4 ms·

They are not wrong, but also not right in all scenarios. Truth very much depends on the reactor design. Thorium is often associated with Gen4 reactors which are

by HorstG 7y ago

They are not wrong, but also not right in all scenarios. Truth very much depends on the reactor design. Thorium is often associated with Gen4 reactors which are responsible for the claims of superior safety. Not much, but some of the safety benefit comes from thorium. Similar for the claim of less waste: Some reactors have better neutron economy, burning their own waste down to more shortlived and therefore "better" isotopes. Or, by the same mechanism, can utilize existing waste as fuel. Also, continuous loading and separation of isotopes only works well with liquid fuels which is a Gen4 idea. Thorium is more of a side-topic there. On the economic side of whether thorium is cheaper, the submission argues in a very underhanded manner. Yes, fuel is cheap compared to building the plant in all cases. But the fuel cost of thorium is an order of magnitude below uranium due to no enrichment (for light water reactors in the fuel, for heavy water reactors of the water). And possibly (for liquid core reactors) the unnecessary fuel elements production.

acidburnNSA 7y ago
> But the fuel cost of thorium is an order of magnitude below uranium due to no enrichment This turns out not to be true in practice. Uranium-238 is fertile just like Thorium-232. To run a reactor off either of these fertile fuels requires breeder reactor technology, which involves chemical separations and exotic fluids. In practice, this has always been more expensive, even though the U-238 or Th-232 is not enriched. It turns out that breeder reactor infrastructure outweighs the cost reduction in not having to enrich. In fact, this is the primary reason that we don't have any breeder reactors today: it's simply cheaper to mine and enrich uranium than to reprocess. There are political reasons as well, but the primary reason is this economics.
pfdietz 7y ago
The FRONT END of the fuel cost is lower. But in a molten salt reactor with fuel dissolved in the salt, reprocessing is not optional! The fission products have to be removed from the fuel salt at some point (reprocessing) because the salt is expensive (especially FLiBe). So the back end of the fuel cycle will impose costs that do not exist with today's once through fuel cycles.

by HorstG 7y ago

acidburnNSA 7y ago

> But the fuel cost of thorium is an order of magnitude below uranium due to no enrichment This turns out not to be true in practice. Uranium-238 is fertile just like Thorium-232. To run a reactor off either of these fertile fuels requires breeder reactor technology, which involves chemical separations and exotic fluids. In practice, this has always been more expensive, even though the U-238 or Th-232 is not enriched. It turns out that breeder reactor infrastructure outweighs the cost reduction in not having to enrich. In fact, this is the primary reason that we don't have any breeder reactors today: it's simply cheaper to mine and enrich uranium than to reprocess. There are political reasons as well, but the primary reason is this economics.

pfdietz 7y ago

The FRONT END of the fuel cost is lower. But in a molten salt reactor with fuel dissolved in the salt, reprocessing is not optional! The fission products have to be removed from the fuel salt at some point (reprocessing) because the salt is expensive (especially FLiBe). So the back end of the fuel cycle will impose costs that do not exist with today's once through fuel cycles.