Re: The Physics Behind the Spanish Blackout

On 12/06/2025 9:51 pm, David Brown wrote:

On 11/06/2025 18:20, Bill Sloman wrote:

On 11/06/2025 11:21 pm, David Brown wrote:

On 11/06/2025 13:41, Bill Sloman wrote:

On 11/06/2025 5:38 pm, David Brown wrote:

On 10/06/2025 19:23, Bill Sloman wrote:

On 11/06/2025 2:32 am, David Brown wrote:

On 10/06/2025 16:16, Bill Sloman wrote:

On 10/06/2025 5:21 pm, David Brown wrote:

On 10/06/2025 07:01, Bill Sloman wrote:

On 10/06/2025 6:44 am, Liz Tuddenham wrote:

Carlos E.R. <robin_listas@es.invalid> wrote:
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On 2025-06-09 21:54, Don Y wrote:

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OTOH, we're sticking with other technologies (fossil fuels -- coal -- and
nukes) despite obvious and yet to be solved problems INHERENT in their
technology.  Adding "inertia" synthetically to a network is a considerably
more realistic goal than sorting out how to deal with nuclear waste or
the consequences of burning carbon.

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Technically and economically, dealing with nuclear waste is many orders of magnitude easier than dealing with the consequences of burning carbon.

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Nuclear fission waste is mixture of isotopes. Some of them are very radioactive and decay fast, and keeping them safe until they've mostly decayed is technically demanding. The less radioactive isotopes are easier to handle, but some of them stay dangerously radioactive for upwards of 100,000 years, and keeping them safely isolated for that length of time is an as yet unsolved problem
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We all know that, I believe.  There are two ways to handle the waste - bury it deep enough, or use reprocessing/recycling to reduce the worst of the waste.  (Of course a better idea is to use more advanced nuclear reactors that produce more electricity for less waste.)

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There aren't any. If you fission U-233 (which is what thorium reactors do) you get slightly different proportions of exactly the same isotopes as you get from U-235 which pose essentially the same problems.

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Estimates by proponents of molten salt thorium reactors are between a hundredth and a thousandth of the levels of the more problematic waste materials for the same generated electricity.

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

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Oh, thanks for that!  I'd never heard of Wikipedia before.  I have also heard rumours that there is a newfangled way to search for information - "goggle", or something like that.  Perhaps you could explain that to us too?
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  No doubt they are overly optimistic, but they are still massively more efficient.

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The claim appears to be total nonsense.
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Ah, well, if you say so it must be true.  You can no doubt refer to some comic book as a reference.
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For the  long-lived transuranic radioactive isotopes,

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Nuclear fission doesn't produce any long-lived transuranic radioactive isotopes.

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Try reading the Wikipedia article you linked - perhaps also the page <https://en.wikipedia.org/wiki/Long-lived_fission_product>.

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Nuclear reactors do produce them, but not by nuclear fission as I explained in the section below, which you clearly hadn't read when you produced your response.
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 Nuclear fission produces long-lived transuranic radioactive isotopes.
 It is quite obvious that when a big nucleus breaks into pieces, the pieces will be smaller than the original nucleus - the fission of a uranium nucleus does not create a transuranic isotope directly.  But sometimes one of these little pieces flies off and sticks to another big nucleus, and that can then give you an even bigger nucleus.  Those big nuclei are sometimes long-lived transuranic radioactive isotopes.  They come about as a result of the nuclear fission in the nuclear reactor.
 Do you /really/ think the technical distinction you are making is remotely relevant to anything?
 

The neutron flux in a nuclear reactor can be captured and promote some of the uranium and plutonium around into even heavier isotopes, but it is very minor component in nuclear waste.
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the thorium cycle in a  molten salt reactor gives about 5% of the quantities you get from standard light-water uranium reactors, and the waste is in a form that is easier to separate and recycle.

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Since the transuranic radioactive isotopes are a very minor problem anyway, who cares?

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It is the long-lived ones that are the problem.  Short-lived isotopes are only an issue if you let them escape before they have decayed.

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What makes you think that transuranic radioactive isotopes are particularly long-lived? Heavier nuclei do tend to be less stable - technicium is the lightest element that doesn't have a stable isotope.

 Here's an idea for you - instead of guessing randomly, try looking it up.  Such information is easily available.  Yes, many very heavy isotopes are unstable and short-lived.  Others are long-lived.

But how much of the radiation emitted from nuclear reactor waste comes from transuranic isotope formed by incidental neutron capture?
What the reactor is there to do is to fission U-235 (or U-233) into isotopes of about half the atomic weight - the two peaks are between atomic masses 85 to 105 and 130 to 145. Lots of them are radioactive, and some of those are quite long-lived.

 Conventional uranium reactors use less than 1% of the uranium for useful energy production - the rest is wasted.  With molten salt thorium reactors, close to 100% of the thorium is used.

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Eventually. You have to take the spent fuel out of the reactor, take out the fission product and the U-233 that has been generated by neutron capture, and put the purified residue back into the reactor

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If only there were a way to do that...

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There is. It involves doing chemistry on very nasty radioactive spent fuel rods so it's difficult and expensive, but perfectly practicable, if mostly economicaly impractical
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 It is entirely possible, and entirely practical - that is how molten salt reactors work.  Of course they don't get everything out, they don't recycle everything, and there are technical and economic limitations. But the fundamentals were figured out in the 1960's, and recent developments have improved on that.

But not enough to let you go out an buy a molten salt reactor.

Fusion energy has been 50 years in the future for the last 80 years. I have not seen anything to suggest that has changed much - and I make a point of keeping up with scientific and technical news.

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But you haven't heard of hydrogen-boron fusion?

 Yes, I have heard about it.  The idea is nice, but the temperature needed to make it work is an order of magnitude higher than for D-T fusion, and no one can make that temperature stably or reliably.

The HB11 crew think that they have scheme for doing it intermittently but rapidly, involving pulsed lasers.

It is, I think, something that might come in the future - /after/ commercial D-T fusion.  Perhaps there will be breakthroughs in containment that will make these high temperatures practical, in which case the H-B fusion's advantages would come into play.  So I think it is good that research is being done in the field, but I am not holding my breath waiting for it to appear.
 

And you haven't noticed that the current generation of hydrogen fusion machines have got pretty close to the Lawson criterion

 And on what basis do you claim to know what I have or have not noticed? Or are you really so naïve as to think momentarily generating more energy than you lose means that practical commercial fusion reactors are just round the corner?
 

(and I did work with John D. Lawson's youngest son, who wasn't remotely in  the same league).

 Name-dropping makes you look pathetic.  "I know nothing myself, but I did meet a relative of someone who did".  It's like Trump claiming to be a scientific genius because he had an uncle who was a professor.

It wasn't name-dropping. I would have been appreciably happier if I hadn't had to work with man, who was bright enough but neuro-diverse.
It's more to make the point that I've known about the  Lawson criterion for about fifty years now.

I believe that eventually, we will have workable fusion power (though it will probably be deuterium / tritium fusion first), and that will be a big step up from fission nuclear power.  For the next 50 years at least, however, thorium fission is the way to go for bulk power production, with solar and other renewables helping out as it takes a long time to get nuclear plants up and running.
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But you have done something unique here - I can't remember anyone else being so confused as to suggest that I am a conservative!

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You've copied a conservative tactic. That doesn't make you a conservative, but it does suggest that you don't think too hard about what you post.

 No, I haven't copied any "conservative tactic".  Saying that fusion technology will take a long time to mature is not some kind of thin-air assertion, or "tactic" - it is demonstrable fact.  Our best shot at real fusion power is ITER - which is a 10 years into a 20 year project to learn about fusion and get the basics working.  Expect another 10 years of updates and improvements to get a solid understanding of making it economically viable and understanding the consequences and handling of waste material.  Then it will be possible to start making the first experimental reactors that will actually generate power for the grid, taking perhaps 15 years to design and build, after at least 5 to 10 years of political arguing about safety and budgets.  At the most optimistic, that's maybe 40 years before fusion is actually producing useful electricity, and perhaps 70 years before it is significant in the world's energy production.
 There is always the outside chance that one of the many alternative fusion ideas will actually work in practice and give breakthroughs significantly earlier (say, the 20-30 year timeframe).  It's a small chance, however.  If you have the spare cash, then it's fine to bet some money on them - but not the future of the world.
 I /have/ thought about it.  I haven't naïvely swallowed the hype from some little startup with a cool idea.  Nor do I accept some fossil fuel supporters claims that there is no alternative and that new technology will never happen.
 So I fully support research into fusion - including the serious stuff like ITER and NIF, and commercial attempts like HB11 and Helion Energy. I am in favour of their work /now/, precisely because it will take decades for the technology to mature.

You can't be precise about when something might happen. It is likely to be a while until somebody finds a practical way of making nuclear fusion happen, but prediction is a imprecise art.

  I am in favour of thorium molten salt reactors, because that will be workable in a much shorter time-frame (10 - 15 years). 

But you don't seem to appreciate that it will produce much the same volume of hard-to-deal with radioactive fission products as U-235 fission.

I am in favour of solar and wind, because they are available now.
 Imagining that someone will solve the world's energy needs in the next few years with fusion shows no more understanding or thought than imagining we should keep burning fossil fuels because fusion will never work, fission is unsafe, and the sound of windmills causes cancer.

It's a rather different kind of error. We could find a practical way of doing nuclear fusion tomorrow. It's unlikely, but not impossible.
Imagining that we have to keep on burning fossil carbon until we can exploit nuclear fusion is simply wrong.
Imagining that ITER and NIF are the only viable routes to nuclear fusion in the short term is equally wrong. They may be the likeliest candidates, but they aren't the only ones.
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Bill Sloman, Sydney