HP question - alpha sources

Progeny ingrowth over 50 years. Po-210 only decays to stable Pb-206 so it is a one-shot deal. Even if you disregard biological clearance, all the Pb-210 is gone in a few years. The others keep producing progeny “forever”, so the activity actually goes up. Remember that the DAC and ALI are based on only the parent and do not account for any progeny in secular equilibrium at the time of intake, but do account for ingrowth over the 50 year span assigned for committed dose.

Regards,

Charlie Migliore

-----Original Message-----
From: owner-radsafe@list.vanderbilt.edu [mailto:owner-radsafe@list.vanderbilt.edu]On Behalf Of Franta, Jaroslav
Sent: Tuesday, June 18, 2002 7:26 AM
To: Radsafe (E-mail)
Subject: HP question - alpha sources

Dear Radsafers,

Would anyone be able to tell me why it is that the ALI (IC-W) for Po-210 is 100 times HIGHER (0.6 µCi) than for Pu-239 & Am-241 (both 0.006 µCi), even though the T½ for Po-210 is 1140-times shorter than that of Am-241, and 63570-times shorter than that of Pu-239 ? Can someone please enlighten me about the reasons for this ?

Thanks in advance.

Jaro