16-01-2014, 03:44 PM
LIQUID METAL FAST BREEDER REACTOR
LIQUID METAL .ppt (Size: 1.85 MB / Downloads: 49)
BREEDER REACTORS
A breeder reactor is a nuclear reactor capable of generating more fissile material than it consumes.
Attractive because of their superior fuel economy.
CONVERSION RATIO
The average number of fissile atoms created per fission event.
In other words, the ratio of new fissile material in spent fuel to fissile material consumed from the fresh fuel.
DOUBLING TIME
The amount of time it would take for a breeder reactor to produce enough new fissile material to create a starting fuel load for another nuclear reactor.
Considered an important measure of breeder performance in early years, when uranium was thought to be scarce.
Doubling time has become a less important metric in modern breeder reactor design.
FAST BREEDER REACTORS
Uses fast (un moderated) neutrons to breed fissile plutonium from fertile uranium-238. The fast spectrum is flexible enough that it can also breed fissile uranium-233 from thorium, if desired.
GENERAL PRINCIPLES OF FAST BREEDER REACTORS
Materials which become fissile upon absorbing neutrons are known as "primary fuel" materials or "fertile" materials.
In the case of fast breeder reactors it is uranium-238 which is the most interesting fertile material, and it is converted into the fissile isotope plutonium-239 through neutron absorption.
A characteristic feature of fast breeders is the fact that while producing energy they also produce more fissile material than they consume, and hence the name "breeder".
WORKING OF LMFBR
Unlike other conventional reactors liquid sodium is used as coolant instead of water.
It flows in primary circuit, absorbs heat and pass it to sodium in secondary circuit through heat exchanger.
This is done in order to eliminate the radioactive effects of liquid sodium in primary circuit.
Liquid sodium in secondary circuit passes heat to steam generator.
Steam thus generated is used to move the turbine.
POOL TYPE LMFBR
Primary pump, reactor core & intermediate heat exchanger are placed in a large pool of liquid sodium.
Liquid sodium is pumped in from the pool and flows through primary circuit.
After completing the cycle it is then discharged in the pool.
This type is widely used in Europe.
CONCLUSION
Since the conventional sources of power generations such as coal etc. are decreasing hence nuclear energy is the future source of energy.
Breeder reactors will soon be operating in full flow.