U.S. Attorney Mary Beth Buchanan and a delegation of U.S. authorities are in Russia this week to discuss the case against Yevgeny O. Adamov, the former Russian nuclear minister indicted in Pittsburgh on charges of stealing up to $9 million intended to improve nuclear security in Russia.

Ms. Buchanan, Assistant U.S. Attorney Bruce Teitelbaum, the lead prosecutor, and agents from the Pittsburgh offices of the IRS Criminal Investigation Division and the FBI are meeting with members of the Procurator General's Office in Moscow.

Mr. Adamov faces charges in the U.S. and Russia.

Ms. Buchanan said yesterday from Moscow that "we are discussing various aspects of the case, but cannot disclose the specific nature of the meetings."

Switzerland announced Mon- day that it would extradite Mr. Adamov to the U.S. He was arrested in Bern May 2.

Russian authorities had said they hoped to try Mr. Adamov rather than risk that he will reveal nuclear secrets to the U.S.

Mr. Adamov, who has agreed to return to Russia, has 30 days to appeal the Swiss decision. If the Swiss ruling is upheld, Mr. Adamov will face trial in Pittsburgh with his former business partner, Mark Kaushansky, of Monroeville, a former nuclear power plant engineer at Westinghouse.

Mr. Kaushansky's lawyer, Frederick Thieman, said yesterday that his client is innocent.