As an MM2 you're eligible for your Journeyman card in several trade unions. You might wish to contact your local union halls. Or, do some web browsing. You might be required to prove your qualifications through testing or through an apprenticeship program (which should be much shorter for you than for an apprentice who comes in off the street).
Pipefitters-
www.ua.orgMillwrights -
http://www.ubcmillwrights.orgBoilermakers -
http://www.boilermakers.orgWork through a union hall can be anything from long-term work on a fixed location to itinerant outage work (lots of overtime) to a day or two performing a small repair - depending on the needs of the local market. Travel into other jurisdictions is also an option in most unions when demand is high enough.
If you are considering a house job (working directly for a utility) you will possibly be required to join the union which covers their employees once you are hired. Regardless of your actual skill, you'll be in the same union as the other manual trades on site (in most cases). The two largest unions who represent utility employees are the International Brotherhood of Electrical Workers -
http://www.ibew.organd the Utility Workers Union of America -
http://www.uwua.netThese jobs do not necessarily follow the progression from Apprentice to Journeyman - rather, they tend to follow the employers' job classifications and establish pay rates based on their individual contract with the employer.
Getting a Journeyman card will not necessarily be a deciding factor in securing a house job, but it can't hurt. The only caution here is that if you join a union and work as a Journeyman, and then accept work at a non-union power plant, you could lose any accrued pension and benefits that you earned as a union tradesperson. Only in extraordinary circumstances will a union tolerate one of its members working in a similar trade outside of their bargaining jurisdiction - and never without their permission. People do get away with it all the time - some even have books in two or three unions at the same time (which is also frowned upon if any of the work is similar - such as a Boilermaker working as a Pipefitter). But, they sometimes make examples of violators (if they catch them). So, you have to think of it as a one-way ticket when you go into or out of a union. They tend to see membership as a commitment, and not a stepping-stone to other work. Although, I know a few Engineers and management types who are former union tradesmen. Some of them still keep their books and pay their dues. This kind of move is widely accepted if not outright encouraged.
Having said that, I don't think it would hurt you in the least to investigate the various unions. You don't have to join right off. Check them out and decide when it is appropriate.
Now, return the favor and keep us posted on what you find out.
Good luck.