> A quick check of the CRC Isotope table shows that the half life of U-236
> listed as 2.39 x 10^-7 years. (I know that this seems an unusual way of
> presenting that number and might be an error: could it be 10^+7 years or
> 10^-7 seconds.)
>
The half life of U-236 is 2.342 x 10^7 years (Chart of the Nuclides 1977,
General Electric). The CRC handbook is essentially correct.
> If that number is correct, the half life works out to 7.5 seconds. Even
> if the moon were 10,000 years old, there would be no U-236.
I don't see how you can get a 7.5-second half life from the values in the
CRC.
> In trying to backout a source for U-236, I found myself wandering around
> progressively larger transuranic elements of progressively short half
> lives. There seems to be no good explanation for U-236 appearing at all.
> One might question to source of this information.
I had the same problem but postulated neutron irradiation of lunar U-238
(see my earlier post).
Chuck Vandergraaf
Pinawa, MB