Nuclear energy

Question 1

What are some methods of finding uranium?

Answer 1

Geiger counter, scintillation counter and trial drilling
Magnetometry, gravimetry, spectroscopy and seismic surveys

Question 2

What does a Geiger counter detect?

Answer 2

Beta particles, gamma rays and radioactive emissions

Question 3

What do scintillation counters measure?

Answer 3

Ionising radiation

Question 4

What is nuclear energy?

Answer 4

The conversion of small amounts of matter through the fission or fusion of atomic nuclei

Question 5

What is E=mc^2?

Answer 5

Energy released = mass of matter lost x speed of light^2

Question 6

What atoms are used in fission?

Answer 6

Uranium 235 and plutonium 239

Question 7

What atoms are used in fusion?

Answer 7

Hydrogen 2 and 3

Question 8

What are the benefits of nuclear power stations?

Answer 8

Small quantities of reactants required (smaller power stations), don’t need to be located by source and natural uranium can be enriched

Question 9

What is the equivalent of uranium energy to coal energy?

Answer 9

13,000kg of coal gives the same amount of energy as 1kg of uranium

Question 10

What is the cycle of fission?

Answer 10

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

Question 11

What are control rods?

Answer 11

Rods made of the substance needed, one emitting neutrons and the other is a source of uranium

Question 12

Why is nuclear used as the ‘base load’ electricity?

Answer 12

Slow to turn on and off

Question 13

What are the limitations of nuclear?

Answer 13

Complex technology- expensive, only in advanced societies, public oppression, military or terrorism use, disposal of waste, uncertainty in total cost

Question 14

What are the environmental issues associated with nuclear

Answer 14

Mining- habitat loss, noise, dust, turbid drainage water and hazardous waste
High embodied energy- contribution to GCC
Reactor accidents and radioactive waste- health risk

Question 15

How is radiation harm reduced for workers?

Answer 15

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

Question 16

How is waste managed?

Answer 16

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

Question 17

What can fission products be used for?

Answer 17

Caesium-137 for food irradiation and americium-241 is used in smoke alarms

Question 18

What are some new technologies used in the extraction of uranium?

Answer 18

Polymer adsorption, phosphate mining and coal ash

Question 19

How is uranium extracted from polymer adsorption?

Answer 19

Uranium dissolved in seawater adsorbs onto certain polymers placed in the sea, the uranium can be washed off using acids then collected and concentrated

Question 20

How is uranium extracted in phosphate mining?

Answer 20

Uranium is often present in phosphate deposits and can be separated from the material extracted in phosphate mines

Question 21

How is uranium extracted from coal ash?

Answer 21

Can be extracted from coal ash but this will only become economic if the price of uranium rises enough

Question 22

What are the new reactor designs?

Answer 22

Molten salt reactors, plutonium reactors and thorium reactors

Question 23

What is a molten salt reactor?

Answer 23

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

Question 24

What is a plutonium reactor?

Answer 24

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

Question 25

What is a thorium reactor?

Answer 25

Thorium-232 is a fertile fuel and is converted to uranium-233 which is fissile, creating a breeder reactant

Question 26

What are the advantages of thorium reactors?

Answer 26

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

Question 27

What are the disadvantages to thorium reactors?

Answer 27

Breeding rate for U-233 is slow, so fuel is expensive, U-233 releases alpha radiation so very hazardous and remaining development costs high

Question 28

What are the conditions for nuclear fusion to take place?

Answer 28

Hydrogen in the form of plasma, heavy nuclei, very high temp, vacuum and magnetic field

Question 29

Why is hydrogen in the form of plasma needed for fusion?

Answer 29

The repelling electrons around the nuclei need to be removed for collisions

Question 30

Why is a heavy nuclei needed for fusion?

Answer 30

Heavy mass means more momentum so collide with more force to overcome the repulsion

Question 31

Why is a very high temperature needed for fusion?

Answer 31

Increases kinetic energy of the nuclei so more chance of collision

Question 32

Why does fusion need to be done in vacuum?

Answer 32

So the hydrogen plasma isn't cooled by air

Question 33

Why is a magnetic field needed for fusion?

Answer 33

To hold the plasma centrally in the vacuum so it doesn't touch the sides of the container and cool

Question 34

What are the features of toroidal reactors?

Answer 34

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

Question 35

What are the features of laser fusion?

Answer 35

Small scale so avoids problems with plasma containment and frozen H-2 and H-3 dropped into an intense laser beam to initiate diffusion

Question 36

What happens to the outer layer of the nuclei in laser fusion?

Answer 36

Expands in all directions, including inwards, compressing the middle

Question 37

What are the overall benefits of nuclear energy?

Answer 37

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

Question 38

What are the cons of nuclear energy?

Answer 38

New technology, current yield only slightly bigger, expensive and high level knowledge and specialist equipment to run

Question 39

What are the main features of nuclear fission?

Answer 39

Energy density, embodied energy, finite resources, level of technological development, environmental impacts, uranium extraction