Hansen will call the players into camp on each of the last three Mondays in January, but the coach is quick to point out players who remain outside the current list are still in contention for the final squad announcement at the beginning of February.
"Clearly a large percentage of the playing squad will come from this training group, but that doesn't necessarily exclude anyone from outside it," said Hansen. "There are players, Vernon Cooper and Richard Parks are a good example, who will remain within the good training environments of their regions but will be closely monitored.
"Dafydd James will be working away quietly while we keep a close eye on a shoulder injury which is casting doubt on his capacity to cope with international rugby at this stage. There are also a couple of injuries which will prevent the likes of Paul Jones and Gareth Delve from joining us."
The uncapped members in the preliminary squad are Barry Davies, Richard Pugh, John Yapp, Ceri Jones, Peter Sidoli and James Merriman.
"For some, the training squad is about giving them a taste of what it is like to be part of the international set up and in other cases, we need to bring players into the fold to have a closer look at them," added Hansen.
Wales preliminary 2004 RBS Six Nations training squad