The Shaw Group Inc. plans to sell its piece of Westinghouse Group back to Toshiba Corp. in a move that will lower the Baton Rouge-based company’s debt by close to $1.7 billion.

Shaw owns 20 percent of Westinghouse through its special purpose subsidiary, Nuclear Energy Holdings L.L.C. Shaw acquired the Westinghouse stake in 2006.

Shaw Chief Executive Officer J.M. Bernhard Jr. said the move is in shareholder’s best interests and for Shaw’s future business opportunities.

Shaw issued close to $1.1 billion in yen-backed bonds to finance the acquisition, but the debt has swollen by $600,000 in the last five years.

At the Aug. 31 exchange rates, Shaw would have a pre-tax gain of $545 million, the company said.

The Westinghouse deal was part of Shaw’s emphasis on the nuclear power industry. But the tsunami and resulting nuclear crisis in Japan has created some discord about the future of nuclear power.

Shaw said Tuesday it expects to continue working with Westinghouse. Shaw and Westinghouse currently are under contract for six new AP1000 nuclear power units in the U.S., as well as four units under construction in China. In addition, Shaw has a contract for technical support services on an additional two-unit AP1000 project in China that follows the original units at Sanmen and Haiyang.

Shaw also expects to continue to work with Westinghouse on new AP1000 projects and with Toshiba on Advanced Boiling Water Reactor projects. The companies already have begun pre-proposal and study activities in anticipation of those projects.