Nuclear Power Plant MCQ Quiz - Objective Question with Answer for Nuclear Power Plant - Download Free PDF

Explanation:

Moderators in Nuclear Reactors:

• In a nuclear reactor, a moderator is a material used to slow down the speed of neutrons produced during nuclear fission. Slowing down neutrons increases the probability of successful fission reactions, particularly in reactors using uranium-235 or plutonium-239 as fuel. Moderators are critical for maintaining a sustained nuclear chain reaction.
• During nuclear fission, fast neutrons are released. These neutrons must be slowed down to "thermal" speeds (low kinetic energy) to effectively collide with fissile nuclei like uranium-235. Moderators achieve this by allowing neutrons to lose energy through elastic collisions with the nuclei of the moderator material, which have comparable mass to the neutron.

Properties of an Ideal Moderator:

• Should have low neutron absorption to avoid capturing neutrons and disrupting the chain reaction.
• Should be effective in slowing down neutrons (high scattering cross-section).
• Should be chemically stable and able to withstand high temperatures and radiation exposure.

Common Moderator Materials:

• Heavy Water (D₂O): Contains deuterium, which has a lower neutron absorption cross-section compared to hydrogen and is highly effective in slowing down neutrons.
• Beryllium: A lightweight metal with excellent neutron-scattering properties and low neutron absorption.
• Graphite: A form of carbon that is commonly used as a moderator in reactors such as the RBMK and Magnox types.

Beryllium and heavy water

• Beryllium: Beryllium is an excellent moderator due to its low neutron absorption cross-section and high neutron-scattering capability. Its lightweight nuclei are comparable in mass to neutrons, enabling effective energy transfer during collisions. Beryllium is commonly used in specialized reactors where high performance is required.
• Heavy Water: Heavy water (D₂O) is another widely used moderator, especially in reactors like the CANDU (Canada Deuterium Uranium) reactors. The presence of deuterium instead of regular hydrogen reduces neutron absorption significantly while maintaining high scattering properties. Heavy water is particularly advantageous in reactors that use natural uranium as fuel.

The correct answer is 1.

Key PointsBreeder reactor:

• Statement 1: More fissile materials are produced than it is consumed.
  • In a breeder reactor, a significant feature is its ability to produce more fissile material than it consumes.
  • This is achieved through a process where fertile materials like U-238 or Th-232 are converted into fissile materials like Pu-239 or U-233.
  • Hence, statement 1 is correct.
• Statement 2: Less fissile materials are produced than it is consumed.
  • This contradicts the fundamental operation of a breeder reactor, which is designed to produce more fissile material than it consumes.
  • Hence, statement 2 is incorrect.
• Statement 3: Neutrons are slowed down by moderator.
  • Breeder reactors typically use fast neutrons and do not employ moderators to slow them down. Neutron moderation is a characteristic of thermal reactors.
  • Hence, statement 3 is incorrect.
• Statement 4: U-238 a fissile material is produced from Pu-239 a fertile material.
  • This statement is factually incorrect. U-238 is not a fissile material but a fertile material, and Pu-239, which is a fissile material, is produced from U-238.
  • Hence, statement 4 is incorrect.

Additional Information

• Breeder Reactors are a type of nuclear reactor that generates more fissile material than it consumes. This is typically achieved using fast neutrons and without the use of neutron moderators.
• Fertile Materials such as U-238 and Th-232 can be converted into fissile materials like Pu-239 and U-233 respectively in a breeder reactor.

The correct answer is Heavy Water.

Key Points

• Heavy water is used as a neutron moderator in some types of nuclear reactors.
• Its chemical formula is D₂O where D stands for Deuterium, an isotope of hydrogen with one neutron.
• Heavy water has a higher neutron capture cross-section which slows down neutrons effectively, allowing nuclear fission to occur more efficiently.
• It is produced by the electrolysis of water, a process that enriches the deuterium content.
• Due to its properties, heavy water is crucial for the operation of certain reactor designs, including the CANDU reactors.

Additional Information

• Heavy water was first produced in 1932 by Harold Urey, who was later awarded the Nobel Prize in Chemistry for his discovery of deuterium.
• It has a slightly higher boiling point (101.4°C) and freezing point (3.82°C) compared to ordinary water.
• Heavy water is more expensive to produce than ordinary water, making nuclear reactors that use it more costly to build and operate.
• Aside from nuclear reactors, heavy water is also used in nuclear magnetic resonance imaging and in certain types of neutrino experiments.

CONCEPT:

• Cadmium is used as a control rod in a nuclear reactor.
• 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 undergoing fission.

The correct answer is Dhruva.

Key Points

• Dhruva:
  • The largest research reactor is the Dhruva at the Bhabha Atomic Research Centre (BARC) in Mumbai.
  • Dhruva and CIRUS are the two weapons-grade plutonium-producing reactors that are crucial to the Indian strategic program.
  • DHRUVA Reactor at BARC was designed, constructed, and commissioned by Indian Engineers and scientists.
  • Natural U is the fuel used and heavy water as moderator and coolant, Dhruva enabled India to attain self-sufficiency in the production of radioisotopes.
  • Dhruva is a 100MW (thermal) research reactor with metallic natural uranium as fuel, heavy water as moderator, coolant, and reflector, giving a maximum thermal neutron flux of 1.8×1014n/cm2/s.
  • Since its first criticality on 8th August 1985, several experimental facilities have been added which have proven to be highly attractive for universities and industrial researchers for their scientific merits in various fields. 
  • It produces medical isotopes, operated at full power throughout the year, and touched its highest ever capacity factor since its commissioning.

 Additional Information

• Bhabha Atomic Research Centre (BARC), Trombay
  • A series of 'research' reactors and critical facilities were built here.
  • Reprocessing of used fuel was first undertaken at Trombay in 1964.
  • It is also responsible for the transition to thorium-based systems.
  • It is responsible for India's uranium enrichment projects, the pilot Rare Materials Plant (RMP) at Ratnahalli near Mysore.
• Nuclear Power Plants in India 2021- Operational

 

Power Plant	Location	Operator	Type	Total Capacity (MW)
Kaiga	Karnataka	NPCIL	IPHWR-220	880
Kakrapar	Gujarat	NPCIL	IPHWR-220 IPHWR-700	1,140
Kudankulam	Tamil Nadu	NPCIL	VVER-1000	2,000
Madras (Kalpakkam)	Tamil Nadu	NPCIL	IPHWR-220	440
Narora	Uttar Pradesh	NPCIL	IPHWR-220	440
Rajasthan	Rajasthan	NPCIL	CANDU IPHWR-220	1,180
Tarapur	Maharashtra	NPCIL	BWR IPHWR-520	1,400

All the Nuclear Plants in India:

The correct answer is Mumbai.

• Bhabha Atomic Research Centre (BARC) is located in Mumbai.

Key Points

• Bhabha Atomic Research Centre:
  • It was established in 1954.
  • Its headquarters is in Trombay, Mumbai.
  • Earlier, it was known as Atomic Energy Establishment.
  • At present, BARC house has eight research reactors:
    • Apsara, a one MW Swimming pool-type reactor.
    • Cirus, a 40 MW reactor.
    • Dhruva, a 100 MW high power nuclear research reactor.
    • Zerliana, Purnima I, Purnima II, Purnima III and Kamini
  • It comes under the aegis of the Department of Atomic Energy.

Additional Information

• Other Atomic Research Centres in India: 
  • Atomic Minerals Directorate for Exploration and Research (AMD) is located in Hyderabad.
  • Indira Gandhi Centre for Atomic Research (IGCAR) is located in Kalpakkam, Tamil Nadu.
  • Variable Energy Cyclotron Centre (VECC) is located in Kolkata.

The correct answer is Russia.

• Russia has developed the world's first floating nuclear plant.

Key Points

• Akademik Lomonosov is the world’s first floating nuclear reactor. 
• Akademik Lomonosov was named after 18th-century Russian scientist Mikhail Lomonosov.
• Recently, It is completed its epic 5,000 km Arctic voyage in 22 days, despite environmentalists warning of serious risks to the region. 
• The plant was launched by Russia on 19 May 2018 at the St Petersburg shipyard.
• Akademik Lomonosov has painted with signature red, white, and blue colors of the nation's flag at its exterior.

Concept:

• The fuel used in the Nuclear power plant is usually Uranium although Plutonium can also be used.
• Thorium is not a nuclear fuel itself, it can be turned into a suitable isotope of Uranium in a nuclear reactor.
• Thorium is naturally occurring like, Uranium, but Plutonium is only produced during nuclear reactions so its main source is nuclear reactors. 
• However for most of the world's reactors, naturally occurring Uranium is not sufficiently active and it must be enriched so that the proportion of U-235, the main uranium isotope responsible for fission, is increased. 
• Naturally, occurring Uranium only contains around 0.7% of this isotope.
• Uranium enrichment can be carried out by two methods i.e. gaseous diffusion and gas centrifuge enrichment.
• In both cases, the proportion of U-235 is increased by up to 5%.
• Due to high enrichment, the primary fuel used in nuclear power plants is U-235.

CONCEPT:

Nuclear reactor:

• It is a device in which a nuclear reaction is initiated, maintained, and controlled.
• It works on the principle of controlled chain reaction and provides energy at a constant rate.

EXPLANATION:

• The function of the moderator and coolant in the Canada Deuterium Uranium (CANDU) reactor is performed by heavy water
• The moderator's function is to slow down the fast-moving secondary neutrons produced during the fission. T
• The material of the moderator should be light and it should not absorb neutrons.
• Usually, heavy water, graphite, deuterium, and paraffin, etc. can act as moderators.
• The heat released by fission in nuclear reactors must be captured and transferred for use in electricity generation.
• To this end, reactors use coolants that remove heat from the core where the fuel is processed and carry it to electrical generators. 
• Coolants also serve to maintain manageable pressures within the core.

Explanation:

• In Boiling Water Reactor (BWR), water serves the triple functions of coolant, moderator, and working fluid. 
• In this case, the steam flow to the turbine is produced directly in the reactor core. 
• In the case of BWR because of steam being generated at the reactor itself, there is no need for a heat exchanger.
• Steam is separated and dried by mechanical devices located in the upper part of the pressure vessel assembly.
• That’s why, water serves the triple functions of coolant, moderator, and working fluid.
• So, the coolant used in a boiling water reactor is a mixture of water and steam

Fig shows a schematic diagram of the boiling water reactor power plant.

      

The correct answer is option 2):(Energy obtained by fission of 1 kg uranium )

Concept:

•  8 kWh of heat energy can be generated from 1 kg of coal. Energy obtained by burning 1500 tonnes of high-grade coal is 12,000,000 kWh.The low-grade coal will produce heat energy less than the high-grade coal.
•  12 kWh from 1 kg of mineral oil
• 24,000,000 kWh from 1 kg of uranium-235. 
• Thorium-based nuclear power generation is fueled primarily by the nuclear fission of the isotope uranium-233 produced from the fertile element thorium. The energy produced by  1 kg thorium is less than  uranium-235.
• Energy obtained by fission of 1 kg uranium can result in a large amount of energy production

Ozone depletion describes two distinct but related phenomena observed since the late 1970s: a steady decline of about four percent in the total amount of ozone in Earth's stratosphere (the ozone layer), and a much larger springtime decrease in stratospheric ozone around Earth's polar regions. The latter phenomenon is referred to as the ozone hole. In addition to these well-known stratospheric phenomena, there are also springtime polar tropospheric ozone depletion events.

The most important process in both depletion types is catalytic destruction of ozone by atomic halogens. The main source of these halogen atoms in the stratosphere is photo-dissociation of man-made halocarbon refrigerants, solvents, propellants, and foam-blowing agents (chlorofluorocarbon (CFCs), HCFCs, freons, methyl bromide, halons). These compounds are transported into the stratosphere by winds after being emitted at the surface.

Boiling water reactor is used in Tarapur atomic power plant.
Types of reactors:

• Molten salt reactor: These are the nuclear reactors that use a fluid fuel in the form of very hot fluoride or chloride salt rather than solid fuel. Since the fuel salt is liquid, it can be used as both, the fuel and the coolant.
• Boiling water reactor: These are the type of nuclear reactors that use light water as their coolant and neutron moderator. Boiling water reactors use enriched uranium as their nuclear fuel.
• Fast neutron reactor: These are the type of nuclear reactors that produce more fissile materials than they consume. A fast neutron reactor employs either uranium-238 or thorium as its fuel.

Explanation:

Nuclear reactor:

• It is a device in which a nuclear reaction is initiated, maintained, and controlled.
• It works on the principle of controlled chain reaction and provides energy at a constant rate.
• The moderator's function in the reactor is to slow down the fast-moving secondary neutrons produced during the fission.
• The material of the moderator should be light and it should not absorb neutrons.
• Usually, heavy water, graphite, deuterium, and paraffin, etc. can act as moderators.

CANDU Reactor:

• CANDU stands for Canada Deuterium Uranium nuclear reactor.
• The function of the moderator and coolant in the CANDU reactor is performed by heavy water.
• Natural Uranium is used as fuel for fission in the CANDU reactor.
• The heat released by the fission of natural uranium in nuclear reactors must be captured and transferred for use in electricity generation.
• To this end, reactors use heavy water coolants that remove heat from the core where the fuel is processed and carry it to electrical generators. 
• Coolants also serve to maintain manageable pressures within the core.

The correct statement about the breeder reactor is:

In the breeder reactor, fissionable material is produced while it generates energy.

Key Points

• Breeder reactors are designed to create more fissile material than they consume.
• They work by using fertile materials, such as uranium-238, as fuel, which is converted into fissile plutonium-239 during the nuclear reaction.
• The breeder reactor generates energy through the process of nuclear fission, which is the splitting of atoms.
• As the reactor operates, it produces more fissile material than it consumes, which can be used as fuel in other reactors.
• This makes breeder reactors a potentially sustainable and efficient source of nuclear energy.

Additional Information

• Breeder reactors are so named because they "breed" more fissile material than they consume.
• They achieve this by using a special type of fuel called "breeder fuel" that is enriched in fissile material, such as plutonium-239, and surrounded by a "blanket" of fertile material, such as uranium-238 or thorium-232.
• When the breeder reactor is operating, neutrons from the fission process are absorbed by the fertile material in the blanket, converting it into fissile material.
• This newly created fissile material can then be used as fuel in other reactors or recycled back into the breeder reactor.
• The advantage of breeder reactors is that they can potentially provide an almost limitless supply of nuclear energy since they can produce more fissile material than they consume.
• Additionally, the use of breeder fuel reduces the amount of high-level nuclear waste produced, since the spent fuel can be recycled and reused.
• However, there are also some potential drawbacks to breeder reactors. They require careful control and monitoring to prevent the production of unwanted isotopes, such as plutonium-240, which can reduce the efficiency of the reactor and increase the risk of nuclear proliferation.
• Additionally, breeder reactors are more complex and expensive to build and operate than traditional light-water reactors, which are currently the most common type of nuclear reactor in use today.