Powell had hoped to forge a successful career in France when he signed for Beziers last season.
But the transition proved difficult and Powell was released from his contract by mutual consent after experiencing problems with both the language and the French culture after just five months in France.
Powell returned to more familiar soil last December, and has been training alongside his newly confirmed team-mates since that point.
The Wales A player had been linked with moves with Leicester and Bath, but has opted to stay with the current Celtic League champions.
