1.What is the use of moderator in a nuclear power plant?

Ans-A moderator in a nuclear power plant is used to slow down fast neutrons
produced during nuclear fission. By reducing the speed of these neutrons, the
moderator increases the likelihood of them causing further fission reactions,
thereby maintaining a sustained nuclear chain reaction. Common moderators
include water, heavy water, and graphite.
2.What is the function of cooling tower in a modern, steam power plant?
Ans-The function of a cooling tower in a modern steam power plant is to
dissipate excess heat from the plant's cooling system. It cools the water used in
the plant’s condenser by transferring heat to the atmosphere, typically through
evaporation. This process ensures the proper functioning of the steam cycle and
prevents the overheating of plant equipment.
3.Name different non-conventional energy resources?
 Ans-Different non-conventional energy resources include:
 Solar energy
 Wind energy
 Biomass energy
 Geothermal energy
 Tidal energy
 Ocean thermal energy.
4.Name different types of water tube boiler and fire tube boiler?
Ans-Types of Water Tube Boilers:
 Drum Boiler
 Cross Drum Boiler
 Penthouse Boiler
 Package Boiler
Types of Fire Tube Boilers:
 Single-Tube Fire Tube Boiler
 Multi-Tube Fire Tube Boiler
 Lancashire Boiler
 Scotch Marine Boiler.

5.What are the basic components Of steam Generator?

Ans- The basic components of a steam generator are:
  Boiler – Heats water to produce steam.
 Steam Drum – Collects steam and separates it from water.
 Economizer – Preheats feedwater using residual heat from exhaust gases.
 Superheater – Increases the temperature of steamabove its saturation
point.
 Air Preheater – Heats the incoming air before it enters the furnace.
 Feedwater Pump – Circulates water into the boiler.
6.What is the function of steam generator?
Ans- The function of a steam generator is to convert water into steam by
heating it, typically using fuel or heat from a nuclear reaction. The steam
produced is then used to drive turbines in power plants for electricity generation
or for other industrial processes.
7.What do you mean by calorific value of fuel?
Ans- The calorific value of a fuel is the amount of heat energy released when a
specific quantity of the fuel is completely burned. It is usually measured in units
like kilojoules per kilogram (kJ/kg) or kilocalories per kilogram (kcal/kg). It
indicates the efficiency of the fuel in producing energy.
8.Illustrate different non-conventional energy resources with examples.
Ans- Different non-conventional energy resources include:
 Solar Energy: Harnessed from the sun using solar panels or solar
thermal systems (e.g., photovoltaic cells).
 Wind Energy: Captured from wind using wind turbines (e.g., offshore
and onshore wind farms).
 Biomass Energy: Derived from organic materials like wood, agricultural
waste, and animal dung (e.g., biogas production).
 Geothermal Energy: Sourced from the heat beneath the Earth's surface
(e.g., geothermal power plants).
 Tidal Energy: Generated from the movement of ocean tides (e.g., tidal
power plants).
 Ocean Thermal Energy: Uses the temperature difference between
surface water and deeper ocean water to generate electricity.

9.Explain the different types of mountings used in a boiler.

Ans- The different types of mountings used in a boiler are:
 Safety Valve: Prevents excessive pressure buildup inside the boiler by
releasing steam when the pressure exceeds a safe limit.
 Water Level Indicator: Displays the water level inside the boiler to
ensure it remains within the safe operating range.
 Pressure Gauge: Measures and indicates the internal pressure of the
boiler.
  Blow-off Valve: Allows the removal of sediment and sludge that may
accumulate in the bottom of the boiler.
10.Show how the combustion of coal produces heat and steam in a thermal
power plant.
Ans- In a thermal power plant, coal combustion produces heat and steam
through the following process:
 Coal combustion: Coal is burned in the furnace, where it reacts with
oxygen to produce heat. This heat is absorbed by the surrounding
water in the boiler.
 Heat conversion to steam: The intense heat from the combustion of
coal converts water in the boiler into steam, which is then directed to
drive turbines for electricity generation. The steam is subsequently
cooled and condensed before being reused in the cycle.
11.Explain the main purpose of a captive power plant and how it differs
from a centralized power plant.
Ans- The main purpose of a captive power plant is to generate electricity
primarily for the internal use of a specific industry or organization, such as a
factory or a large commercial facility. It ensures a reliable and uninterrupted
power supply for the specific needs of that organization.
Difference from a centralized power plant:
 A captive power plant generates power for a single user or a small group
of users, while a centralized power plant generates power for distribution
to a large grid, supplying electricity to multiple consumers.
 Captive power plants are usually smaller in scale and located near the point
of consumption, whereas centralized plants are large, centralized facilities
serving broader geographic areas.
12.Illustrate the combustion process of a solid fuel like coal in a thermal
power plant.
Ans- The combustion process of solid fuel like coal in a thermal power plant
involves the following steps:
 Coal Feeding: Coal is fed into the furnace where it is finely ground to
increase its surface area for efficient combustion.
 Ignition: The coal is ignited by burners, and it reacts with oxygen from
the air. This exothermic reaction produces heat.
 Combustion: The heat generated by the coal’s combustion converts water
in the surrounding boiler tubes into steam. The combustion process also
releases gases like carbon dioxide (CO₂), sulfur dioxide (SO₂), and nitrogen
oxides (NOₓ).
 Heat Transfer: The produced heat is transferred to water circulating
through the boiler, producing steam that drives turbines to generate
electricity.
13.Explain the effect of air leakage in a condenser
Ans- Air leakage in a condenser can have the following effects:
 Reduction in Efficiency: Air entering the condenser increases the pressure
inside, reducing the vacuum required for efficient heat transfer. This lowers
the condenser's ability to cool the steam effectively, thus reducing the
overall efficiency of the power plant.
 Corrosion and Damage: Air contains moisture and oxygen, which can lead
to corrosion of the condenser tubes and other components, causing potential
damage and increasing maintenance costs.
14.What are the types of water tube boiler, fire tube boiler?
Ans- Types of Water Tube Boilers:
 Longitudinal Drum Boiler: A boiler where the drum runs along the length
of the furnace.
 Cross Drum Boiler: The drum is placed across the furnace to enhance
steam generation.
 Bent Tube Boiler: Features bent tubes to improve heat transfer and
efficiency.
 Types of Fire Tube Boilers:
 Single-Tube Fire Tube Boiler: Has one large tube through which hot gases
pass.
 Multi-Tube Fire Tube Boiler: Contains multiple tubes for heat exchange
between flue gases and water.
 Scotch Marine Boiler: A type of multi-tube fire tube boiler with a
cylindrical shell and large furnace.
15.What is the function of superheating?
Ans- The function of superheating is to increase the temperature of steam above
its saturation point, making it dry and more energetic. This enhances the
efficiency of the steam turbine by providing higher thermal energy, which
improves power generation and reduces the risk of turbine blade erosion caused
by wet steam.
16.Define the working of an economizer in a boiler.
Ans- An economizer in a boiler is a heat recovery device that preheats the
feedwater using the residual heat from the flue gases exiting the boiler. By
transferring heat from the exhaust gases to the incoming feedwater, it reduces
the amount of fuel needed to heat the water to the desired temperature, thus
improving the overall efficiency of the boiler.
17.Explain how an air pre-heater enhances the thermal efficiency of a
boiler system.
Ans- An air pre-heater enhances the thermal efficiency of a boiler system by
using the residual heat from the flue gases to preheat the incoming air before it
enters the furnace. This process reduces the amount of fuel required to reach the
desired combustion temperature, resulting in lower fuel consumption, reduced
emissions, and improved overall efficiency of the boiler system.
18.Explain the impact of dissolved salts like calcium and magnesium on the
operation of a power plant’s boiler.
Ans- Dissolved salts like calcium and magnesium in water can have a
detrimental impact on the operation of a power plant's boiler:
 Scaling: These salts can precipitate out of the water and form scale deposits
on the boiler tubes. This reduces heat transfer efficiency, causing the boiler
to work harder and consume more fuel.
19.Explain about different boiler accessories.
Ans- Boiler accessories are components that support the operation of a boiler
system. Key accessories include:
 Feed Pump: It pumps water into the boiler to replace the steam that is
generated, maintaining the water level.
 Superheater: It increases the temperature of the steam above its saturation
point to improve turbine efficiency.
 Economizer: It preheats the feedwater using the residual heat from the flue
gases, improving the boiler's efficiency.
 Air Preheater: It preheats the incoming air using the waste heat from flue
gases, reducing fuel consumption and enhancing efficiency.
20. Why cola is considered the most promising source of energy presently
in India?
Ans- Coal is considered the most promising source of energy in India because:
 Abundant Availability: India has significant domestic coal reserves,
making it a reliable and cost-effective source of energy for power
generation.
 Infrastructure and Dependence: India’s existing infrastructure is largely
designed around coal-based power plants, and a large portion of the
country's electricity is still generated from coal, making it crucial for
meeting the nation's growing energy demands.

21. What is the difference between boiler mountings and accessories?

Ans- The difference between boiler mountings and accessories is:
 Boiler Mountings: These are essential components directly attached to the
boiler for its safe operation, such as the safety valve, water level indicator,
pressure gauge, and feed check valve. They are required for the basic
functioning and safety of the boiler.
  Boiler Accessories: These are additional components that enhance the
efficiency of the boiler, such as the economizer, superheater, air preheater,
and feed pump. While not essential for operation, they improve
performance and reduce fuel consumption.
22. What is the role of a condenser in a thermal power plant?
Ans- The role of a condenser in a thermal power plant is to convert the exhaust
steam from the turbine back into water by cooling it. This is achieved by
transferring the heat from the steam to a cooling medium (usually water), which
allows the steam to condense. The condensed water is then pumped back into
the boiler for reuse, maintaining the efficiency of the steam cycle and ensuring
the continuous operation of the plant.
23. Name four accessories used in a boiler
Ans- Four accessories used in a boiler are:
 Economizer: Preheats the feedwater using residual heat from flue gases,
improving efficiency.
 Superheater: Increases the temperature of steam above its saturation
point to enhance turbine efficiency.
 Air Preheater: Preheats the incoming air to the furnace using heat from
the flue gases.
 Feed Pump: Pumps water into the boiler to replace the steam that is
generated.
24.What is the function of heat exchanger in thermal power plant?
Ans- The function of a heat exchanger in a thermal power plant is to transfer
heat from one fluid (usually hot steam or flue gases) to another fluid (typically
water or air) without mixing the two fluids. This process helps in improving the
efficiency of the plant by recovering waste heat, such as in economizers and air
preheaters, and utilizing it to preheat feedwater or air, thus reducing fuel
consumption and enhancing overall energy efficiency.
25.Illustrate how the boiler unit works in a thermal power plant to produce
high-pressure steam for the turbine.
Ans- In a thermal power plant, the boiler unit works as follows to produce high-
pressure steam for the turbine:
 Fuel Combustion: Fuel (such as coal) is burned in the furnace, producing
heat. The combustion of fuel releases thermal energy.
 Heat Transfer: The heat from the combustion process is transferred to
water circulating through the boiler tubes. This heats the water to its
boiling point, turning it into steam.
 Steam Generation: The generated steam is collected in the steam drum,
where it is further heated (superheated) to increase its temperature and
pressure, creating high-pressure steam.
  Steam to Turbine: The high-pressure steam is then directed to the
turbine, where it expands and drives the turbine blades, generating
electricity.
26.What is the function of reflector in a nuclear power plant?
Ans- The function of a reflector in a nuclear power plant is to redirect neutrons
that escape the reactor core back into the core. This helps to increase the
efficiency of the nuclear reaction by maintaining the neutron population,
ensuring that more neutrons are available to sustain the chain reaction. The
reflector also helps in moderating neutrons, improving the overall stability and
performance of the reactor.
27. What is the function of moderator in a nuclear power plant?
Ans- The function of a moderator in a nuclear power plant is to slow down fast
neutrons produced during nuclear fission. By reducing the speed of these
neutrons, the moderator increases the probability of them causing further fission
reactions, thereby sustaining the chain reaction. Common moderators include
materials like water, heavy water, and graphite.
28. What is CANDU reactor?
Ans- A CANDU reactor (Canada Deuterium Uranium reactor) is a type of
nuclear reactor that uses heavy water (deuterium oxide, D₂O) as both a
moderator and coolant, and natural uranium as fuel. It is a pressurized heavy
water reactor (PHWR) designed for efficient, safe, and continuous operation,
with the ability to be refuelled while still in operation. This design allows it to
operate on natural uranium, unlike many reactors that require enriched
uranium.
29.Apply the concept of a nuclear chain reaction to explain how it is
sustained safely in a nuclear reactor.
Ans- In a nuclear reactor, a nuclear chain reaction is sustained safely by carefully
controlling the number of neutrons produced during fission. When a uranium
or plutonium nucleus undergoes fission, it releases neutrons that can initiate
further fission reactions. To maintain a steady rate of reaction:
 Control Rods: Made of materials like boron or cadmium, control rods are
inserted or withdrawn from the reactor core to absorb excess neutrons,
regulating the chain reaction and preventing it from becoming too fast or
uncontrollable.
1. Explain the working of a boiler with neat sketch.
Ans-A boiler is a closed vessel that generates steam by heating water. The steam
produced is used for various applications, such as power generation, heating, or
industrial processes. Boilers operate on the principle of heat transfer from a heat source
(combustion of fuel) to the water inside the boiler.
Working of a Boiler
 Heat Source: Fuel (e.g., coal, oil, gas, or biomass) is burned in the furnace,
releasing heat energy.
 Water Circulation: Water enters the boiler through the feedwater system. It is
circulated through tubes or shells to absorb heat from the combustion gases.
 Heat Transfer:
o Conduction: Heat transfers from the furnace walls to the water or tubes.
o Convection: The heated water circulates within the boiler to form steam.
 Steam Formation: When the water reaches its boiling point, it changes to steam,
which accumulates in the steam drum.
 Steam Output: The generated steam is sent to turbines, process equipment, or
heating systems through a steam outlet.
 Flue Gas Exit: The exhaust gases from combustion are discharged through a
chimney or stack.
Below is a description for the sketch you can draw:
 Furnace: At the bottom, with flames indicating combustion.
 Water Tubes/Drums: Tubes filled with water, connected to a larger steam drum at
the top.
 Steam Outlet: Pipe coming out of the steam drum.
 Chimney: Extending upwards for exhaust gases.
 Safety Valve: Located on the steam drum.
 Economizer & Superheater: Positioned near the furnace and steam outlet.

2. Compare the merits and demerits of surface condenser over jet condenser.
Ans-In a surface condenser, steam passes through a set of tubes while cooling water
flows around these tubes, condensing the steam.

Merits:

 Pure Condensate: The condensed steam does not mix with the cooling water,
making it suitable for reuse as boiler feedwater.
  E iciency: Enables higher vacuum in the system, improving turbine e iciency.
 Scalability: Suitable for large power plants with higher capacities.
 Material Compatibility: Can use treated water, reducing scaling and corrosion in
the boiler.
 Flexibility: Allows the use of impure cooling water since it doesn’t mix with steam.
Demerits:
 Higher Initial Cost: More expensive to construct due to complex design.
 Maintenance: Requires regular cleaning of tubes and inspection for scaling or
fouling.
 Space Requirement: Occupies more space due to the separate water flow paths.
 Energy Consumption: Needs additional pumps to circulate cooling water and
maintain vacuum.
Jet Condenser
In a jet condenser, steam is directly mixed with cooling water, condensing it.
Merits:
 Simple Design: Compact and easier to construct.
 Lower Initial Cost: Less expensive compared to surface condensers.
 Compact Size: Requires less space due to the simpler construction.
 E ective for Small Plants: Ideal for small-scale applications where water quality
is not critical.
Demerits:
 Mixing of Water: Condensate mixes with cooling water, making it unsuitable for
reuse without treatment.
 Lower E iciency: Limited vacuum generation capability reduces turbine
e iciency.
 Cooling Water Quality: Requires clean water to avoid fouling and operational
issues.
 Environmental Impact: Discharge of mixed water may require additional
treatment to meet environmental standards.

3. Explain the working of surface condenser with neat sketch.

Working of Surface Condenser

 Steam Entry: Exhaust steam from the turbine enters the condenser shell through the inlet.
• The steam flows over a series of tubes inside the condenser.
 Cooling Water Flow: Cold water is circulated through the tubes, either drawn from a
natural source (river, lake) or a closed cooling system.
• The cooling water absorbs the heat from the steam as it passes through
the tubes.
 Condensation: The steam loses its latent heat to the cooling water and condenses into
water (condensate).
• The condensate collects at the bottom of the condenser in a hot well.
 Vacuum Maintenance:A vacuum pump or air ejector maintains a vacuum inside the
condenser, reducing the boiling point of the steam and ensuring e icient condensation.
• The vacuum also improves turbine e iciency by allowing the steam to
expand further.
 Condensate Removal:The condensate is pumped back to the boiler for reuse.
 • Non-condensable gases (e.g., air) are extracted by an air ejector to
maintain e iciency.

4. Which factors are considered for deciding the size of economiser?

Ans-Factors for Deciding the Size of an Economizer

 Boiler Capacity:The steam-generating capacity of the boiler determines the amount of

feedwater that needs to be preheated.
 Larger boilers require larger economizers to handle the higher flow rates of
feedwater.
 Fuel Type and Combustion E iciency:The type of fuel used a ects the flue gas
temperature and heat recovery potential.
 Fuels with higher combustion temperatures (e.g., coal, oil) require a larger
economizer to recover more heat from the exhaust gases.
 Flue Gas Temperature:The temperature of the flue gases leaving the boiler determines the
amount of heat available for transfer.
 Higher flue gas temperatures necessitate a larger economizer to optimize heat
recovery.
 Feedwater Temperature:The inlet temperature of the feedwater influences the heat
transfer requirements.
 Colder feedwater requires a larger economizer to achieve the desired
temperature rise.
 Heat Transfer Area:The size of the economizer is directly related to the heat transfer
surface area required to achieve the desired heat recovery.
 Factors like tube length, diameter, and arrangement are considered.
 Steam Pressure and Temperature:High-pressure boilers require more e icient heat
transfer to preheat the feedwater, influencing the economizer size.
 Flow Rates:Both the flue gas flow rate and the feedwater flow rate impact the heat
exchange process.
 Larger flow rates demand a larger economizer.
 E iciency Improvement Goals:The desired increase in boiler e iciency determines how
much heat needs to be recovered from the flue gases.
 More ambitious e iciency targets require a larger economizer.
  Material Constraints:The material of construction (e.g., steel, alloy) a ects the size due
to thermal and structural limitations.
 High-performance materials may allow for compact designs.
 Space Availability:The physical space available in the boiler house can limit the size of
the economizer.
 In such cases, compact or modular economizer designs may be preferred.
 Cost and Budget:Larger economizers increase initial costs but can result in greater fuel
savings over time.
 A balance between cost and e iciency must be achieved.
 Environmental Regulations:Regulations regarding flue gas temperature and emissions
may require larger economizers to maximize heat recovery and minimize environmental
impact.
 Type of Economizer:Di erent economizer designs (e.g., finned tube, plain tube) have
di erent size requirements for the same heat recovery performance.

5. What is the di erence between jet and surface condenser?

Jet Condenser: Direct contact between steam and cooling water.

 Simple design with low capital cost.

 Cooling water is discarded after use, leading to wastage.

Surface Condenser: Indirect contact; steam flows outside the tubes while water flows
inside.

 No contamination of boiler feed water, allowing reuse.

 Higher capital and maintenance costs

6. Define solid fuel with an example.

Ans- Solid Fuel:Solid fuel refers to any type of solid material that can be burned to produce heat
or energy through combustion. These fuels are typically organic or inorganic and are used in
various applications, including domestic heating, industrial processes, and power generation.

Examples of Solid Fuels

 Coal: A carbon-rich fossil fuel commonly used in thermal power plants.

 Wood: Includes logs, chips, or pellets used for domestic and industrial heating.
 Charcoal: Produced by heating wood in the absence of oxygen, often used for cooking or
industrial purposes.
 Peat: Partially decomposed organic matter found in wetlands, used as a low-grade fuel.
 Biomass: Organic materials like agricultural waste, crop residues, or sawdust.
 Coke: A refined form of coal used in metallurgy and industrial furnaces.

7. Explain the criteria for site selection of thermal power plant.

Ans-Criteria for Site Selection of a Thermal Power Plant-

The location of a thermal power plant significantly a ects its operational e iciency, cost, and
environmental impact. Below are the key factors considered for site selection:

 Availability of Fuel:-The plant should be located near coal mines or fuel sources to reduce
transportation costs.
 o For gas-fired plants, proximity to gas pipelines is essential.
 Water Supply:-Abundant water is required for cooling, steam generation, and other
processes.
o The plant should be located near a reliable water source, such as a river, lake, or
reservoir.
 Land Availability:-The site must have su icient land for the plant’s infrastructure,
including the main plant, coal storage, ash disposal area, cooling towers, and future
expansion.
o Land should be relatively flat to minimize construction costs.
 Proximity to Load Centers:-The plant should be located near industrial areas or cities to
reduce transmission losses and costs.
o Proximity ensures e icient power delivery to consumers.
 Transportation Facilities:-Good connectivity through rail, road, or ports is required for
transporting fuel, equipment, and other materials.
o E icient logistics reduce operational costs.
 Environmental Considerations:-The site should comply with environmental regulations to
minimize pollution and ecological impact.
o Adequate arrangements for ash disposal, flue gas treatment, and water discharge
should be possible.
 Climatic Conditions:-Extreme weather conditions can a ect plant e iciency and
maintenance.
o Moderate climates are preferred to ensure uninterrupted operation.
 Distance from Populated Areas:-The plant should be located away from densely
populated areas to avoid health and safety risks caused by emissions, noise, or
accidents.
 Cost Factors: -Total investment, including land acquisition, construction, fuel
transportation, and maintenance, should be economically viable.
o Subsidies or incentives from local authorities can influence the site selection.
 Geological and Seismic Considerations: -The site should have stable geological
conditions to support heavy machinery and infrastructure.
o Avoidance of areas prone to earthquakes, floods, or landslides is critical.
 Waste Disposal: -Adequate space and facilities should be available for safe disposal of
ash and other waste products.
o Proximity to areas where fly ash can be used (e.g., cement factories) is beneficial.
 By carefully evaluating these criteria, the location of a thermal power plant can be
optimized for e iciency, cost-e ectiveness, and environmental sustainability.
 9. Di erentiate between fission and Fusion process.

Nuclear Fission Nuclear Fusion

 The combining of two light nuclei to form a
 The splitting of a heavy nucleus into smaller heavier nucleus, accompanied by the release of
nuclei, along with the release of energy. energy.
 Heavy elements like Uranium-235, Plutonium-  Light elements like Hydrogen isotopes
239. (Deuterium and Tritium).
 Produces a significant amount of energy, but  Produces much more energy per reaction than
less than fusion. fission.
 Can occur at relatively lower temperatures and  Requires extremely high temperatures (millions
pressures. of degrees) and pressure.
 Produces radioactive waste that requires long-  Produces minimal radioactive waste, often
term storage and management. Helium (non- radioactive).
 Artificially induced in nuclear reactors or  Occurs naturally in stars (e.g., the Sun) and is
atomic bombs. being researched for controlled use on Earth.
 A chain reaction can occur, where one fission  No chain reaction; reactions need to be
event triggers others. continuously maintained.
 Less e icient compared to fusion.  Highly e icient in terms of energy output.
 Used in nuclear power plants and atomic  Being developed for fusion power plants and is
bombs. already bserved in hydrogen bombs.

10. Design a schematic for a thermal power plant by showing di erent units (boiler, turbine,
condenser, and generator) and explain how energy flows through the system.

Ans-Schematic of a Thermal Power Plant

The schematic below outlines the major components of a thermal power plant and their
arrangement:

 Boiler: Generates steam by heating water using the combustion of fuel.

 Turbine: Converts the energy in the high-pressure steam into mechanical energy by
rotating blades.
 Condenser: Cools the exhaust steam from the turbine back into water for reuse.
 Generator: Converts the mechanical energy from the turbine into electrical energy.
 Cooling Tower: Provides cooling water for the condenser.

Energy Flow in a Thermal Power Plant

 Fuel Energy:Coal, oil, or gas is burned in the boiler to produce heat energy.
 Heat Energy to Steam:The heat energy converts water into high-pressure, high-
temperature steam in the boiler.
 Steam Energy to Mechanical Energy:The steam is directed to the turbine, where it
expands and rotates the turbine blades, converting steam energy into mechanical energy.
 Mechanical Energy to Electrical Energy:The turbine is coupled to the generator, where
mechanical energy is converted into electrical energy through electromagnetic induction.
 Condensation:After passing through the turbine, the steam enters the condenser, where
it is cooled and condensed back into water using cooling water.
 Recirculation:The condensate is pumped back to the boiler to repeat the cycle.
11. Identify and explain the key factors that engineers must consider when determining the
appropriate size of an economizer for a given boiler system. How do these factors impact
the e iciency and performance of the system?

Ans-When determining the appropriate size of an economizer for a given boiler system, engineers
must consider several key factors that a ect both the e iciency and performance of the system.
These factors help ensure optimal heat recovery, fuel economy, and operational e iciency. Below
are the key considerations:

 Boiler Capacity
 Definition: The steam-generating capacity of the boiler determines how much
feedwater needs to be preheated.
 Impact on Size: Larger boilers require larger economizers to handle greater
volumes of feedwater. The economizer must have su icient surface area to
transfer enough heat to the feedwater.
 E iciency: A properly sized economizer ensures that a significant portion of the
heat in the flue gases is recovered, reducing the overall fuel consumption and
improving boiler e iciency.
 Temperature of the Flue Gas
 Definition: The temperature of the exhaust gases leaving the boiler is a critical
factor in determining the heat available for recovery.
 Impact on Size: Higher flue gas temperatures provide more heat that can be
captured and used to preheat the feedwater. An economizer needs to have
enough surface area to capture this heat e ectively.
 E iciency: Recovering more heat from high-temperature flue gases improves
system e iciency by reducing the fuel needed to heat the feedwater.
 Feedwater Flow Rate
 Definition: The rate at which feedwater is supplied to the boiler (usually measured
in gallons or liters per minute).
 Impact on Size: The economizer must be sized to match the feedwater flow rate
to achieve the required temperature rise in the feedwater.
 E iciency: A properly matched economizer ensures that the feedwater is heated
to the desired temperature, which enhances the thermal e iciency of the boiler
system.
 Desired Feedwater Temperature
 Definition: The temperature to which the feedwater must be raised before it enters
the boiler for steam generation.
 Impact on Size: The larger the temperature rise required, the more heat must be
recovered from the flue gases, thus requiring a larger economizer.
 E iciency: Properly heating the feedwater reduces the load on the boiler and
improves overall e iciency by making the steam generation process more energy-
e icient.
 Heat Transfer Surface Area
 Definition: The surface area of the economizer tubes where heat is transferred
from the flue gas to the feedwater.
 Impact on Size: A larger heat transfer surface area allows for more e icient heat
exchange, improving the economizer’s ability to preheat the feedwater.
  E iciency: A larger surface area increases the heat recovery rate, reducing the
energy demand from the boiler and improving overall fuel e iciency.Impact on
E iciency and Performance

The size of the economizer plays a crucial role in determining how much heat is recovered from
the exhaust gases and used to preheat the feedwater. When optimally sized:

 Increased E iciency: More heat is recovered, reducing the need for additional fuel
to heat the feedwater, improving overall thermal e iciency.
 Fuel Savings: By recovering more heat, less fuel is needed to achieve the desired
steam output, leading to lower operating costs.
 Reduced Emissions: E icient heat recovery reduces the burning of fuel, which
can decrease harmful emissions from the plant.
 Improved Boiler Longevity: Properly sized economizers reduce thermal stress on
the boiler by reducing the demand on its heating surfaces

12. Evaluate the advantages and disadvantages of using an evaporative surface condenser
compared to a traditional direct-contact condenser in a large-scale industrial setup.

Ans-Evaporative Surface Condenser: -An evaporative surface condenser uses cooling water that
is indirectly cooled by evaporation, typically in cooling towers. It cools the steam via a heat
exchange surface, where water absorbs heat but does not directly contact the steam.

Advantages:

 Improved E iciency: Provides better heat transfer due to the larger surface area and more
controlled cooling processes.
 Higher cooling capacity, which makes it suitable for high-capacity power plants
and industrial applications.
 Cleaner Condensate: Since steam and cooling water do not mix, the condensate is pure
and can be reused directly in the boiler, reducing water treatment requirements.
 Lower Environmental Impact- The absence of direct contact with water helps in reducing
contamination, so fewer chemicals are needed to treat the cooling water.
 Reduced Risk of Scaling: As there is no direct contact with the cooling water, the risk of
mineral deposition (scaling) in the condenser is lower.
 Suitable for Areas with Limited Water Supply: Works well in regions with strict regulations
on water quality and availability because it minimizes water wastage.

Disadvantages:

 Higher Initial Cost:More expensive to install than direct-contact condensers due to the
complexity of the heat exchanger system and the additional infrastructure like cooling
towers.
 Space Requirements:Requires more space for the installation of cooling towers and
related infrastructure.
 Energy Consumption:The cooling tower consumes energy for pumping and circulating
water, which adds to the overall operational costs.
 Maintenance Complexity:Maintenance can be more complex due to the additional
components like the heat exchanger and cooling towers, as well as the need for periodic
cleaning of the heat exchange surfaces.
  Dependence on Ambient Conditions-Evaporative cooling performance can be a ected
by ambient temperature and humidity. In hot, dry conditions, the cooling e iciency may
decrease.

Direct-Contact Condenser:-A direct-contact condenser cools the steam by directly mixing it

with water. The steam condenses as it comes into contact with the cooling water, which absorbs
the heat.

Advantages:

 Lower Initial Cost:Typically, less expensive to install than evaporative surface condensers
because the system is simpler and doesn’t require cooling towers or heat exchangers.
 Compact Design:The system requires less space compared to evaporative condensers,
making it suitable for applications with limited space.
 High Heat Transfer Rate:Direct contact between steam and water facilitates rapid heat
exchange, potentially o ering higher heat transfer rates than surface condensers.
 Simplicity and Lower Maintenance:Fewer components mean lower maintenance costs
and simpler operation. Maintenance is mainly focused on the water treatment and
cleaning of the cooling system.
 No Need for Cooling Towers:This system doesn’t require separate cooling towers,
simplifying the overall plant layout and reducing the need for large, complex
infrastructure.
Disadvantages:
 Contamination of Condensate: Since steam and cooling water mix directly, the
condensate can be contaminated with impurities from the cooling water, requiring
additional water treatment before reuse in the boiler.
 Water Quality Requirements: The cooling water must be of high quality to prevent
corrosion, scaling, and fouling in the condenser. This leads to higher water treatment
costs and potential environmental concerns.
 Environmental Impact: Direct-contact cooling can result in the discharge of warm water
into local water bodies, which may a ect aquatic life and lead to regulatory issues.

14. Explain about Evaporative surface condenser with suitable sketch

Ans: Evaporative Surface Condenser:-An evaporative surface condenser is a type of heat

exchanger used in power plants to condense exhaust steam from the turbine. It combines the
benefits of both evaporative cooling (like a cooling tower) and surface cooling (like a shell-and-
tube heat exchanger). The primary function of an evaporative surface condenser is to cool the
exhaust steam by transferring heat from the steam to a cooling medium (typically water) without
the steam directly coming into contact with the cooling water.

Working Principle:

 Steam Inlet: Exhaust steam from the turbine enters the evaporative surface condenser at
a high temperature and pressure.
 Heat Exchange: The steam passes through a series of tubes that form the heat exchange
surface. The cooling water, which is typically colder than the steam, flows over these
tubes.
 Evaporation: As the steam flows over the tubes, heat is transferred to the cooling water,
causing the steam to condense into liquid water. Part of the cooling water evaporates as
it absorbs heat from the steam. The evaporative process helps to cool the cooling water.
  Condensed Steam: The condensed steam (now in liquid form) is collected in the bottom
of the condenser, and it is pumped back to the boiler as feedwater.
 Cooling Water Circulation: The cooling water circulates in a closed-loop system. It
absorbs heat from the steam and partially evaporates to release this heat. The evaporated
water is carried away, and the remaining water is cooled in the cooling tower before being
recirculated to the condenser.
 Heat Rejection: The heated, evaporated cooling water is expelled into the atmosphere
through a cooling tower, while the remaining cooled water is reused in the system.

Components of Evaporative Surface Condenser:

 Tubes: The tubes are made of materials that have high thermal conductivity (such as
copper or stainless steel) and form the surface through which heat transfer occurs.
 Cooling Water System: Circulates water over the tubes to absorb heat.
 Evaporation Area: The part of the system where the water evaporates, typically in the
cooling tower.
 Condensate Collection: A section at the bottom of the condenser where condensed
water (feedwater) is collected for recirculation

15. Explain the deference between an impulse turbine and a reaction turbine.

Ans-An impulse turbine and a reaction turbine are both types of steam or water turbines, but they
operate based on di erent principles of energy conversion:

1.Impulse Turbine: In an impulse turbine, the steam or water enters the turbine through
nozzles that convert pressure energy into kinetic energy.

 The high-speed jet of fluid strikes the turbine blades, causing them to move.
 The pressure of the fluid does not change significantly as it passes through the blades.
The energy transfer is mainly due to the change in velocity of the fluid.
 The most common example of an impulse turbine is the Pelton wheel.
 Key point: Energy is transferred via high-velocity fluid jets, and the blades experience a
sudden impulse.
2.Reaction Turbine:In a reaction turbine, the fluid undergoes both pressure and velocity
changes as it passes through the blades.
  The blades are designed to have a shape that causes the fluid to expand and lose pressure
as it moves through the turbine, which also accelerates the flow.
 The energy transfer occurs due to the continuous reaction force between the fluid and the
blades throughout the blade’s motion.
 The Francis turbine and Kaplan turbine are examples of reaction turbines.
 Key point: Energy is transferred continuously, with both pressure and velocity changes
acting on the blades.

16. Apply your understanding explain water tube and fire tube boilers to select the most
appropriate boiler type for a specific industrial requirement

Ans- 1. Fire Tube Boilers

 Design: In a fire tube boiler, the hot gases from the combustion chamber pass through tubes,
and the water is on the outside of these tubes. The heat from the gases is transferred to the
water surrounding the tubes, which heats the water to produce steam.
 Pressure & Temperature: Fire tube boilers are generally designed for low to medium pressure
applications. The maximum pressure typically ranges from 15 to 25 bar, and they are not
suitable for very high-temperature or high-pressure steam generation.
 Capacity: These boilers are typically smaller in capacity, ranging from small to medium
outputs.
 Applications: Fire tube boilers are commonly used in small-to-medium industries like:
 Heating systems
 Hotels, hospitals, and small manufacturing plants where moderate steam output is needed
 Advantages:
 Simple design and easy to operate
 Lower initial cost
 Easier maintenance due to accessible design
 Disadvantages:
 Limited to low-to-medium pressure and steam output
 Slower steam generation and recovery times

2.Water Tube Boilers

 Design: In a water tube boiler, the water flows inside the tubes, and the hot gases
pass around them. This design allows water to be heated rapidly and can handle
much higher pressures and temperatures than fire tube boilers.
 Pressure & Temperature: Water tube boilers are designed for high-pressure and
high-temperature applications. They can typically operate at pressures above 25
bar, and they can handle steam pressures up to 100 bar or more.
 Capacity: Water tube boilers are larger and can handle much higher steam
output, making them suitable for large-scale industrial processes.
 Fire tube boiler: Suitable for small to medium steam output, typically up to 10-20
tons of steam per hour.
 Water tube boiler: Suitable for large-scale applications needing high steam
output (50 tons per hour or more).
 Space Constraints:
 Fire tube boiler: These tend to have a more compact design and require less
space.
 Water tube boiler: These boilers take up more space due to their larger design.
17. Explain the working principle of an impulse turbine and how it diapers from that of a
reaction turbine in terms of energy conversion.

Ans-Impulse Turbine: Working Principle

An impulse turbine operates based on the conversion of pressure energy into kinetic energy,
followed by the conversion of that kinetic energy into mechanical energy (work) through the
action of the fluid on the turbine blades.

1. High-Speed Jets: In an impulse turbine, steam or water is directed through

nozzles, where its pressure energy is converted into high-velocity kinetic energy (a jet of fluid).

2. Blade Action: The high-velocity fluid jet strikes the blades of the turbine (also
called buckets in some cases, like the Pelton wheel), causing them to move. The turbine blades
change the direction of the fluid, which results in a change in momentum.

3. Energy Transfer: The energy from the fluid’s high velocity is transferred to the
blades. As the fluid hits the blades, it slows down, transferring its kinetic energy to the turbine
blades, causing them to rotate and perform mechanical work.

Di erences in Energy Conversion:

1. Energy Conversion in Impulse Turbines:

• Impulse turbines convert pressure energy into kinetic energy using nozzles.

• The blades absorb this kinetic energy (high-velocity fluid) when the fluid jet strikes
them.

• The pressure remains almost constant as the fluid passes through the blades.

• The energy conversion happens primarily through the change in velocity of the
fluid (impulse action).

2. Energy Conversion in Reaction Turbines:

• Reaction turbines convert both pressure energy and kinetic energy during the
passage of fluid through the blades.

• As the fluid flows through the blades, its pressure decreases, and its kinetic
energy increases.

• The energy is transferred continuously as the fluid passes through the blades, and
the blades experience both a pressure di erence and velocity change (reaction action).
18. Evaluate the deference between jet and surface condensers in terms of e iciency.

Ans- Surface condensers (or non-mixing type condensers). In surface condensers, there is no
direct contact between the exhaust steam and the cooling water. Jet condensers (or mixing type
condensers). In jet condensers there is direct contact between the exhaust steam and cooling
water

Surface condensers Jet condensers

 Steam and Cooling water are not  Cooling water and steam are mixed
mixed up. up Less suitable for high capacity
 More suitable for high capacity plants.
plants.  Condensate is wasted
 Condensate is reused.  It requires less quantity of
 It requires large quantity of circulating water
circulating water.  Condensing plant is economical
 The condensing plant is costly and and simple
complicated.  Its maintenance cost is low.
 Its maintenance cost is high.

20. Write a short note on bleeding of steam turbine

Ans-Bleeding of Steam Turbine refers to the controlled extraction of steam from intermediate
stages of a steam turbine for various purposes. This process improves the overall e iciency of the
turbine and the connected system.

Purpose of Bleeding:

1. Feedwater Heating: The extracted steam is used to preheat the feedwater before
it enters the boiler. This reduces the thermal shock to the boiler and increases its e iciency.

• Preheating the feedwater also reduces the amount of fuel required to convert
water into steam, leading to cost savings.

2. Process Applications: In industries like paper, sugar, and textiles, the extracted
steam can be used for process heating.

3. Improved E iciency:

• By extracting steam at intermediate pressures, the turbine operates with reduced

exhaust losses, thereby enhancing the cycle e iciency (commonly in Regenerative Rankine
Cycles).

How Bleeding Works:

• Steam is extracted from specific stages of the turbine at intermediate pressures,

depending on the temperature and pressure required for the feedwater heaters or industrial
processes.

• The remaining steam continues to expand in the turbine to generate power.

21. What do you mean by energy losses in steam turbine?

Ans-Types of Energy Losses in Steam Turbines

1. Thermodynamic Losses (Irreversibility Losses):

• Occur due to entropy generation during the expansion of steam.

• Results from friction, heat transfer, and turbulence within the turbine.

• These are inherent to the process and cannot be completely eliminated.

2. Mechanical Losses:Caused by friction in bearings, gears, and moving parts of the

turbine.

• Lead to a portion of the mechanical energy being wasted as heat instead of being
converted into useful work.

3. Leakage Losses:Occur when steam leaks through the clearances between

stationary and moving parts, such as the clearance between blades and casing or at the shaft
seals.

• Leakage reduces the amount of steam available for performing work.

4. Blade Losses:Shock losses: Caused by improper steam flow alignment with the
blades, leading to ine icient energy transfer.

• Friction losses: Result from friction between the steam and blade surfaces as the
steam flows over the blades.

• Trailing edge losses: Occur at the blade’s exit due to flow separation or
turbulence.

5. Exhaust Losses:Occur when the steam exits the turbine with residual kinetic
energy that is not utilized.

• These losses depend on the design of the exhaust system and the pressure
di erence between the exhaust and the condenser.

6. Moisture Losses:In the later stages of expansion, the steam may become wet
(contain water droplets).

• These water droplets increase erosion of the blades and reduce the e iciency of
energy transfer.

7. Radiation and Heat Losses:Heat loss occurs when the turbine casing radiates
heat to the surroundings.

• These losses are generally small but can become significant in poorly insulated
systems.

Impact of Energy Losses-Reduced E iciency: Energy losses reduce the turbine’s overall
e iciency, meaning less work output for a given amount of steam input.

 Increased Fuel Consumption: Lower e iciency leads to higher fuel consumption in the
boiler to produce the same power output.
22. Explain with help of neat diagram the construction and working of a nuclear power plant

Ans-A nuclear power plant generates electricity by harnessing the heat produced during a
controlled nuclear fission reaction. Below is the explanation of its construction, working
principle, and a simplified diagram.

A nuclear power plant typically consists of the following main components:

1.Reactor Core: Contains fuel rods made of enriched uranium or plutonium, which
undergo fission to release heat.

• Also includes control rods (made of materials like cadmium or boron) to control
the fission process by absorbing excess neutrons.

2.Moderator:Slows down neutrons to sustain the chain reaction.

•Common materials: Heavy water, light water, or graphite.

3.Coolant: Transfers heat from the reactor core to the steam generator or directly to the
turbine.

•Common coolants: Water, liquid sodium, or gas.

4.Steam Generator:Converts water into steam using the heat extracted by the coolant
from the reactor core (in pressurized water reactors).

5.Turbine and Generator:The steam drives a steam turbine, which rotates a generator to
produce electricity.

6.Condenser: Condenses the exhaust steam from the turbine back into water for reuse in
the cycle.

7.Cooling System:Uses a cooling tower or water from a nearby river/lake to dissipate

excess heat.

8.Containment Structure:A heavily shielded building made of concrete and steel that
encloses the reactor to protect against radiation leakage.

9.Control Room:Houses the equipment to monitor and control the entire operation of the
nuclear power plant.
23. Explain about di erent advantages and limitations of nuclear power plant.

Ans-Advantages of Nuclear Power Plants

1. High Energy Density: Nuclear fuel (e.g., uranium) has an extremely high energy
density compared to fossil fuels.

• A small quantity of nuclear fuel can produce a large amount of electricity.

2. Low Greenhouse Gas Emissions: Nuclear power plants produce minimal carbon
dioxide (CO₂) and other greenhouse gases during operation.

• Helps in combating climate change.

3. Continuous Power Generation: Operates continuously, providing a reliable and

consistent power supply (base load power).

• Unlike renewable energy sources like wind and solar, it is not weather-dependent.

4. Reduced Fuel Transportation: A small amount of nuclear fuel is needed, reducing

the cost and environmental impact of fuel transportation.

5. Long Fuel LIFE: Nuclear fuel, such as uranium or plutonium, can last for several
years before replacement is necessary, leading to fewer operational interruptions.

6. Small Land Footprint:

• Requires less land compared to renewable energy sources like solar and wind
farms for an equivalent amount of power generation.

Limitations of Nuclear Power Plants

1. High Initial Cost: Nuclear power plants are expensive to build due to the
complexity of safety measures, containment structures, and regulatory compliance.

2. Nuclear Waste Management: Spent nuclear fuel is highly radioactive and requires
secure storage and disposal for thousands of years.

• Managing nuclear waste remains a significant challenge.

3. Safety Concerns: Accidents like those at Chernobyl (1986) and Fukushima (2011)
highlight the catastrophic risks of nuclear power plants.

• Public perception of nuclear safety can be a barrier.

4. Non-Renewable Resource: Uranium, although abundant, is still a finite resource

and will eventually deplete if not used sustainably.

5. Complex Technology: Requires highly skilled personnel for operation and

maintenance.

24. Explain di erent components of nuclear power plants with neat sketch.

Ans-A nuclear power plant is a complex system consisting of several components that work
together to generate electricity by harnessing energy from nuclear fission. Below is an explanation
of the key components along with a simplified sketch.

1. Reactor Core:The heart of the nuclear power plant where nuclear fission takes place.

• Contains fuel rods made of uranium-235 or plutonium-239, which undergo

fission.

• Control rods (made of boron or cadmium) are inserted to absorb neutrons and
control the fission reaction.

• A moderator (graphite, heavy water, or light water) is used to slow down fast
neutrons to sustain the chain reaction.

• Function: Generates a large amount of heat through controlled nuclear fission.

2. Moderator: A material (e.g., heavy water or graphite) that slows down the neutrons produced
during fission.

• Function: Ensures that the neutrons remain at the right speed to sustain a chain
reaction.

3. Coolant: A fluid (water, liquid sodium, or gas) that flows through the reactor core to absorb heat
generated by fission.

• Function: Transfers the heat from the reactor core to the steam generator or
directly to the turbine.

4. Steam Generator: A heat exchanger where the heat from the coolant is used to convert water
into steam.

• Function: Produces high-pressure steam to drive the turbine.

5. Turbine: A rotary machine driven by high-pressure steam.

• Function: Converts the thermal energy of steam into mechanical energy.

6. Generator: A device connected to the turbine shaft.

• Function: Converts mechanical energy from the turbine into electrical energy.

7. Condenser:A heat exchanger where the exhaust steam from the turbine is cooled and
condensed back into water using cold water from a cooling system.
 • Function: Recirculates water to the steam generator and dissipates waste heat.

8. Cooling System:Consists of a cooling tower or uses water from a nearby natural source (river,
lake, or sea).

• Function: Removes excess heat from the condenser and dissipates it into the
atmosphere or a water body.

9. Containment Structure:A thick concrete and steel building that houses the reactor.

• Function: Protects against radiation leakage and external hazards such as earthquakes
or explosions.

10. Control Room:A centralized area with monitoring and control systems for the entire plant.

• Function: Manages the operation of the reactor and other systems, ensuring
safety and e iciency.

26. Analyse the working of a Pressurized Water Reactor (PWR) using a suitable diagram.
Explain how its components interact to produce energy and discuss the advantages and
limitations of this reactor.

Ans-Working of a Pressurized Water Reactor (PWR)

1. Nuclear Fuel: The core of a PWR contains nuclear fuel, typically uranium-235 or
plutonium-239, arranged in fuel rods. These rods are bundled together to form fuel assemblies.

2. Moderator: The fuel is surrounded by a material known as the moderator, typically

water, which slows down the fast neutrons produced during fission. This slowing down process
increases the likelihood of further fission reactions, sustaining a controlled chain reaction.

3. Coolant: Water is also used as the coolant in a PWR, circulating under high
pressure to remove the heat generated by the fission process. The water in the reactor core is
pressurized to prevent it from boiling, even at high temperatures (typically 300°C).
 4. Pressurizer: The pressurizer maintains the water at high pressure (about 150–160
atm) to prevent it from turning into steam. This is a key component to ensure that the coolant can
e ectively transfer heat while remaining in liquid form.

5. Steam Generator: The hot, pressurized water from the reactor core (primary loop)
flows to a steam generator, where heat is transferred to a secondary loop of water, which is kept
at a lower pressure. This secondary loop produces steam.

6. Turbine and Generator: The steam produced in the steam generator is sent to a
turbine, where it spins the blades of the turbine. The turbine is connected to a generator that
converts the mechanical energy into electrical energy.

7. Condenser: After passing through the turbine, the steam is cooled and
condensed back into water in the condenser. This water is returned to the steam generator,
completing the secondary loop.

8. Control Rods: Control rods, made of neutron-absorbing materials like boron or

cadmium, are inserted into the reactor core to control the rate of the fission reaction. By
absorbing neutrons, control rods reduce the number of available neutrons for further fission, thus
controlling the power output of the reactor.

Interaction of Components to Produce Energy

The process begins with nuclear fission in the reactor core, where the uranium-235 nuclei split
into smaller fragments, releasing a significant amount of energy in the form of heat. The coolant
(water) absorbs this heat and is pressurized to prevent boiling. This hot, high-pressure water is
then sent to the steam generator, where it transfers its heat to the secondary loop, causing the
secondary water to turn into steam.

The steam drives the turbine, which converts thermal energy into mechanical energy. The
generator connected to the turbine then converts this mechanical energy into electricity. The
steam is condensed back into water in the condenser and returned to the steam generator,
completing the cycle. Meanwhile, the control rods adjust the fission rate to maintain the reactor’s
power output.

27. Utilize your knowledge of nuclear reactors to explain, with a neat sketch, how a CANDU
reactor works.
Ans-A CANDU (Canadian Deuterium Uranium) reactor is a type of nuclear reactor that utilizes
natural uranium as fuel and heavy water (deuterium oxide, D₂O) as both the coolant and the
moderator. The design of the CANDU reactor is unique because it uses natural uranium, which
does not require enrichment, and it features a horizontal fuel channel design, which distinguishes
it from other reactor types like the Pressurized Water Reactor (PWR).

How the CANDU Reactor Works

1. Nuclear Fission: Inside the reactor core, uranium-235 nuclei undergo fission reactions
when they absorb neutrons. This process generates a large amount of heat.

2. Moderator Function: The heavy water (D₂O) surrounding the fuel slows down the neutrons
produced during fission, increasing the likelihood of further fission reactions. This makes natural
uranium a viable fuel, as the slower neutrons are more likely to interact with the uranium-235
nuclei.

3. Heat Transfer: The heat generated by the fission reactions is carried away by the heavy
water coolant. The coolant flows through the reactor core, where it absorbs the heat and is
pumped out to the heat exchanger.

4. Steam Generation: In the heat exchanger, the hot heavy water transfers its heat to a
secondary loop of ordinary water. The secondary loop water turns to steam, which is used to spin
a turbine connected to a generator, producing electricity.

28. Explain the working of BWR reactor with a suitable diagram.

Ans- A Boiling Water Reactor (BWR) is another type of nuclear reactor used for generating
electricity, similar to the Pressurized Water Reactor (PWR) but with a key di erence: in a BWR, the
water used to cool the reactor core is allowed to boil directly in the reactor vessel. The resulting
steam is then used to drive a turbine and generate electricity. Here’s a breakdown of how the BWR
works, along with a suitable diagram to illustrate its components and their interactions.

Working of a Boiling Water Reactor (BWR)

The BWR is a type of nuclear reactor where the core heats water, and the heated water boils to
produce steam. The steam is directly used to drive a turbine, which is connected to a generator
to produce electricity. After passing through the turbine, the steam is cooled and condensed back
into water, and then the cycle is repeated.
Diagram of a Boiling Water Reactor (BWR)