Energy From Thorium Discussion Forum

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PostPosted: Jul 18, 2009 2:45 pm 
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jaro wrote:
Lars wrote:
...the accelerator takes them the last little bit to criticality.

No, it doesn't.

OK poor choice of words. The accelerator provides some neutrons. If the Keffective is 0.95 then each neutron provided by the accelerator ends up generating 1/(1-keff) or 20 neutrons from fissioning fissile material. The point being that the fissile material must be there to start with. You can't start a reactor with an accelerator with just thorium.


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PostPosted: Jul 18, 2009 2:58 pm 
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Re: "You can't start a reactor with an accelerator with just thorium."

Is that always true; maybe not. If a fusion source of neutrons produces 10exp20 neutrons/second as well as the heat from the fusion reactions, an energy multiplication of up to 10 times the fusion energy rate can be obtained from just ordinary thorium. It depends on the Q (1< Q) value of the neuton source.

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PostPosted: Jul 18, 2009 3:16 pm 
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We were talking about an accelerator not fusion.


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PostPosted: Jul 18, 2009 3:19 pm 
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Well, perhaps "no fissile" was a wrong choice of words.

Could it be that someone aims to make a system that has fissile material only from what has been "bred" from Thorium in another reactor, and not "enriched uranium" which might have non-proliferation related complications?


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PostPosted: Jul 19, 2009 4:33 am 
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Molten salt technology is definitely a promising line of development but reprocessing of fuel to remove the fission product poisons is still a grey area. Partly balancing it is ease of removing volatile poisons. Therefore the Indian scientists are treading the more beaten path to a MOX fueled reactor. The next step is metallic fuel.
ADS remains in the region of basic research as the particles of required energy are not easily produced.
Hopefully, Sodium coolant/heat transfer medium shall be replaced before a major accident. Pb-Bi eutectic seems to be under study.
Molten salt could have been an alternative but the fluid-container compatibility is very important. Gas cooled systems may have other problems like lack of assured heat transfer under operating and emergency conditions.


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PostPosted: Sep 19, 2009 6:38 am 
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This description from the WNA makes the Indian AWHR interesting to me. It states that the reactor will consume 65% of the fuel potential energy, with 2/3 of that from thorium. I guess there has to be some extensive, offsite reprocessing.
Quote:
India is developing the Advanced Heavy Water reactor (AHWR) as the third stage in its plan to utilise thorium to fuel its overall nuclear power program. The AHWR is a 300 MWe reactor moderated by heavy water at low pressure. The calandria has about 450 vertical pressure tubes and the coolant is boiling light water circulated by convection. A large heat sink - "Gravity-driven water pool" - with 7000 cubic metres of water is near the top of the reactor building. Each fuel assembly has 30 Th-U-233 oxide pins and 24 Pu-Th oxide pins around a central rod with burnable absorber. Burn-up of 24 GWd/t is envisaged. It is designed to be self-sustaining in relation to U-233 bred from Th-232 and have a low Pu inventory and consumption, with slightly negative void coefficient of reactivity. It is designed for 100 year plant life and is expected to utilise 65% of the energy of the fuel, with two thirds of the energy coming from thorium.

Once it is fully operational, each AHWR fuel assembly will have the fuel pins arranged in three concentric rings arranged:

Inner: 12 pins Th-U-233 with 3.0% U-233,
Intermediate: 18 pins Th-U-233 with 3.75% U-233,
Outer: 24 pins Th-Pu-239 with 3.25% Pu.

The fissile plutonium content will decrease from an initial 75% to 25% at equilibrium discharge burn-up level.

In 2009 an export version of this design was announced: the AHWR-LEU. This will use low-enriched uranium plus thorium as a fuel, dispensing with the plutonium input. About 39% of the power will come from thorium (via in situ conversion to U-233), and burn-up will be 64 GWd/t. Uranium enrichment level will be 19.75%, giving 4.21% average fissile content of the U-Th fuel. While designed for closed fuel cycle, this is not required. Plutonium production will be less than in light water reactors, and the fissile proportion will be less and the Pu-238 portion three times as high, giving inherent proliferation resistance. The AEC says that "the reactor is manageable with modest industrial infrastructure within the reach of developing countries."

In the AHWR-LEU, the fuel assemblies will be configured:
Inner ring: 12 pins Th-U with 3.555% U-235,
Intermediate ring: 18 pins Th-U with 4.345% U-235,
Outer ring: 24 pins Th-U with 4.444% U-235.


Here is the list with the portfolio of new technologies from WNA

http://www.world-nuclear.org/info/inf08.html


Last edited by robert.hargraves on Sep 19, 2009 11:48 am, edited 1 time in total.

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PostPosted: Sep 19, 2009 7:05 am 
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robert.hargraves wrote:
This description from the WNA makes the Indian AWHR interesting to me. It states that the reactor will consume 65% of the fuel potential energy, with 2/3 of that from thorium. I guess there has to be some extensive, offsite reprocessing.


The article appears to discuss both the third stage reactor in India's nuclear power program and the AHWR-LEU that they intend to export. It's not clear to me that they intend for the AHWR-LEU fuel to be reprocessed. Their three stage program involves an extensive amount of reprocessing.


Last edited by Jess Gehin on Sep 19, 2009 1:13 pm, edited 1 time in total.

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PostPosted: Sep 19, 2009 12:18 pm 
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The AHWR-LEU appears to be designed for export and the fuel is not expected to be reprocessed in user countries. Thorium can be used in twin roles to give a high burn up of 64 GWd/t. Initially it acts as a consumable poison for 19.75% Uranium-235. When the fission product poisons bring down the reactivity, the U-233 created supplements the fissile component. It is stated to be designed for export to developing countries with medium sized grids where 300MW makes a good power source.
The reactors for internal use shall use thorium-U233 and thorium-Plutonium fuel, which can be reprocessed and produce 65% of power from thorium converted and consumed in situ. It shall also produce as much U-233 as in initial un-irradiated fuel. only plutonium shall have to be supplemented from PHWR/LWR initially and later from FBR corresponding to 35% energy produced by burning of plutonium.


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PostPosted: Sep 19, 2009 2:37 pm 
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The burnup specified (64 GWd/t) is not that spectacular. A PWR with 5% enrichment can get in excess of 50 GWd/t average burnups (an OECD/NEA report on very high burnups says that with a 4.81% average enrichment in a PWR, the average discharge burnup is 61.9 GWd/t). In a once through scenario, enriched uranium + thorium does not provide much benefit. It would probably be more cost effective to just go with 5-6% enriched uranium and skip the thorium all together.


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PostPosted: Sep 19, 2009 9:09 pm 
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Even in high burn up LEU fuels, part of power comes from in situ conversion of U238 to plutonium and its burning. In case of AHWR it also happens in Th-U233-fission route. In the original AHWR fuel it is 65% by thorium route. In AHWR-LEU, it is reduced to 39% due to presence of U238.
The figures do not include reprocessing. The original AHWR fuel recovers 100% U233 on reprocessing. Only plutonium is depleted and has to be supplemented as there is no U238 in the fuel.
What is specific to AHWR design is use of thorium as fuel. It is achieved by providing U233 and plutonium as fissile feed in the original fuel design and 19.75% LEU in the new design. Both these possibilities have been considered in LFTR discussion in this forum but 100% of power from thorium is possible as there is partial removal of volatile fission product poisons from fluid fuel.
The comparison of solid fuel designs and fluid fuel concepts is interesting for participants in the forum.


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PostPosted: Sep 26, 2009 12:36 am 
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Thorium: A new American foreign policy tool.



By Dr. Gal Luft (...his thorium facts are a little off but it is a good start)


The Obama administration should actively promote alternative energy corridors which will prevent Iranian gas from reaching major markets while addressing Asia’s and Europe’s energy needs. Washington should therefore impress upon Islamabad, recipient of $1 billion-plus yearly of U.S. aid, to adopt TAPI rather than the Iran-Pakistan-India pipeline.


If the United States aims to stop Iran’s ambitions for regional hegemony, it is also in its interest to advance Europe’s and India’s use of renewable electricity and even coal rather than natural gas. And if those two markets insist on using gas, this gas should come in the form of liquefied natural gas (LNG) which can be imported from any gas exporter rather than in the form of Iranian gas.


The United States should cooperate with India on the development of a thorium nuclear fuel cycle rather than the commonly used highly problematic uranium-based nuclear fuel cycle. Thorium cannot be used as bomb material in any way; its fuel cycle is inherently incapable of causing a meltdown; its waste material consists mostly of 233-uranium, which can be recycled as fuel; its waste material is radiotoxic for tens of years, as opposed to the thousands of years with today’s standard radioactive waste; and it exists in greater abundance than uranium.


Only this month India announced that it has designed a new version of its advanced heavy water atomic reactor which will use thorium and low-enriched uranium (instead of highly enriched uranium) as fuel. At a time when the entire Middle East is going nuclear, this is a major opportunity for the United States to cooperate with India—after Australia, India and the United States have the second- and third-largest reserves of thorium—on advancing a safe pathway to globally-used peaceful nuclear power.


-----------------------------------------------------------------------------------------------------------------


Dr Gal Luft is executive director of the Institute for the Analysis of Global Security (IAGS) a Washington based think tank focused on energy security and co-founder of the Set America Free Coalition, an alliance of national security, environmental, labor and religious groups promoting ways to reduce America's dependence on foreign oil. He specializes in strategy, geopolitics, terrorism, energy security and economic warfare. Newsweek Magazine called him a “tireless and independent advocate of energy security,” the business magazine Poder called him "one of the most recognizable figures in modern energy and security issues," and Esquire Magazine included him in its 2007 list of America's Best and Brightest.


Dr. Luft has published numerous studies and articles on security and energy issues in various newspapers and publications such as Foreign Affairs, Foreign Policy, The American Interest, Commentary Magazine, Middle East Quarterly, LA Times, The Washington Post and The Wall Street Journal. He holds degrees in international relations, international economics, Middle East studies and strategic studies and a doctorate in strategic studies from the Paul H. Nitze School of Advanced International Studies (SAIS,) Johns Hopkins University.

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PostPosted: Sep 26, 2009 4:56 am 
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The main bottleneck in India's thorium fuel development is a shortage of starter fissile load. Kakodkar has insisted that it shall take decades of fast reactor development to collect enough fissile matter to start with thorium fuel commercially. Extending access to reactor grade plutonium or U-233 stocks shall really expedite matters. The least that can be done is to clear reprocessing of spent fuel from US supplied reactors under IAEA safeguards for power production. This should cover use of recovered reactor grade plutonium for fast reactors or thorium fuel. Best for India would be import of reactor grade plutonium from UK, France or Russia.


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PostPosted: Nov 23, 2009 1:13 am 
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The link for brochure of AHWR300-LEU :-
http://www.dae.gov.in/gc/ahwr-leu-broc.pdf
It is a design of a reactor using 79% thorium in the fuel. Interesting part is the uranium recovered from the used fuel. It has 6.5% U233 and 1.6%U235 and could be used as a fuel in a LWR probably after adding an equal quantity of thorium. The uranium recovered after second use could, I think, be used neat as a fuel for the third cycle.
The italicized part is my guess.


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PostPosted: Nov 26, 2009 7:42 pm 
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There has been a minor setback to stage 2 of Indian nuclear plan with failure of Indian PM in obtaining a US clearance for reprocessing fuel used in the US supplied power plants.
http://www.hindu.com/2009/11/26/stories ... 670100.htm
I only hope that the PM's statement is a correct state of negotiations and not a face saving explanation.
The reactor grade plutonium available, though of poorer isotopic quality than that recovered from the PHWR used fuel, may be enough for one 500MW fast reactor.


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PostPosted: Nov 28, 2009 11:37 pm 
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There is comment on the AHWR300 LEU.broc:-
http://theenergycollective.com/TheEnerg ... (all+posts)
The only problem in implementation is non-availability of 19.75% enriched uranium with India. It is an industrial and not a technical problem. Hopefully the Russians can supply that.


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