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RE: Activation of concrete

We had similar experiences recently during decommissioning of a production cyclotron facility.
We detected both Eu-152 and Eu-154 in the concrete shielding.  Ours was a 30 MeV cyclotron

Ashok Dhar
Mallinckrodt Group
St. Louis

From:  Tupin, Edward A. 301-827-1230 Fax 594-4760[SMTP:EAT@FDADR.CDRH.FDA.GOV]
Sent:  Wednesday, August 14, 1996 10:32 AM
To:  Multiple recipients of list
Subject:  RE: Activation of concrete

Eu-154 is a thermal neutron capture product from (stable, 52% of 
naturally occuring Eu) Eu-153.  The capture cross section is about 1400 
barns. 43 MeV is enough energy to produce photo neutons from the 
accelerator.  With a half life of 16 years, it is not surprising that 
the Eu-154 is still around.

You may actually have both Eu152, as Les Slaback noted, and Eu154.  The 
decay emmissions are similar, as are the half lives and modes of 

Eu-152 is the thermal neutron capture product of (stable, 48% of 
naturally occuring Eu) Eu-151.  The capture cross section is about 5000 

Ed Tupin
RSO, Center for Devices and Radiological Health
(301) 827-1230
Fax:  (301) 594-4760