- #1
Garlic
Gold Member
- 181
- 72
Are there isotopes that decay only through spontaneous fission, or in other words can normally stable nuclei decay through spontaneous fission?
mfb said:There are a few nuclides where spontaneous fission is the only possible decay mode (apart from proton decay maybe), but it has never been observed and the expected lifetime is so long that it is unlikely that we will ever see such a decay.
As usual, Wikipedia has a list.
The natural reactors at Oklo were active about 1.7 billion years ago. At that time, the percentage of U-235 in uranium deposits was several times the current fraction of 0.7% found in natural uranium. Since that time, the percentage of U-235 has declined, because its half-life is roughly 700 million years or so.mfb said:Oklo is the most prominent place. It happened in the past, when the fraction of fissile uranium was higher. Today it is too low.
Spontaneous fission is a type of radioactive decay in which an unstable isotope splits into two or more smaller nuclei without any external stimulus or trigger.
Spontaneous fission occurs when an unstable nucleus has a high enough energy to overcome the strong nuclear force that holds it together. The nucleus then splits into two or more smaller nuclei, releasing energy and particles in the process.
Only very heavy isotopes with a high atomic number, such as uranium and plutonium, are capable of spontaneous fission. These isotopes have an unstable ratio of protons to neutrons, making them more likely to undergo fission.
The products of spontaneous fission can vary, but they typically include two smaller nuclei, such as barium and krypton, as well as neutrons and energy in the form of gamma rays.
Spontaneous fission is used in nuclear power plants to generate electricity and in nuclear weapons for explosive energy. It is also used in research to study the properties of heavy isotopes and in the production of medical isotopes used in diagnostic imaging and cancer treatment.