3 ms·

U-235 has a half life of 700 million years. When it decays, it releases alpha radiation (Helium neclei), which is not that dangerous. As long as you don’t inges

U-235 has a half life of 700 million years. When it decays, it releases alpha radiation (Helium neclei), which is not that dangerous. As long as you don’t ingest or inhale it, U-235 is harmless. If you do ingest or inhale it, it will probably harm you more because it is a heavy metal than because it is radioactive.

willis936 4y ago
Do you know how many people you can threaten and actually kill with 1 kg of U-235?
- credit_guy 4y ago
  I don't fully understand where you're going with this question. Maybe you are implying a terrorist could get their hands on 1kg of U-235 and either make a dirty bomb or a nuke. A dirty bomb would not really be more dangerous than a dirty bomb made with Cadmium. As for a nuke, 1kg is well below the minimum necessary to make a nuclear bomb, which is about 15 kg. But that's not the only thing. You need weapons grade Uranium for that, i.e. Uranium where U-235 constitutes at least 85% of the whole. Civilian reactors use Uranium that is enriched to much lower levels. Currently, the vast majority of the civilian reactors use Uranium enriched to 4.5%. A terrorist who gets their hands on that, can forget about building a nuclear bomb, except if they have means to further enrich that Uranium. In other words, if they have centrifuges, like Iran does. I might remind you that Iran is a state, not a single person. In any case, if you have centrifuges, you might as well start with Uranium ore, there's no point in stealing from an existing civilian reactor.
- MertsA 4y ago
  Basically one. Now if it was 50 kg then you're getting into the realm of criticality.
ouid 4y ago
Unlike in most cases, where there is a conflation of fissile and radioctive substances, I believe that the parent comment was actually referring the the problem that occurs when you allow people to get their hands on too much enriched uranium.

willis936 4y ago

Do you know how many people you can threaten and actually kill with 1 kg of U-235?

credit_guy 4y ago
I don't fully understand where you're going with this question. Maybe you are implying a terrorist could get their hands on 1kg of U-235 and either make a dirty bomb or a nuke. A dirty bomb would not really be more dangerous than a dirty bomb made with Cadmium. As for a nuke, 1kg is well below the minimum necessary to make a nuclear bomb, which is about 15 kg. But that's not the only thing. You need weapons grade Uranium for that, i.e. Uranium where U-235 constitutes at least 85% of the whole. Civilian reactors use Uranium that is enriched to much lower levels. Currently, the vast majority of the civilian reactors use Uranium enriched to 4.5%. A terrorist who gets their hands on that, can forget about building a nuclear bomb, except if they have means to further enrich that Uranium. In other words, if they have centrifuges, like Iran does. I might remind you that Iran is a state, not a single person. In any case, if you have centrifuges, you might as well start with Uranium ore, there's no point in stealing from an existing civilian reactor.
MertsA 4y ago
Basically one. Now if it was 50 kg then you're getting into the realm of criticality.

ouid 4y ago

Unlike in most cases, where there is a conflation of fissile and radioctive substances, I believe that the parent comment was actually referring the the problem that occurs when you allow people to get their hands on too much enriched uranium.