In early January, the Chinese announced with fanfare a “great breakthrough” reported to make uranium sixty times more efficient. Technical translation was not too good in this case. Essentially, the Chinese have developed, at a nuclear research facility in Gansu province, a spent fuel reprocessing strategy known elsewhere in the world as a “closed fuel cycle.” Indeed, a technical achievement requiring a lot of skill and resource. The US ceased reprocessing back in the 1970’s under President Carter. The UK, France, Russia and Japan all continue to operate reprocessing lines.
Today, the Chinese went on to clarify what China National Nuclear Corporation (CNNC) really might have meant. In short, it will likely be 10 years before you see any spent fuel enter the processing cycle and then an ensuing 4-5 years to cook the spent fuel into plutonium to be mixed back into fuel for electricity generation. This is meaningful, though, as it demonstrates that China is planning for nuclear power to be a significant element of the mix and that they wish to minimize their long-term dependency on foreign supplies of uranium.
All those countries with re-processing know-how treat the technology as highly classified. Every one has their own unique implementation based on the costs (direct and indirect) that country believes appropriate to bear. There are varieties of reprocessing cycles and the “full on” fast breeder approach designed for maximum reprocessing yields is what gets one to the point of saying “sixty times more efficient.”
If you want to read more expert explanations of this stuff, please take a look at the excellent public resources from that fine school in Cambridge MA, MIT, The Future of Nuclear Power and The Future of the Nuclear Fuel Cycle .
Let me take a crack at a simple explanation of what is going on here. At the most basic level, China believes it now understands how to build a high yield fast breeder reactor to consume post fission waste and convert non-fissile U-239 into Pu-239 (plutonium, the stuff that goes boom) and the related chemical extraction, purification, metal fabrication and waste processing operations that, collectively constitute a “closed” fuel cycle. The adjective “closed” is used here because you can build systems that create more fissionable stuff to be burned for electricity than one consumes. No laws of thermodynamics are being broken, just basic nuclear fission principles. This stuff is not cheap and has associated with it a host of waste, safety and weapons proliferation issues. China does not view costs the same way as might the West and from a security perspective, things here in China can be a tad more, shall we say, assertive, when making certain no one goes where one is not welcome.
Ok.. Quick Fission 101. Most nuclear reactors that make electricity are big pots of water with a heating element inside them. That heating element is a thing called a “core” and looks like a pretty nifty piece of metals engineering. In that core is a mix of powdered metals inside metal tubes or plates. Overall, there might be 3-5% uranium-235 in the fuel when we start up. There are multiple flavors (“isotopes”) of uranium. Uranium with 235 neutrons (U-235) is the one that naturally splits apart (fissions) easily and is the principal fuel for nuclear power generation. Uranium with 238 neutrons (U-238) is referred to as depleted uranium since it does not do much other than sit there and be quite dense (ever hear the phrase depleted uranium ammunition?). Normally the U-235 is what is in the core and as it fissions, or splits apart, it releases neutrons. Those neutrons bang around in the water and slowly transfer their high energy to the water, making it hot (this process is called thermalization and, despite the name, has nothing to do with making the water hot, but instead relates to the neutron energy level). As the neutrons lose their energy, they can then, interestingly, serve to trigger neighbor U-235 atoms to fission as well. This is called a self-sustaining chain reaction. There are lots of ways to control it, so don't fret, and it is too darned complicated and not worth talking about here.
After about 5-10 years of heating water with neutrons, the U-235 concentrations decrease and the buildup of fission waste products reaches the point where we can say, effectively, “out of gas” even though there remains considerable amounts of useful U-235 in the tired fuel. Since uranium is relatively inexpensive (~$60/kg) we use up the fuel and send it to the graveyard to be stored somewhere safe until we either decide we need to reprocess it (for example if uranium were to become quite expensive or inaccessible because some foreign government decided it did not want to sell it to others) or figure out something else clever to do with it. This entire process is called the “Once Through” process and is how things in the West pretty much operate as there is a liquid and economic uranium market, at least for now.
So what if we decided to recover the “unburned” U-235 from the exhausted fuel? Indeed, we can. Just remember nothing is cheap. And what about all the other nuisance nuclear “ash” in the exhausted fuel (ok, ok.. the engineers refer to this as “actinide waste”)? It might also have some value other than as a trope in a bad sci-fi movie.
Remember the not so useful U-238 from above? It wont’ fission by itself, even if incited to do so be all types (e.g. energy levels) of neutrons. Yet it can be converted into plutonium-239 if it absorbs just the right kind of neutron. And Pu-239 can fission and be used as a fuel like U-235 (or be swiped by ne’er do-wells for Dr. Evil purposes).
In order to efficiently convert the U-238 to Pu-239, one must have just the right kind of neutron. The type of reactor that makes that kind of neutron is referred to as a “fast” breeder reactor. The neutrons are “fast” (they have high energy levels compared to “slow,” lower-energy “thermal” neutrons).
Making a fast breeder reactor requires a completely different set of skills because the reactor does not use water. It uses liquid/molten metals and is controlled and managed in ways profoundly different than those methods used to keep water-filled reactors in control. For that nuisance, though, there is a benefit: A fast breeder can consume as fuel the highly radioactive actinide ash created in electricity generation in addition to being able to burn Pu-239.
As they say on TV, “No, wait, there’s more!” You can surround the “core” of fast breeder reactor with a “blanket” of U-238. After tanning in that bath of fast neutrons for 4-5 years, the U-238 has become Pu-239. At this point, the blanket can be harvested and the Pu-239 extracted. Hard to believe, but you can actually design these things to generate more Pu-239 than they consume, so long as you have actinide ash from electricity generation to power the breeder. The “manufactured” Pu-239 can then be extracted and mixed back into a raw U-235 fuel as a fuel “extender” (think hamburger helper). Thus, we are able to reduce the raw U-235 demand and more efficiently use the U-235 we have and get some energy out of the “ash” waste. The downside is there still are waste streams from the breeder process and then you have the weapons proliferation issue. Oh, then there is also the issue of a breeder reactor being more technically challenging to control and if it goes boom, it really will be a very messy BOOM.
In short, the Chinese have said they believe they have worked out a full system design for this breeder process. Why? Well, national interests, desire to not rely on imported uranium sources, a profoundly different concept of cost vs. the West, no effective public opposition, ability to secure a facility in ways the West would find more challenging (assume you will be shot if you can even see the darned place in the distance) and some degree of national pride.
CNNC says it will take them 10 years before they can begin commercial operation. I think this means it will take them 10 years to build the breeder reactor, source the spent fuel and build all the attendant reprocessing bits. Then the spent fuel will need to be cooked and processed into Pu-239 for subsequent mixing into the U-235 fuel stream. Say another 5 years or so. Thus, we are likely ~15 years away from China being able to actually operate a closed fuel cycle and that assumes everything goes smoothly. The Chinese note their process is “home grown” and thus they may encounter some bugs as they work to scale up to commercial-level operations.
While a step forward for China’s nuclear industry, it is not yet something that will have much impact, near-term, on the current uranium market. It does demonstrate, again, that China does think and plan for the long-term because nuclear power will be a key element of the power portfolio as the Chinese decarbonize their economy.
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