The future of Westinghouse Electric Co.'s global nuclear business now rests in the hands of Brookfield Asset Management Inc.'s private equity arm.

Canada's biggest alternative asset manager agreed to buy what remains of the former nuclear energy powerhouse's U.S. business, as well as its non-bankrupt European business, for $4.6 billion. It's the first foray into the nuclear sector for Brookfield Business Partners LP, a publicly traded unit.

The deal marks a positive turn in a long saga of financial woes stemming from U.S. reactor projects that dragged Westinghouse into bankruptcy, ensnared its parent, Toshiba Corp., and also battered U.S. utilities that had taken on their construction.