Kuiper strikes a pose in front of #EBR1 near Arco, Idaho. Remember Chicago Pile 1 from last week (the Do Not Dig sign)? This is CP-4, aka #EBR1 or “Experimental Breeder Reactor.” It operated from 1951 to 1964 and is now a National Historic Landmark. We had a super rad time in the museum.
In addition to being the 1st reactor to generate electricity, what made this reactor unique was its cooling system. It used NaK, a liquid alloy of sodium and potassium. Although NaK is a spectacularly dangerous (it explodes on contact with air or water) and corrosive chemical, it’s also spectacularly efficient as a coolant. More importantly, NaK also enabled EBR1 to be the world’s first breeder reactor.
Nuclear reactors generate electricity (and heat) by splitting a uranium atom which spits out neutrons that go pew pew and split other U atoms, and so on. On their own, they would pew pew super fast, which makes it harder for them to hit their targets. Thus we usually use H2O or graphite to slow them down. In EBR we used NaK. Like Idaho, it sets a slightly higher “speed limit” for the neutrons.
Reactor fuel includes two types of U. U235 is what is largely consumed, but it is only a few % of the material. There’s also a bunch of U238 along for the ride. The use of NaK enables more of the neutrons to pew into the U238 and turn it into Plutonium 239, which can also be used as fuel. This type of reactor is about 100x more efficient, and the waste is less radioactive. In theory, with breeder reactors we could reprocess our spent nuclear waste from e.g. Hanford, generate a lot of electricity, and make it a lot less dangerous. This is actually what several other countries do.
Unfortunately, President Carter signed an executive order in 1977 making nuclear recycling illegal. There were concerns about the Pu being stolen for nuclear weapons. However, reactor-grade Pu is both not ideal for weapons and extremely dangerous to handle compared to weapons-grade Pu (which is generally produced slowly in dedicated reactors.)
Out of room now; Google “EBR II reactor safety” (yes that’s a 2) to learn how liquid metal cooled reactors can also be MUCH safer than current designs in use
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