Fissionable elements for Fission

[fog37]

TL;DR Summary

materials suitable for fission

Hello,

Quick question: in fission, which is a nuclear reaction, a large element is hit with neutrons and broken/split into two smaller elements while lots of energy is released. Does the starting element, which must be large in size (like uranium-235 or plutonium-239) need to be an element that is naturally radioactive? Or is it enough for it to just be a large atomic number Z element? What if we hit a large non-radioactive element with fast particles? Can we still split it and have the release of energy? Or is it too hard to do so we rely on naturally radioactive materials to start the fission process?

I understand natural radioactivity: some elements spontaneously decay and transform into new elements (until the final element is a stable one).
In the case of artificial radioactivity, we create new elements by forcing an element (does it have to be naturally radioactive to start with) to change into a new one by hitting it with fast particles (neutrons, alpha particles, etc.).

Are the new, artificial elements that we create through this process automatically radioactive? I don't think so. They are simply called artificially radioactive because when they were created some radioactive particles were also released, correct?

Thanks!

 

[mfb]

All suitable nuclides happen to be radioactive, but this is not a requirement, and not every large Z nucleus will work.

In principle energy can be released if you shoot a fast particle onto e.g. lead and it splits, but that is a very unlikely reaction. You are more likely to get something else, like kicking out a few neutrons and protons. And you can't get a chain reaction with lead.

Are the new, artificial elements that we create through this process automatically radioactive?

All elements with stable isotopes occur in nature. If we create an element that doesn't occur in nature then it has to be radioactive... but of course we can also create stable elements. It is just less interesting, because we can simply mine them.

 

[gmax137]

a large element is hit with neutrons and broken/split into two smaller elements

Just as an aside, this mental image of the nucleus being "broken or split" by the incoming neutron is not accurate. It is not a kinetic effect, like a target being shattered by a bullet. Google "liquid drop model"