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In most nuclear fission examples and exercises, the products of a nuclear fission of Uranium-235 are two light nuclei of Krypton and Barium:

$$\mathrm{ _0^1n + U \longmapsto Kr + Ba + energy }$$

Is there some fission reaction that produces more stable nuclei instead of Krypton and Barium?

Please mention all possible fission equations of Uranium-235. There's another question, is Uranium-235 the only fissile nucleus?

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  • $\begingroup$ In the case of large nuclei things are rarely always the same way. The usual question is "What is the branching ratio to [some particular state]?" $\endgroup$ Commented Jul 13, 2014 at 2:58
  • $\begingroup$ For a detailed description you may read this Wikipedia article $\endgroup$
    – hsinghal
    Commented Aug 22, 2016 at 16:13

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They don't. Here's a figure from Wikipedia:

distribution of fission product masses

Typically there's daughter with mass around 95, a daughter with mass around 140, and two or three extra free neutrons. In discussion of environmental contamination after nuclear accidents, you hear a lot about iodine-133 and strontium-90, because they are relatively long-lived and biologically active. Iodine-133 lives for about a week and accumulates in the thyroid; strontium-90 lives for about 30 years and can replace calcium in bones.

There are several heavy isotopes which can spontaneously fission; the big ones are uranium, plutonium, and californium.

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No, there are many nuclei produced by fission. You should show the mass numbers in any case-you have only specified the division of the protons, not the neutrons. This Wikipedia article discusses the range of fission products and states that each decay is not predictable, but the probability distribution is measurable.

For the second question, no, $\mathrm U^{235}$ is not the only fissile nucleus. $\mathrm{Pu}^{239}$ is used in reactors as well. Many other heavy nuclei will undergo spontaneous fission.

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