AW: Identifying contamination....

[Navert Stephan <Stephan.Navert@hsk.psi.ch>]

> -----Ursprüngliche Nachricht-----
> Von:	Joelle Key [SMTP:jkey@mail.state.tn.us]
> Gesendet am:	Donnerstag, 7. Januar 1999 16:57
> An:	Multiple recipients of list
> Betreff:	Identifying contamination....
> 
> Can anyone out there help with this one?
> 
> A metals processor received a shipment that contained some
> radioactivity... we have been unable to identify where the material
> originated... this is what we know about the shipment.
> 
> The material was part of a bin of metal chips and shavings from a
> machine shop. Only a portion of the metal in the bin is contaminated.
> 
> Preliminary results of the laboratory analysis of a piece of metal the
> size
> of a head of a pin indicated three radionuclides:
> 
> Units are in  picoCuries  per sample, since the metal fragment was too
> small for the laboratory to weigh.  
> 
> Cobalt 57         5823   +/-     24       
> Cobalt 58            706   +/-     55
> Zinc    65        20056   +/-   104
	[Navert Stephan]  All these isotopes are positron emitters.
Assuming that these isotopes have been produced by irradiating inactive
materials with protons i checked whether these is feasable, and it seems
to be. 

	Co 57 is produced by the reaction p + Fe-57, Co-58 by p + Fe-58.
What I miss in these scheme is Co-56, because most of iron is Fe-56!
Zn-65 comes from Cu-56, and the other from Copper produced Zn-isotope is
Zn 63 with a reasonable short half life so that you dont measure it any
more.

	If my production scheme is correct, these isotopes might have
been produced at a proton accelerator (needs to have the power of
several MeV!!)

> Has anyone out there seen this or something similar before?  Any help
> would be appreciated.
> 
> Joelle Key
> TN - Division of Radiological Health
> jkey@mail.state.tn.us
> 
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---
Dr. Stephan Navert
Hauptabteilung fuer die Sicherheit der Kernanlagen
Sektion Radiologischer Arbeitsschutz
CH 5232 Villigen HSK

Tel:	+41 56 310 3858 	FAX: ++41 56 310 4905
e-mail:	navert@hsk.psi.ch

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