Back in the early 90's Diablo was staffed by Bartlett as a vendor, they then had us staff them as a head hunter where we went out and hired techs to work directly and temporarily for the utility(I do believe that somewhere during all this transition they might of had NSS/Numanco or PSESI staff'em 1 season), after building thier data base with the information we provided they started doing it themselves, and to thier credit they do it very well -
the reason why utilities (plants) utilize contract companies is due to many reasons, the biggest is flexibility. Basically a contract staffing company can get things done a lot faster then most plants as far as mobilization of a work force. They also pay us to absorb administrative issues and any/all problems that might arise from the workforce such as insurance & benefits, workers comp, hiring and terminations, etc... It also comes down to money, in the long run its less costly to bring in a vendor that is set up to staff plants than it is to do it themselves do to the associated costs such as insurance, workers comp, taxes, etc...
As I see it, and I could be wrong, Diablo has it pretty easy as it stands now but if they(the other plants) all did it that way you'd have 30-40 plants per season all competing for the same techs which in turn would mean they'd all have to increase they're "staffing dept" from the couple of people that Diablo utilizes to staff to many people in order to compete against one another, thus creating a bureaucracy at each site that would tie things up and take too long to get anything accomplished - kinda like government. So like goverment, by privatizing staffing they end up getting a more efficient service and a better product. Just my opinion which I'm sure many will disagree with.
Eric