Here we present a white paper, written by the Berkeley Conferees and SCGI, for the 2012 Dubai World Energy Forum. The focus is expediting the commercial demonstration of the Integral Fast React - a generation IV design which safely recycles nuclear waste to create abundant zero-carbon electricity.
This BNC Discussion Forum thread is for the comments related to this BNC post.
There's no 'silver bullet' for solving the climate and energy crises. The bullets are made of depleted uranium and thorium...
The Russians have had a BN600 running for years, a BN800 coming up next year, and several proposed for China.
The GE Prism is likely too little too late.
I wouldn't be too sure about that. The BN reactors use lead-bismuth coolant (corrosive, and produces radio-polonium) and oxide fuel. The PRISM's metallic fuel has unique advantages, if it can be brought to market in time.
Post by Tom Blees on Oct 25, 2012 17:54:13 GMT 9.5
Metal fuel is a key difference between the PRISM and all these other designs. The Koreans are hip to it and intend to build metal-fueled fast reactors. India intends to switch to metal eventually, and the Russians have talked about it as their intention too. This is one reason it behooves GE to get the PRISM up and running, otherwise they'll definitely be late to the party.
Sorry to be a bit negative as I'm certainly in favor of the IFR system getting a fair chance to prove itself but there are some somewhat dubious claims floating around out there. My research specialty is Molten Salt Reactors and I certainly know some in the associated thorium community tend to stretch the facts as well (which I try to correct when possible).
The main technical point I wish to bring up is the often repeated claim that running IFR's will mean only a waste stream of fission products because all transuranics (Np,Pu etc) are recycled. Thus, the logic goes, after 300 years for fission products to mostly stabilize you are back to radiation levels in the original ore. First minor point is the "original ore" quote refers to comparing to the radiotoxicity of 200 tonnes of natural uranium that would used by a LWR per GWe year. The real issue I have though is that the IFR pyroprocessing was never shown to be extremely effective at avoiding Pu and other tranuranics slipping past into the waste stream. This review by Los Alamos quotes 1% loss, whereas the PUREX process (with its many negatives such as cost) can obtain as low as 0.01% loss.
ADVANCED NUCLEAR FUEL PROCESSING OPTIONS FINAL REPORT October 6, 1997 LA-UR-98-2773
I don't have a reference handy but I've heard from many sources that typical losses in practice were up to 3% and 0.5% was thought likely the best obtainable. To crunch those numbers, if an IFR is processing on site 2000kg of transuranics per GWe year then 0.5% loss would be 10 kg per year. Doesn't sound like much and this is indeed about a 25 fold improvement over PWR Once Through (250 kg) but that 10 kg of mainly Pu will be roughly 1000 times more radiotoxic than the associated fission products after the 300 year mark and about still 20 times higher than fission products after 10,000 years. These log log graphs of PWR Once Through actinides radiotoxicity vs fission products are shown many places, sorry for no reference.
So in my view IFR can really not claim to be that drastically changing the waste profile. Also, I've never been able to find out where that waste Pu ends up. If it is mixed in with tonnes of other process residues it may represent and even greater problem for long term disposal.
I'm sure at least a few IFR advocates will claim the process can be made more efficient with time and maybe that's true but keep in mind, billions were already spent developing pyroprocessing which had an early goal of 0.1% transuranic losses which they clearly came no where near obtaining.
My other slight pet peeve is the usual quote that fast breeders are needed because PWRs only use 1% of the available energy of uranium (thorium community does the same). OK, well if I could show you practical D-D fusion at a low cost would someone then say, sorry we don't want it because you are only using a tiny fraction of water's available energy? No, it has to come down to fuel costs and resource sustainability. Even current LWRs converter reactors could likely supply the world's energy as long as the price of uranium rose somewhat to allow mining of lower grade ores (but I'd completely agree we should try to do better). And of course to end with shameless self promotion, running Molten Salt Reactors as simple converter reactors without processing to remove fission products (just using the salt in multi-year batches) could replace all fossil fuel derived electricity without increasing uranium production or enrichment as they are 4 to 6 times more efficient on uranium use than LWRs (up to 10 times with more optimization).
ORNL TM 7207 (Conceptual design characteristics of a Denature Molten Salt Reactor with Once Through Fueling, 1980) Molten Salt Reactors: A new beginning for an old idea Nuclear Engineering and Design 240 (2010) 1644–1656
Metallic fuel and pyroprocessing of used fuel are good points. Sodium coolant is something else. Development of fast reactors was halted in the US, France, UK and Japan due to sodium fires. Working fast reactors in France, Russia, China and India are also sodium cooled. A safer coolant in form of salt or metal eutectic will be a great positive step in fast reactors.
Post by David B. Benson on Oct 26, 2012 11:46:21 GMT 9.5
David LeBlanc --- Pyroprocessing is electrochemistry and if indeed about 1% goes to the wrong 'ode' (cathode, anode) then it is mixed in with all the fission products. The volume is rather small, about 1 part in 14.5 by weight (see the article for this thread).
Rather than bury in vitrified form, it would surely be possible to run the waste stream through some chemical process to separate the Pu from the fission products. Possibly just pyroprocess the waste stream alone. Assuming there is still 1% going the wrong way, the resulting waste stream would have but 10^(-4) = 0.01% of the total Pu.
And of course to end with shameless self promotion, running Molten Salt Reactors as simple converter reactors without processing to remove fission products (just using the salt in multi-year batches) could replace all fossil fuel derived electricity without increasing uranium production or enrichment as they are 4 to 6 times more efficient on uranium use than LWRs (up to 10 times with more optimization). David LeBlanc
Ok David, I'm sold. Really. I saw your TEAC4 video on Youtube. Any chance to see it soon? (an educated guess would suffice).
With regards to transuranics leaking into the fission product stream.
If this is a problem you could dissolve the accumulated pyroprocessing salt into water (since it is a mix of alkali and alkali earth halides) and then run it through PUREX, except now the fissile content of the waste stream is rather lower than in the original fuel, and thus your criticality issues go away.
And since it doesn't contain any of the Uranium the mass of material to be processed is drastically reduced.
Could do pyroprocessing on site and ship the salt for processing at a central facility that is better equipped to do PUREX.
it doesnt seem necessary on theoretical grounds. The operator sets the voltage to draw down Pu from the chloride melt and yawns till the current vanishes - no more Pu in the melt. Perhaps the production guys got on top of the quality guys again!