Nuclear energy Flashcards
What are some methods of finding uranium?
Geiger counter, scintillation counter and trial drilling
Magnetometry, gravimetry, spectroscopy and seismic surveys
What does a Geiger counter detect?
Beta particles, gamma rays and radioactive emissions
What do scintillation counters measure?
Ionising radiation
What is nuclear energy?
The conversion of small amounts of matter through the fission or fusion of atomic nuclei
What is E=mc^2?
Energy released = mass of matter lost x speed of light^2
What atoms are used in fission?
Uranium 235 and plutonium 239
What atoms are used in fusion?
Hydrogen 2 and 3
What are the benefits of nuclear power stations?
Small quantities of reactants required (smaller power stations), don’t need to be located by source and natural uranium can be enriched
What is the equivalent of uranium energy to coal energy?
13,000kg of coal gives the same amount of energy as 1kg of uranium
What is the cycle of fission?
Neutrons are bombarding a fissile nuclei, which splits to release large amounts of heat energy, waste products and more neutrons which can be used for the next nuclei
What are control rods?
Rods made of the substance needed, one emitting neutrons and the other is a source of uranium
Why is nuclear used as the ‘base load’ electricity?
Slow to turn on and off
What are the limitations of nuclear?
Complex technology- expensive, only in advanced societies, public oppression, military or terrorism use, disposal of waste, uncertainty in total cost
What are the environmental issues associated with nuclear
Mining- habitat loss, noise, dust, turbid drainage water and hazardous waste
High embodied energy- contribution to GCC
Reactor accidents and radioactive waste- health risk
How is radiation harm reduced for workers?
Radiation absorbing materials, dose limits, maximum time for exposure, dust suppression, remote handling of material, minimum distance from source, PPE, detection equipment and decontamination procedures
How is waste managed?
Fuel rods remain in the reactor for several years and even then they are reprocessed in the UK, meaning most radioactive materials can be concentrated. Some materials can be reused and disposal depends upon state of matter
What can fission products be used for?
Caesium-137 for food irradiation and americium-241 is used in smoke alarms
What are some new technologies used in the extraction of uranium?
Polymer adsorption, phosphate mining and coal ash
How is uranium extracted from polymer adsorption?
Uranium dissolved in seawater adsorbs onto certain polymers placed in the sea, the uranium can be washed off using acids then collected and concentrated
How is uranium extracted in phosphate mining?
Uranium is often present in phosphate deposits and can be separated from the material extracted in phosphate mines
How is uranium extracted from coal ash?
Can be extracted from coal ash but this will only become economic if the price of uranium rises enough
What are the new reactor designs?
Molten salt reactors, plutonium reactors and thorium reactors
What is a molten salt reactor?
Molten salt is the reactor coolant, which increases the efficiency of generation, meaning the reactor can be a much higher temp without needing high pressure to prevent coolant boiling, cheaper
What is a plutonium reactor?
Uranium-238 (not fissile) is a fertile fuel that is then converted into plutonium-239 by bombarding with neutrons as this is fissile, however this is more complex and expensive to operate but higher energy yield
What is a thorium reactor?
Thorium-232 is a fertile fuel and is converted to uranium-233 which is fissile, creating a breeder reactant
What are the advantages of thorium reactors?
Thorium is three times more abundant than uranium, more difficult to make weaponry, less radioactive waste produced and that waste has shorter half lives and no fuel enrichment required
What are the disadvantages to thorium reactors?
Breeding rate for U-233 is slow, so fuel is expensive, U-233 releases alpha radiation so very hazardous and remaining development costs high
What are the conditions for nuclear fusion to take place?
Hydrogen in the form of plasma, heavy nuclei, very high temp, vacuum and magnetic field
Why is hydrogen in the form of plasma needed for fusion?
The repelling electrons around the nuclei need to be removed for collisions
Why is a heavy nuclei needed for fusion?
Heavy mass means more momentum so collide with more force to overcome the repulsion
Why is a very high temperature needed for fusion?
Increases kinetic energy of the nuclei so more chance of collision
Why does fusion need to be done in vacuum?
So the hydrogen plasma isn’t cooled by air
Why is a magnetic field needed for fusion?
To hold the plasma centrally in the vacuum so it doesn’t touch the sides of the container and cool
What are the features of toroidal reactors?
May not be commercially viable for years, ITER operational by 2025, 500MW output from 50MW input, maintains fusion for longer periods and has blanket of lithium to breed tritium
What are the features of laser fusion?
Small scale so avoids problems with plasma containment and frozen H-2 and H-3 dropped into an intense laser beam to initiate diffusion
What happens to the outer layer of the nuclei in laser fusion?
Expands in all directions, including inwards, compressing the middle
What are the overall benefits of nuclear energy?
Releases 4,000,000 times the amount of energy in chemical reactions, abundant, waste products (Helium) isn’t GHG, H fuel isn’t exploitable for nuclear arms, no risks of meltdown and similar costs
What are the cons of nuclear energy?
New technology, current yield only slightly bigger, expensive and high level knowledge and specialist equipment to run
What are the main features of nuclear fission?
Energy density, embodied energy, finite resources, level of technological development, environmental impacts, uranium extraction
