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Comment by Klinky | Hacker News Reader

Scaling down power generation when demand is low is not something nuclear is good at. Battery or energy storage systems that could store excess power from the grid would help any sort of power generation technique become more efficient and reliable.

There is a lot of hand waiving and fudging the numbers when it comes to the cost of nuclear. One-off proprietary designs, using proprietary fuel systems, using proprietary operational methodologies is not cost effective. Economies of scale are not in nuclear's favor, and even "at scale" you're looking at billions of dollars worth of investment before the first watt is produced. The need for large-scale waste transportation, storage and reprocessing is not a solved problem. The Nuclear Solves Everything™ thought process requires a lot of head-in-the-sand thinking.

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As a species, we have been generating electricity by nuclear fission for 60 years, and in the process, have produced hundreds of thousands of tons of extraordinarily toxic waste. In all that time, no one has found a final resting place for it. Only one serious DGR has even begun construction— and that's Onkalo (Finland), set to begin receiving waste in 2020, should things go to plan.

All that spent fuel is just sitting on the surface at hundreds of sites worldwide, in pools, dependent on a power supply and ongoing maintenance to the pumps which circulate cooling waters. If those pumps malfunction, or the power supply ceases, the water will boil off, and the wastes will be released into the biosphere. If the US electrical grid ever fails, fossil fuels will have to be trucked to these sites, forever. As long as the grid never fails in the next, oh, few ten to hundred thousand years, we should be all good. How confident are we in the political and economic stability of the US, for millennia to come?

Is it not immensely immoral to be generating power this way, and handing the problem to our distant descendants to deal with? How are they supposed to pay these costs, when we were apparently unable to, despite enjoying the front end benefits of cheap power? Can you imagine if instead of building pyramids in the desert, the ancient Egyptians had left behind a monster that required ongoing babysitting even today, to prevent unleashing catastrophe on the planet?

The more radioactive something is, the shorter the half-life. High-level nuclear waste from spent fuel rods has three components:

- U-238: less radioactive than uranium ore, makes up most of the waste. Only a problem because of all the other stuff that's mixed in with it.

- Transuranics, mainly plutonium: radioactive for millennia. About 3% of the waste.

- Fission products: the broken-up atoms. The most troublesome are radioactive for decades. About 1% of the waste. Since they have fairly short half-lives, they're the most radioactive.

So it's the fission products which make lots of decay heat and have to be kept cool, but that heat production goes away fairly quickly. It's the transuranics that have to be stored for millennia, but they don't need cooling; since they have long half-lives they don't generate much heat.

However, the U-238 and transuranics could be used as a fuel in more advanced reactors, either fast reactors or molten salt reactors. So actually we only need to store that waste until the more advanced reactors become available.

In the article Thiel advocates pursuing new reactor types, including those that can eliminate long-term waste. If we do that, we'll end up with less long-term waste than we have right now.

> Scaling down power generation when demand is low is not something nuclear is good at.

Isn't that what control rods do?

They control the reaction within the reactor, and in newer reactors can be used to regulate load. France & Germany do have a load following system in place for their nuclear reactors. It's not a simple matter of turning off a reactor, as this is a large maintenance task. Various mechanisms and regulations have been developed to handle load following for a Nuclear plant. There are still negatives to doing this, such as reduced efficiency, additional operator training, and additional wear on control, fuel and the plant. Positives likely outweigh the negatives, but the reactor must be designed to do load following and regulations need to be in place to ensure it is done safely. It is another thing to consider when talking about the cost of nuclear.

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