EVinci nuclear microreactor moves towards commercialization | Hacker News Reader

EVinci nuclear microreactor moves towards commercialization

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34 pointspeutetre16 comments

Reactors like this (and like Bill Gates' Natrium reactor) use HALEU (high-assay low-enriched uranium) which is above 19% fissile (U-235), compared to the usual 5% or 6% in a large pressurized water reactor (e.g., https://en.wikipedia.org/wiki/AP1000).

For comparison, a nuclear bomb or military microreactor (on a submarine, for example) uses fuel that's 90%+ fissile. This difference in fissile concentration is the reason why non-military nuclear reactors can never explode like a nuclear bomb.

The bottleneck for nuclear energy is the yellowcake. This is the uranium that comes out of the ground, which is 0.7% fissile and must be enriched. A pound of HALEU requires many pounds of yellowcake. Conversion and enrichment are also in short supply today, but the centrifuges can be built.

There is a profound near-term undersupply of this natural uranium due to the fact that the mining companies were allowed to die after Fukushima. The mining companies died due to low uranium prices: $16 per pound at the market bottom.

The two big miners that survived (Cameco and Kazatomprom) are together unable to increase supply to match demand. Big new mines, like NexGen's, are years away, and the supply they provide will not close the supply/demand gap. Mining uranium is slow and difficult, even if you have access to good ore.

Alternative sources of uranium are even more expensive to exploit (seawater, phosphate deposits, etc.).

If you want to benefit (monetarily) from nuclear energy, and you're willing to suffer through the EXTREME volatility of owning a niche commodity, one way is through the Sprott Physical Uranium Trust (ticker: SRUUF) which owns 65 million pounds of uranium oxide and purchases more whenever it trades above Net Asset Value. WARNING: this is not an investment for the faint of heart. YOU HAVE BEEN WARNED.

You can watch the spot uranium market (intra-day bid/ask) here: https://numerco.com/NSet/aCNSet.html

You can see the uranium long-term contract price (and spot uranium price) monthly history at Cameco's website here: https://www.cameco.com/invest/markets/uranium-price

Given the extensive security requirements for nuclear and the cost of this reactor itself, I struggle to see how it can be cost effective compared to renewables or even a diesel generator. Discussions on hacker News, which is very pro nuclear always tend to emphasise the technical advantages and neglect economic considerations.

Most of the security around nuclear reactors is to prevent disruption of critical power infrastructure and barring access to spent fuel rods. This design would need far less security since it is sealed and not a huge plant that would cut power to half the USA if destroyed.

Stealing one of these would be pretty pointless. It would be far easier to get much more dangerous isotopes from one of the thousands of hospitals that use such things or a laboratory. The 20% enrichment is not enough to produce viable weapons either. Uranium enrichment has just gotten way too easy with new centrifuge designs.

Applications are mostly stuff like Antarctic research projects and remote oil fields. Also, if it is approved for such uses, it could power a container ship saving huge amounts of money on diesel fuel which is about half their operating cost.

> Given the extensive security requirements for nuclear

I can see a need for security, but I think power plants in general must be quite secure, otherwise a terrorist can waltz in, put a stick of dynamite under a boiler and boom, one gigawatt of electricity goes offline.

> the cost of this reactor itself

Westinghouse is quite tight-lipped about this reactor design. If you go to the NRC site with their application, most stuff is withheld from the public view [1]. However, they seem to have addressed the 2 big cost drivers of nuclear reactors. Their reactor does not need a high pressure vessel, and it has passive cooling, so that it can't melt down. The second part is kind of trivial. The square-cube law says that smaller reactors are more efficient at passive cooling, the smaller the better. That's one of the reasons the US Navy never had an accident with one of its hundreds of naval reactors. The no need for the high pressure vessel is quite unique. The cooling is done with liquid sodium, not with water. Water at high temperature needs to be kept under huge pressures to not boil, but liquid sodium does not have that problem.

I think Westinghouse envisions that they will, at some point, be able to manufacture these reactors on an assembly line, and maybe build several per day. If they get to that point, then maybe a reactor will be more expensive than a diesel generator, but it will not need to be refueled for eight years. A diesel generator burns about 0.4 liters per kWh, so a 5 MW generator would burn about 500 gallons liters per hour, or in dollars, it would be about $1500/hour. Over 8 years, that is about $100 million. If Westinghouse can get to the point of making one reactor for $20 million, they will have a huge market.

[1] https://www.nrc.gov/reactors/new-reactors/advanced/who-were-...

I take your point on the economics, especially if transport costs of diesel fuel are high.

It would mainly hinge on whether the site has viable wind/solar + battery options. On ships/arctic bases renewable is not viable.

I was thinking security costs of 24/7 manned security which would probably not be needed for Wind/Solar farms. It would be the same costs for fossil fuel plants that's true.

You could have multiple reactors at the same site. Like 100 for example.

That's true and would bring down the average cost a lot

Hacker News tends to be pro-solar, pro-wind, and anti-nuclear.

Discussions on Hacker News tend to overlook the unreliable nature of intermittent solar and wind power sources.

The hidden costs of solar and wind are also overlooked: the cost of land, the cost of transmission infrastructure, the cost of battery storage, the short lifespan of the hardware, the requirement for fossil fuel backup generators, etc.

Here's Yann LeCun (Vice-President, Chief AI Scientist at Meta) describing the advantages of nuclear versus solar and wind in a different, larger-scale context:

  AI datacenters will be built next to energy production sites that can produce 
  gigawatt-scale, low-cost, low-emission electricity continuously.

  Basically, next to nuclear power plants.

  The advantage is that there is no need for expensive and wasteful
  long-distance distribution infrastructure.

  Note: yes, solar and wind are nice and all, but they require lots of land
  and massive-scale energy storage systems for when there is too little sun
  and/or wind. Neither simple nor cheap.

Link to LeCun's comment on X here, along with a discussion of why solar and wind are not enough:

https://news.ycombinator.com/item?id=41621097

The same is true on smaller scales.

Also, plenty of locations where cooling is free.

This will make AI OpEx almost negligible.

In line with OpenAI's premise of making intelligence very cheap.

Only issue but not a big one is latency, i.e. Starlink will become extremely valuable in the upcoming years.

This is great and I think is the way to go.

>produces a self-limiting nuclear reaction that cannot go out of control

Anyone knows if this holds true even if someone tampers with the device?

In my opinion TRISO fuel is bad because it has very low burn-up and is difficult to re-process.

These things together mean it has quite low utilization of enriched uranium.

This particular design has a very low burn-up indeed, but that's not because of the TRISO fuel. The Chinese HTR-PM helium cooled reactor, that went live 2 years ago, has a burnup of 90 GWd/ton of uranium, which is enriched at 8.5% U-235 [1]. That is an exceptionally high burn-up rate.

The eVinci reactor has an exceptionally low burn-up rate: about 4 GWd/ton, despite using a much more enriched fuel,at 19.75% ([2], but note that this is just an estimate, Westinghouse did not disclose the actual burnup). Why? That's the price you have to pay to have a micro-reactor. The square-cube law says that for such a reactor the surface of the core is very high compared to its volume, so the neutron economy is extremely poor. The only way to make it work is to use highly enriched uranium. Uranium enriched to more than 20% is considered weapons grade, so commercial reactors need to use fuel below that limit, and 19.75 is basically as high as you can go.

TRISO fuel is actually a miracle of science. It addresses many problems of the current generation reactor fuels. Fission results in transmutation. By the very nature of the fission process, you end up with fission products in burned fuel. Some of these products are gases (like Xeon) and they create pressure, and when you have hundreds of thousands of fuel elements some will burst, resulting in fission product discharge in the cooling water. Nasty stuff. The fuel in TRISO is encapsulated in some poppy-seed-sized granules, and it can withstand immense pressures, so this bursting scenario just does not happen. In addition to that, they can withstand immense temperatures as well, and they are surrounded by graphite that has an exceptional heat conductivity, and is also a very good moderator. From the point of view of reactivity control, graphite is actually the best moderator out there, ahead of hydrogen, deuterium and beryllium.

> is difficult to re-process

That's not a problem. You just don't reprocess it.

> it has quite low utilization of enriched uranium

This reactor will have low utilization, as discussed, but not because of the TRISO fuel.

[1]https://aris.iaea.org/PDF/HTR-PM.pdf

[2] https://www.osti.gov/servlets/purl/1501599

Thanks for the detailed info, this was the stuff I was looking for but couldn't find quickly.

>> is difficult to re-process

> That's not a problem. You just don't reprocess it.

There's not enough uranium in the world to last us more then a few decades if we leave 60-80 percent of it unreacted in spent fuel.

That is an often repeated but incorrect thing. At the current rate of utilization, the proven reserves of uranium would last for one hundred years. What people miss is the fact that elevating a reserve to the status of “proven” (from the lower status of “probable”) costs money. Mining companies spend this money in order to get loans. Loan interest rates are better if the collateral is “proven” reserves. But the financing needs of these companies are limited by the business opportunity, so there is no incentive to “prove” more than 100 years worth of consumption. If the demand increases however, immediately you will see an increase of “proven” reserves. In the end we can extract unlimited amounts of uranium from seawater for only about 5x the current market price. It sounds like a lot, but it translates in less than one extra cent per kWh. The average retail price of 1kWh in the US is about 15 cents.

So what happens if the alkali elements can not remove heat, for example during a fire?

Can someone knowledgeable tell me what happens if you blow it up?

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