Thorium reactors

Proliferation is only 1 aspect that I'm interested in, I'm big on the safety and the potential to reduce the worst waste. But of these I think the political 'gold' of non-proliferation could be the best bet to kick start the thorium industry since waste and safety concerns come along as bit later.

I don't really understand about the liquid salt, but believe you when you say the liquid salt is part of the 'thorium package' if you want the benefits, without the whole 'package' then the idea isn't much chop and if it takes until the 90s for the 'thorium package' to be viable then we're screwed because we'll have had 25-30 years of uranium entrenchment with the attendant waste, safety, cost and proliferation problems.
 
I can agree it's better to keep options open than to close them arbitrarily...

But if in fact substituting thorium for uranium would both eliminate risk of nuclear weapons proliferation and somewhat ease waste disposal problems, and if in addition to that thorium is more abundant and requires less processing to be suitable fuel...

Why not then focus on the thorium and let the uranium go hang?

Well, a couple of reasons:

  • I haven't looked into this in detail, but my understanding is that extracting thorium from ore requires a lot more work than uranium. So fuel preparation is, at best, a wash, maybe a net loss.
  • Fuel shortages aren't going to be a serious issue in this half of the century, even under very optimistic buildout projections. The actual uranium ore is only 5% of the cost of nuclear electricity, so utilities can afford to spend a LOT more on fuel without equivalent increases in the price of electricity. And if you double the fuel price, a LOT more uranium becomes profitable to mine. And uranium breeding, while harder than thorium breeding, has the same benefits in terms of fuel efficiency.
  • Thorium doesn't eliminate the risk of nuclear proliferation, it just decreases it. And there seems to be some disagreement among the relevant experts about the tradeoffs between the gamma from U-232 making weapon fabrication harder, versus the neutrons from Pu-240 making design harder. Also, it may be possible to modify the processing system to extract the U-232 - both U-232 and U-233 are produced from Pa progenitors that have different half-lives, so timing your processing right may make it possible to extract weaponizable quantities of pure U-233. (Remember, the US actually tested a U-233 bomb back in the 50s...)
  • And the absolute biggest reason: most of the benefits from thorium require breeding. Breeding is hard to get right, economically and technically. Thorium breeding is easier than uranium breeding, since you don't need a fast reactor, but that doesn't mean it will be easy.

But it sounds like you're just caviling at a technicality. Yep, we could run the MSRs on uranium too--good to know. But we would be creating more of a proliferation liability, we would be producing radioactive waste that has a much longer half-life--all true? Then why not take advantage of thorium and leave the uranium as a possible back-up?

In short, what's wrong with selling it as a thorium reactor, aside from the observation that it doesn't strictly have to be?

We could use open-cycle uranium MSRs as a bridge, to develop the technology for thorium breeder MSRs. That's the big reason. And you can get a lot of the same benefits from a uranium breeder as you can from a thorium breeder.

Edit to Add: Also, breeding is expensive. If we do go heavily nuclear in the future we'll need it eventually, but I would be okay with spending a few decades first building open-cycle uranium MSRs, which are likely to be cheaper and easier to develop.

Basically, there's three things going on here: breeding, thorium fuel, and MSRs. Breeding essentially eliminate long-lived waste and increase fuel efficiency by roughly a factor of 100x. MSRs will hopefully provide greatly increased safety and economics. Thorium (hopefully) provides proliferation resistance, and has chemical and nuclear properties that make it very well-suited to breeding in an MSR. But there are other options as well, and thorium-fueled MSR breeders may not be the best one.

Proliferation is only 1 aspect that I'm interested in, I'm big on the safety and the potential to reduce the worst waste. But of these I think the political 'gold' of non-proliferation could be the best bet to kick start the thorium industry since waste and safety concerns come along as bit later.

I'm not sure how much the technical advantages of thorium fuels really matter. Fundamentally, the main obstacles to building a bomb are political, not technical.

I don't really understand about the liquid salt, but believe you when you say the liquid salt is part of the 'thorium package' if you want the benefits, without the whole 'package' then the idea isn't much chop and if it takes until the 90s for the 'thorium package' to be viable then we're screwed because we'll have had 25-30 years of uranium entrenchment with the attendant waste, safety, cost and proliferation problems.

I'm not sure what you mean by being screwed; we may still get MSRs working yet.
 
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I'm not sure what you mean. Are you talking about the plutonium production reactors at Hanford and Savannah River? Because the US government said upfront what those were for.

Edit: Also, the last US plutonium pile was finished in 1963, well before the great bandwagon market in nuclear power reactors.

No, I was talking about the reactors that are coming on line for commercial power production, if I read Riain's suggestion correct, a lot of those in the nuclear weapon countries are going to be uranium fuel cycle ones.
 

Archibald

Banned
I think the ideal would be to get Jimmy Carter on board with the LFTR. I don't know enough about Carter to know if that's plausible. But, if we can keep the MSR program alive until he's in office, it might be a plausible alternative to the LMFBR. By 1976 the LMFBR program was centered around the Clinch River Breeder Reactor, which was suffering enormous cost overruns that were choking out the rest of the Department of Energy's research budget. At the same time the perceived need for the LMFBR was receding rapidly as demand for nuclear reactors fell off and further exploration expanded uranium supplies. Finally, the fact the LMFBR was, by design, a plutonium factory conflicted with Carter's anti-proliferation agenda. Now, IOTL the MSR project had already been essentially shut down by the time Carter was in office, but if Weinberg in the 60s can get it more funding, it will hopefully be able to hold out until 1977, and present a viable alternative to Clinch River and the LMFBR. Carter could use it as a sop to the pro-nuclear lobby to get Clinch River cancelled - he wanted to kill it IOTL but wasn't able to get that past Congress.

So, let's say Carter manages to kill Clinch River in 1978, offering up the MSR as a replacement. I'm not sure where to go from there. Getting the money for a commercial demonstration plant would be tricky in the 80s, given the public mood, although it would be an easier sell than the LMFBR, with its flammable sodium coolant. Moreover, it would probably be a better idea to build the MSR as a U-235-burner rather than a thorium breeder, at least at first, but the ORNL team seems to have been pretty attached to thorium. But even if they develop the tech for thorium, private industry could hopefully apply it to uranium. Assuming they get the money, and being moderately optimistic, I could see construction starting on the first commercial uranium-fueled MSR in the late 80s/early 90s. If the optimistic cost projections of Kirk Sorenson et al actually pan out, you could see a second bandwagon market in nuclear tech, this time with MSRs, in the 90s.
In my space TL where the shuttle gets canned in 1971, NASA blunders with the NERVA in 1972 and run into Ralph Nader (and a huge scandal).

The NERVA scandal then triggers a chain reaction (pun intended) across the Atomic Energy Commission which led to Alvin Weinberg not being fired by Chet Holifield.

The Molten Salt Reactor then find its way into the space program - because, according to Kirk Sorensen, that reactor is just perfect for space power and nuclear electric propulsion. The Soviets are also involved - in the wake of the Apollo-Soyuz joint flight.
Which bring us to the year 1977 and the Carter presidency.

The real missed opportunity with molten salt is not the thorium or breeder but the MSRE - a non-breeder molten salt reactor closer from a classic nuclear plant... except it can't melt, can't produce nuclear bomb fuel, and has very little waste (300 years instead of million years)
Unfortunately no-one cared about the MSRE (not even the Oak Ridge scientists who build it) because, well, it was not a breeder, and in the 70's everybody was obsessed with breeders because of the impending uranium crisis (that never happened)
The MSRE had been build as a first step on the way to the Molten Salt Thorium breeder, and that was it.
When they understood the uranium crisis never existed (in the 80's) it was too late - the MSRE had been shut down, dismantled and forgotten (in 1975).

Having the MSRE in place of the classic nuclear power plants - now that would be a fabulous alt-history. Even a Fukushima-like tidal wave wouldn't wreck a MSRE, since it has no vulnerable water cooling system nor pumps, not even an overheating solid-core made of uranium rods.
 
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No, I was talking about the reactors that are coming on line for commercial power production, if I read Riain's suggestion correct, a lot of those in the nuclear weapon countries are going to be uranium fuel cycle ones.

I don't think I understand what you mean? Thorium reactors won't be commercially viable until the 80s at the earliest, and probably much, much later.

In my space TL where the shuttle gets canned in 1971, NASA blunders with the NERVA in 1972 and run into Ralph Nader (and a huge scandal).

The NERVA scandal then triggers a chain reaction (pun intended) across the Atomic Energy Commission which led to Alvin Weinberg not being fired by Chet Holifield.

The Molten Salt Reactor then find its way into the space program - because, according to Kirk Sorensen, that reactor is just perfect for space power and nuclear electric propulsion. The Soviets are also involved - in the wake of the Apollo-Soyuz joint flight.
Which bring us to the year 1977 and the Carter presidency.

The real missed opportunity with molten salt is not the thorium or breeder but the MSRE - a non-breeder molten salt reactor closer from a classic nuclear plant... except it can't melt, can't produce nuclear bomb fuel, and has very little waste (300 years instead of million years)
Unfortunately no-one cared about the MSRE (not even the Oak Ridge scientists who build it) because, well, it was not a breeder, and in the 70's everybody was obsessed with breeders because of the impending uranium crisis (that never happened)
The MSRE had been build as a first step on the way to the Molten Salt Thorium breeder, and that was it.
When they understood the uranium crisis never existed (in the 80's) it was too late - the MSRE had been shut down, dismantled and forgotten (in 1975).

Having the MSRE in place of the classic nuclear power plants - now that would be a fabulous alt-history. Even a Fukushima-like tidal wave wouldn't wreck a MSRE, since it has no vulnerable water cooling system nor pumps, not even an overheating solid-core made of uranium rods.

Why have I not been reading your TL before now?

If you'll excuse me, I'm going to remedy that error.
 
I don't think I understand what you mean? Thorium reactors won't be commercially viable until the 80s at the earliest, and probably much, much later.

Yes but if development had continued and they are safer as suggested, then there are bound to be questions as to why continue building or even planning ones using the uranium cycle.
 
Yes but if development had continued and they are safer as suggested, then there are bound to be questions as to why continue building or even planning ones using the uranium cycle.

The safety improvements mostly come from the use of molten salt rather than thorium. (Thorium by itself does offer some modest improvements, since its ceramic oxide has better thermal properties, but they're fairly modest.) Molten salt probably won't be technically viable until the mid-80s, maybe later, and at that point would probably be running on an open uranium cycle rather than thorium. By that point the great bandwagon market is long over, and the US hasn't started construction on a new nuclear reactor of any type since the mid 70s. So, while the existing reactor manufacturers may feel threatened by MSRs, what they're offering isn't finding any takers anyway.
 

Archibald

Banned
Why have I not been reading your TL before now?

If you'll excuse me, I'm going to remedy that error.

Wait, it is still on my hard disk, first because it is loooooooooong, second because I may never finish it, third because I don't know whether I will put it on this forum - I'm hesitating.

But we may discuss by mail if you're interested !
 
As people have pointed out, indirectly, thorium is not usable on its own, being like U238 in being fertile, not fissile. (Ie, it can be easily converted to a fissile material by absorbing netrons in a reactor, but does not, itself, undergo fission.) Therefore ANY thorium reactor needs fissile material, either U235, u233 or Pu239 to get the reaction started, and start converting Th to U to continue.

So you pretty much need that uranium cycle to start with.

Btw, some work has been done in Canada and China on using Thorium in Candus, and it looks very feasible. If Canada had had significant Thorium resources, we might have done that a lot earlier.
 
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