Discussion in 'Science and Technology' started by Harpreet, Jul 8, 2011.
Some of the advantages of Moltan salt reactor(LFTR) over current reactors:-
1. It's safe to operate and maintain: Molten fluoride salts are mechanically and chemically stable at sea-level pressures at intense heats and radioactivity. Fluoride combines ionically with almost any transmutation product, keeping it out of circulation. Even radioactive noble gases come out in a predictable, containable place, where the fuel is coolest and most dispersed, the pump bowl.
2. A molten salt reactor's fuel can be continuously reprocessed with a small adjacent chemical plant. The requirement is a 4-meter-tall molten niobium column to separate proactinium from the fuel salt, and a small vapor-phase fluoride-salt distillation system to remove fission waste products. The amounts involved are about 80kg of waste per year per GW generated, so the equipment is very small. A sparge of fluorine will even remove U233 from the salt. There has to be a small storage facility to let the proactinium from the niobium column decay to U233. A very small reprocessing facility will service a large 1Gw power plant.
3. With continuous reprocessing, a fluid-salt-fueled reactor has >97% burn-up of fuel. This is -very- efficient, compared to -any- system, -anywhere-.
4. The molten-salt-fueled reactor operates much hotter than LWR reactors, near 900C, so that very efficient Brayton cycle (turbine) generators are possible. This is -also- -very- efficient, a -goal- of so-called generation IV reactors. MSRs have -already- reached this goal.
5. MSRs work in small sizes, as well as large, so a utility could easily build several small reactors (say 100Mwe) from income, reducing interest expense and business risks.
6. Molten salt fuel reactors are not experimental. Several have been constructed and operated at high temperatures for extended times, with simple, practical validated designs. There's no need for new science at all, and very little risk in engineering new, larger or modular designs.
Combining 3 to 6, a molten-salt thorium breeder is the most efficient well-developed way of converting a fuel metal into electricity.
7. Extensive validation (fuel rod design validation normally takes -years- and prevents effective deployment of new nuclear technologies) is not needed. The fuel is molten, chemical reprocessing eliminates reaction products, and there are tested fuel mixtures.
8. There's no need for fuel fabrication. This makes the reactors even cheaper to operate. It poses a business challenge to the industry, because reactor manufacturers are customarily paid by fuel fabrication profits. A government agency could, however, type-license a design, and license it to utilities.
9. Molten-fuel reactors can be made inherently safe: Tested fuel-salt mixtures have negative reactivity coefficients, so that they decrease power generation as they get too hot. Most fuel-salt reactor vessels also have a freeze-plug at the bottom that has to be actively cooled. If the cooling fails, the fuel drains to a subcritical storage facility.
10. Continuous reprocessing reduces numerous reactor design issues. For example, the poisoning effects from Xenon-135 are not present. Neutron poisoning from fission products can be continuously mitigated.
11. A fuel-salt reactor is mechanically and neutronically simpler. There are only two items in the core: fuel salts and moderators. This reduces concerns with moderating interactions with positive void coefficients as water boils, chemical interactions, etc.
12. Coolant and piping need never enter the high-neutron-flux zone, because the fuel is used to cool the core. The fuel is cooled in low-neutron-flux heat-exchangers outside the core. This reduces worries about neutron effects on pipes, testing, development issues, etc.
13. The salt distillation process means that chemical separation and recycling of fission products, say for nuclear batteries, is actually cheap. Xenon and other valuable transmuted noble gases separate out of the molten fuel in the pump-bowl. Any transuranics go right back into the fuel for burn-up.
Don't confuse molten-salt-fueled reactors (MSFR) with molten-salt-cooled reactors (MSCR), a Gen IV proposal. The MSCR can't reprocess fuel easily and has fuel rods that need to be fabricated and validated, delaying deployment by up to twenty years from project inception.
There are some advantages from Thorium fuel, that the India project might capture:
14. The thorium fuel cycle produces almost no (theoretically none) long-lived transuranic wastes. The fission wastes are less radioactive than natural ores in 300 years. The India proposal may get this, but only by adding a large, expensive fuel reprocessing factory.
15. Thorium can resist proliferation. An easy variation of the thorium fuel cycle contaminates the Th232 fuel with chemically inseparable Th230. The Th230 breeds into U232, which has a powerful gamma emitter in its decay chain (Tl-208) that makes the reactor fuel U233/U232 impractical in a bomb, because it harms electronics.
16. Thorium is more abundant than uranium, especially in India.According to recent estimates india have 8,46,477 tonnes of thoriumPress Information Bureau English Releases which is more than 50% of the total proven thorium reserves of the world.
Thorium is a largely unexplored alternative and hence limited discussion, but its promise is huge.
Its intriguing how our scientific godfathers back in 50s and 60s perceived this to be a lucrative and "must go" area while the technically advanced west is still just waking up to Thorium.
They must've seen something in Thorium. We already have a good base of research and reserves. The only need is to maintain momentum and keep the stupid political fraternity from messing the scene.
God willing, like ISRO the Thorium technology would be a "touch wood" silver lining for us.
Thorium could be fuel of the near future for nuclear plants. - swissinfo
Swiss nuclear future could hinge on thorium
Hello Kunal and Harpreet,
Thanks for the initial info I sought sometime back.
I've been thinking of Molten Salt reactors and India's reluctance to look at this technology. It may not be a very bad thing. This is why I think we have decided to stick with the AHWR.
Firstly we need to understand that LFTR does not replace all three stages of the current Indian program. It only replaces the third stage, ie the AHWR stage. We still need to generate seed fuel to start the LFTR cycle. With the way India has been treated wrt nuclear technology by the west, it is critical that we master the fast breeder stage so that adequate plutonium is available to then go for a large scale deployment of thorium based reactors. This deployment could be based on any thorium technology. Hence if LFTR has matured as an option, then it is actually quite simple to adopt and deploy it. In the meantime, if the AHWR has also been mastered, then it gives us a competitive thorium fuel cycle advantage. The critical aspect if to be abel to master the fuel cycle.
Secondly, all arguments being made by the proponenets of the LFTR are based on the Oak Ridge reactor that the US ran decades ago. There is no working model yet even on an experimental scale and only diagrams exist. On the other hand the first AHWR will hopefully go critical within 5-6 years from now. The AHWR is nothing but a proven PHWR modified to use thorium as the primary fuel. The news of Kakrapar 1 using thorium was basically BARC testing a PHWR to run thorium. In other words the AHWR will be quite a mature technology even before the first reactor goes critical.
Further, if we are to become an advanced nuclear technology nation, it is critical that we do not restrict ourselves to just one channel or direction. Versatility is important. I have a sneaky feeling that BARC alredy has started studies in MSR's, probably even decades ago, as this is not new technology. The Indian nuclear industry is one of the most creative. They wouldnt ignore an outright winner - if the LFTR was it.
Either way - the most critical of the three phases is not the third. It is the second. Let us hope that our FBR's are safer and more robust than what other countries have managed thus far.
p.s. I would actually put BARC way ahead of ISRO. Its just that ISRO is more high profile because its space and visibility is more. C'mon, even you have to admit that the 1998 test of the thermonuke was a pleasant and unexpected surprise to the common Indian man and a rude shock to the rest of the world.
Apologies if this was posted earlier, however if not please read this
Daily Kos: The Light of Day: India's Fast Breeder Nuclear Reactor: Some Technical Comments. (Pt. 7)
This is the last part of a seven part analysis of the Indian FBR program. The author concludes...
What is interesting is that the residual U-233 (of which the US has only a few tons) can be used, as Rod Adams helped me to show in the earlier member of this series, to turn almost all of the world's existing nuclear infrastructure into breeders, more or less, albeit marginal breeders.
It is very clear that India is well on its way to building a considerable inventory of U-233.
I ain't got a problem with that. As I pointed out earlier in this series, the only constraint on scaling nuclear energy by a factor of 10 to wipe out dangerous fossil fuels is having readily available fissile nuclei and the more U-233 that is available anywhere on earth, the easier it will be to accomplish this at something like the time scale required.
Let me qualify that. It's too late now to talk about what's "required." The best we can hope for is "as fast as possible to minimize the inevitable damage.
Beyond that, I oppose all nuclear weapons, and I do have a problem with the Indian (and American) nuclear weapons programs, but it is clear to me that India has made a huge technological advance on finding a way to make weapons disarmament technically feasible. That's more than I can say for some other countries in the world.
This is such a well elicited article even though there is a lot of technical analysis.
If india goes for LFTR there will be no need for of first 2 stages because few LFTRs will produce enough U233 which will act as the fissile material of 100s of moltan salt reactors.
yes 3 or 4 reactors which ran under the supervision of Alvin Martin Weinberg are the only examples of MSRs and this is the point if they were able to built this cycle in 60s than why can't we do it even after 50 year with much better technology and brains.
yes u r right all the technologies of MOX fuel cycle of AHWR are well proven at laboratory scale and the design of AHWR having 300 MW capacity is under review of Atomic Energy Regulatory Board .AHWR will be the first reactor which will use Th but thats not the point .what india needs is a cheep energy source which can fuel its fast growing economy and AHWR is like other heavy water high pressured reactor which will need billions of dollars of initial investment for single reactor whereas LFTR is a small reactor which is far more safe the any heavy water reactor requires less investment and even can be built within cities .Some MSRs advocate scientists say that a 10000 MWe single LFTR can be built.
yes u are right again before the start of 3 stage th program they studied all the possible fuel cycles and according to leading thorium scientists of India Balakrishnan,majumdar,Ramanujan,kadodkar this was the result
Thanks Harpreet, this answers quite a few questions. I also wanted to clarify my point regarding Fissile feed. Per my understanding, fast breeders have the best doubling time of generating fissile material. With our existing stock of reactor grade plutonium, we would be able to only start a few LFTR, which in turn would take several years to supplement us with more fissile feed. I may have misunderstood though. Could you clarify if LFTR's produce more fissile feed at a faster rate that FBR's?
Also I dont think I have read the paper you have referenced to. I will search on google, but would be grateful if you could provide a link. Thanks again.
thorium breeder reactor using slow thermal energy neutrons has a low breeding rate each year it can only breed thorium into about 109% of the uranium-233 fuel it consumes. This means that obtaining enough uranium-233 for a new reactor can take eight years , which would slow deployment of this type of reactor. For fast deployment plans plutonium from FBRs ,decommissioned nuclear weapons and LWRs would start the new thorium reactors .An alternative starting procedure is use of a simple proton beam source (ADS) and there is a small scale research on ADS in india and england.
with our current reactor grade Pu yes only few Th reactors can be started and it is very good that india is investing in FBR technology ,i think 4or 5 FBRs will be sufficient for first generation of LFTRs .
But sad thing is that nobody in taking about LFTR in here india is the only country which is obsessed with solid form of Th(AHWR) and after spending 50years and billions of $ i think we will end up importing LFTRs from china because recently they announced there programme to research in liquid form of Th and research head is the son of former president Jiang Zemin(1993-2003)and if he has decided to do it no one can stop him and we can expect chinese LFTRs within this decade.
I am not so sure about China being able to have a working model of the LFTR within the decade. The LFTR is simple on paper, but this is not another reverse engineering project that their scientists can take apart and mass produce. It takes decades to understand a nuclear fuel cycle, fuel fabrication etc. At most I would expect the Chinese to have a working prototype by the turn of the decade. Add another decade for 2-3 commercial units. But anyway, who am I to speculate
I completely agree that it is important for India to spend money on research on the LFTR. However, private western funding will beat either India or China on commercial LFTR's and I feel this is at least 15 years away.
Our current research is quite diversified both in terms of fuel cycles - Uranium and Thorium as well as in terms of reactor technology, PHWR, BWR, LWR, FBR, AHWR and in development ADS as well as CHTR's. The only one we are missing is the LFTR's. I hope this will be included into the portfolio within 2 years. If we do, our understanding and expertise with the Thorium fuel cycle will then count for a lot as I think we will be able commercialize LFTR's much faster than China or the cash strapped West.
Is there any calculation other than Sorenson et al on efficiency of LFTR? Why is everyone so keen on believing his website?
The eta factor from Indian FBTR is a measured quantity. What has been measured and established (at a realistic prototype scale) for the LFTR?
It is not small. Look up CAT, Indore. There is collaboration with Fermilab in USA on ADS.
The european project is more advanced - they are building a demonstrator project in Belgium.
India's experimental Thorium Fuel Cycle Nuclear Reactor [NDTV Report]
Thorium Energy Alliance produced this very short video to help the general public understand the basic operation of the Liquid Flouride Thorium Reactor (Molten Salt Reactor). It covers the main areas of operation of a Thorium Based Power Plant - Join Us!: thoriumenergyalliance.com
Sorensen is basing the calculations on the Oak Ridge reactor that went critical and was later shut down in the 60's. This still does not change the fact that the technology is promising and India should also invest in its Research or at least partner with other entities.
We are spending 20 billion dollars on solar energy this decade, which is absolute rubbish as solar technology is still 15 years from reaching the efficiency levels that will beat coal from a cost perspective. The only positive about it is that we would have some base infrastructure in place to scale up later if the costs come down.
Even if 5 out of that 20 billion was diverted to LFTR research, we may be able to reap much richer benefits.
India will start Thorium-based Advanced Heavy Water Reactor(AHWR,300-MWe) project
India will start Thorium-based Advanced Heavy Water Reactor(AHWR,300-MWe) project in next 18 months
Chennai, Feb. 21:
Tapping its abundant thorium reserves, the Government has decided to commence the construction of 300-MW thorium-based Advanced Heavy Water Reactor in the next 18 months, a senior official said on Tuesday.
â€œUnder the third stage of nuclear programme based on thorium utilisation, a reactor of 300 MW will be constructed in a year and a half from now..,â€ Kalpakkam-based Indira Gandhi Centre for Atomic Research Director, Mr S.C. Chetal, told reporters here.
â€œThe work for that will commence in the next Five-Year Plan,â€ he said on the sidelines of a function.
According to Bhabha Atomic Research Centre (BARC), the currently known thorium reserves in India amount to 3,58,000 GWe-yr of electrical energy and can â€œeasily meet the energy requirements during the next century and beyond.â€
Mr Chetal said, a technology to separate uranium from thorium was being developed by BARC in the third phase of its nuclear programme.
India was also having collaboration with France and the US.
â€œWe will have reactors at different parts of the country... at Jaitapur in Maharashtra with the help of the French (1,650 MW) and with US, sites are being identified and target for nuclear energy is 20,000 MW. Today we have 4,780 MW,â€ he said.
Asked whether States were keen to set up nuclear power facilities, he replied in the affirmative.
â€œIn fact, the rush is much from various States which are not able to fulfil (energy) requirements.
For example, we have potential sites at Hisar in Haryana and sites in Madhya Pradesh, Andhra Pradesh and West Bengal. We have demand from every State.â€
A large part of construction of India's first Prototype Fast Breeder Reactor at Kalpakkam had been completed. .
â€œAs of last month, 81.5 per cent of the construction is over,â€ Mr Prabhat Kumar, Project Director, Bharatiya Nabhikiya Vidyut Nigam Ltd, said.
Business Line : Industry & Economy / Economy : Work on thorium-based reactor to commence soon
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