The ten-thousand-fold difference between fossil waste and nuclear waste

The waste footprint of electricity generated with the “cleanest” fossil fuel is tens of thousands of times bigger than that of nuclear energy.

Crunching the numbers from a recent NWMO report on CANDU fuel burnup and its implications for the design of a deep geological repository for spent fuel, I thought it might be fun to calculate the spent fuel intensity per kilowatt-hour of nuclear energy and see how it compares with the waste product of fossil fuels. As you can see from tables A1 and A2 on the left sidebar of this blog, the waste product of gas-fired power generation is quite substantial: between midnight and eleven a.m. on Monday July 13 gas-fired plants had dumped nearly 12,000 tons of carbon dioxide (CO2) into our atmosphere. The gas plants had collectively contributed just over 11 percent of Ontario’s electrical energy over that period. Tables A1 and A2 are dynamic, so the values you see now will be different from those when I wrote this piece. No matter: the main thing is to note how much CO2 is coming out of the gas plants. Also note that that amount is metric tons; one metric ton is one million grams.

And as you can also see, the nuclear fleet, which produced more than 65 percent of the electricity, produced zero CO2. But what about spent fuel? This is commonly referred to as “waste.” How much waste did the nuclear plants create, en route to generating the 135 million kilowatt-hours they contributed to Ontario’s grid from midnight to eleven a.m.?

I have mentioned elsewhere that a Darlington-size reactor will discharge around 16 used fuel bundles per day. The NWMO report corroborates this: in Table 1 on page 3 you can see that the Darlington units discharged 102,229 (unit 4) to 110,309 (unit 2) used fuel bundles from their start dates until late August 2012. This covers periods of 7,784 days (unit 1), 7,972 days (unit 2), 7,082 (unit 3), and 6,909 days (unit 4). Divide the bundles discharged by days and you get roughly 14 bundles per day for units 1 and 2, and 15 per day for units 3 and 4.

A Darlington-size CANDU fuel bundle weighs roughly 23 kilograms, or 23,000 grams.

If a reactor discharges 15 bundles per day, that is 345,000 grams (0.345 metric tons) of nuclear waste per day. That same reactor (let’s continue with Darlington-size machines, which were rated at 860 megawatts net but were subsequently uprated to around 930 MW) will generate roughly 18.5 million kilowatt-hours per day. So divide 345,000 grams of spent fuel by 18.5 million kilowatt-hours, and you get roughly 0.0185 grams of spent fuel per kilowatt-hour.

Now, look again at tables A1 and A2 on the upper left. For the gas-plants to produce the 1,966 and 11,723 metric tons of CO2 from midnight to eleven a.m., while generating less than 12 percent of Ontario’s electricity, their CIPK must be over 500 grams. How much greater is that than the nuclear waste intensity per kilowatt-hour?

The nuclear WIPK is 0.0185 grams; the CIPK of the most efficient gas-fired generator is close to 400 grams.

Which means the gas-fired CIPK is more than 21,000 times greater than the nuclear WIPK.

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james greenidge
8 years ago

Excellent stats! Now if you can break it all down into Joe six-pack terms it’d be even more strikingly impressive and awe inspiring to a clueless public reguarly fed how clean fossils are by the natural gas lady and that there’s so much nuclear waste that their cans are literally rolling around the streets via the wit and wisdom of Homer Simpson.

James Greenidge
Queens NY

Oscar Archer
8 years ago

Well, at least in Australia the average electric kettle is 2200W. If it boils within 3 minutes, that’s about 0.1kWh – responsible for 1.85 milligrams of used fuel by Steve’s arithmetic.

Mass-wise, you’ll get over 10 times as much caffeine in your cup of tea as is fuel coming out of the reactor.

8 years ago

I’d like to know how much radioactive gasses are emitted by coal, natural gas, wind, and solar (with life-cycle emissions) per KWh. Coal and natural gas would be ridiculous!

The IPCC already has life-cycle CO2 emissions for solar and it is worse than nuclear, plus you have to dig radioactive crap out of the ground for those elements for solar cells.

19mg is so tiny!

5 years ago

The funny thing is, that the falsity of the LNT conjecture, and the probability of the radio-hormesis effect, in one study almost seemed to indicate that for protection against lung cancer, living where radon emissions from neighbouring rock formations are highest, might be beneficial!
There are too many other health-beneficial influences in Norway to let me conclude that its thorium deposits are beneficial, but it might be true.