The document discusses Magnox nuclear reactors. Magnox reactors use natural uranium fuel clad in an alloy of magnesium called Magnox. They have a graphite moderator and use carbon dioxide as a coolant. Key features include low neutron capture cross-section of Magnox but low maximum temperature. The first Magnox reactors produced plutonium and electricity. They were later replaced by Advanced Gas-cooled Reactors but some remain in operation today.

1. PRESENTED TO
SIR SHAHID KHALIL
PRESENTED BY
SAMEED QADRI ( 11-ME-69)
M.ALI KIANI (11-ME-198)

2. 

Nuclear reactors are devices in which fissionable
elements such as uranium, thorium, or plutonium
are made to undergo a nuclear chain reaction.
Neutrons are bombarded to Uranium nuclei. It
disintegrates into two smaller atoms ( Ba &
Kr), releasing neutrons and binding energy . One
of the neutron hits another Uranium-235
atom, thus furthur releasing neutrons and binding
energy. Thus , process continous if it is not
controlled. This is called chain reaction.

4. 1)
2)
3)
4)
5)
6)
Fuel rods ( Packets of Uranium oxide
arranged in tubes to form rods )
Moderator
Control rods
Coolant
Pressure vessel
Steam generator
Containment

5. 
Magnox is short for Magnesium non-oxidising

It is basically an alloy mainly of magnesium with small amounts of aluminium
and other metals

It is used to clad the fuel rods inside the reactor.

This material has the advantage of a low
neutron capture cross-section, but has two major
disadvantages:

It limits the maximum temperature, and hence the thermal efficiency, of the plant.

It reacts with water, preventing long-term storage of spent fuel under water.

6. 

Magnox is an old type of nuclear power reactor
which was designed in the United
Kingdom, and was exported to other
countries, both as a power plant ( as a power
reactor ) and producer for plutonium ( as a
research reactor )
Wylfa Nuclear Generating Facility contains the
world's last operating Magnox reactor

8. 
These are graphite moderated reactors and use
natural uranium as fuel & MAGNOX as fuel
cladding.

Working pressure varies from 6.9 to 19.35 bar

9. 
The first Magnox reactors at Calder Hallwere
designed principally to produce plutonium for
nuclear weapons.

The production of plutonium from uranium
generates a large amount of heat also , which could
be used in a turbine to generate electricity.

Nuclear power generation is 25 % expensive than
electricity from coal, yet economical due to
production of plutonium.

10. There are two nuclear fuel reprocessing plants at
Sellafield
1.
Advanced Gas-cooled Reactors (AGR)
2.
Light Water Reactors (LWR)
This all happens in the Fuel Handling Plant. The fuel is
then transferred to the Magnox Reprocessing Plant.

11. 
In early operation it was found that there was
significant oxidation of mild steel components by
the high temperature carbon dioxide
coolant, requiring a reduction in operating
temperature and power output.

For example the Latina reactor was derated in 1969
by 24%, from 210 MWe to 160 MWe, by the
reduction of operating temperature from 390 to 360
°C.

12. 
Magnox plants literally means magnox nuclear
reactor.

A small 5 MW experimental reactor at
Yongbyon, operated from 1986 to 1994, and
restarted in 2003. Plutonium from this reactor's
spent fuel has been used in the North Korea nuclear
weapons program.

A 200 MW reactor at taechon, construction of
which also halted in 1994.

13. 
This is the general term for all type of carbon
dioxide-cooled, graphite-moderated
reactors, including the Magnox.

The Magnox was replaced in the British power
station program by the Advanced gas-cooled reactor
or AGR.

A key feature of the AGR was the replacement of
magnox cladding to allow higher temperatures and
greater thermal efficiency.

14. 
The Magnox reactors were considered at the time to
have a considerable degree of inherent safety
because of their simple design, low power
density, and gas coolant.

Failure of the reactor shutdown system to rapidly
shut down the reactor, or failure of natural
circulation, was not considered in the design.