Chinese Fast Nuclear Reactor Starts High-power Operation

China has a sodium-cooled, pool-type fast reactor. It was refueled and had maintenance at the end of July 2020. It completed a power test phase last year. The reactor has a thermal capacity of 65 MW and can produce 20 MW in electrical power. The CEFR was built by Russia’s OKBM Afrikantov in collaboration with OKB Gidropress, NIKIET and the Kurchatov Institute.

Nuclear fission produces neutrons with a mean energy of 2 MeV (200 TJ/kg, i.e. 20,000 km/s), which qualifies as “fast”. However the range of neutrons from fission follows a Maxwell–Boltzmann distribution from 0 to about 14 MeV in the center of momentum frame of the disintegration, and the mode of the energy is only 0.75 MeV, meaning that fewer than half of fission neutrons qualify as “fast” even by the 1 MeV criterion.

Thermal Neutrons:- It refers to the neutrons which are in thermal equilibrium with the surrounding medium, that is they have average energy which is comparable to the energy of the other particles in medium. The energy is usually nearby 0.025eV.

Fast Neutrons:- These are the fast-moving neutrons, just emitted after fission. They can have an energy of order of several MeV.

Slow Neutrons:- These are the neutrons which are slowed by the collecting medium (eg heavy water) They have energy of order of few eV or fractions of eV.

Natural uranium consists mostly of three isotopes: 238U, 235U, and trace quantities of 234U (a decay product of 238U). 238U is 99.3% of natural uranium and undergoes fission only by fast neutrons. About 0.7% of natural uranium is 235U, which undergoes fission by neutrons of any energy, but particularly by lower-energy neutrons. When either of these isotopes undergoes fission, it releases neutrons with an energy distribution peaking around 1 to 2 MeV. The flux of higher-energy fission neutrons (ocwe 2 MeV) is too low to create sufficient fission in 238U, and the flux of lower-energy fission neutrons (lwaa 2 MeV) is too low to do so easily in 235U.

The common solution to this problem is to slow the neutrons using a neutron moderator, which interacts with the neutrons to slow them. The most common moderator is water, which acts by elastic scattering until the neutrons reach thermal equilibrium with the water. The key to reactor design is to carefully lay out the fuel and water so the neutrons have time to slow enough to become highly reactive with the 235U, but not so far as to allow them to escape the reactor core.

Fast-neutron reactors can reduce the total radiotoxicity of nuclear waste using all or almost all of the waste as fuel. With fast neutrons, the ratio between splitting and the capture of neutrons by plutonium and the minor actinides is often larger than when the neutrons are slower, at thermal or near-thermal “epithermal” speeds. The transmuted even-numbered actinides (e.g. 240Pu, 242Pu) split nearly as easily as odd-numbered actinides in fast reactors.

After they split, the actinides become a pair of “fission products”. These elements have less total radiotoxicity. Since disposal of the fission products is dominated by the most radiotoxic fission products, strontium-90, which has a half life of 28.8 years, and caesium-137, which has a half-life of 30.1 years the result is to reduce nuclear waste lifetimes from tens of millennia (from transuranic isotopes) to a few centuries. The processes are not perfect, but the remaining transuranics are reduced from a significant problem to a tiny percentage of the total waste, because most transuranics can be used as fuel.

A 600 MWe design – the CFR-600 – was developed by the CIEA. Construction of a demonstration unit in Xiapu County, in China’s Fujian province began in December 2017. This will have a power output of 1500 MWt and 600 MWe. The reactor will use mixed-oxide (MOX) fuel with 100 GWd/t burnup, and will feature two coolant loops producing steam at 480°C. Later fuel will be metal with burnup of 100-120 GWd/t. The reactor will have active and passive shutdown systems and passive decay heat removal. Construction of a second CFR-600 unit at the Xiapu site began in December 2020. Xiapu 1 is expected to be grid connected in 2023.

Regular pressure water reactors have a fuel burnup level of about 45-55 GWd per ton. The fast reactors are 2 to three times more efficient with nuclear fuel.

A commercial-scale unit – the CFR1000 – will have a capacity of 1000-1200 MWe. Subject to a decision to proceed, construction could start in December 2028, with operation from about 2034. That design will use metal fuel and 120-150 GWd/t burnup.

SOURCES World Nuclear News, Wikipedia
Written By Brian Wang,

26 thoughts on “Chinese Fast Nuclear Reactor Starts High-power Operation”

  1. Most of the talking heads on 'Titans of Nuclear' are actually working on LWRs. You should give it a go too – you might get your own fan-boy club !

  2. Areva claim about 36.5% for the EPR, but ultrasupercritical coal plants are getting 47.5% at 650 C. Light water reactors might be able to run a bit hotter with the new accident tolerant fuels, as well as getting higher burnup, and running longer between refueling stops.

  3. Actually the delayed neutron effect appears to be more important – this is when daughter nuclides fission over the course of ten minutes, replacing the "prompt" neutrons from the original actinide fission. These delayed nuclides have effects in spite of the best efforts to manage and increase the ratio of thermal neutrons. The nuclides, plus the presence of pernicious neutron poisons such as Xe-135 have surprised many an operator.

  4. Actually Sorenson confirmed that a roughly 1:1 ratio of Th and U233 would sustain breeding in a seed blanket MSR. In the 90's a revival of an old diffusion enrichment facility at Piketon successfully recovered 10 months of U233, sparking interest in building a new MSR to try it out. Alas, DOE scotched it. USEC, the enrichment operator declared bankruptcy, but revived as Centrus, premised around centrifuge enrichment. Shucks!

  5. Thanks, Brian, to tipping me off to read World-Nuclear News, because your explanation of neutronics and competitive reactor design is just mumbo jumbo.

  6. Also more heat means greater thermal efficiency for the turbine, approaching 38% at 700 deg C, v. 31 % for PWR's. A big economic consideration.

  7. We tried to build a fast reactor for more than a decade and for billions over budget. No luck. It was eventually cancelled. If building it is an hassle then you shouldn't go there. Always go with the KISS principle. Keep it simple.

    One of my memories from HS Chem Lab was the demonstration of put a small chuck of sodium into a container of water. It was explosive.

  8. Sodium not a good choice, air, water, fire. But I guess they know what their doing I hope they know what their doing. Reprocessing and glass virtracation of the waste seems a better deal. If China was accepting suggestions mine would be single plant design throughout the country and a U tube steam generator.

  9. The sodium isn't very radioactive either even in the primary loop, which isn't usually where the leaks happen. We're not talking spent fuel here. The offsite consequences of a sodium fire with sodium from the primary loop sodium is still nil, but with a lot of hand-wringing and radiophobia.

  10. That's economically true but it's not actually true that you must have higher enrichment in fast reactors. The fission cross section is less, but the parasitic cross sections like capture are *much* less. That means you can still have very low enrichment core in principle, it will just be too large to be practical and the breeding ratio not be good.

  11. OK this reactor is near Beijing. I was concerned it might be downstream of the Three Gorges Dam. I think that one might circle back around.

  12. Maybe it's the 'at normal PWR pressure/temperature' bit – sodium would be about 200C hotter and 150 bar less pressure, which should mean cheaper reactor vessels, and more power per fission. Anyway, I didn't think there was that much current interest in sodium, outside China. Russia's put the BN1200 on hold, India's 500MW reactor seems to be advancing at the pace of a tectonic plate, and the French government killed Astrid.
    Is there much divergence between the theoretical 'infinite pin array' studies and the real reactors you work with ? I'm guessing the neutrons would travel a lot further in heavy water, so you'd need a larger pot.

  13. Anything as hot as the sodium you speak of, or the molten salts in a LFTR react violently with water. It's called a steam explosion.
    That being said, molten sodium, solid fueled reactors are not the most promising reactor designs under consideration. About the only things liquid metal coolants(lead, lead-bismuth, sodium) have over molten salts is superior heat transfer by conduction, and less corrosive when exposed to hydrogen.

  14. The best things you can say about 60 years of mainstream fusion research is that it has pushed the state of the art in superconducting magnets, and served as make work for plasma physicists. Even if "breakeven" is reached, you still must somehow deal with neutron damage to the hardware of the reactor, and somehow get the energy released to a heat engine. In short, mainstream fusion concepts will never be economically viable. If there is ever to be economically feasible fusion energy, there will have to be a different approach used.
    On the other hand, there is plenty of fertile thorium, and uranium already on planet earth to supply energy for an unimaginably long period of time.

  15. Much less violently than natural gas when exposed to air and a spark. Russia has been operating sodium cooled reactors for sixty years. They had a lot of small fires when they started, but they'd designed the plant to contain that, and since then they've improved their systems and had no problems.

  16. Liquid Salt Thorium Reactors can be breeders without the need for sodium. The problem with sodium is that it reacts violently when expose to moisture or water.

  17. Fast and slow in nuclear reactors can refer to the time delay between the nuclear collision and the emitting of a neutron. It can be fast 1 millisecond or slow 100 seconds. To avoid over heating when things are happening at the 1ms scale is hard and dangerous. At the 100 second scale even a human operator can keep ahead of it.

  18. No obligatory "Texas wouldn't be in this mess if they didn't retire some nuclear plant way back when"?

    Incompetence and insufficient job killing regulation is usually to blame. It's never the reason that persecution against the new age Facebook religion that is nuclear advocacy is ever to blame.

  19. Fusion is a rabbit track. We have squandered and squandered on fusion, and it has gotten us nowhere. The only advantage I can see potentially for fusion is lower mass in space propulsion increasing speed and range. All purely theoretical. We don't really know what these things will weigh. And antimatter is probably better, if it is not crazy hard to do, or nearly impossible to do safely.

  20. This is great, and a good bridge between many older reactors and fusion, but fusion is still the end game. This is awesome though because it's able to use so much of its own waste for fuel. The less we have to store, the better.

  21. There's a US company called Elysium industries that has a very interesting molten salt fast reactor design. It operates on the uranium-plutonium cycle, and uses chloride salts. They have a number of informative videos on youtube.

  22. One drawback of fast spectrum reactors is that their fuel must be of much higher enrichment than thermal spectrum reactors, because of the lower cross section of capture of fast neutrons. In the past fast reactors using the uranium-plutonium fuel cycle have generally been desirable because they can act as breeder reactors, creating more fissionable material than they consume. Fast spectrum reactors create extra neutrons by spallation, making for good neutron economy.

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