9 uranium mining + is nuclear green

Question 1

beta emitter point source dose rate

Answer 1

800 A mSvh-1 at a distance of 10cm in air

Question 2

less energetic gamma rays will have

Answer 2

shorter attenuation legths

Question 3

nuclear is green because
(fossil fuels)

Answer 3

nuclear doesn’t produce same amount of greenhouse gas emissions
nuclear power plants don’t emit air pollutants (so2, VOCs -volatile organic compounds)
reliable stable base energy- compliments variable wind and solar

Question 4

nuclear is green because
(efficiency)

Answer 4

small amounts of nuclear fuel produces large amuonts of electricity
land efficent
U is more abundant than fossil fuels (have 70yrs of fuel in the mines we currently know about)

Question 5

nuclear is not green because
(mining)

Answer 5

open pit mining produces lots of spoils/tailings -harmful to enviro (chemicals)
Jet +raise boring- noise and air pollution, disruption to local wildlife, collapse concern, groundwater contamination potential

Question 6

jet boring

Answer 6

jet blast it out with water, suck it all out

Question 7

mining (open pit)

Answer 7

need to clear habitats, massive mining sights
scar in landscape

Question 8

mining (underground types)

Answer 8

cut and fill -back fill everything (labour intensive)
stope and pillar - leave pillars so can’t extract everything
raise boring- drill down corrode it

Question 9

mining (in-situ leaching)

Answer 9

getting big recently
pump acid into ground, and U leached out into solution
cut out steps- don’t have to crush and preconcentrate
wildlife not as disturbed

Question 10

U 6

Answer 10

soluble sparkerly

Question 11

ore milling

Answer 11

turn into yellow cake
vast facilities- huge amount of ENERGY
problem with radioactive dust
grind it

Question 12

crushing and grinding (1st stage of milling)

Answer 12

uniform size- slowly finer and finer
ENERGY INTENSIVE
VAST mill
powder easier to do chemical process
ENERGY AND WATER WASTAGE

Question 13

Preconcentraion (2nd milling process)

Answer 13

take out U grains- concentration means more efficient down the line
radiometric sorting, photometric or gravity separation
remove minerals that are likely to hinder Uranium leaching or recovery (increase efficiency)
Provide clean tailings that can be rejected without causing environmental concerns.

Question 14

radiometric sorting

Answer 14

Efficient, inexpensive process sorting fragments on the basis of radioactivity. Material needs to have:
* Have heterogeneous U concentrations
* Coarse fragmentation (200-250 mm)
* Secular equilibrium between uranium and radium i.e. the isotopic ratio is constant.

Question 15

gravity seperation -preconcentration

Answer 15

u doesn’t float, quartz floats away
no moving parts so won’t break
sprial- U goes into center as heaviest

Question 16

leaching (3rd milling process unless in-situ then it’s the 1st)

Answer 16

either acid or alkali leaching is used.
Leaching is performed in stirred tanks, heaps or in-situ.
4 to 6 (U soluble)
Choice of leaching method depends on:
* Ore grade
* Complexity of mineralisation
* Reagent costs
* Time required for solubilisation
* Capital costs
* Operating costs

Question 17

acid leaching

Answer 17

leaches to heavy metals and contaminants, mobilise metals
would need lots of acid -dangerous
need to cool everything
30% of mills energy consumption

Question 18

alkaline leaching

Answer 18

less common, less efficient
less enviro implications
less soil acidification & fewer toxins
lower temp and less energy usage

Question 19

liquid-solid separation (4th milling process)

Answer 19

enhance- ENERGY INTENSE

Question 20

solution purification (5ht milling process)

Answer 20

ion exchange- more concentrated
uranyl complexes (gets sucked onto) to this resin

Question 21

product recovery (6th milling process)

Answer 21

dry it into yellow cake
use precipitates to do this
change it back into U4 (immobile)
more energy in drying

Question 22

yellow cake formular

Answer 22

U3O8

Question 23

U235 enrichment (centrifuge enrichment)

Answer 23

need to be greater than 3.2% (reactor grade)
normally very small concentration (0.7) so more waste of U238 to enrich the fuel
centrifuge enrichment- mass difference, U238 move to outside via centrifugal forces, have to spin it
many centrifuges, more energy

Question 24

Purification (final)

Answer 24

before UF4 is formed- yellowcake must be purified
remove- reactor poisons, compounds that form volatile fluorides and impurities
then mix with acid -create UF6

Question 25

depleted Uranium

Answer 25

waste product of the enrichment process
U238 used as tank armour (dense)
on going problem- hydrogen storage

Question 26

nuclear isn’t green summary

Answer 26

-mining U process takes a lot of energy
-waste & disposal
-renewable alternatives that don’t require as energy intensive mining and milling nor do they produce the level of waste
-accident risk
-fossil fuel used in fuel transport

Question 27

accident risk

Answer 27

risk of nuclear accidents
risk to workers at all stages
Cs in soil
remediation efforts disrupt habitats
wildfires can be caused
shooting of livestock and bulldozing

Question 28

waste disposal

Answer 28

nuclear fuel cycle produces waste at every step
radioactive waste- concern to environment
mill tillings provide contamination hazard

Question 29

thorium reactors

Answer 29

can use all of Th unlike only 0.7% of uranium
Th is biproduct of rare earths
technology very expensive and only testing rn

Question 30

gCO2 eq / KWh

Answer 30

coal: 820
nuclear: 12
solar: 41
wind: 11.5
median lifecycle emissions including albedo effect and infrastructure
IPCC report 2014 (Bruckner et. al, 2014)

Question 31

the question of is an energy source green

Answer 31

has to be compared against other energy sources because no energy source is green
just comparably it is better for the environment that other things

Question 32

roasting -preconcentraiton

Answer 32

can produce pollutants (SO2) -ACIDIC, METALIC AND TOXIC COMPOUNDS