Energy Northwest, a premier provider of carbon-free electricity, and X-Energy Reactor Company (“X-energy”), a leading developer of advanced small modular nuclear (pebble bed fission) reactors and fuel have a joint development agreement for up to 12 Xe-100 advanced small modular reactors in central Washington capable of generating up to a total of 960 megawatts of carbon-free electricity. Energy Northwest expects to bring the first Xe-100 module online by 2030.
Energy Northwest owns or operates numerous clean energy generating facilities throughout the Northwest region of the United States, including Columbia Generating Station in Richland, which is the only commercial nuclear energy facility in the region. Under the JDA, the Xe-100 project is expected to be developed at a site controlled by Energy Northwest adjacent to Columbia Generating Station.
The Xe-100 can operate for 60 years without stopping to refuel. There will 200,000 fuel pebbles constantly being fed through the system.
China has built and started operating a similar dual module 200 Megawatt pebble bed reactor.
Small modular reactors with 80 MWe of power each enable utilities to build a module at a time for less than $1 billion instead of spending $10 billion or more for a 1 gigawatt reactor.
Each Xe-100 module can provide 80 megawatts of full-time electricity or 200 megawatts of high-temperature steam. X-energy’s innovative and simplified modular design is road-shippable and intended to drive scalability, accelerate construction timelines and create more predictable and manageable construction costs. The Xe-100 high-temperature gas-cooled reactor technology can power a broad range of applications through its high-temperature steam output that can address the needs of large regional electricity providers as well as industrial manufacturing systems.
In May 2023, Dow Inc. (NYSE: DOW) selected its UCC Seadrift Operations manufacturing site on the Texas Gulf Coast for X-energy’s first deployment of the Xe-100 as part of the U.S. Department of Energy’s Advanced Reactor Demonstration Program (“ARDP”). X-energy was awarded $1.2 billion from the U.S. Department of Energy in 2021 under the ARDP in federal cost-shared funding to develop, license, build and demonstrate an operational advanced reactor and fuel fabrication facility by the end of the decade.
Brian Wang is a Futurist Thought Leader and a popular Science blogger with 1 million readers per month. His blog Nextbigfuture.com is ranked #1 Science News Blog. It covers many disruptive technology and trends including Space, Robotics, Artificial Intelligence, Medicine, Anti-aging Biotechnology, and Nanotechnology.
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Where will they get the fuel? There’ no HALEU infrastructure today. Urenco is not making investments in >10% enrichment supply any time soon.
I get the benefits of TRISO, though it’s expensive, but I don’t like merging the fuel with the moderator. It doesn’t buy you anything substantial and just makes for bulky fuel and high level waste form.
I think it would be better to have graphite channels with bulk triso particles fed in. It is easy to transport spherical particles pneumatically or mechanically. Radial coolant flow would avoid high pressure loss.
The TRISO fuel is pretty rugged and can withstand high-temperatures, unlike conventional water reactor fuel. The use of graphite means gas reactors are much larger than their conventional water reactor cousins. The large size and low power density means gas reactors can be passively cooled. This is an advantage of using a graphite moderator instead of water.
The higher enrichments are generally associated with longer periods between refueling.
The TRISO fuel is also much easier to entomb as it is not particularly prone to reacting with the environment because it is largely inert – a property associated with the use of silicone. That same property makes it very difficult to reprocess, thus making the fuel more-or-less useless for making nuclear weapons. Water reactor fuel reacts with the environment and has to be made into a glass before being disposed of, presumably somewhere underground.
The X-energy reactor is significantly more efficient than an equivalent water reactor which means it produces significantly less radioactive waste (by mass) than a water reactor. Volume measurements are pretty much of a red-herring consideration – it’s the amount (mass) of radioactive spent fuel that is important. Also the gas reactor’s high burn-up as well as fuel enrichment are about 3 times that of a water reactor. That means the gas reactor produces much less plutonium than an equivalent output water reactor. Burn-up is a measure of how much nuclear material (uranium) is usefully fissioned.
All of those benefits would be there if the triso was separate from the graphite.
So making a reactor big and bulky (and thus expensive) is an advantage?
You can get passive cooling using little heat exchangers in the reactor. Go for compact and passive.
And you haven’t answered where they get the fuel.
The bulky gas reactors have very low power densities which allows the heat to be passively removed. Conventional reactors have vastly higher power densities that generally require pumps, electrical power and a water supply to prevent the core from melting. Heat exchangers are also typically needed. However, the driver is getting the heat out of the core quickly enough and that means pumping water. In such a situation, compact heat exchangers are not that much of a consideration.
The latest advanced water reactors generally rely on boiling and condensation of water to passively remove heat from the core through natural circulation of water. However, that typically only works for a few days, at which point more water is needed. The cores of older conventional water reactors will melt if cooling is lost for more than about a half hour. That is what happened at Fukushima.
X-energy will have to wait for a production facility to be built that can supply the fuel. Technically, need a large number of cascading centrifuges. Likely several years out into the future, but then so is building the XE100 reactor.
Building a commercial centrifuge facility is expensive and too financially risky unless a number of reactor cores are are supplied. Alternatively, the taxpayer subsidizes the effort (current strategy) to take the financially risk off the enrichment facility manufacturer.
In passing, the TRISO fuel production facility was to be built a couple of years ago, but the DOE nixed the effort in favor of laser enrichment. That technology did not work.
Is it designed to “burn” the plutonium transmuted from U238 and the fission products ? If not, it is wasteful and will generate large amounts of used fuel unsuited for reprocessing (no energy gain by burning plutonium in MOX fuel).
Does not matter what is in the pellets when they are spent, they are already in a containment that will last longer than the contents are radioactive.
In the last 30 years have you seen a single person with a sign protesting used fuel? If you have ,there is the natural gas stockholder.
Small modular fission reactors would help our energy needs, but if they are throwing around a timeframe of 2030…I feel like at that point we might as well just keep more focus on fusion.
There’s no such thing as a fusion power plant. Nobody is likely to build a demonstration plant before 2030 and it won’t be ready to build on a large scale until 2040 on the most optimistic timeline imaginable assuming you can get a demonstration plant by 2030. Permitting, powerlines, construction etc takes on the order of a decade; this is also true of wind farms and major power lines etc.
Fusion won’t make a difference until 2050 and it may never be cost competitive with fission, because fission is so easy that it could have been worked out and operated in the victorian era if they knew about it.
Fission is more economical than the vast majority of fusion reactor designs. Tokamaks and stellarators in particular will never be able to compete with fission on cost and it isn’t even close.
SMR Fission reactors can be inherently, walk away safe and cheap when produced in quantity. For fusion to be viable it needs to compete on cost. Focus Fusion, Helion, HB11, TAE, General Fusion are probably the only potentially viable paths forward to viable fusion power and *none* of them look like magnetic doughnuts.
Ok, so it will obviously work and optimistically, could require fewer people/MWe to operate than a LWR (although it is still a steam plant). Assume it has an awesome 45% thermal efficiency with the claimed 565C steam temperature, compared to 30% at LWR. The X-energy website says it has 200,000 pebbles and operates at 200 MWt. This design is based on the South African PBMR; X-energy acquired that IP and some of the engineers. The PBMR pebbles were 60mm in diameter; that seems consistent with the shiny sphere in the palm of a hand as shown on the X-energy website. PBMR pellets contained 9 grams of U at about 10% enrichment. Generously assuming that this core, with it’s 8:1 length to diameter aspect ratio, has a 0.8 conversion ratio (1.01 is a breeder, 0.6 is LWR) it should have a throughput of about 130 pebbles/day or 64,600 pebbles in 18 months with a displacement of 7.3m^3 (neglecting stacking void). The 1.1GWe LWR discharges ~14m^3 (envelope, not displacement) at the end of 18-months. The volume/MWe of the waste stream of PBMR/Xe-100 is AT LEAST 6 times that of the LWR. The claimed 160GWD/Ton discharge burnup of Xe-100, relative to the 50GWD/Ton discharge burnup of LWR appears to compensate for doubling (220%) of per-kg feed+conversion+SWU, but the manufacturing of TRISO (UO2 grains CVD with SiC) and then layering pyrolytic graphite on graphite compacts (CVD with CH4) cannot be cheaper than putting oxide pellets in tubes. I’m pretty sure the fuel cost/MWe will be double that of LWR. Perhaps the higher temperature steam will find a niche? Perhaps it’ll run with less manpower? Energy Northwest is a very small utility; they run one single-unit BWR in Washington.
If I stick around long enough and get high enough on my organization’s corporate ladder, I wouldn’t look twice at this thing. It doesn’t look like money to me.
Here shows 170 pebbles per day and 15.5% enrichment.
https://www.nationalacademies.org/documents/embed/link/LF2255DA3DD1C41C0A42D3BEF0989ACAECE3053A6A9B/file/DCB77DCC95AEF75D0CA6FE9C717CAA34436F7817D15A?noSaveAs=1
It’s even worse than I thought.
The reactor is heavily subsidized by DOE. With most of the capital cost absorbed by the taxpayer, debt repayment costs are essentially zero. That might make the operational costs acceptable, with even more taxpayer subsidies are provided for energy production (basically, $/MWh).
Looks to me the small reactor business model is based on perpetual taxpayer subsidies. Just like green energy.
Brian, do you think we’ve reached the point where the NRC and the American public will support new nuclear plant commissioning?
In certain states yes. I wouldn’t put Washington on the list of pro nuclear power states.
I’m not quite sure what the allure of this reactor is. Is it air cooled? Is it to be used for process heat? Pebble bed reactors have always been expensive.
It is cooled with helium gas. Were a breach to occur, the release to the environment in terms of the violin go medium would not be radioactive. All safety systems are passive. Reactor will cool off without need for external coolant circulating through the core.
Pebbles have a very high melting on temp due to silicone carbine coating. Carbon structure of the fuel itself traps xenon inside of the pebbles to keep the reactor from becoming poisoned.
It’s not perfect, but it’s a definitely a culmination of lessons learned. I know these guys, and they are some of the best. There are a number of others out there who are working on similar tech, some with this same fuel (Kairos).
By air cooled I mean its turbine is not water cooled. Being air cooled means you can dump your waste heat directly to atmosphere. This means you don’t have to locate a reactor near a river, lake, or ocean and can place the reactor in deserts, inland, etc.
You can do air cooling if the reactor temperature is high enough.
This tech been on the shelf tech since the ’60s… refined through the ’00s and NOBODY wants it. China runs 2- whoop dee do.
Technically, a large breach causes the helium to be belched into the atmosphere, with the remaining gases residing with in a “confinement building”. A containment building that prevents leakage is not used. The theory behind the design is that there is not much radioactive material contained in the helium coolant, so belching the gas into the environment is acceptable.
High temperature (process heat, more efficient conversion to electricity).
Online refueling and redistribution of fuel (just cycle through pellets and they redistribute for even burnup), remove high burnup pellets and add fresh ones as needed.
Passive safety (doesn’t matter so much to me; first gen LWRs are already safe enough and safer than any other form of energy except newer nuclear plants).
No real need for a large containment building (a small containment building may still be needed for regulatory reasons; e.g. aircraft resistance; but it does not need hundreds of times the water volume in the core).
Ability to cycle quickly as long as you don’t use a steam plant (which XE-100 is doing). Instead of a steam plant a faster responding brayton cycle supercritical CO2 or helium turbine can be used. This is mostly useful if someone insists on filling the grid with unreliable energy generators.
Potentially it may have a better chance of being allowed where LWR can’t due to regulations (e.g. as a combined heat and power plant somewhat close to populated areas), but this is uncertain and requires an expensive regulatory battle in the first place that LWRs can’t win and pebble beds might.
One of the draw backs is the form of the fuel. You can’t really reprocess it and if you’re just going to burry it; it is bulky because it’s mostly graphite.
Commercially and technically viable supercritical CO2 cycles remain elusive after 50 years of development. Also, unclear if CO2 interaction with core (caused by heat exchanger tube leak) would be acceptable from a safety standpoint, particular in the absence of a containment building. The pressure of the supercritical CO2 is higher than the helium pressure used with the core.
As far as the high temperature/pressure steam cycle is concerned, an interaction (again caused by heat exchanger tube leaks) with core materials could be problematic from a safety standpoint. The steam pressure is also much higher than the helium pressure. The absence of a containment building is unhelpful from a radiation release standpoint. The likely scenario is the relief valves used to protect the reactor vessel will lift, dumping the helium/steam mixture into the confinement building, which will belch the gas into the atmosphere. That gas will contain radioactive material. Same scenario plays out with supercritical CO2.
Heat exchanger tubes leaks are inevitable. Occurs from time-to-time in all power plants.
Yet another consideration with a large hole in the reactor system and air entering the core. Air and hot graphite generate CO gas, which is combustible.
All these accident scenarios have to be analyzed to confirm the public is safe from the likely radiation releases. From an investment standpoint, introduces an element of risk to profitability that is difficult to quantify.
These helium blowers also need magic bearings that don’t need oil because any oil spray will turn to char in the pebble bed.
Real turbines consume some lube oil. Goes out the back of the jet. Steam turbines at electric plants are oil lubed too.
I believe they are using magnetic bearings, possibly with ceramic bearings used in event of magnetic bearing loss while blower(s) coast down.
Personally I would say yes, and from across the political spectrum. With several caveats.
1) Safety is the biggest concern. The new reactors would need to be walk away safe.
2) Price would need to be cost competitive within the geographic region with wind/solar plus storage.
3) Nuclear waste is a concern, especially for people without a strong understanding of it. Reactors that burn current waste are not only a huge selling point but if I am not mistaken also more economically viable.
All of this is dependent on the new technologies of millimetric wave drilling enabled geothermal power. The only thing nuclear might, maybe, beat that on is price. Quaise is one example. If those technologies pan out the only place you will find nuclear power is in space.
The proposed NRC regulations (10CFR53) for advanced reactors are more than twice the size of current regulations for water reactors. The nuclear industry had hundreds of pages of comments on the proposed regulation. None of the comments were responded to by the NRC.
Have we reached the point where the NRC will support advanced reactors? Not no, but hell no.