extracts heat from nuclear reaction
The efficiency of a nuclear power plant in comparison to a conventional thermal power plant is
Same
More
Less
May be less or mote depending on size
Pick up the wrong statement
In a heterogeneous or solid fuel reactor, the fuel is mixed in a regular pattern within moderator.
Slow or thermal neutrons have energy of the order or 0.025 eV
Fast neutrons have energies above 1000 eV
Fast reactor uses moderator
The most commonly used moderator in nuclear plants is
Heavy water
Concrete and bricks
Graphite and concrete
Graphite
The primary fuel used in nuclear power plants is
U₂₃₅
U₂₃₈
Pu₂₃₉
Pu₂₃₃
In order to have constant chain reaction to produce a constant rate of heat output, the value of ratio of the number of neutrons in one generation to the number of neutrons in the immediately preceding generation must be
Greater than 1.0
Less than 1.0
Equal to zero
Equal to 1.0
Electron volt is the unit of
Atomic power
Energy
Voltage
Radio activity
In a fission process, maximum percentage of energy is released as
Kinetic energy of neutrons
Kinetic energy of fission products
Instantaneous release of gamma rays
Gradual radioactive decay of fission products
A nuclear unit becoming critical means
It is generating power to rated capacity
It is capable of generating much more than rated capacity
There is danger of nuclear spread
Chain reaction that causes automatic splitting of the fuel nuclei has been established
In triggering fission, the following types of neutrons are desirable
Fast moving
Slow moving
Critical neutrons
Neutrons at rest
One gram of uranium will produce energy equivalent to approximately
1 tonne of high grade coal
4.5 tonnes of high grade coal
10 tonnes of high grade coal
100 tonnes of high grade coal
The following present serious difficulty in designing reactor shield
Alpha particles
Beta particles
Thermal neutrons
Fast neutrons and gamma rays
Amongst the following, the fissionable materials are
U₂₃₃ and Pu₂₂₉
U₂₃₁ and Pu₂₃₃
U₂₃₅ and Pu₂₃₅
U₂₃₈ and Pu₂₃₉
Hydrogen is preferred as better coolant in comparison to CO₂ because former
Is lighter
Is inert
Has high specific heat
Is a good conductor
U233 is produced
As basic raw material
By neutron irradiation of Uz
By neutron irradiation of thorium
Artificially
In nuclear fission
The original elements change into completely different elements
The electrons of the element change
The molecules rearrange themselves to form other molecules
None of the above
Effective moderators are those materials which contain
Light weight atoms
Heavy weight atoms
Critical atoms
Zero weight atoms
Ideally the neutron flux in reactor should be
Maximum in centre and zero at side
Maximum at side and zero in canter
Uniform throughout
Zero throughout
U₂₃₃ is produced
Artificially
As basic raw material
When thorium is irradiated by neutrons
By fission of U₂₃₈
The mass number of a substance represents the sum of total number of
Protons and neutrons in an atom
Protons and electrons in an atom
Neutrons and electrons in an atom
Protons and neutrons in a nucleus
The material most commonly used for shielding is
Carbon
Lead
Concrete
All of these
A fast breeder reactor uses
90% U₂₃₅
U₂₃₈
U₂₃₅
Pu₂₃₉