MORGANTOWN, W.Va. (AP) _ Nearly a year after he began his firsthand study of the capitalist system, Soviet economist Mikhail Popov says he's ready to put his knowledge to work as part of the sweeping reform in his homeland.

''I will use the ideas of American scholars,'' said Popov, a regional economist for the Siberian Branch of the Soviet Union's Academy of Sciences. ''Many of them are new and up-to-date and not available in the Soviet Union.''

Popov has studied such capitalist cornerstones as rents, interest rates and prices since his arrival last September at West Virginia University's Regional Research Institute under an international exchange program.

''When I look at things in the United States, I usually think 'How can I use them to restructure our economy?''' Popov said. ''I also look at the history. What worked and what didn't?''

During an interview on the eve of his scheduled Fourth of July departure, the 35-year-old expert on Soviet industrial production said he was anxious to share his experience with colleagues who are intimately involved in ''perestroika'' - Soviet leader Mikhail Gorbachev's effort to overhaul the Soviet system.

Popov said his study of the decline of the steel industry in Pittsbugh and of coal mining in Appalachia could help ease the transition of the Kuzbass region of Siberia, where much of the country's heavy industry once was centered.

''We have similar problems in some areas and wanted to look at the tremendous changes that have occurred in Pittsburgh, for example, and study the optimal way to shift from basic industries to high-tech,'' Popov said.

Gorbachev began pressing for the restructuring of Soviet society shortly after taking office three years ago.

Last week, during a national meeting of the Communist Party, he called for democratization, economic reform and changes in the Soviet political system that he said would make perestroika ''irreversible.''

''Perestroika really is an expression of our society,'' Popov said. ''It just didn't happen with a change of leadership. It was inevitable, a natural evolution of the socialist system.

''We couldn't have avoided it,'' he concluded.

Some commentators in the U.S. have said Gorbachev's attempts to introduce market mechanisms into the Soviet system prove that communism is doomed. Others in the Soviet Union say Gorbachev has gone too far too quickly.

Popov, an unabashed Gorbachev supporter, said he disagreed on both counts.

''I'm not afraid that we will lose the main ideas of socialism,'' said Popov. ''If someone is willing to produce much more than the other guy and works harder, he deserves to be rewarded.

''That doesn't threaten socialism at all.''

During his stay, Popov also has presented several papers on the Soviet economy, visited Penn State University and the Massachusetts Institute of Technolgy and given dozens of lectures.