John Riley, legislative assistant to Sen. Dave Durenberger (R-Minn.), is expected to be the nominated this week as chief of the Federal Railroad Administration. Riley, a trial lawyer before joining Durenberger's campaign in 1978, helped develop Minnesota's response to the Midwest rail crisis that year. Durenberger, representing a state that needs strong rail support to get its agricultural products to market, has been active in railroad matters as a member of the Senate rail caucus.

Alma Riojas Esparza has been named head of the Agriculture Department's Minority Affairs Office. Esparza has been executive assistant for the Defense Department's Office of Small and Disadvantaged Business Utilization since January. Previously, she was served as member of President Reagan's transition team. She succeeds Isidoro Rodriguez, who was dismissed after calling for elimination of hiring quotas.

Thomas O. Kay has been appointed deputy assistant secretary of USDA for governmental and public affairs. Kay, a former Hill staffer and Senate liaison for the National Association of Realtors, has been part of USDA's congressional relations staff for three years. And William J. Riley, acting director of personnel for USDA since July, 1982, has been named to the post on a permanent basis.

Thomas E. Murley has been appointed administrator of the Nuclear Regulatory Commission for the region that includes Maryland and the District. Murley now is director of the NRC's regional operations and generic requirements staff.