Energy Secretary James D. Watkins yesterday named John Wagoner, deputy manager of the Savannah River, S.C., nuclear weapons plant, manager of the vast plutonium processing plant at Hanford, Wash.

Wagoner, a nuclear Navy veteran, has been a special assistant to Watkins for several months. He will succeed Mike Lawrence, who resigned to take a job with ChemNuclear Inc., a nuclear waste cleanup contractor.

Wagoner will take command of a facility the size of Montgomery County with 13,000 employees that has been a center of nuclear weapons production since the World War II Manhattan Project. Now that the Cold War is over and "we won," Watkins said at a news briefing yesterday, Hanford has a new mission: not weapons production but cleanup of toxic and nuclear wastes from 45 years of plutonium processing.

Watkins also said he expects to sign today a "memorandum of understanding" with the Army Corps of Engineers that will guarantee the Corps a role in planning and managing the nuclear waste cleanup nationwide.

Members of the Washington state congressional delegation, and especially House Speaker Thomas S. Foley (D-Wash.), had been pressing Watkins to find a role for the Corps. The House Appropriations Committee last month voted to transfer management of the Hanford cleanup to the Corps' office in Walla Walla, Wash., which is in Foley's district.

"Foley and others inspired us to get this signed," Watkins said. "He was very pleased when I spoke to him today." If Foley approves, Congress is expected to accept the compromise and drop the mandatory transfer language.