The 604-acre site proposed for Rhode Island's first nuclear power plant will become a wildlife refuge and recreation area, the General Services Administration said today.

The decision apparently ends six years of controversy which involved state politicians, labor leaders and thousands of citizens over the future of the unspoiled oceanfront site and the safety of nuclear power. Unions, citing thousands of jobs in the $3 billion construction project, led proponents, while environmentalists led the opposition.

The decision was made by Paul E. Goulding, a Rhode Islander who is GSA's acting director. The GSA controls the site because it is surplus federal property, a portion of which was once used as a naval air station.

Andrew C. Kadak, New England Power Co. chief spokesman, said the utility will appeal the decision. However, he added, growing opposition in the state, including that of Gov. J. Joseph Garrahy following the March incident at Three Mile Island in Pennsylvania, make it unlikely that a nuclear plant will ever be built in Rhode Island.

Kadak said the utility will seek sites elsewhere in New England.

"It would be ridiculous to start dancing in the streets over this decision," said Sen. John H. Chafee (R.R.I.), who has long expressed concern about nuclear power plant safety and waste disposal. "This doesn't do away with the problem, which is, 'What are we going to do for power in the North-east?"