Re: Ac-227 electroplated disk source

[JGinniver@AOL.COM]

Hi, perhaps I am about to reveal my ignorance, but I'm intruiged as to why you require an Ac-227 source?


We use similar units in the UK, manufactured by Canberra Harwell (formerly Harwell instruments  AB96 now being replaced with a unit called the i-CAM) and Lab Impex (CMS-2000 a number of which I believe are being installed in a new facility at INEEL) both of which use silicone diode (PIPS?) detectors.  We generally calibrate these using the main artificial alpha isotope on interest in the workplace.


We therefore have a Pu-239, U-235 (If I recall correctly) and Th-232 for the different fuel reprocessing plants we have.  We haven't as far as I'm aware used Ac-227 sources.


The units we have do have the capability to compensate for Radon (and it daughters) when in use.  However any compensate (which is different from the factory pre-set values) is only carried out after obtaining data by running the units in-situ within the plants.  The degree of compensation for the various naturally occuring radionuclides is dependant on the ingress of radon local to the units and the rate of air change locally within the facility.  The compensation values used in the instrument software can vary significantly even within the same plant  We do not test the units with sources composed of naturally occuring radionuclides.  We do however review the data held within the units to confirm that the appropriate level of 'radon' compensation is being used.


Hence my interest in the use of an Ac-227 source.


Warmest regards

                         Julian Ginniver