Well, I coaxed a bit of glow out of mine by taking it into a dark room and charging it with a very bright Fenix LED flashlight. I also measured it with a Lionel* geiger counter and could not measure anything. To check the counter, I measured one of the meters on a R-390a Radio and got about 1 to 2 Mr/hr, so I think my clock is safe... but it is possible that radium paint could have been used on earlier builds of the clock.
jr
*yes, that Lionel... It appears that they made radiation counter sets for CD in the 60s.