Borealis Infrastructure, the investment arm of one of the country’s largest pension funds, will soon become the majority owner of Bruce Power, which operates Ontario’s biggest nuclear power complex.

Borealis, a division of the Ontario Municipal Employee Retirement System, announced Friday it will pay $450 million to Cameco Corp. (TSX:CCO) to expand its current stake in Bruce Power by one-third.

Upon completion of the sale, Borealis will become the majority partner of Bruce Power with 56.1 per cent ownership.

The other large partner is TransCanada Corp. (TSX:TRP), the Calgary-based pipeline company. While the other stakeholders include the Power Workers’ Union and the Society of Energy Professionals.

Bruce Power’s site assets will remain owned by the Ontario government, but the partnership will continue to run four of its eight nuclear reactors in Tiverton, Ont., on the eastern shore of Lake Huron.

Last year, the site produced about a third of Ontario’s electricity.

Ontario has recently announced plans on going ahead with the refurbishment of six more reactors at the Bruce generating station, which is the world’s largest nuclear power plant.

The cost and timelines associated with such a massive project have yet to be released.

Duncan Hawthorne, Bruce Power’s president and CEO, said the deal is an opportunity to revamp the partnership and put Ontario’s long-term energy plan into effect.

Cameco Corp., which mines and processes uranium for use in nuclear reactors around the world, said the deal is good for its investors, as it can now refocus on its main business.

“We believe the best option for our shareholders is to sell our interest in Bruce Power and continue to reinvest in our core uranium business where we see strong potential for growth,” said Tim Gitzel, Cameco’s president and CEO.

Cameco is one of the world’s largest uranium producers with mines, mills and conversion plants in Canada, the United States and abroad.

Michael Rolland, president and CEO of Borealis Infrastructure, said the purchase fits with the investment fund’s strategy.

“Bruce Power is an investment that continues to fit with our long-term strategy to invest in core, large-scale and high-quality infrastructure assets. It also plays a critical role in meeting the supply needs of the province of Ontario,” he said in a statement.

OMERS, which has a membership of more than 430,000 members, manages more than $60 billion in net assets.

Last month, the Ontario Power Authority said it was still undecided over whether Bruce Power will be on the hook for missing a deadline to restart two nuclear reactors in 2012.

Bruce Power said the delay in getting two refurbished units back online was attributable to an equipment problem, which it said should not result in a penalty because it was beyond their control.

In May 2012, damage to some non-nuclear equipment forced a delay in reconnecting the refurbished Unit 2 to the provincial power grid.