Good evening all, and Happy New Year!
Here is a link to the Gaffer Glass site. http://www.gafferglass.co.uk/technical/uranium.htm
The technical info, downloadable as a pdf is worth reading and self explanatory.
Most glassmakers such as myself use pre-melted colours these days. The people who produce these colours used to be in Germany or what is now the Czech republic, but Gaffer Glass in New Zealand are perceived by many as the preeminent colour makers for artists. There are still some European suppliers, Kugler (Friedrich and Schreibler)and Reichenbach, are notable. Ornela, unfortunately, closed a few years ago, but fortunately, I still have some stock of some of their rarer colours, including some uranium bearing colours.
So far as I am aware, there are no restrictions that limit the use of these colours as they have been pre-melted and to all intents and purposes the uranium is inert, (used in layman's terms and not as a scientific statement) once the colour has been pre-melted. (Nonetheless, when it is in granular form, as with other colours, care should be taken not to inhale or ingest).
While I can't speak for Richard Golding, I think it is safe to say that he uses the same kind of pre-melted colour.
I hope that this clarifies the position. Most people don't produce their own colours.
To an artist such as myself, it is the colour that matters, not the chemical content, but that it is a personal opinion, which may not be shared by all.