So far the companies taking part are metal giant Outokumpu, the German utility E.ON and a smaller Finnish utility, Rauman Energia, as well as two Swedish companies, Boliden and Katternö.
To push ahead with the project, the group is establishing a new power company to be known as Fennovoima Oy.
The intention is to construct a plant to meet a projected growth in demand for electricity. Plans call for a 1000-1800 MW nuclear power plant, to be operational sometime between 2016-18. A survey for a suitable site for the facility is underway.
The German company E.ON, which is involved in the project, previously advanced plans to build a nuclear plant in Finland, but its application for a site was recently rejected by the City of Loviisa.
If successful, Fennovoima would supply its owners with power at cost. Each partner would be entitled to output in line with its share of ownership.
About half of the projected generating capacity would be reserved for other companies that may wish to become part-owners. A number of Finnish companies, including both industrial concerns and electric power companies, have reportedly expressed interest.
Two other energy companies, Fortum and TVO, are already further advanced with their own proposals for a sixth nuclear reactor. Any such plan must be approved by Parliament.
Construction of a fifth reactor is now underway at Olkiluoto on the west coast, but is far behind schedule and over budget.