star trek - What happens to a TNG-era Romulan Warbird power core when it is destroyed in combat or decommissioned?

In the trek novel Badlands 2, Captain Janeway encounters a "free-range" artificial quantum singularity:

No wonder they couldn’t find the source of the tetryon shockwaves. The
AQS must be moving much faster than the speed of light, at nearly warp
10. It would be impossible for sensors to detect until it was on top of them and already gone in its tremendous orbit. The subspace
shockwave would therefore dissipate quickly, less than two hundred
million kilometers away from the source. Any ships unlucky enough to
be close to it when it passed by would suffer a lapse in gravity,
sensor overload, and disruption of the power circuits. And the passage
of tetryons through the ship would cause radiation poisoning in the
crew members.

Since the singularities are apparently quite valuable and not (at least in theory) prone to the effects of aging, I think we can reasonably assume that singularities that are no longer needed in one vessel are simply returned to the dockyard to be re-implanted into new ships.