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Comment by mimixco | Hacker News Reader

I know of no technology that would allow a plant operator to simply walk away. Even spent fuel rods have to be cooled for years in a swimming pool (with constantly added fresh water) or they too will heat and catch fire.

Care to explain your "carefree" nuclear or give an example of a plant that has solved this problem?

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Gen IV is passively safe: https://en.wikipedia.org/wiki/Generation_IV_reactor

Sadly, it's also non-existent!

Yes, we already see cost overruns for existing nuclear reactor design which should be well understood by now. A new design isn't going to make nuclear power more predictable in terms of safety and costs.

Reactors on Powerpoint slides have excellent safety records!

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

This isn't just some theory work in academic papers. It isn't even "new", lots of research dating back to the 1960s.

The "safe nuclear" future is always right around the corner, yet it never arrives. There are no commercial molten salt plants and all proposed and under construction plants around the world are "old nuclear" PWRs or BWRs.

The design from the 1960s had remaining material issues that were never fully solved. Optimism that they were solvable was expressed, but optimism and $5 will get you a coffee at the bistro.

The design from the 1960s would require online reprocessing of the salt. This is an immediate showstopper for utilities. No utility wants to operate a highly radioactive reprocessing plant at each of their reactors, especially when that complex equipment could not be maintained with direct human contact.

The MSR design from the 1960s used FLiBe. The total world annual production of beryllium is maybe 220 tonnes; the estimated resource, 100,000 tonnes. The design could not be scaled to supply world energy demand.

Pebble bed reactors and small modular reactors are two examples. Also, even a conventional light water reactor can be passively safe on shutdown if the reactor cooling system is designed to take advantage of natural convection. US submarine reactors do it that way because it's quieter (no noise from reactor coolant pumps), but the passive safety benefit is also there.

> in a swimming pool

I don't think they use swimming pools for that purpose.

I would hope no one would try to swim in one, but if you empty the pools where the vast majority of America's nuclear waste is stored, most people would say the resulting cavity strongly resembles a swimming pool.

You can swim in spent nuclear fuel pools. I know a professional diver who did it for a living.

https://what-if.xkcd.com/29/

Love the revelation that swimming down to touch the spent fuel rods would be fatal. Pro-nuclear folks don't like facts like that because they want to pretend that either there is no waste, the waste won't hurt you, or we've solved the problem of storing it safely. None of these is true.

Nuclear professionals are made acutely aware of the dose they would get on a work task, and what to do if the conditions aren't as expected. This kind of work isn't a "do whatever you feel like" scenario.

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