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It still blows my mind that a sub only needs to refuel once every 15 years. One of the things making this possible is 90+ percent enrichment of U235 in the fue
by inejge 4y ago
It still blows my mind that a sub only needs to refuel once every 15 years.
One of the things making this possible is 90+ percent enrichment of U235 in the fuel. That's weapons grade and won't fly in a civilian reactor. I haven't read NuScale's application in great detail but I'd be surprised if they used anything above 5 percent.
- schrodinger 4y agoCan you explain more about what that means or suggest what to Google to learn more?
- gautamcgoel 4y agoThere are two uranium isotopes present on earth, U-235 and U-238. U-235 is the fissile material which powers nuclear reactions in both nuclear bombs and nuclear power plants. The 5% number represents the fraction of uranium in the fuel which is U-235 instead of U-238. Anything above 20% or so is considered "highly enriched", and nuclear bombs often have fuel which is 80-90% U-235.
- gambiting 4y agoAnd the reason why bombs have more of the U-235 is because is splits easier than U-238, so it's easier to end up with a self sustaining chain reaction, where every U-235 that splits produces enough neutrons to split off two more U-235 atoms, which in turn splits 4, then 8, then 16 and so on - the chain reaction splits the whole lot all at once and you've got a bomb.
- WatchDog 4y agoTo add to what other commenters have said, apart from the weapons proliferation issues, enriching uranium is very expensive. U-235 only makes up about 0.72% of natural uranium, the rest of it being U-238. Running a reactor on low enriched uranium is much more cost effective, although reactor designs that can run on LEU can be less safe, like Chernobyls RBMK design.