14 15 Flashcards
Mox
mixed oxide fuel
separating plutonium from everything else- but not good cause ppl use plutonium for weapons
nuclear waste
mining & milling -large volumes of mine tailings
Spent fuel
decommissioning of nuclear facilities
nuclear waste-recycling
if you separate out the fission products it produces from U and plutonium
you get concentrated fiffion products in nitric acid
so concentrated it precipitates
very radioactive and dangerous
dry it out then set it in glass
secondary waste
Derived from the process of
handling or processing
radioactive materials.
- Largest volume of waste
- Least radioactivity
- e.g. reagents, solvents, plant,
protective clothing etc.
more secondary but less dangerous
how radioactive for deep burial disposal
4,000 alph, 12000 beta/gamma Bq/g
waste classification
need to consine waste to right catorgory as deep disposal is extremely expensive
high level waste
very hot- facility need to be able to deal with heat (corrosion faster when hot)
spent fuel -high level waste
sits in pond for at least a year and cooled
can’t go underground until surface temp is under 100oC (50yrs)
Objectives of waste management are to
- Minimise the production of secondary waste
- Convert waste forms into the least practicable volume of a solid that is suitable for long-term storage/disposal
- Keep environmental impact as low as is reasonable attainable (ALARA).
Always within strict limits set by regulatory bodies
Mill Tailings (long answer chill out about memorising)
Mill Tailings from Uranium mills are a type of waste specific to
countries, which mine uranium.
– Not relevant to the UK United Kingdom.
– Mill tailings commonly have low levels of radioactivity and
comprise a dirty mix of ore material including elements such as
Thorium and Radium.
– Tailings leave the mill as a radioactive sludge, and are allowed to
dry.
– Radioactive mine tailings sites provide an obvious contamination
hazard (water supplies, wind-blown dust etc.)
radioactivity vs time
high level waste drops off first
U radiation increase with time as the daughters are more reactive than U
Storage
Typically in surface facilities, where
material is being ‘stored’ indefinitely or pending future disposal. Some facilities may store material for decades or centuries placing an economic burden on future generations.
Disposal
Material is isolated (typically
underground) from humans and the environment. Isolation can be permanent and future generations
can ‘ignore’ its existence
nuclear waste disposal
legacy mine working
going back to U mines and putting the waste back where it is from
good as tunnels are already there so less expensive
maybe ppl could steal it
government don’t like it
Low level waste disposal
LLW is typically disposed in ‘nearsurface’ facilities, at either at Ground level, or In caverns just below ground
level (at depths of 10m’s)
cost low
not safe enough for dangerous waste
isolating it from water
could be a problem with sea level rise
good rock for geological disposal
no fissures (pathway to surface) no interesting/valuable minerals nearby (later generations might want to extract)
tectonically stable
climate change resilient
dry rocks, impermeable, no ground water flow
evaporates would be perfect -dry, concealed themselves but valuable and weak (open crack cant be sustained)
higher strength rock
igneous, metamorphic or older sedimentary
low matric porosity & permeability
water movement confined to fractures
more joints
take heat away effectively
hard to break (expensive) could go down soft rock and punch through the side of high strength rock
lower strength rock
sedimentary, fine-grained, high clay content
mechanically weak
radionuclide transport is by diffusion
disposal facility
multi barrier covering the waste- glass, metal, clay then rock for high level waste
Net zero by 2050
unbelievably expensive to change everything
decarbonising transport very hard
development of hydrogen and investing in off sore wind
fossil fuels
still the cheapest and easiest
Coal and Oil biggest contributors to CO2
the switch to gas is better but not great
very good to meet needs of consumer (turn up and down easily)
fracking
cheaper gas
earthquake risk
contamination of water
methane released into atmosphere (can’t control where it comes out)
carbon capture and storage
capture off gasses, liquify it and pump it underground into old oil wells
cost a lot of energy to do it (takes half the energy made by plant)
need to monitor that it isn’t coming to surface
solar +desert problem+pros and cons
not very efficient so have to have big areas
desert problem - semi-conductors can’t work in over 35oC & sand storms scratch and break pales
waste materials to make them are really bad for environment
need to change to AC-difficult
solar predictable- weather and sunset
individual solar- no transmission loss
space solar
no clouds and cold so very efficient
have to beam it down to array
energy security -how to protect your assets in space
wind turbines
bigger more efficient but break quicker
difference in wind speed between top and bottom so unevenly wears the drive shaft
only work between 10-22 mph
UK fantastic wind resource (especially Scotland)
magnetics in gear boxes full of rare earths (China has monopoly on them)
off shore- more efficient, more expensive, more materials, hard to get it onshore
wave
damage of infrastructure when storms -damage connection
issues with corrosion
tidal
tide comes in, hold water into lagoon
stored water so can release it on demand
concerns about habitats
corrosion
how to get all renewabe
need to make renewables cheaper so can better compete with fossil fuels
lobby governments (legislation)
need good storage capacity
hydrogen
produces water -clean
can use in domestic gas grid
gunna be massive
energy density
nuclear is very dense
solar and wind much less dense
