Not to persue this for too long but you should know that "depleated"
uranium means that the isotope U-235 has been removed from natural uranium
which is mostly U-238. This is usually done by gas diffusion. The reason
for this is that U-235 is fissionable and U-238 is not. (i.e. U-235 can
be used a fuel in a nuclear reactor). Even though the U-235 is removed,
there is stll pleanty of U-238 left behind since the amount of 235 in
natural uranium is very small. While "depleated" means that some uranium
has been removed it does not mean that there is a significant reduction
of the level of radiation.
The total amount of activity from a radioactive source is a function
of the total mass and halflife of the isotopes present.
I'm not sure what you mean by "the more dangerous isotopes." Danger
, as I believe you to mean, would be associated with the amount of
radiation( radioactivity) and that is more closely related to mass that
the isotope number. All radioactive isotopes produce either alpha particles
(fairly easily stopped) or beta particles (not so easy). Most also
produce gamma rays which are very highly penetrating.
The "danger" of a particular isotope is a complex problem. There are a
lot of factors such as short term physical damage, long-term genetic
damage, type of radiation, energy of radiation, etc. etc.
Anyway, I assure you, "depleated" uranium is not significantly "less
dangerous" than "undepleated" uranium.
Bob Schramm