request for info - Gravity meter containing Ra-226

["Dahlskog, Leif" <Leif.Dahlskog@health.wa.gov.au>]

I hope a fellow radsafer could provide a little information concerning
an interesting scientific instrument.

A local mining company has a Worden Gravity Meter Model No. 121
manufactured by Texas Instruments.  The operating manual accompanying
the device (manual no. 081537-008 revised 1975) has a label on the
inside cover which makes reference to Ra-226 being contained in the
device.  No other reference or information to the activity or purpose of
the Ra-226 is given in the manual and there are no labels or tags on the
device which mention the Ra-226.

As the instrument has historical value for the company they wish to
place the instrument in a display following the removal of the Ra-226. 

As illumination appears to be provided by a incandescent lamp, what
purpose does the Ra-226 serve and what activity of Ra-226 did these
devices contain ?

Any information appreciated. Alternatively a contact for the appropriate
person at Texas Instruments is welcome.

Regards

Leif Dahlskog
Radiation Health Section
Health Department of Western Australia.