James McConnell is the new No. 3 and top career civil servant at the National Nuclear Security Administration (NNSA), the semi-autonomous Department of Energy nuclear-weapons agency said before New Year’s.

McConnell was appointed associate principal deputy administrator in December, according to the NNSA website. In that role he would backstop the agency’s politically appointed administrator and principal deputy administrator if either of those people leave or could not do their jobs managing the civilian nuclear-weapons steward.

McConnell was most recently deputy associate administrator for infrastructure and operations, in which role he oversaw big building projects across the nuclear security enterprise. 

NNSA promoted McConnell with major infrastructure upgrades ongoing, such as the Uranium Processing Facility for nuclear-weapon secondary stages in Oak Ridge, Tenn., and with other big construction programs about to ramp up, such as the Los Alamos Plutonium Pit Production Project in Los Alamos, N.M.

McConnell has been with the NNSA since 2008, according to his LinkedIn profile. Before that, the retired submarine officer worked for the Defense Nuclear Facilities Safety Board, the federal government’s independent health-and-safety watchdog for active and shuttered nuclear weapon sites.