[aftbit]

>Nuclear power plants are largely considered as one of the most reliable sources of energy. Inside the plants, reactors use fission to heat water into steam, which is then used to spin turbines and produce carbon-free electricity. However, nuclear fission produces nuclear waste, which requires great amounts of regulation for safe storage and disposal.

This is an odd angle to highlight. The risk of long-lived nuclear waste is extremely overblown, and the sheer volume of it that we produce (or even would produce, in the worst case of a once-through fuel cycle and nuclear power providing 100% of our energy needs for a century) pales in comparison to the amount of toxic and radioactive fly ash that even a single coal plant produces in a decade.

The real problems with nuclear fission power are threefold, in my opinion:

1. It is too expensive in terms of capital costs. Fusion will likely not help with this, but building a lot of identical large fission plants would probably help with economies of scale. Solar plus batteries might still end up being cheaper though.

2. Accidents have the potential to be catastrophic. Think Fukushima or Chernobyl, where entire towns have to be abandoned due to contamination. Fusion would help here, I believe.

3. There is a major proliferation concern. A civilian nuclear power program, especially one with breeder reactors, is not very far away from producing a fission bomb, and the short-lived high-activity nuclear wastes could be stolen and misused to make a dirty bomb. Fusion is perhaps better in this way, though an operating fusion reactor would be a very powerful neutron source of its own.

[perihelions]

It is not true that coal is more radioactive than spent nuclear fuel. It's very much the opposite: SNF is 10^11 times more radioactive than coal per kilogram, or 10^6 times more radioactive per energy unit.

Per the EPA, US coal has, at the high end, 10^3 Becquerel/kg of natural radioactivity [0].

Spent nuclear fuel has 3 million Curies/tonne (33 MWd/kg burnup fuel, at the age of 1 year) [1], which is equal to 10^14 Bq/kg. Since 33 MWd/kg is an energy density a factor of 10^5 greater than that of coal, the normalized ratio of [radioactivity]/[energy] is 10^6.

The graph in [1] depicts the decay of SNF activity on a log-log scale. It reaches the same radioactivity level as coal (again, normalized by energy output) at about 1 million years.

I'm fairly confident I know the origin of this social media-popular pseudofact. It's this poorly-titled Scientific American [2] article from 2007, which is about the (negligible) amount of radioactivity that nuclear plants release into the environment in the course of routine operation. It is *not* about spent fuel. It's a fair—but nuanced and easy to grossly misunderstand—point that coal power plants throw up all their pollution into the environment in routine operation, while nuclear plants, by default, contain theirs.

[0] https://www.epa.gov/radiation/tenorm-coal-combustion-residua... ("TENORM: Coal Combustion Residuals")

[1] https://www.researchgate.net/figure/n-situ-radioactivity-for... ("Impact of High Burnup on PWR Spent Fuel Characteristics" (2005))

[2] https://www.scientificamerican.com/article/coal-ash-is-more-... ("Coal Ash Is More Radioactive Than Nuclear Waste [sic]" (2007)

[aftbit]

Sure, the spent fuel is considerably more radioactive per kilogram, but how many kilograms of coal does a typical plant burn in a decade, versus how many kilograms of nuclear fuel are spent?

[perihelions]

I answered that exact question! :)

[aftbit]

My mistake - I reread your post, and I understand you to be saying that a nuclear plant generates a 10^6 (USA million) times as much long-lived radioactive waste as a coal plant for each unit of energy.

As everyone acknowledges, coal plants don't contain their waste, and fly ash has bad chemical, medical, and ecological properties aside from its radioactivity. Everyone fears nuclear waste and requires it to be contained in nearly impervious vessels with century long management plans. Those same people happily let the coal plants just pump their wastes into the air and discharge captured fly ash into ponds and piles on the ground.

Coal also produces many times more fly ash by volume and mass than nuclear plants produce high-level long-lived wastes.

Luckily even fossil-fuel power generation is moving away from coal in favor of natural gas plants right now, which are cheaper and cleaner (still CO₂ though).

More about fly ash as an underappreciated pollutant:

https://www.sciencedirect.com/science/article/abs/pii/S00128...

https://en.wikipedia.org/wiki/Kingston_Fossil_Plant_coal_fly...

[albumen]

If you did, it's not very clear.

The OP to which you replied didn't say that coal is more radioactive than spent nuclear fuel; but that radioactive waste's volume is much smaller than the fly ash produced by a single coal plant in a decade.

Is fly ash per kg more radioactive than nuclear waste? No. But you did acknowledge that the coal plant emits its waste into the atmosphere, unlike a fission plant, which I think is the more relevant point.

[kaonwarb]

I agree with your logic. However, fear of nuclear waste, rational or not, has been a major driver of public opposition for decades, and is worth the focus.