Power Plant Engineering - Study Mode
[#71] The coolant used in boiling water reactor is
Correct Answer
(C) Mixture of water and steam
Explanation
Solution: A boiling water reactor (BWR) uses demineralized water as a coolant and neutron moderator. Heat is produced by nuclear fission in the reactor core, and this causes the cooling water to boil, producing steam.
[#72] A moderator
Correct Answer
(B) Does not absorb neutrons
Explanation
Solution: The moderator, which is of importance in thermal reactors, is used to moderate, that is, to slow down, neutrons from fission to thermal energies. Commonly used moderators include regular water , solid graphite and heavy water
[#73] Pressurized water reactor is designed
Correct Answer
(D) To prevent the water coolant from boiling in the core
Explanation
Solution: Pressurized water reactor is designed To prevent the water coolant from boiling in the core Pressurized water reactor is a nuclear reactor in which the fuel is uranium oxide clad in zircaloy and the coolant and moderator is water at high pressure so that it does not boil at the operating temperature of the reactor.
[#74] The efficiency of a nuclear power plant in comparison to a conventional thermal power plant is
Correct Answer
(C) Less
Explanation
Solution: The efficiency of a nuclear power plant in comparison to a conventional thermal power plant is less. Typical nuclear power plants achieve efficiencies around 33 - 37%, comparable to fossil fueled power plants. Higher temperature nuclear reactors could potentially reach above 45% efficiency.
[#75] Effective moderators are those materials which contain
Correct Answer
(A) Light weight atoms
Explanation
Solution: Moderators are made from materials with light nuclei which do not absorb the neutrons but rather slow them down by a series of collisions. Carbon in the form of graphite is a material used for moderators as is heavy water which is Deuterium an isotope of Hydrogen with an atomic mass of 2 bonded to Oxygen.