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Thorium nuclear reactors: a possible solution of the energy crisis? (video)

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Re: Thorium nuclear reactors: a possible solution of the energy crisis? (video)

#41

Post by DennisP »

jpk wrote: post #11
api wrote: post #7

I hear a lot about the LFTR, and I wonder what the problem is. Is there a major technical hurdle that prevents this from seeing widespread use? Sometimes there is, sometimes there isn't. Sometimes a really good idea never gets used because... well... because nobody really picks it up and runs with it. It's that simple sometimes. But sometimes there's some hidden gotcha.

My understanding is that building the reactors are significantly more expensive. So until the price of Uranium increases enough to justify the total cost of the Thorium reactors, we won't see many of them outside research settings. The other issue is building a new reactor of any type right now is a giant pain in the ass, which doesn't help either.

Thorium reactors should be quite a bit cheaper. Light-water reactors operate at 160 atmospheres of pressure. They need a very strong reactor vessel, which currently can only be forged by a single facility in Japan. They need a large containment dome because if a pipe breaks, that high-pressure water will flash into steam with a thousand times the volume. They use lots of redundant emergency active cooling mechanisms. Some of them have giant slabs of ice inside the containment dome, which reduce the volume of steam if it's released but have to be constantly refrigerated, to keep them frozen in close proximity to a nuclear reactor core.

LWRs are resupplied every year with expensive fabricated fuel rods, which are non-standard and can only be purchased from the company that sold the reactor. The fuel rods are complicated because they have to withstand a thousand-degree temperature gradient, and the fuel pellets are prone to cracking from the production of xenon gas. Xenon and other reaction products prevent the use of more than one percent or so of the energy potential of the nuclear fuel, another reason the rods are frequently replaced, and the reason we have so much nasty nuclear waste.

The nuclear industry makes most of its revenue from selling those fuel rods.

LFTRs operate at atmospheric pressure. No super-strong steel, no containment dome, no ice. It's a liquid fuel, so no proprietary fuel rods. Xenon just bubbles out of it.

The fuel has a strong "negative coefficient," meaning the reaction slows down as it gets hotter. If it nevertheless gets too hot, a salt plug melts and all the fuel drains into a passive cooling tank. No need for all those active cooling systems.

On top of that, LFTRs operate at higher temperature, so the turbine is more efficient, and the waste heat can be used to desalinate seawater. They don't require water cooling. As a bonus, marketable reaction products can be separated from the liquid fuel (http://flibe-energy.com/products/).

Misguided government regulation is the main problem, but Sorenson's company plans to get around that by selling to the military first.

Re: Thorium nuclear reactors: a possible solution of the energy crisis? (video)

#42

Post by pilom »

static_cast wrote: post #40
rmason wrote: post #26

I've studied this for years and haven't found any credible reason why we couldn't do this today. But there are a lot of forces allied against Thorium in both the government, energy companies and the current nuclear industry. Senator Hatch (R) Utah with support from Harry Reid (D) Nevada has introduced a bill annually for five years to fund $200 million to research to commercialize Thorium power. Yet every year the bi…

I'm not sure if the following links refer to the same thorium architecture but in Germany there was a test-reactor and several rather hard to solve problems appeared http://en.wikipedia.org/wiki/THTR-300 http://juwel.fz-juelich.de:8080/dspace/bitstream/2128/3136/1... [50+ page PDF outlining the problems]

That was a pebble bed reactor which had issues with high pressure containment vessels and solid fuel. The reactors recommended in the video are molten salt reactors which do not have the same issues.

Re: Thorium nuclear reactors: a possible solution of the energy crisis? (video)

#43

Post by zherbert »

I go to school at Boston University and took an Energy class with a Nobel Laureate in physics, Sheldon Glashow, last semester. He spoke in great depth about Thorium reactors, and is very supportive of the technology.

One of the main hurdles is that we have poured money into our modern-day reactors, and have constructed hundreds of plants. If we were to switch to thorium, we would have to essentially start from scratch - new research, new plant designs, new training, etc. It is very difficult to justify a complete switch from uranium, as it would be incredibly costly.

In other countries, however, thorium reactors could be very beneficial. Countries using thorium would not be able to produce nuclear weapons, which would give the world great peace of mind. This could minimize risks in unstable countries - we wouldn't worry if Iran was building a thorium reactor, for example.

There are also other types of reactor designs that use nuclear waste to create power. I believe our nuclear future lies with these types of reactors, rather than with uranium or thorium.

Re: Thorium nuclear reactors: a possible solution of the energy crisis? (video)

#44

Post by jackpirate »

DennisP wrote: post #30
ChuckMcM wrote: post #21

Earlier quoted context omitted.

The most common 'gotcha' is that you can't make a thorium reactor critical with just thorium. It needs 'boost' neutrons. The most way that was done in the past was a small bit of uranium or plutonium that was critical to provide the neutrons. A more innovative way is to use a small particle accellerator to provide the thorium with neutrons [1]. [1] http://www.physorg.com/news/2011-06-pint-sized-particle-nucl...

It's actually U233 that fissions. The neutrons convert thorium to U233, and when U233 fissions it produces neutrons that convert more thorium. So once you get the reaction started, you don't need an external neutron source. LFTR proponents figure the simplest approach is to just go ahead and use U233 to seed the reaction. The U.S. has one ton of U233, which it currently plans to dispose of.

Short answer: yes, you do need to maintain an external neutron source for Thorium reactors.

The advantage of Thorium is that you can maintain the reaction subcritical. That means it is much easier to shut down by simply removing the neutron source. In a critical reactor, you have to physically inject control rods containing a neutron sink (usually Halfnium or Boron). These elements can jam or be ejected under certain unlikely conditions (this is one of the things that happened at Chernobyl, and has happened at a handful of military test reactors in the US that no one has ever heard of).

In practice, however, modern reactors are designed to take this type of jamming into account. There is no known failure mechanism where it would become an issue.

FWIW, I was an engineer on a nuclear submarine.

Re: Thorium nuclear reactors: a possible solution of the energy crisis? (video)

#45

Post by Create »

Create wrote: post #38
DennisP wrote: post #33

Earlier quoted context omitted.

Corrosion is one of the main objections people bring up, given that the fuel is a liquid salt. Sorenson says there's an alloy that solves the problem.

I do not think that corrosion is the showstopper. It rather seems to be the lack of irresponsible megalomania, which actually fuelled the GE/Westinghouse frenzy. And I can hardly blame anybody for the lack of it, because for all the better... Our planet has became smaller in the last 50 years, and running (tea)pot operations would be a tough sell, even on Fox. But obviously (offshore) oils rigs and gas are no better…

Watch Seaborg and some engineers from ex-USSR above before downvoting without reasoning.

And imagine the powerlines in a play, where Seaborg himself feels he can only act as a puppet -- randian rationalism doesn't work in society. (I do not agree/disagree with all of the comments above, just note)

Re: Thorium nuclear reactors: a possible solution of the energy crisis? (video)

#46

Post by jackpirate »

DennisP wrote: post #34
api wrote: post #7

I hear a lot about the LFTR, and I wonder what the problem is. Is there a major technical hurdle that prevents this from seeing widespread use? Sometimes there is, sometimes there isn't. Sometimes a really good idea never gets used because... well... because nobody really picks it up and runs with it. It's that simple sometimes. But sometimes there's some hidden gotcha.

Mainly it's historical reasons. Light-water reactors were developed first, for nuclear submarines. Once they had those working, everybody went with what they knew, and thorium advocates got fired. Then people forgot about thorium. At this point, NRC regulations assume solid fuel, and the nuclear industry makes most of its money from selling complex fabricated fuel rods. However, there was a small liquid-fluoride reac…

The first reactors were actually heavy water for producing plutonium for nuclear weapons. Light water reactors were developed next because they could still produce plutonium, were cheaper, and could be put on a submarine. But their usefulness on subs was secondary. The USSR built Pb moderated reactors for some Alfa class subs that didn't require anyone working in the engine room. For lots of reasons, this is obviously superior as a submarine reactor tech. (See http://en.wikipedia.org/wiki/Alfa_class_submarine)

The real reason we never went to Thorium is the best reason to go to Thorium. It creates U233, which is not usable for nuclear weapons. (Or at least, no nuclear weapon has ever been built with it.) This would have made it great for exporting to countries without worrying about proliferation. That's the reason we're seeing it become discussed so much more often now.

Re: Thorium nuclear reactors: a possible solution of the energy crisis? (video)

#47

Post by icarus_drowning »

mrothe wrote: post #3

This cutted version feels like none of these persons said anything that is in the video, because the statements (or even words) are "out of context". I just can assume the author of the video has good intentions and did not change the context.

I've watched all of the videos-- this is a very good summary of them. Plus, it isn't like the editor/uploader doesn't make it easy to find the original videos anyway.

Re: Thorium nuclear reactors: a possible solution of the energy crisis? (video)

#48

Post by Create »

pilom wrote: post #42
static_cast wrote: post #40

Earlier quoted context omitted.

I'm not sure if the following links refer to the same thorium architecture but in Germany there was a test-reactor and several rather hard to solve problems appeared http://en.wikipedia.org/wiki/THTR-300 http://juwel.fz-juelich.de:8080/dspace/bitstream/2128/3136/1... [50+ page PDF outlining the problems]

That was a pebble bed reactor which had issues with high pressure containment vessels and solid fuel. The reactors recommended in the video are molten salt reactors which do not have the same issues.

I think the issues were not only technical, as in P and fuel. The trouble was with those who were responsible for the pebble bed reactor project, and accountancy to the public.

The moment management knowingly blamed accidents on Russians with oversight from the authority, they played away their authority to the right of running such experiments: be it solid fuel or liquid.

People (rightly) assume, that the blatant lies were independent of the phase of the fuel

(AVR and HTR as separate projects make no difference in this respect either). And this is what is biting TEPCO: the series of "white" lies.

Re: Thorium nuclear reactors: a possible solution of the energy crisis? (video)

#49

Post by vamsee »

goombastic wrote: post #39
shailesh wrote: post #37

Earlier quoted context omitted.

Another data point: Even in India (which has 25% of world's Thorium reserves), it is a mystery to many, as to why the Govt. chose not to invest more heavily in Thorium based research, rather than going for traditional ones. Edit: grammar.

India seems to only go for technologies that foreign companies have developed. Guess why? Kick backs are a nice way of living the good life. This, even as recent hikes in fuel prices across the country are putting paid to the dreams of a growing economy.

You guys must be kidding: http://www.youtube.com/watch?v=Nl5DiTPw3dk
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