Power Plant Engineering — Part 2 MCQs with Explanations

moderator is a medium that reduces the speed of fast neutrons, thereby turning them into thermal neutrons capable of sustaining a nuclear chain reaction involving uranium-235 or a similar fissile nuclide

Uranium is ferrite material Uranium is a chemical element with symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons.

A moderator, apart from its high neutron slowing power, and low non-productive neutron, should be Stable under nuclear radiation and Corrosion resistant and Good thermal conductor

For economical operation of a nuclear plant used fuel should be reprocessed. Fuel, operational and maintenance costs are relatively small components of the total cost.

The mass number of a substance represents the sum of total number of Protons and neutrons in a nucleus

A boiling water reactor uses Enriched uranium as fuel

A fast breeder reactor uses U 235 as fuel.

A gas-cooled reactor (GCR) is a nuclear reactor that uses graphite as a neutron moderator and carbon dioxide as coolant. Superheated steam is generated in gas-cooled reactor

The risk of radioactive hazard is greatest in the turbine with Boiling water reactor

The nuclear energy is measured as MeV

In a fission process, maximum percentage of energy is released as Kinetic energy of fission products

A nuclear reactor coolant is a coolant used to remove heat from the nuclear reactor core and transfer it to electrical generators and the environment. Light or heavy water ,Helium and Liquid Sodium can be used as coolant in a nuclear reactor.

Natural uranium is made up of U 234 = 0.006%, U 235 = 0.712% and U 238 = 99.282%.

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

Solid fuel for nuclear reactions may be fabricated into various small shapes such as Plates and Pallets and Pins

No moderator is used in the breeder reactor since fast neutrons are more efficient in transmuting U 238 to Pu 239 . At this concentration of U 235 , the cross-section for fission with fast neutrons is sufficient to sustain the chain-reaction.

Electron volt is the unit of Energy

Mass number is an integer equal to the sum of the number of protons and neutrons of an atomic nucleus.

Enriched uranium is a type of uranium in which the percent composition of uranium-235 has been increased through the process of isotope separation. Natural uranium is 99.284% U 238 isotope, with U 235 only constituting about 0.711% of its mass.

Where reactor operation is designed with fast neutrons such as in reactors using highly enriched fuel No moderator is needed

A fission chain reaction in uranium can be developed by Slowing down fast neutrons so that Uz fission continues by slow motion neutrons

The total energy released in fission of U is 199 MeV

Nuclear fission is a process where the nucleus of an atom is split into two or more smaller nuclei, known as fission products. The fission of heavy elements is an exothermic reaction, and huge amounts of energy are released in the process.

The energy required to be applied to a radioactive nucleus for the emission of a neutron is 7.8 MeV

Electromagnetic type of pump is used in liquid metal cooled reactor for circulation of liquid metal

Artificial radioactive isotopes are formed when an atom is bombed with an accelerator or exposing it to slow moving neutrons in a nuclear reactor. Artificial radioactive isotopes find application in Medical field

U 235 will undergo fission by either fast or slow neutrons. For fission of uranium-235, the predominant radioactive fission products include isotopes of iodine, caesium, strontium, xenon and barium.

U 238 will undergo fission by high energy (fast) neutrons alone. The much more abundant uranium-238 does not undergo fission and therefore cannot be used as a fuel for nuclear reactors. However, if uranium-238 is bombarded with neutrons it absorbs a neutron and is transformed into uranium-239.

A nuclear unit becoming critical means Chain reaction that causes automatic splitting of the fuel nuclei has been established when the reactor is in a configuration such that one neutron from each atom fissioned causes another fission and then the reactor is said to be critical

Fast neutrons and gamma rays presance are serious difficulty in designing reactor shield

Uranium has isotopes U 234 U 235 U 238

Graphite is the most commonly used moderator in nuclear plants

In a breeder reactor, the conversion ratio is higher than 1. "Break-even" is achieved when the conversion ratio reaches 1.0 and the reactor produces as much fissile material as it uses

Hydrogen is preferred as better coolant in comparison to CO 2 because former has high specific heat.

Half life of a radioactive isotope corresponds to the time required for half of the atoms to decay

When a reactor becomes critical, then the production of neutrons is Exactly balanced by the loss of neutrons through leakage

The energy released during the fission of one atom of Uranium 235 in million electron volts is about 200

Plutonium is made from U-238. Pu-239 is normally created in nuclear reactors by transmutation of individual atoms of one of the isotopes of uranium present in the fuel rods. Occasionally, when an atom of U-238 is exposed to neutron radiation, its nucleus will capture a neutron, changing it to U-239.

A visual representation of an induced nuclear fission event where a slow-moving neutron is absorbed by the nucleus of a uranium-235 atom, which fissions into two fast-moving lighter elements (fission products) and additional neutrons.

Breeder reactors employ liquid metal coolant because it transfers heat from core at a fast rate It has a large specific heat so that it is an efficient heat-transfer fluid. In practice, those reactors which have used liquid metal coolants have been fast-neutron reactors.