RE: Russian space probe hysteria! -Reply

[Charles Willis <CAW@nrc.gov>]

If you just look at the inhalation issue, Pu-238 is one of the most hazardous nuclides, at least
as indicated by the DAC.  It is equal to Pu-239.  A few nuclides have lower DACs, viz. Cf-251,
Cf-249, Bk-247, Cu-248, Np-237, Pa-231, Th-232, Th-229 and Ac-227.  (Some 300,000 Ci of
Pu-239 have been released into the atmosphere and thorium is everywhere.) As a practical
matter, many other nuclides are more troublesome, e.g. Po-210 because of the creep
problem, Ra-226 because of the external radiation, etc.  Of course, Sternglass followers are
likely to contend the Sr-90 is much worse.

Charlie Willis