Energy From Thorium Discussion Forum

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PostPosted: Sep 08, 2016 6:04 pm 
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KitemanSA wrote:
Ummm, no, it can't. The U/Pu fuel cycle CANNOT burn as much of the U238 as a Th/U cycle can burn thorium, no mtter how the thermal cycle is engineered. The Pu fission just does not produce enough neutrons to burn up the fuel all the way. Pu thermal fission only produces ~1.9 neutrons while a mininmum of 2 is needed to burn fully even in a neutronincally perfect reactor.

But 238U in spent fuel is effectively an inert diluent radiologically, even after a hundred thousand years this is the case.
Having a few tonnes of 238U mixed in with your fission products does not significant change your disposal costs or volumes (since uranium is so dense and most stores are thermally limited for the first few millenia).

You are chasing a cycle with negligible fuel costs, which is unfortunately not particularily valuable since existing fuel cycles have nearly negligible fuel costs.


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PostPosted: Sep 09, 2016 11:39 am 
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Joined: Jun 05, 2011 6:59 pm
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E Ireland wrote:
KitemanSA wrote:
Ummm, no, it can't. The U/Pu fuel cycle CANNOT burn as much of the U238 as a Th/U cycle can burn thorium, no mtter how the thermal cycle is engineered. The Pu fission just does not produce enough neutrons to burn up the fuel all the way. Pu thermal fission only produces ~1.9 neutrons while a mininmum of 2 is needed to burn fully even in a neutronincally perfect reactor.

But 238U in spent fuel is effectively an inert diluent radiologically, even after a hundred thousand years this is the case.
Having a few tonnes of 238U mixed in with your fission products does not significant change your disposal costs or volumes (since uranium is so dense and most stores are thermally limited for the first few millenia).

You are chasing a cycle with negligible fuel costs, which is unfortunately not particularily valuable since existing fuel cycles have nearly negligible fuel costs.
That doesn't matter to many people. Having wastes of that volume and activity for that long is "bad", in most people's minds. Wasting fuel is bad in mine. With proper engineering, both fuels can be burned to completion and in percentages near their relative occurence on earth. The engineering should be quite easy.

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PostPosted: Sep 09, 2016 1:18 pm 
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Joined: Nov 18, 2011 11:44 pm
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Having wastes of that volume and activity for that long is "bad", in most people's minds.


Such people typically demand that nuclear be perfect or else shut up shop. It explains the fascination with fusion because it's some non existant technology that is sold as being perfect. You'll never win the waste debate with perfectionists no matter how many decades you spend on engineering down the waste profile. Just put the best information out there then avoid wasting too much time on the debate.

Once nuclear power is in and working most people never give it a second thought unless there is an accident or you decide to build another one. So I think the most important thing in winning the PR debate is to avoid having accidents and make them quick to build.


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