Discussion > Thorium question
Worse than that. You can't run thorium reactors without uranium reactors. Where would you get the tritium?
Entropic man
Out of old Trimphones.
Martin A
Apr 22, 2014 at 4:53 PM | Unregistered CommenterEntropic man
What is Tritium used for in a Thorium reactor?? I don't really know much about the detailed processes in nuclear reactors.
Rob Burton
Rob - I assume it is a bit of EM BS.
My understanding is very limited but...
- Tritium has no role in a normal fission reactor (whether thorium or uranium); such a reactor depends on a chain reaction to produce the neutrons needed.
- Someone recently proposed a new reactor concept which would use thorium in which fission would be produced by neutrons generated by an external accelerator of some sort, so it did not need to maintain a chain reaction.
It might be this that EM has at the back of his mind somewhere, as tritium is useful in generating neutrons using an accelerator. But it's an untried concept that sounds very unlikely to be practical to me - in view of how neutrons are pretty hard to generate in quantity OTHER than via a fission chain reaction, which generates oodles of them.
Martin A
It seems likely that EM is thinking of the use of thorium in combined fission/fusion reactors. In conventional thorium reactors tritium is usually seen as an annoying byproduct, and most of the discussion is about minimising its production. (A few enthusiasts note that tritium leads to 3He and so quite like the idea of making and collecting it).
Jonathan Jones
There's an interesting discussion/article on world-nuclear.org on Thorium reactors. When I first read references to Chinese research last year I too was interested in finding out why they were working on this technology. This was a succinct summary.
This states that a neutron source is required, they say U-233, U-235 or Pu-239 are the only options, so the suggestion about using an external source has a good technical reason behind it. Heavy water reactors also get a mention but I can't see any reference to Tritium.
SandyS
SandyS,
Don't forget spallation sources, which are a logically distinct approach to thorium reactors; they have advantages and disadvantages of their own. See http://en.wikipedia.org/wiki/Energy_amplifier for a brief introduction.
Jonathan Jones
Jonathan Jones
Thanks I hadn't read about that, going to the cinema shortly but I'll read the article tomorrow. Looks like there are a lot of avenues to investigate for those of us interested as well as technicians and researchers.
SandyS
This states that a neutron source is required, they say U-233, U-235 or Pu-239 are the only options, so the suggestion about using an external source has a good technical reason behind it. Heavy water reactors also get a mention but I can't see any reference to Tritium.
Apr 23, 2014 at 1:01 PM SandyS
SandyS - Tritium is just an Entropic red herring.
To get a thorium reactor started it needs a fissile element added - as you say U-233, U-235 or Pu-239. Otherwise, with only thorium in it, there would be nothing there to fission. Once it has been running for a while, sufficient U-233 has been bred from the thorium and it can then continue to run, burning up the U-233 that is generated as it runs.
Martin A
There are designs for thorium reactors using a modulated neutron source based on the same technology used in nuclear weapons. This replaces some or all of the initial uranium 233 charge. The initiator works by accelerating deuterium and tritium at a target, where fission/ fusion reactions generate neutrons.
Entropic man
So some reactor designs might use tritium, EM.
That's not the same as your first comment which clearly implied that it was a necessary requirement when, in fact, removal of tritium produced is considered one of the engineering obstacles to be dealt with.
michael hart
Entropic man
Do you have a reference for the use of Tritium?
Having read some of the links supplied above I can't find a definitive reference, in fact no reference at all. The link supplied by Jonathan Jones is worth a read.
Thanks
SandyS
http://www.youtube.com/watch?v=uK367T7h6ZY
'LFTR in 5 minutes'.
Adrian
Longer watch....
http://www.youtube.com/watch?v=bbyr7jZOllI
Adrian
http://www.youtube.com/watch?v=AHs2Ugxo7-8
Adrian
http://www.the-weinberg-foundation.org/wp-content/uploads/2013/06/Thorium-Fuelled-Molten-Salt-Reactors-Weinberg-Foundation.pdf
Adrian
http://energyfromthorium.com/ornl-document-repository/
Adrian
http://blogs.telegraph.co.uk/finance/ambroseevans-pritchard/100026863/china-going-for-broke-on-thorium-nuclear-power-and-good-luck-to-them/
Adrian
Adrian
Are those links to anything specific or do we have to go through them one at time to find out, for example, if they answer the tritium question? Personally I'd have been if they'd been in a single posting.
SandyS
Hi SandyS - starting with the first link (just 5 minutes) enough info for anyone with some scientific/engineering understanding to 'get' the potential for Thorium based power. 'LFTR' = Liquid Fluoride Thorium Reactor' - the design that the Chinese seem to pedalling at full tilt towards.
Then, 2 more videos with more detail on the technology and history. If you have trouble sleeping, the Oak Ridge document repository list shows how far the Americans took it all, before it was shut down. The wet chemistry is horrible (and the main focus of current Chinese research), but the positives - reactor runs at atmospheric pressure, high temperature output and 'safe shutdown with no need for power' are sufficient. The main reason 'Thorium' lost out to Uranium was that a) The US Navy pushed Uranium PWRs (first mover, and they did a good job), and b) Thorium based reactors were not that good at making material for bombs.
So, yes. If you are interested in learning more about the potential for Thorium based power, worth looking at (in approx the order I posted them).
BTW, 'EM' I conclude that you really haven't the slightest clue.
Adrian
SandyS - sorry - specifically, 'The Tritium Question' is an utter nonsense. Ignore EM.
Adrian
Thanks Adrian,
working my way through the presentations. just finished the third. Interesting stuff, will look at some more tomorrow.
SandyS
Sandy S
This is the type of thing I had in mind, along with the need for tritium production for other uses in neutron generators and as an initiator in nuclear weapons.
mragheb.com/.../Fission%20Fusion%20Thorium%20Hybrid.pdf
Entropic man
There are designs for thorium reactors using a modulated neutron source based on the same technology used in nuclear weapons. This replaces some or all of the initial uranium 233 charge. The initiator works by accelerating deuterium and tritium at a target, where fission/ fusion reactions generate neutrons.
Apr 25, 2014 at 12:18 AM Entropic man
More EM BS.
EM - if you believe that, you'll believe anything. [And in any case, it's well known that you will believe anything you read that 'climate scientists' have said.]
To get a thorium reactor to start, it has to have sufficient fissile material (U-233, U-235 or Pu-239) in its core to go critical and sustain a chain reaction.
The number of neutrons needed to initiate the chain reaction in the already supercritical core of a nuclear weapon is utterly utterly miniscule compared with the number of neutrons needed to transmute sufficient kilograms of Th-232 into U-233 to fuel a nuclear reactor.
The only thing known on the Earth that produces sufficient neutrons to do that is a nuclear reactor, by many many orders of magnitude.
Martin A
I have the impression that a number of BH commenters agree that there is great potential for nuclear power generated from thorium.
It is said to have many potential advantages over power generated from uranium (or from the plutonium legacy). However, I have a feeling (no more than that) that some of the challenges may have been understated. A little bit like the way that the issues involved with fast breeder reactors were, some decades ago, widely understated.
One significant advantage of thorium is said to be that it results in less long term radwaste than uranium.
I'd like to see a table of the number of becquerels of radioactivity remaining after 10, 100, 1000, 10,000, 100,000, 1,000,000 years for each MWh produced in:
(a) a uranium reactor
(b) a thorium reactor.
Is this, or something similar, available anywhere?