future of energy supplies- nuclear power

Question 1

what is the difference between nuclear fission and fusion

Answer 1

1) fission is the splitting of nuclei in large atoms such as uranium 235
2) fusion is the joining of nuclei of small atoms such as isotopes of hydorgen-2

Question 2

how are large nuclei split in nuclear fission

Answer 2

1) neutron bombardment which causes them to split releasing more neutrons and large amounts of energy

Question 3

list the factors which constrict the growth of nuclear power

Answer 3

1) tech is very complex so is hard to use unless societies are technologically advanced
2) technology is very expensive
3) public opposition from concerns over safety after reactor accidents such as Chernobyl
4) concerns over links to nuclear materials for military use
5) uncertainty over safe disposal methods of waste

Question 4

outline the main features of nuclear energy

Answer 4

1) very high energy density so small amounts needed to produce large amounts of energy, don’t need continual supply so can be located where transport infrastructure isn’t as good
2) high embodied energy- process which require to produce the fuel are high
3) finite source- non-renewable

Question 5

how have nuclear reactors improved in design

Answer 5

1) longer reactor life
2) more reliable operation
3) lower fuel consumption

Question 6

list the environmental impacts of nuclear energy

Answer 6

1) habitat loss, noise, dust, turbid drainage water, hazardous waste from mining and processing
2) GCC- high embodied energy of material used
3) health risks from ionising radiation- reactor accidents and radioactive waste

Question 7

outline possible political and international difficulties surrounding nuclear energy

Answer 7

1) link between civil nuclear energy and the preparation of weapon grade fuel as caused countries to restrict available technology to other countries that could be considered untrustworthy

Question 8

outline possible economic issues of nuclear energy

Answer 8

1) new power stations require expensive engineering
the inclusion of new design and possible unforeseen accidents means costs exceed benefits most the time

2) few old reactors have yet to be decommissioned so costs may be greater than anticipated and funds been put aside

Question 9

list new technologies for the extraction of materials for nuclear energy

Answer 9

1) polymer adsorption- uranium dissolved in seawater absorbs onto polymers placed into the sea, it can be washed off using acids and collected
2) phosphate mining- uranium is often present in phosphate deposits and can then be separated from the material extracted from mining
3) coal ash- uranium can be extracted from the ash of coal

Question 10

outline molten salt reactors

Answer 10

1) a new reactor design for nuclear fission

• use of molten salt as a reactor coolant increases efficiency or electricity generation
• this allows reactor to operate at higher temps without needing high pressures to prevent coolant boiling
• cheaper to run as it is a liquid cooled reactor not gas so can be smaller

Question 11

outline plutonium reactors

Answer 11

1) a new technology for nuclear fission
- allows much more energy to be harnessed from original mined uranium however are expansive and complex
- uranium is converted into plutonium 239 via neutron bombardment, the reactor is using fissile fuel however more is producing when it is converted into fissile plutonium 239
- no fissile uranium is known as a fertile fuel as it can be converted to produce a fissile fuel

Question 12

outline thorium reactors

Answer 12

1) new technology for nuclear fusion

• thorium 232 is not fissile so doesn’t release energy when bombarded with neutrons
• it is a fertile fuel so is converted into a fissile uranium 233
• design includes rods of uranium 233 which release energy and neutrons to maintain the chain reaction
• roads of thorium 232 are bombarded with neutrons to breed uranium 233

Question 13

outline the advantages and disadvantages of thorium reactors

Answer 13

advantages- more abundant than uranium, more difficult to make weapons from, less radioactive waste produced

dis- breeding rate is slow so fuel is expensive, uranium 233 produces alpha radiation so is hazardous

Question 14

what conditions are needed for nuclear fusion to occur

Answer 14

1) plasma hydrogen - removes the electrons around the nuclei allowing nuclei to collide as they aren’t repelled by each other
2) heavy nuclei - greater mass means greater momentum and more ability to overcome repelling positive charges
3) high temperatures - increased kinetic energy increased chance of collision
4) a vacuum - so the plasma isn’t called by air
5) a magnetic field - to hold plasma central in a vacuum so doesn’t touch sides of container and cool

Question 15

outline a toroidal reactor

Answer 15

1) a research technology for nuclear fusion developed by the ITER

• releases more energy than it uses 500MW out for 50MW in
• maintains fusion for longer periods
• uses a blanket of lithium around reactor to breed new fuel

Question 16

outline laser fusion

Answer 16

1) a research technology into nuclear fusion

• high power laser energy research (HiPER)
• the process involves small scale fusion tech which avoids problems of plasma contaminates and refueling such as toroidal reactors
• small spheres of frozen deuterium and tritium dropped into an intense laser beam to initiate fusion

Question 17

what is a control rod

Answer 17

a bar of material which absorbs neutrons helping to slow the chain reaction or to stop it in emergencies

Question 18

outline factors which influence where a nuclear PowerStation is located

Answer 18

1) water for reactor cooling
2) large flat sites
3) easy access for construction
4) access for workers