airport explosive detection systems -Reply

[FRAMEP@ORAU.GOV]

wrt:
>>I believe the systems all use Cf-252, but since
>>DoE has not made any for a while the inventory
>>is going away fast.

 Barbara Hamrick wrote
>How much Cf-252 is in these devices?  Less than 1 nCi?

The systems did/do use Cf-252 but the information that DoE is not making
Cf-252 is incorrect.  ORNL has been cranking out Cf-252 at their high flux
isotope reactor for some time. There was a period when the reactor
was shut down but that was a while ago. Even during shutdown the
had an inventory close to 1 gram (ca 500 Ci).

The SAIC developed explosives detectors were set up to use, I believe,
100 to 200 ug. ( ca. 0.05 -0.1 Ci).

For what its worth, the N-14 absorbed a neutron to become N-15 (which
is stable) and a prompt gamma at around 10 MeV was given off. The
gamma indicated nitrogen and that indicated the possible presence of
explosives.  

I'm treading on thin ice but I'll guess that SAIC is no longer manufacturing
the devices: these things were expensive, the Cf-252 had to be replaced
regularly   (2.6 year half life) and there was the hassle associated with
the radioactive source.   Thats pure speculation.

Paul Frame
Professional Training Programs
ORISE
framep@orau.gov