Nuclear Reactors: Types, Components, Advantages and Disadvantages

This presentation provides an overview of nuclear reactors, including their types, components, advantages, and disadvantages. It explains the working of Pressurized Water Reactors and Advanced Gas Cooled, Graphite Moderated Reactors. The presentation also includes comparison charts and references.

NUCLEAR
REACTORS

Nuclear Power Plant
Main Components
• Electric
Generator
• Condenser
• Nuclear Reactor
• Heat Exchanger
• Steam Turbine
Source: Tsumune et al. (2012)

Types of Nuclear Reactors
They are classified on the basis of:
• Neutron Energy
• Fast Reactors
• Thermal Reactors
• Fuel Used
• Natural Fuels
• Enriched Uranium
• Moderator Used
• Heavy water
• Water Moderated
• Beryllium Moderated
• Graphite Moderated
Source: Tsumune et al. (2012)

• Coolant Used
• Gas Cooled
• Liquid Metal cooled
• Organic liquid cooled
• Water cooled

Pressurized Water Reactor
• The most common nuclear reactor type,
accounting for about 60% of all the nuclear power
reactors globally
• Work by maintaining water under pressure so as
to heat but does not boil
• No mixing occurs between the water from the
reactor and that in the steam generator
• This makes most of the reactivity remain in the
reactor area
• It uses the light water cooled system of cooling

Pressurized Water Reactor
Source: Souza et al. (2014)

Working of a PWR
• Heat is created inside the reactor vessel by the core
• The generated heat is then carried by the
pressurized water in the primary coolant loop to the
steam generator
• Vaporization of the water in the secondary loop by
the heat from the primary coolant loop occurs
inside the generator leading to the production of
steam Dwyer, D. A., & Langford, T. J. (2015).
• The steam is directed to the main turbine by the
streamline making it to turn the turbine generators
which in turn produce electricity.

Heat Exchange Mechanism of Generation of Electricity in PWR
Source: Souza et al. (2014)

Layout of PWR
Fuel Used
Enriched Uranium
• The fuel has a
higher amount
of fuel that in
the uranium-235
fuels
• Uranium oxides
are used in
place of pure
uranium
• Uranium oxides are used because they are
very resistant to irradiation damage as well as
properly adopted to the extreme burn-raps
• It is quite resistant to corrosion by water
Source: Souza et al. (2014)

Advantages
Less control rods required
Ease of maintenance due to the
independence of the two
circuits of each other.
High power density which when
combined with the fact that
enriched uranium is used as the
fuel generates a highly
compact core size for a specific
output of power
• Uses water that is free from radioactive steam
hence does not call for special shielding materials
during piping
• Uses water that is cheap in cost and plenty in
supply as the coolant , moderator and reflector
Source: Féron, Herms, &
Tanguy (2012)

Disadvantages
• High temperature and high pressure in the
primary circuit promotes corrosion
• A very strong material is thus needed for the
construction of the vessel for example stainless
steel which leads to increased cost of construction
• Charging of the PWR fuel demands for a shut
down of the plant which lengthens the time into at
least some months
• Low pressure in the secondary circuit in
comparison to the primary circuit
• Low pressure values in the secondary circuit lead
to low thermal efficiency of the reactor
• Very low thermal efficiency of the plant at about
20%
•

Benefits of PWR
• They offer tremendous importance to different
militaries across the globe due to their use on
nuclear ships and naval vessels.
• The nuclear power enables the ships to navigate
over very long periods of time without calling for
refueling.
• The Pressurized Water Reactors is an excellent
reactor for the ships due to their high specific
power as it uses high pressure.
• This permits the reactors to remain fairly intact
especially if high enriched uranium is used Zhang,
L., & Wang, J. (2014).

Source: Zhang & Wang (2014)

Advanced Gas Cooled, Graphite Moderated
Reactors
• Fuel: Natural Uranium
• Coolant: Gas, carbon dioxide and Helium are the
most preferred
• Moderator: Graphite which makes up 20% of the
Plants
• Technologies used: UNGG (Uranium Natural
Graphite Gas in France) and Magnox (Magnesium
Alloy in UK)
• The coolant gas is supplied by the circulator
• The gas is made to circulate from the bottom
upwards and then gets heated up.

Source: Pioro & Kirillov (2013)

Source: Terrani, Snead & Gehin (2012)

Gas-cooled fast reactor
Features
• It is a helium
cooled system
• Uses fast-
neutron
spectrum
• Adopts direct
Brayton cycle
gas turbine
• Able to
generate
electricity and
generating new
nuclear fuel at
the same time
Source: Katoh et al. (2012)

Gas turbine Modular Reactor
Features
• Cross vessel
• Helium is used as
a coolant
• Has an efficiency
of up to 48%
which is higher
than any other
reactor type
• Uses graphite as
the moderator
• The reactor and
power conversion
systems are
placed below the
Source: LaBar (2002)

Advantages
• Not associated with corrosion
• It is a simple fuel process
• Uses graphite which is very stable even at very
high temperatures
• The use of carbon dioxide eliminates the chances
of explosion
• The use of uranium carbide and graphite help in
resisting the high temperature in the system

Disadvantages
• It is a complicated consolation
• Requires high quantity of fuel which is expensive
• It has very low power density
• It requires more power for the circulation of the
coolant
• Due to the high critical mass, it requires very high
initial fuel

Comparison Charts

Features of AGR Vs PWR

References
• Zhang, L., & Wang, J. (2014). Effect of dissolved
oxygen content on stress corrosion cracking of a
cold worked 316L stainless steel in simulated
pressurized water reactor primary water
environment. Journal of Nuclear Materials, 446(1-
3), 15-26
• Glasstone, S., & Sesonske, A. (2012). Nuclear
reactor engineering: reactor systems engineering.
Springer Science & Business Media
• Stacey, W. M. (2018). Nuclear reactor physics.
John Wiley & Sons
• Vujić, J., Bergmann, R. M., Škoda, R., & Miletić, M.
(2012). Small modular reactors: Simpler, safer,
and cheaper. Energy, 45(1), 288-295