atomic128
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

killingtime74
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.
bbojan
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.

BMc2020
Can someone knowledgeable tell me what happens if you blow it up?
Log_out_
So what happens if the alkali elements can not remove heat, for example during a fire?
moralestapia
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?