Energy From Thorium Discussion Forum

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 Post subject: Re: Waste Disposal
PostPosted: May 23, 2014 9:06 am 
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This is so obvious. Somebody needs to explain to DOE
and NRC the difference between gamma and alpha.


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 Post subject: Re: Waste Disposal
PostPosted: May 23, 2014 11:52 pm 
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The Russians, Chinese and Indians are going to close the fuel cycle and go to fast reactors anyway. US could keep ahead only by using fast MSR's. The Chinese are striding past in MSR too.


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 Post subject: Re: Waste Disposal
PostPosted: Jul 05, 2014 1:40 am 
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http://www.world-nuclear-news.org/WR-Tr ... 06147.html
What would be the problems, if any, in drying the sludge to solid blocks for storage? The dry blocks could be partitioned by chloride volatility and fractional distillation. The uranium and trans-uranics could be recycled. Transuranics could also be used with thorium as fertile fraction of fuel, in solid or liquid fueled reactors.


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 Post subject: Re: Waste Disposal
PostPosted: Aug 31, 2014 2:52 am 
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EDWARD DAVIS, USNIC: In the Matter of Waste Confidence, We so Deem
http://www.nucleartownhall.com/blog/edw ... e-so-deem/
It looks like the US has opted out of central storage and closed cycle. Any changes in the nuclear are going to be only evolutionary. MSR/LFTR will have to go abroad for survival.


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 Post subject: Re: Waste Disposal
PostPosted: Sep 02, 2014 9:29 pm 
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Location: Portland Oregon
Interesting fact, the biggest vitrification plant in world is being built in the USA, specifically at Hanford. The plant is planned to be completed in 2016.

https://www.youtube.com/watch?v=na8qqyYb5dg

They will have two types of vitrification systems. One for high level waste in smaller 14 foot stainless steel cylinders and one for low level waste in larger stainless steel containers. The high level waste will be “temporally” stored at Hanford, pending a permanent site location selection. The low level waste will be permanently stored at Hanford.

Clearly, and the stated purpose of this plant if for the cleanup of Hanford, however when they are done, they will still have the worlds largest vitrification plant. Someone is thinking about long term storage in the USA.

Being optimistic, when LFTR and other MRS that can burn up high level waste come on line, only low level will be left do deal with, and Hanford has already said they will vitrify and permanently store low level waste.


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 Post subject: Re: Waste Disposal
PostPosted: Sep 02, 2014 11:23 pm 
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There are others who think that it makes on-site storage permanent.
http://www.forbes.com/sites/jamesconca/ ... ear-waste/
If Yucca could be abandoned after so much time and effort, whither a mere vitrification plant? There has never been any talk of reprocessing for decades now. Logically, it comes before MOX, MSR or LFTR. Vitrification only comes later. Hello China!


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 Post subject: Re: Waste Disposal
PostPosted: Sep 03, 2014 7:25 pm 
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Location: Idaho Falls, Idaho
That is assuming they ever get the thing built and running. The US government is not very resource savvy. They will trash it when done. They are in the businesses of spending money not saving it.


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 Post subject: Re: Waste Disposal
PostPosted: Sep 04, 2014 6:08 am 
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michael.runyan wrote:
Being optimistic, when LFTR and other MRS that can burn up high level waste come on line, only low level will be left do deal with, and Hanford has already said they will vitrify and permanently store low level waste.

Would the long lived FPs that remain after the proverbial 300 years be considered HLW or LLW?

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 Post subject: Re: Waste Disposal
PostPosted: Sep 04, 2014 12:10 pm 
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Location: Portland Oregon
KitemanSA wrote:
michael.runyan wrote:
Being optimistic, when LFTR and other MRS that can burn up high level waste come on line, only low level will be left do deal with, and Hanford has already said they will vitrify and permanently store low level waste.

Would the long lived FPs that remain after the proverbial 300 years be considered HLW or LLW?

Excellent question. To clarify what they said was High and Low “Activity” wastes. And to clarify what I was thinking when I made that statement; LLW being side product of fuel refining (daughter products found in the ore), handing materials, waste handing materials and equipment, other things that become contaminated from these activates, etc. AND have medium to long length (300 – 300,000+ year) decay out times. So, things with traces of trans-uranics, long decay chains or small traces of high activity material.

The Fission products (1-300 years for decay out) would be concentered High Activity. However, one could argue if vitrification would be the right choice for those anyway. With LFTR or MSR, the fission product could be separated at least into groups or specific elements. Most of them will be decay out by 10 years (probably spend that much time in line for vitrification), so just put it in a Stainless Steel can and wait. Cs-137 and Sr-90 are the two that have 300 year decay out times. However, other more useful thinks could be done with them. But if it was chosen to vitrify that material, it would be High Activity waste. However, I think coming up with a plan to store material for 300 year is more doable because that is it time scales that humans can understand. So, I stand corrected, if we chose to vitrify Cs-137 & Sr-90, that would be a HLW, but I think it would be a waste of useful material and the other fission products make no since to vitrify because the decay out so quickly.


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 Post subject: Re: Waste Disposal
PostPosted: Sep 04, 2014 12:24 pm 
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Just put the fission products in concrete dry casks fo ra few centuries.
Then run extractions and concentration operations to remove the decayed away material and leave only LLFPs, then vitrify.


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 Post subject: Re: Waste Disposal
PostPosted: Sep 05, 2014 8:12 am 
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Fission products Cs-137 and Sr-90 re useful decay fuels like Pu-238. They could be put in as fuel for an RTG and safely buried with leads coming up.


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 Post subject: Re: Waste Disposal
PostPosted: Sep 05, 2014 11:33 am 
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jagdish wrote:
Fission products Cs-137 and Sr-90 re useful decay fuels like Pu-238. They could be put in as fuel for an RTG and safely buried with leads coming up.

Sr90, yes, almost all it's energy comes out in a beta. Cs137, not so much. Its energy comes out in a strong gamma which is much more difficult to thermalize. Cs137 seems like a much better fit with irradiative preservation.

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 Post subject: Re: Waste Disposal
PostPosted: Sep 05, 2014 12:55 pm 
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KitemanSA wrote:
jagdish wrote:
Fission products Cs-137 and Sr-90 re useful decay fuels like Pu-238. They could be put in as fuel for an RTG and safely buried with leads coming up.

Sr90, yes, almost all it's energy comes out in a beta. Cs137, not so much. Its energy comes out in a strong gamma which is much more difficult to thermalize. Cs137 seems like a much better fit with irradiative preservation.


Its too bad there aren't any non-water-soluble forms of cesium - or are there?


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 Post subject: Re: Waste Disposal
PostPosted: Sep 05, 2014 1:17 pm 
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You can make borosillicate glasses that use caesium instead of sodium. Up to 55% caesium by mass apparently.


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 Post subject: Re: Waste Disposal
PostPosted: Sep 10, 2014 4:51 pm 
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I suspect the most cost effective thing to do with the fission products is to simply store them for a long time (a few hundred years). This is a time scale we can engineer for. The volumes and heat are quite manageable. I bet the world will want the trans-uranics removed as best we can first.
But there will still be residual TRUs and "plutonium is the most deadly material known" or some such non-sense has been planted into the public's mind so because of the trace TRUs I presume we would still need to vitrify and bury the stuff. From an engineering perspective likely a waste of money but probably cheaper than the fighting the PR battle.

I wouldn't be in a hurry to vitrify. As things decay they change elements, which changes the chemical compounds. It is probably bad for the vitrification to expose it to the heat, radiation, and chemical changes inherent with the decay of isotopes. So be patient.

The other thing that comes along with a low TRU thorium cycle is a much higher Pu238 content with its 88 year half-life. The Pu-238 changes the heat output of the spent fuel significantly after a few decades. So if the TRUs are not extracted then the heat load is higher and longer lasting.


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