The situation here in New Jersey with the "tritium" EXIT signs was a  portion of a State owned hospital was being demolished and the sings were demolished along with the walls as general demolition. A juvenile got into the site, found a sign and broke it open and then broke open a tritium capsule from the stencil.  He was then exposed to the tritium.

Later the demolition contractor or the state project manager sent the waste from the sign out of state as medical, not radioactive wastes, and the State of New Jersey was fined by the receiving state (not sure about the  NRC) for doing so.

I have not seen anything recently that prohibits the use of tritium filled sings, although most institutional safety practitioners don't recommend them.  

We have many local large retail facilities in our area that use them routinely.

Your AHJ may have some other regulations about them.

Most fire code regs say something that the EXIT signs must be provided with alternative power, and therefore discourage the glow in the dark signs.