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I know I've posted about the flexible nature of the CANDU reactor in the past. Not sure if my American friends on here are aware, but the US actually briefly pursued (and constructed) a heavy water reactor too, but it never amounted to anything.
PHWR reactors have the relatively unique characteristic of being extremely flexible with what fuels them, this is due to the much better neutron economy as the result of the deuterium moderator. It requires much lower levels of fissile material in order to sustain a chain reaction, which is why natural uranium can be used as fuel, requiring no enrichment.
Of course, if you can use natural uranium, that means you can use anything else that provides a similar fissile equivalence, this includes:
- Depleted uranium
- Spent PWR/BWR fuel
- Thorium blended with plutonium or LEU
SNC Lavalin, the company that bought CANDU energy from Atomic Energy Canada Limited produced the following advert for the AFCR CANDU, which is just a slight evolutionary "tweak" of the mature Enhanced CANDU 6, itself a tweak of a design that has been around since the 1970's, but had been evolved into a Gen3/Gen3+ design; kept current.
Which sounds novel, until you look back to historic AECL CANDU vision documents:
Because alternative fuel cycles for the CANDU had been a part of its development all along. They were just never pursued because the market didn't exist.
Put a different way, all existing CANDU reactors are technically capable of running on these alternative fuel cycles, but this has never been advertised as a feature until the AFCR, as part of its development, which happened using the C6's at Qinshan, was for the use of used LWR fuel, and that created the foundation for the "flexible" moniker/designation even though it's basically just a C6 with a few tweaks.
China is the only place in the world currently leveraging an alternative fuel cycle with a CANDU. The rest of them are using the traditional NU fuel bundle design, even India, which has substantial thorium reserves. The reason is that the uranium supply chain and fuel cycle is already well established, which makes it cheap. If uranium were to become more scarce, I suspect we'd see a renewed interest in not only alternative fuel cycles, but also reprocessing.
While there's a ton of interest, presently, in some very revolutionary reactor designs, this also brings with it significant risk. There have been hundreds if not thousands of paper reactors designed over the years that were not pursued or abandoned for reasons that killed their commercial viability. Water has proven to be the most successful moderator, even though it is not the only one to reach commercial success. The UK has had mixed results with graphite, as have the Soviets/Russians. Therefore, it should surprise nobody then that a "modern" spin on traditional designs has become a thing with respect to the latest SMR craze. GE Hitachi are now offering a BWR SMR and SNC has revived the old CANDU 3 design and are now pitching it as an SMR. Both based on mature reactor designs and thus no impediments to their viability and construction.
Contrarily, MSR (molten salt) reactors have some significant hurdles to overcome, one of which being the inherently corrosive nature of the salts, which has proven to be a significant problem with selection of materials and durability of not only the vessels themselves, but pumps and other components. This is why they were never pursued beyond testing back in the 1960's.
Since the C3 is just a scaled-down C6, it has the same potential for flexible fuelling, whether anyone adopts it and uses it however, is another thing entirely.
The next 10-20 years will be an interesting time for the nuclear industry, there's a ton of new technology, something we haven't seen since the 1960's before the PWR and BWR took hold and became the dominant designs. Whether that will translate into an actual uptake of alternative fuel cycle designs will be something to watch. For the US, being able to use their existing waste stores as fuel should have appeal, but there has been no interest in reactors that can actually do that, like the CANDU, thus far. Even PUREX reprocessing, which is tried and true and used extensively in Europe hasn't been pursued. So, if there are alternative fuel cycle reactors built, I suspect they will be the result of private capital invested by folks like Gates.
It all comes back to the established and optimized supply chain. Conceivably a MOX and/or RU or NUE fuel cycle agreement could be negotiated between Ontario and the US, but that's never come to be either, even though the viability of such an arrangement has already been explored. There are all kinds of possibilities, it seems that, for the time being, that status quo has some tremendous staying power, so I'm hesitantly optimistic to see what the future brings.
PHWR reactors have the relatively unique characteristic of being extremely flexible with what fuels them, this is due to the much better neutron economy as the result of the deuterium moderator. It requires much lower levels of fissile material in order to sustain a chain reaction, which is why natural uranium can be used as fuel, requiring no enrichment.
Of course, if you can use natural uranium, that means you can use anything else that provides a similar fissile equivalence, this includes:
- Depleted uranium
- Spent PWR/BWR fuel
- Thorium blended with plutonium or LEU
SNC Lavalin, the company that bought CANDU energy from Atomic Energy Canada Limited produced the following advert for the AFCR CANDU, which is just a slight evolutionary "tweak" of the mature Enhanced CANDU 6, itself a tweak of a design that has been around since the 1970's, but had been evolved into a Gen3/Gen3+ design; kept current.
Which sounds novel, until you look back to historic AECL CANDU vision documents:
Because alternative fuel cycles for the CANDU had been a part of its development all along. They were just never pursued because the market didn't exist.
Put a different way, all existing CANDU reactors are technically capable of running on these alternative fuel cycles, but this has never been advertised as a feature until the AFCR, as part of its development, which happened using the C6's at Qinshan, was for the use of used LWR fuel, and that created the foundation for the "flexible" moniker/designation even though it's basically just a C6 with a few tweaks.
China is the only place in the world currently leveraging an alternative fuel cycle with a CANDU. The rest of them are using the traditional NU fuel bundle design, even India, which has substantial thorium reserves. The reason is that the uranium supply chain and fuel cycle is already well established, which makes it cheap. If uranium were to become more scarce, I suspect we'd see a renewed interest in not only alternative fuel cycles, but also reprocessing.
While there's a ton of interest, presently, in some very revolutionary reactor designs, this also brings with it significant risk. There have been hundreds if not thousands of paper reactors designed over the years that were not pursued or abandoned for reasons that killed their commercial viability. Water has proven to be the most successful moderator, even though it is not the only one to reach commercial success. The UK has had mixed results with graphite, as have the Soviets/Russians. Therefore, it should surprise nobody then that a "modern" spin on traditional designs has become a thing with respect to the latest SMR craze. GE Hitachi are now offering a BWR SMR and SNC has revived the old CANDU 3 design and are now pitching it as an SMR. Both based on mature reactor designs and thus no impediments to their viability and construction.
Contrarily, MSR (molten salt) reactors have some significant hurdles to overcome, one of which being the inherently corrosive nature of the salts, which has proven to be a significant problem with selection of materials and durability of not only the vessels themselves, but pumps and other components. This is why they were never pursued beyond testing back in the 1960's.
Since the C3 is just a scaled-down C6, it has the same potential for flexible fuelling, whether anyone adopts it and uses it however, is another thing entirely.
The next 10-20 years will be an interesting time for the nuclear industry, there's a ton of new technology, something we haven't seen since the 1960's before the PWR and BWR took hold and became the dominant designs. Whether that will translate into an actual uptake of alternative fuel cycle designs will be something to watch. For the US, being able to use their existing waste stores as fuel should have appeal, but there has been no interest in reactors that can actually do that, like the CANDU, thus far. Even PUREX reprocessing, which is tried and true and used extensively in Europe hasn't been pursued. So, if there are alternative fuel cycle reactors built, I suspect they will be the result of private capital invested by folks like Gates.
It all comes back to the established and optimized supply chain. Conceivably a MOX and/or RU or NUE fuel cycle agreement could be negotiated between Ontario and the US, but that's never come to be either, even though the viability of such an arrangement has already been explored. There are all kinds of possibilities, it seems that, for the time being, that status quo has some tremendous staying power, so I'm hesitantly optimistic to see what the future brings.
