PWR,BWR,GAS-COOLED REACTOR

GROUP MEMBERS:- 1. UTSAV PRAJAPATI

(13BME091)2. YASH PATEL (13BME087)3. YATIN PATEL (13BME088)4. SHUBHAM PRAJAPATI

(13BME090)

Nuclear Power Plant Main Component:-1. Nuclear Reactor

2. Heat Exchanger

3. Steam Turbine

4. Condenser

5. Electric Generator

BWR-Boiling Water Reactor In a Boiling Water Reactor (BWR), water in the core is flashed directly to steam.

The steam is piped to a turbine/generator, where it is converted to electricity for use by the grid.

The unused steam that exits the turbine/generator is changed back into water in a condenser and pumped back to the reactor vessel to complete the cycle.

BWR

BWR Advantages:-

No heat exchanger ,Gain in thermal efficiency and cost

Lower pressure vessel for reactor which reduces cost

BWR is more efficient than PWR

Outlet temperature of steam is appreciably higher

Pressure inside of the pressure vessel is not so high so thicker vessel is not required

BWR Disadvantages:-

Possibility of radioactive element in turbine mechanism

More elaborate safety precautions needed which are costly

Wastage of steam lowering the thermal efficiency on part load operation

3 to 5% by mass can be converted to steam per pass through the boiler

Possibility of burn out of fuel is more than PWR

PWR-Pressurised Water Reactor Primary Loop

◦ Water is heated in the reactor core and pumped through steam generator tubes, where it gives up heat to the secondary side water, causing it to flash to steam.

◦ Water in the primary loop is maintained at a high temperature and pressure to prevent unwanted boiling in the core.

Secondary Loop◦ The secondary loop in a PWR takes the water that flashes to steam around the outside of the tubes in the

steam generator and pipes it to a turbine/generator, where it is converted to electricity for use by the grid.◦ The unused steam that exits the turbine/generator is changed back into water in a condenser and pumped

back to the steam generator to complete the cycle.

In a PWR, the primary and secondary water never come in direct contact with each other.

As a result of this, the secondary side steam and water are not radioactive as they are in a Boiling Water Reactor.

PWR

PWR Advantages:-Water used in reactor is cheap and easily availible

Compact and high power density

Fission product remain contained

Complete freedom to inspect and maintain the turbine, feed heater and condenser during operation

Extracting more energy per unit weight of fuel

PWRDisadvantages:-Capital cost is high as primary circuit requires strong pressure vesselIn the Secondary circuit the thermodynamic efficiency of this plant is quite lowSevere corrosion problemsShut down the reactor for fuel charging which requires couple of month’s timeFuel element fabrication is expensive

Gas-Cooled ReactorCoolant : Gas , CO2 and Helium are preferable.Moderator : Graphite ( 20% of the Nuclear Power Plants)Fuel : Natural UraniumTechnologies : Magnox (Magnesium Alloy-UK) and UNGG(Uranium natural Graphite Gas-FRANCE)

Coolant gas supplied by circulator.Gas circulates from Bottom to Top and gets heated.

Gas-Cooled Reactor

Gas-Cooled reactor

Gas Cooled Graphite Moderator Reactor(GCGM)

Fuel : Natural Uranium

Coolant pressure : 7 bar

Coolant temperature : 336 ͦC

High Temperature Gas Cooled Reactor(HTGC)

Fuel : Uranium carbide + thorium carbide (clad with graphite)Coolant pressure : 15 to 30 bar

Coolant temperature : 700 ͦC to 800 ͦC

Gas Cooled Reactor

Gas Cooled Graphite Moderator Reactor(GCGM)

High Temperature Gas Cooled Reactor(HTGC)

Gas-Cooled Reactor Advantages:-1. Simple Fuel Process2. No corrosion3. Graphite – stable at high temperature

4. CO2 eliminates the possibilities of explosion

5. Uranium carbide and graphite : resist high temperature

Gas-Cooled Reactor Disadvantages:-1. Fuel : More Quantity and costly2. Power density : very low3. More Fuel (initially) : High Critical Mass4. More power for coolant circulation5. Complicated consolation

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