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• Liquid METAL (Na (or) Na K)
• Helium (He)
• CARBON DIOXIDE.

The process of producing fissionable material from a fertile material such as uranium 238 (U 238) and THORIUM 232 (Th 232) by neutron absorption is KNOWN as breeding.

The process of producing fissionable material from a fertile material such as uranium 238 (U 238) and thorium 232 (Th 232) by neutron absorption is known as breeding.

1. Fuel processing is SIMPLE.
2. The use of C02 as coolant COMPLETELY ELIMINATES the possibility of explosion in reactor.
3. No corrosion PROBLEM.

• The pressurized water REACTOR is compact
• In this type, water is USED as coolant; MODERATOR and reflector water is CHEAP and available in plenty)
• It requires LESS number of control rods.

1. Nuclear fuel 
2. Moderator 
3. Control rods 
4. REFLECTORS
5. REACTOR vessel 
6. BIOLOGICAL shielding 
7. COOLANT

Uranium exists in different isotopes of U 238, tP34 and U 235. Out of these, EP35 is most unstable.

When unstable HEAVY nucleus is bombarded with high-energy neutrons, it SPLITS up roughly into two equal fragments and about 2.5 neutrons are released and a large amount of energy is PRODUCED. This process is called nuclear fission.

Uranium exists in different isotopes of U 238, tP34 and U 235. Out of these, EP35 is most unstable.

When unstable heavy nucleus is bombarded with high-energy neutrons, it splits up roughly into two equal fragments and about 2.5 neutrons are released and a large amount of energy is produced. This process is called nuclear fission.

Its own weight which is CONSIDERED to ACT on single VERTICAL force ACTING through the centroid

The wind PRESSURE, which is considered to act on the horizontal force acting on the centroid of vertical projected area.

Its own weight which is considered to act on single vertical force acting through the centroid

The wind pressure, which is considered to act on the horizontal force acting on the centroid of vertical projected area.

The CONTROL rods are used to start the CHAIN reaction, maintain the chain reaction at REQUIRED LEVEL and to shut down the reactor during emergency.

The control rods are used to start the chain reaction, maintain the chain reaction at required level and to shut down the reactor during emergency.

The working principle of MHD is as like that of dynamo. Instead of solid conductor HIGH temperature PLASMA is passed through the magnetic field at sonic speed. When the GAS is passed through magnetic field, current is induced. Electrodes collect this induced current.

The working principle of MHD is as like that of dynamo. Instead of solid conductor high temperature plasma is passed through the magnetic field at sonic speed. When the gas is passed through magnetic field, current is induced. Electrodes collect this induced current.

• Open CYCLE MHD
• CLOSED cycle MHD
• Closed cycle MHD with liquid METAL

• Sodium has very low absorption cross-sectional area.
• It POSSESS GOOD heat transfer PROPERTIES at high TEMPERATURE and low pressure.
• It does not REACT with any of the structural materials used in primary circuits.

• HIGHLY enriched FUEL is required
• Control is difficult and expensive
• SAFETY must be provided against MELT down
• Handling of sodium is a major problem

• It gives HIGH power DENSITY than any other reactor.
• High BREEDING is possible.
• High burn-up of fuel is ACHIEVABLE.
• The operation of the reactor is not limited by Xe POISONING.

• GASES do not react chemically with the structural materials.
• GAS can attain any temperature for a particular pressure.
• They do not absorb NEUTRON.
• The LEAKAGE of gas will not affect the reactivity.
• The gas coolant provides best neutron economy.

Fast REACTORS, THERMAL reactors, natural fuel reactors, Enriched URANIUM reactors, WATER moderated reactors, HEAVY water moderated reactor, graphite moderated reactor, gas cooled reactors and Sodium cooled reactors.

Fast reactors, Thermal reactors, natural fuel reactors, Enriched Uranium reactors, water moderated reactors, heavy water moderated reactor, graphite moderated reactor, gas cooled reactors and Sodium cooled reactors.

• It should not ABSORB NEUTRON
• Have high chemical and radiation stability
• Non-corrosive
• Have high boiling POINT
• Non-toxic

• It must be as light as possible It must slow down the neutron as QUICK as possible.
• It must have resistance to corrosion.
• It must have GOOD machinability.
• It must have good CONDUCTIVITY and HIGH MELTING point.

There are MATERIALS LIKE U 235 and Th232 which are not fissile but can be converted into fissile materials by the BOMBARDMENT of neutrons. Such materials are known as fertile materials.

The process of converting more fertile MATERIAL into fissile material in a reaction is known as BREEDING.

There are materials like U 235 and Th232 which are not fissile but can be converted into fissile materials by the bombardment of neutrons. Such materials are known as fertile materials.

The process of converting more fertile material into fissile material in a reaction is known as breeding.

K =NUMBER of NEUTRONS of any one GENERATION/number of neutrons of IMMEDIATELY preceding generation.

k =number of neutrons of any one generation/number of neutrons of immediately preceding generation.

• The bombarded neutrons MUST have sufficient ENERGY to cause fission.
• The number of neutrons produced must be ABLE to create the rate of fission.
• The fission PROCESS must GENERATE energy.
• The fission process must be controlled.

Some elements have the same number of PROTONS in the nucleus but different number of NEUTRONS. As a RESULT, these elements have the same atomic number but different MASS number. Such type of elements which ‘have the same atomic number – same number of protons the same chemical properties but different mass NUMBERS due to different number of neutrons, are known as in the isotopes of an element.

Some elements have the same number of protons in the nucleus but different number of neutrons. As a result, these elements have the same atomic number but different mass number. Such type of elements which ‘have the same atomic number – same number of protons the same chemical properties but different mass numbers due to different number of neutrons, are known as in the isotopes of an element.

The nucleus CONTAINS protons and neutrons. The number of protons in a given ATOM is an atomic number (Z). The atomic number for H is 1 and He is 2.

The nucleus contains protons and neutrons. The number of protons in a given atom is an atomic number (Z). The atomic number for H is 1 and He is 2.

Depreciation cost is the amount to be set ASIDE per year from the INCOME of the PLANT to meet the depreciation caused by the age of service, WEAR and tear of the machinery and equipments. Depreciation amount collected every year helps in replacing and repairing the equipment.

Depreciation cost is the amount to be set aside per year from the income of the plant to meet the depreciation caused by the age of service, wear and tear of the machinery and equipments. Depreciation amount collected every year helps in replacing and repairing the equipment.

Operating cost includes the FOLLOWING cost.

• Cost of fuel
• Cost of operating labour,
• Cost of maintenance labours and materials.
• Cost of supplier like

Water for feeding boilers, for CONDENSER and for general USE.

• Lubrication OIL and, grease.
• Water treatment chemicals.

Operating cost includes the following cost.

Water for feeding boilers, for condenser and for general use.

Fixed cost includes the FOLLOWING cost.

1. Cost of land
2. Cost of building
3. Cost of EQUIPMENT
4. Cost of installation
5.  INTEREST
6. DEPRECIATION cost
7. Insurance
8. MANAGEMENT cost

Fixed cost includes the following cost.

Load FACTOR is DEFINED as the ratio of AVERAGE load to the PEAK load (or) maximum demand.

Load factor is defined as the ratio of average load to the peak load (or) maximum demand.

Load curve is a GRAPHICAL representation between load in kW and time in hours. It. shows variation of load at the power station. The AREA under the load curve represents the energy generated in a PARTICULAR PERIOD.

Load curve is a graphical representation between load in kW and time in hours. It. shows variation of load at the power station. The area under the load curve represents the energy generated in a particular period.

• Demand factor is defined as the ratio of MAXIMUM demand to connected LOAD.
• Connected load is the sum of ratings in KW of equipment installed in the consumer’s premises.
• Maximum demand is the maximum load, which a consumer USES at any time.

• To DETERMINE the thermal EFFICIENCY of the boiler when working at a definite PRESSURE.
• To draw up heat balance sheet for the boiler to CHECK the performance of the boiler.

STEAM is generated in BOILERS under certain conditions of feed water and exists as steam while a certain amount of fuel is burnt.

To study the performance of boiler, some experiments are conducted by operating, the boiler for a certain length of TIME and RECORDING the data. This procedure is known as boiler trial.

Steam is generated in boilers under certain conditions of feed water and exists as steam while a certain amount of fuel is burnt.

To study the performance of boiler, some experiments are conducted by operating, the boiler for a certain length of time and recording the data. This procedure is known as boiler trial.

The devices used for the efficient operation, proper maintenance, and safe operation BOILER mountings.

The different boiler mountings are:

1. Water GAUGE (or) water level indicator
2. Pressure gauge (or) steam gauge
3. Safety VALVES
4. Fusible plug
5. Stop VALVE
6. BLOW off cock
7. Feed check valve.

The devices used for the efficient operation, proper maintenance, and safe operation boiler mountings.

The different boiler mountings are:

AIR pre heater is used to transfer heat from the FLUE GASES to the air before it passes into the furnace for combustion. It is placed between the ECONOMIZER and chimney. The overall efficiency of the plant may be increased by 10 per cent by the use of air preheater.

Air pre heater is used to transfer heat from the flue gases to the air before it passes into the furnace for combustion. It is placed between the economizer and chimney. The overall efficiency of the plant may be increased by 10 per cent by the use of air preheater.

The ELECTRICAL LOAD on POWER plant varies IRREGULAR manner. The automatic man control provided at a steam power plant successfully meets over the variable load. The automatic control for feed water is necessary sine the supply of feed water depends upon plant load.

The electrical load on power plant varies irregular manner. The automatic man control provided at a steam power plant successfully meets over the variable load. The automatic control for feed water is necessary sine the supply of feed water depends upon plant load.

1. Wet SCRUBBING
2. Solid ADSORBENT
3. CATALYTIC OXIDATION

The appliances USED to increase the EFFICIENCY of the boiler are known as boiler accessories.

The important boiler accessories are:

1. ECONOMIZER
2. SUPER heater
3. Air preheater
4. Feed PUMP
5. Injector

The appliances used to increase the efficiency of the boiler are known as boiler accessories.

The important boiler accessories are:

The main PURPOSE of automatic combustion’ control system is to maintain load against demand, to prevent smoke, to increase boiler HOUSE EFFICIENCY, to CARRY out ROUTINE adjustments and to provide interlocking safe guards.

The main purpose of automatic combustion’ control system is to maintain load against demand, to prevent smoke, to increase boiler house efficiency, to carry out routine adjustments and to provide interlocking safe guards.

1. SINGLE ELEMENT PILOT operated system
2. Single element self operated system
3. TWO element pilot operated system
4. Three element pilot operated system

In THERMAL power plants, it is necessary to KEEP the concentration Of CO2 is low is necessary as possible. To achieve this, a constant recording of concentration Of CO2

These recorders are based on the three DIFFERENT principles, as given below.

• Thermal conductivity cell
• Chemical absorption cell
• Density BALANCE

In thermal power plants, it is necessary to keep the concentration Of CO2 is low is necessary as possible. To achieve this, a constant recording of concentration Of CO2

These recorders are based on the three different principles, as given below.

1. Wet scrubbing
2. SOLID ABSORBENT
3. Catalytic OXIDATION

Desulphurization of fuel is the PROCESS of REDUCING the SULPHUR content in the fuel. The FOLLOWING METHODS are adopted for desulphurization.

• Chemical treatment
• Forth flotation
• Magnetic separation

Desulphurization of fuel is the process of reducing the sulphur content in the fuel. The following methods are adopted for desulphurization.

• ELECTROSTATIC PRECIPITATOR
• Fly ash scrubbers
• CINDER catcher
• CYCLONE dust collector

The effects of particulates can be reduced by the following methods.

• COAL cleaning.
• USING improved electrostatic precipitator design.
• Controlling the dust within allowable LIMIT. This can be DONE by increasing the height of chimney thereby reducing the CONCENTRATION.

The effects of particulates can be reduced by the following methods.

The dry type cooling towers are CLASSIFIED into TWO TYPES ‘as follows:

1. Indirect dry type (or) HELLER cooling system
2. DIRECT dry type-cooling system

The dry type cooling towers are classified into two types ‘as follows:

MECHANICAL draft COOLING tower is CLASSIFIED into three types:

1. FORCED draft tower.
2. INDUCED draft counterflow tower.
3. Induced draft cross flow tower.

Mechanical draft cooling tower is classified into three types:

In atmospheric (or) NATURAL cooling towers, the natural air provides the required cooling without the use of fans.

This is CLASSIFIED into three types:

1. Natural DRAFT spray filled towers.
2. Natural draft PACKED type towers.
3. HYPERBOLIC cooling towers.

In atmospheric (or) natural cooling towers, the natural air provides the required cooling without the use of fans.

This is classified into three types:

The cooling TOWERS are classified as follows.

ACCORDING to the CONSTRUCTION of material:

1. Timber for small tower
2. FERRO concrete for large capacity stations.
3. Multi deck concrete towers for large steam stations
4. Metallic

According to the nature of air draught:

1. Atmospheric (or) Natural draught cooling SYSTEM
2. Mechanical draught cooling tower.

The cooling towers are classified as follows.

According to the construction of material:

According to the nature of air draught:

The hot water is sprayed from the top of the TOWER, while the air is MADE to FLOW from the bottom of the tower to the top. This air cools the hot water in the cooling tower. Air evaporates a small percentage of water, there by cooling the remaining water.

The air absorbs the heat and LEAVES at the top of the tower and cooled water leaves at the bottom and recirculated to the condenser.

The hot water is sprayed from the top of the tower, while the air is made to flow from the bottom of the tower to the top. This air cools the hot water in the cooling tower. Air evaporates a small percentage of water, there by cooling the remaining water.

The air absorbs the heat and leaves at the top of the tower and cooled water leaves at the bottom and recirculated to the condenser.

• Amount of WATER surface AREA exposed.
• The time of exposure.
• The relative VELOCITY of AIR PASSING over the droplets.
• The RH of air.
• The direction of airflow relative to water.

• Since no fans are used power cost and auxiliary equipments cost is REDUCED.
• Hyperbolic tower CHIMNEY creates its own DRAFT even when there is no WIND.
• GROUND fogging and warm air re-circulation are avoided in hyperbolic towers.
• The structure is more or less self-supported.

1. The outlet water COMES in contact with the driest air and WARMEST water comes in contact with most humid air.
2. The re-circulation is seldom a PROBLEM.
3. The first cost is low due to the reduction in PUMP power CONSUMPTION.