Vintage radioactive wrist watches - Is Radium really nasty?

[everettr]

(01-18-2015 11:19 AM)jebem Wrote:  At last, the watch hands radiation emitting testing...
Considering the current safety standards, what would be the risk level for someone using that watch for a full year, accepting the monitored value of 39uSv/h?

I don't think that there is currently any reason to wear a radium dial watch instead of a normal watch. My understanding is that the typical luminescent material, for example ZnS, breaks down over the years, so that the radium + phosphor mixture no longer glows, even though there is still plenty of radioactive decay. Do you observe any glow from your watch hands?

Here is a link to an interesting article about the Radium thumb rule, for estimating the activity and the amount of radium that you actually have.
Radium Thumb Rule

Note that your GM tube will overestimate the activity, especially if you choose a short (less than 15 cm) measurement distance. The article explains that if the source is too close to the detector, you start measuring beta particles in addition to gamma rays. The radium thumb rule assumes you are only measuring gamma rays.

It might be interesting for you to try and detect radiation from your source with a webcam. The CMOS sensor in a typical webcam responds to betas and gammas. See:
Photographing radioactivity with a webcam