The Department of Energy on Friday made official a long-rumored bureaucratic reorganization that puts the agency’s Cold War nuclear-cleanup programs under new management but leaves the quasi-independent National Nuclear Security Administration essentially unchanged.

The Department of Energy’s (DOE) roughly $6.5-million-a-year Office of Environmental Management (EM), steward of environmental remediation of Cold War nuclear weapons sites across the country, now is nested in the agency’s Office of Science. Previously, EM was part of the Office of Management and Performance. DOE’s Office of Legacy Management, which handles completed Cold War cleanups, likewise moved into the Office of Science.

In the new reporting structure, the head of EM — or DOE’s assistant secretary for environmental management — will report to Paul Dabbar: the former investment banker and nuclear navy veteran the Senate confirmed as the agency’s undersecretary for science in early November.

Under the reorganization, DOE reverted EM’s old stovepipe, the Office of Management and Performance, back into the Office of the Undersecretary of Energy: a designation used in previous administrations. Mark Wesley Menezes, a former lobbyist for Berkshire Hathaway Energy, is the current undersecretary of energy. The Senate also confirmed him in early November.

Meanwhile, the National Nuclear Security Administration is unchanged in the new organization chart DOE published Friday. The semiautonomous nuclear-weapons agency still includes 12 reporting offices and still reports directly to the secretary and deputy secretary of energy.

The reorganization was among the worst-kept secrets in Washington. Industry and government officials have privately discussed it for months. DOE only made the move official Friday.

“This new structure will support American energy dominance, enhance our energy and national security, and improve outcomes in environmental management while ensuring DOE remains the leader in scientific innovation,” Energy Secretary Rick Perry said in a statement posted to the agency’s website.