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.
| Activity | Energy GJ/kg | Source |
|---|---|---|
| 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.