How much uranium did Klaproth actually isolate? A natural uranium reactor needs a really big critical mass, because something like 98% of the metal is a neutron sink rather than fission fuel.

BTW, read up on what Verne gave as a power source for Nautilus.

The USS Nautilus was the first nuclear vessel, but Jules Verne had an electric motor powered by sea salt: "... I examined in order to understand the machinery of the Nautilus. "You see," said the Captain, "I use Bunsen's contrivances, not Ruhmkorff's. Those would not have been powerful enough. Bunsen's are fewer in number, but strong and large.. The electricity produced passes forward, where it works, by electro-magnets of great size, on a system of levers and cog-wheels that transmit the movement to the axle of the screw. This one... performs about 120 revolutions in a second."

Nemo: "Professor, my electricity is not everybody's. You know what sea-water is composed of. In a thousand grammes are 96%. of water, and about 2.3% of chloride of sodium (salt); then, in a smaller quantity, chlorides of magnesium and of potassium, bromide of magnesium, sulphate of magnesia, sulphate and carbonate of lime. You see,... salt forms a large part of it. So it is this sodium that I extract from the sea-water, and of which I compose my ingredients. I owe all to the ocean; it produces electricity, and electricity gives heat, light, motion, and, in a word, life to the Nautilus."

(1) 100 kW is a trivially small power, about 134 horsepower; that's a compact car, such as a Volkswagen Golf. (2) The Oklo natural reactor was distributed over a very large area. (3) Natural uranium is not particularly radioactive, and cannot boil water; it is barely luke-warm. That's why we need artificial means of enhancing the fission reaction, either by enriching the uranium (cannot be done in the 19th century), or using heavy water as a neutron moderator (as in CANDU reactors, which can use natural uranium). (You need heavy water; light water doesn't work for unenriched uranium.)

@AlexP Partly agreed. But surely An especially talented person would have been needed to fine tune it to usefulness. The actual exposed U deposit measured in centimeters, not at all a wide area.

A premise of "naturally occurring nuclear reactor in 1790" is not consistent with real world. Natural reactor was possible 1.7 billion years ago because U-235 was much more abundant. "the current abundance of U-235 in natural uranium is only 0.72%. A natural nuclear reactor is therefore no longer possible on Earth without heavy water or graphite."

Ahhh, so that’s what was in the pond. Graphite. Makes sense now. “ Graphite occurs in metamorphic rocks as a result of the reduction of sedimentary carbon compounds.”

The British. I didn't write an answer because it was so short, but the British were the technological hegemons at the time. Even developments that largely occurred elsewhere in Europe were best adopted by Britain (the steam engine, for instance). I recently got a lead on a problem I had in what I now know to be called Compositional Data Analysis from a paper published in about 1890 in the Royal -- something or other. A lot was going on in Britain at the time.

I don't disagree, and they would have been first to find the natural reactor. But the question is 'who?" Thomas Edison? Islamabad Brunel Kingdom? Some people were beter connected and had more specialty knowledge than others, and would have become the 'Thomas Newcomen' of nuclear power.

I found this Q in the VTC queue. I do not believe it should be closed. I believe there is enough distinction between the physicists of the day to objectively select who, given the existence of a natural nuclear reactor, could have developed a synthetic nuclear reactor. (The answer might be "none.") (However, please read the reality-check wiki, because you are not using the tag correctly. To do so you would present your own recommendation for who that person would be and we would be testing the consistency of your choice against the reality of your world.)

@JoinJBHonCodidact - The Reality Check is exactly as you said: "Could Martin Heinrich Klaproth have done this?" Please read the question again. Thank you.

@DanielB - 60% concentrations: Researchgate: Special cases of natural analogues: The Gabon and Cigar Lake U ore deposits

@Rekesoft We discovered seventeen naturally formed nuclear reactors in the 1970's. The alt timeline has someone accidentally stumble upon one in 1789 instead. That is the only change to reality. In your comparison, when did we discover naturally occurring supersonic flight? That event which would have prompted us to experiment with it? I linked my real-world example. Provide a link to yours please?

You do ask about Martin, but you also ask, "Into whose hands did this discovery land?" You don't get it both ways. It appears you've edited your question into a condition that is strictly closeable: Needs More Focus. You're allowed to ask one and only one question.