Activation of concrete

[R.Ryder@dl.ac.uk]

To all Radsafers, a question.

We have been carrying out surveys of the concrete walls of a shield 
enclosure prior to decommisssioning. The enclosure was used untill 1977 to 
house a high power 43 MeV electron linac. The concrete is thought to be 
normal concrete. The room has not been used for any other activity involving 
radiation or radioactive materials and so the activation has been decaying 
for almost 20 years.

Gamma spectroscopy of the activity shows isotopes of Co60 which is not 
unexpected but also Eu154 which is unexpected. The activity is only a few 
Bqs per gm of concrete.

Has anyone any ideas how the Eu154 could be formed?

Roy Ryder

Daresbury Laboratory