Roadblocks to burning Solid Thorium Fuel

[koab1mjr]

Hi all

Maybe a juvenile question but throw it out there anyways

I know India is heavily vested in thorium due to the abudance in that region. I was wondering why current vendors are not looking to develop a thorium burning reactor to market to these guys or at least a modificaion to current tech to burn it.

I would figure it would be a goldmine if you could design a thorium bundle that could be stuck in the current nuclear fleet. I assume there is some major issue that is preventing this effort. I know a lot of research is going intto liquid thorium but that adds to the complexity and given the conservative nature small steps are necessary. I feel a thorium fuel rod would be the best bet if the world wants another fuel cycle beside uranium.

Looking for some insight into the subject

Thank in advance.

 

[etudiant]

You are quite correct that thorium could be used in conventional reactors.
There was at least one effort that I was aware of, based on work done in Soviet nuclear facilities, to produce thorium fuel bundles.
Considerable effort was spent to make sure these bundles had the right burn up characteristics to allow them to be used without upsetting the normal reactor schedules. Afaik, there was no unresolved technical obstacle, just very deep reluctance on the part of the US nuclear operators to do anything new and possibly controversial, for a fairly trivial economic gain.

 

[jim hardy]

I thought Thorium was breeder fuel suited for sodium moderated reactors.

Presumably because of the different neutron spectrum from water moderated.

but I'm no nuclear engineer - perhaps a genuine one would elucidate ?

 

[koab1mjr]

hmm that is intersting

is there some efficency hit or something driving such behavior supposedly thorium is really cheap?

In my mind if I were a reactor vendor, I would use this as a ploy to get business from India since it seems they will be major players in the industry for the forseeable future.

 

[Astronuc]

Thorium (Th-232) is fertile, not fissile. It has been considered for a thermal (epithermal) breeder to produce U-233 from neutron capture and successive beta decay (Th-232 + n => Th-233 => Pa-233 => U-233. Otherwise, one must add U-235 to Th-232.

In an LWR, the fuel form would be oxide, i.e., urania in thoria. The problem with that is that one would have to produce highly enriched urania in order to dilute it to a few percent in thoria.

The current square LWR lattices are not necessarily optimized for a thorium based fuel cycle, but the VVER hexagonal (triangular) lattice is well suited to a Th-based cycle.

Thorium based fuel has been irradiated in Shippingport and Indian Point 1 in the US.

 

[gmax137]

There is (or was) an issue over the manufacturers liability in Indian law; I read that this was preventing the US based vendors from selling their current reactors to India. They aren't likely to develop something completely new that they can't sell.

 

[jim hardy]

The problem with that is that one would have to produce highly enriched urania in order to dilute it to a few percent in thoria.

there's the rub -- SWU cost ?

http://www.uxc.com/review/uxc_Prices.aspx

 

[Astronuc]

There is the possibility of hybrid LWR lattices (these have not been optimized), or use of CANDUs for a thorium cycle, in which the SWU penalty is avoided.

For CANDU thorium utilization, see - http://www.nuclearfaq.ca/brat_fuel.htm - toward bottom of page.

 

[etudiant]

Afaik, the fuel cost is a fairly small portion of the cost of reactor produced power.
Hence there is no strong push to reduce fuel costs.
Increased fuel life, to reduce refuelling downtime, would be more attractive. The more serious understanding of what fuel composition it would take to achieve this is beyond me. One could envision thorium getting used to breed U 233, I don't know whether that would extend the fuel life. Some expert might want to contribute and let us know.

 

[Schr0d1ng3r]

There is the possibility of hybrid LWR lattices (these have not been optimized), or use of CANDUs for a thorium cycle, in which the SWU penalty is avoided.

For CANDU thorium utilization, see - http://www.nuclearfaq.ca/brat_fuel.htm - toward bottom of page.

Ah, I was going to mention CANDUs after you brought up the fissile/fertile issue. You beat me to it.

 

[Astronuc]

Ah, I was going to mention CANDUs after you brought up the fissile/fertile issue. You beat me to it.

CANDUs still fission U-235, which is at a level of ~0.71% of natural U. The burnups of the fuel are also low, ~8-10 GWd/tU. Modern CANDU fuel uses slightly enriched uranium.

In thorium, there is no naturally occurring fissile isotope. Thorium fuel needs a fissile component, e.g., U-233, U-235 or Pu-239, Pu241.

 

[Schr0d1ng3r]

CANDUs still fission U-235, which is at a level of ~0.71% of natural U. The burnups of the fuel are also low, ~8-10 GWd/tU. Modern CANDU fuel uses slightly enriched uranium.

In thorium, there is no naturally occurring fissile isotope. Thorium fuel needs a fissile component, e.g., U-233, U-235 or Pu-239, Pu241.

Yes, I know. Poor communication on my part though, I suppose. It just reminded me, that's all. And, correct me if I'm wrong, but don't the operating CANDU fleet all use natural uranium? I was under the impression that only the ACR-1000 is designed to use SEU, and that project is on hiatus since the sale to SNC-Lavalin.

 

[Astronuc]

Yes, I know. Poor communication on my part though, I suppose. It just reminded me, that's all. And, correct me if I'm wrong, but don't the operating CANDU fleet all use natural uranium? I was under the impression that only the ACR-1000 is designed to use SEU, and that project is on hiatus since the sale to SNC-Lavalin.

I haven't kept up with the use of SEU, but it may have been implemented on a limited basis.

http://www.nuclearfaq.ca/brat_fuel.htm has a section on SEU.

http://www.infim.ro/rrp/2005_57_3/margeanuc.pdf
http://www.touchbriefings.com/pdf/2771/ACF1928.pdf

http://www.touchbriefings.com/pdf/2771/ACF1928.pdf

New Perspective on Using Thorium-based Fuel in CANDU Reactors
http://www.jnrd-nuclear.ro/No.1/JNRD_No1_paper05.pdf

Apparently CANFLEX bundles have been used in OH CANDU's.
http://canteach.candu.org/library/D407_scr1.pdf

SEU in CANDU