The table below summarizes her numbers and tries to normalize them all into GJ of work-energy expended per kg of uranium fuel. The given figures are for Canada, which has some of the best uranium ore in the world: in soft rock, and much of it at 2% - 3% uranium - only 50 kg of rock need be mined to get 1 kg of uranium. I have assumed "1%" to be conservative. Some of the lowest-grade mines on earth have less than 0.1% uranium in the rock, and would have about 20% higher overall energy costs.
|Mining of ores, per 1/10th tonne||=1.06/10||Caldicott Book, Page 9 (divide amount for 'per ton of ore' by 10) because at 1% concentration, 1kg from U comes from 1/10th tonne of ore|
|Milling of soft ore, per 1/10th tonne||=2.33/10||Caldicott Book, Page 9 (for "soft" ores; all of Canada's are)|
|Remediation of mill tailings, per 1/10th tonne||=4.2/10||Caldicott book, Page 9 - points out, but doesn't explain, why this is 4X as much as the energy to mine it.|
|Conversion of U to U-hexafluoride, per kg of U||1.478||Caldicott Book Page 10|
|Estimated enrichment energy per kg of U||5.55||Calculations from Caldicott's figure on Page 11 '0.000555 PJ per 1000 SWU' = or 0.555 GJ per SWU and with most natural uranium, it takes <10 SWU to make one kg of enriched uranium .|
|Fuel rod fabrication, per kg of U||0.379||Caldicott quotes '0.000379 petajoules per ton' - same thing|
|Total Energy per kg of fuel with 0.1% ore, in gigajoules, GJ:||15.0||Not Used! Shown to indicate the difference that it would make for low-grade ores - about 7 more GJ on top of 29.2|
|Or, in Canada, where the ores are over 1% Uranium:||8.17||Sums up all the light-blue figures above; will be in sum below|
|Energy to dispose of waste:||1.06||I'm going to assume in can't be worse than mining a tonne OUT of the ground. (More expensive in dollars, likely - but not more energy-intensive than mining one thousand times as much rock.)|
|Energy to build the plant, 40 PJ / 6 million kg U||6.67||Uses Storm/Smiths lower number, still 10X other people's highest numbers! Then assumes 40 year plant life at 150 tonnes of U per year.|
|Energy to decommission plant, 80 PJ / 6 million kg U||13.33||Again, is lower Storm/Smith number but very high to everybody else.|
|Grand Total Energy Inputs to Nuclear Power, per kg U:||29.2||(For Canadian "average" plant using Canadian ore.|
That same assumed "average" plant, nominally 1 GW power output, and running about 85% of the time, produces just over 74 "TWh" (74 million kWh) per year, or 25 PJ of electrical energy. And takes in 150 t - 150,000 kg of uranium per year.
So the final electrical output, per kg of uranium is:
25,000,000 GJ / 150,000 kg = 167 GJ/kg of uranium.
Assuming all the input energy is from fossil fuels that are just as bad as coal, the ratio is: 29.2 / 167 = 18%.
In fact, diesel, gasoline, and other "machinery" fuels are NOT as bad as coal, and the electrical energy to run fuel processing plants is a mix that includes hydro, gas, and nuclear itself. Even Storm and Smith agree that, even with their higher numbers (I used their lower-end for the construction and deconstruction energies), that a nuclear plant has a carbon footprint about 35% that of a gas plant. Gas plants have about half the carbon footprint of coal, so nuclear is about 1/3rd as carbon-producing as gas, 1/6th as bad as coal - even by their figures.