Thorium backed as a 'future fuel' | Hacker News Reader

Thorium backed as a 'future fuel'

bbc.co.uk

105 pointsximeng36 comments

As has been typical over the last year or so of writing about thorium power in the press, this article glosses over the difference between using thorium in a conventional water-cooled reactor and using thorium in a liquid fuel configuration, which is what lots of thorium advocates want. Many of the benefits (particularly in terms of increased fuel burn, and automatic shutoff in the event of failure) are dependent on the LFTR design, but one could easily read this article and assume they also apply to the MOX design being developed in India; for the most part, they don't. Certainly, you get some of the benefits of thorium fuel in that configuration (more abundant fuel as compared to uranium, for example), but it's an important distinction that needs to be part of the conversation.

The Thorium publicity spree is about rebranding nuclear power, not about having a technical discussion. If the only message that gets across is "new thorium reactors are safer than old reactors," it's still a win for everyone involved because this message is a subset of the truth (new reactor designs are safer than old designs in general).

I don't think the public properly appreciates the extent to which nuclear safety mechanisms have improved dramatically over time, not least because a design's safety profile is largely "frozen in" when it is built, so we occasionally see a half-century old "bug" rear its head (Fukushima). The public sees it as evidence against the safety claims of future nuclear plants, even though it is not (quite the opposite: building newer, safer plants lets us retire the old, dangerous ones). Rebranding might get them to take another look.

Actually, I think including as much detail as the parent post did might be a net negative because it muddies the core message. Simplicity and straightforwardness are key.

One big thing that always gets mentioned in any Thorium discussion is that originally, Uranium was chosen over Thorium exactly because it is inherently less safe; it can be used to make bombs, which is what all the nuclear powers were really interested in. So Uranium research got lots of government support while Thorium research was dropped.

I'm no nuclear physicist, so I have no idea if Thorium really is inherently safer than Uranium, but if it is, I'm all for it. But if it is indeed safer and cheaper, and old tech that's been ignored for decades, then why aren't there new Thorium reactors popping up all over the place? Or are there? Is anyone still investing in the Uranium/Plutonium cycle?

As far as I was aware the reactors at Fukushima shut down correctly as soon as the earth quake occurred. While the crisis definitely continued I think the reporters portrayal of the reasoning is somewhat misleading. As it insinuates it was the fuel rods inability to control the reaction was the problem, rather than the cooling system's inability to deal with the excess heat generated post shut down.

"When a uranium reactor overheats and the fuel rods can’t contain the chain reaction, as happened at Fukushima, the crisis continues."

Yes, the reactor shut down correctly. However, in a working uranium reactor, there will be large quantities of fission products that are also radioactive and are therefore spontaneously decaying in a long chain towards stable isotopes. Some of the fission products are quite short-lived, so for quite some time after the reactor is shut down they will be generating a lot of heat.

What happened at Fukushima is that the cooling system that needs to keep running for weeks after a shutdown broke. This caused the water in the reaction vessel to boil, uncovering the tops of the fuel rods, which then got so hot that they broke steam into constituent hydrogen and oxygen (which caused the subsequent explosions) and they cracked open, releasing some nasty isotopes into the coolant water. The coolant water with nasties in is what has been leaking out into the environment.

I agree, well expanded. The mechanism seems to be a lot safer in a liquid thorium reactor where the thorium drains away into a safety chamber in the event of a similar disaster.

I just wanted to point out the events the article portrays are incorrect and the writer could have conveyed this message without insinuating there was a meltdown due to the failure of the (wait he says fuel rods not control rods....) O well.

Another advantage with a liquid fuel is that you can do a continuous reprocessing cycle (pump the fuel through a chemical plant) to remove nasties from the system. With solid fuel pellets all you can do is hope that the pellet doesn't crack and let the nasties out. Having no pressure vessel with ultra-superheated water and a 1000-times-the-size containment building around it in case it all suddenly turns into steam helps too.

There has been some articles indicating that the containment block might have already been compromised prior to the tsunami.

Can you provide a link?

Key words: "I’m a lawyer not a scientist but in my opinion..."

Sounds like he's not a lawyer but a politician.

"the former Swedish foreign minister" - right before the bit you quoted.

My point was I dont want to listen to a lawyer or politician. Give me the words of a scientist, preferably a nuclear one.

He's a lawyer and politicians whose job for many years was to reconcile the views of scientists and politicians with respect to nuclear. And in this case the political impacts of Thorium are just as important as the science, and likely the reason they asked him questions:

Because it is far harder to use it to create nuclear weapons, there are far fewer political hindrances to mining and trade in Thorium, as well as political concerns over letting potential enemies establish Thorium reactors.

The supplies are also larger, and well distributed, which is also politically beneficial.

Nuclear power is not all about the science.

And because Thorium cannot easily be made into weapons, the military will not fund development of the use of it as a fuel - nor will it expend the political will to make the construction of a thorium-reactor possible. And so we keep using Uranium. The political hindrances of using Thorium turn out to be much greater than the political hindrances of using Uranium.

While I agree that up until now most of the developments on nuclear technologies have been funded by the military, it does not mean that a massive push by the public can't force governments to fund new thorium research.

The money needs to come from somewhere.

In the US, for example, the Department of Energy's budget[0] last FY was about 5.5% the size of the Department of Defense Senate proposed budget for FY2014[1] (35B v. 626B).

0: http://en.wikipedia.org/wiki/2013_United_States_federal_budg... 1: https://www.cbo.gov/publication/44459

The military uses nuclear power outside of weapons, especially in the navy. Subs, aircraft carriers and the like are all nuclear powered, so they have an interest in safer nuclear power as well.

Yeah, people seem to forget that the largest operator of nuclear reactors is, if I recall correctly, the US Navy.

Nice summary.

I have wondered since I first heard of thorium reactor why they weren't already adopted. Since some of the country with the civil nuclear power are those with nuclear weapons, is it possible that the military are lobbying for uranium? (I can see two possible reasons: refining price going down with production scaling, or just to hide their own uranium import in the civil import. If Thorium is adopted worldwide and can't be used to build nuke, seeing who is upgrading its nuclear arsenal would way easier, which can be good or bad, depending on your point of view.)

>The technology development is decades in the future.

Well, that's true for every research domain which isn't funded enough.

One fairly major reason is the economics of the nuclear fuel producers (who also tend to be the people building the power plants). Simply put, enriched uranium fuel pellets require huge resources to produce, and are !&^" expensive. Moving to Thorium would remove a load of their revenue stream, as it is a much simpler fuel to produce (well, for the liquid fuel reactors anyway).

Wow, so we aren't moving to thorium because it would cost less than uranium?

Sometime, economy freaks me out even more than politic :'(

Not quite so simple. The nuclear industry wanted/needed federal dollars, so not being in the uranium game looked like a bad bet. Once you have all that infrastructure invested in uranium, investing additional resources into thorium looks less attractive.

The department primarily responsible for the research of nuclear technology including nuclear weapons development is the Department of Energy. Therefore the preferences of the DoD influence DoE decisions.

My guess is that he has a reasonably good overview, although not being a scientist: "He [...] later became the head of the International Atomic Energy Agency. As such, Blix was the first Western representative to inspect the consequences of the Chernobyl disaster in the Soviet Union on site, and lead the agency response to them." http://en.wikipedia.org/wiki/Hans_Blix

Personally, I'd go with the opinion of a nuclear engineer - I've worked on projects involving modelling nuclear power stations and the engineers who did the engineering simulations were some of the brightest and practical people I've ever met.

Could the good Doctor Strangelove be wrong?

Engineer would be even better.

Wernher von Braun once said that the most difficult step towards going to the moon was gathering the will to do it.

The fact that he admits is a big step up form most polticians.

Nuclear engineer here.

The thorium fuel cycle has obvious advantages, but it takes so long to transition from uranium to a pure thorium cycle that I doubt I will see it happen in my lifetime.

There seems to be a lot of confusion about thorium. It isn't thorium that makes LFTR so great, it is type of reactor that makes all the difference. Molten salt reactors can run on any fissile material. The only advantage of using thorium over uranium in an MSR is in the fuel cycle.

(Full disclosure: I'm a founder of a startup (http://transatomicpower.com) that is designing a molten salt reactor to burn spent fuel.)

A Swedish guy rooting for thorium? Odin's beard, how surprising!

(Jokes aside, I've been in love with this idea since my high school studies of nuclear engineering. I know a lot of these things didn't pan out eventually, but I still find that sad.)

Does anyone know if any substantial gains have been made in what I believe is the number one problem with Thorium reactors: that moving liquid salt through the reactor is extreamly corrosive and parts don't last very long (under a year iirc)?

Oak Ridge was actually pretty successful with Hastelloy-N, which pretty much solved the chemical corrosion issue in the absence of neutrons. There was still some concern about the neutrons causing problems, but Oak Ridge thought they'd figured out how to solve it by adding something extra to the alloy. It hasn't been tested long-term though.

See below. It was tested for 9 years and didn't show significant corrosion. The leak happened not in the Hastelloy but in a ceramic seal between the alloy components. An appropriate seal or coating on the seal may be able to fix this issue. Overall, I'd say the containment issue is as you say mostly solved.

Here's the report:http://moltensalt.org/references/static/downloads/pdf/ORNL-T...

Great to hear, thanks.

The ratio of plutonium needed to seed and convert thorium into fissionable uranium-233 is very high (4:5)

But you only need it to start the reactor.

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