The chief of the National Nuclear Security Administration is leaving the Obama administration amid ongoing controversy over the recent break-in at a sensitive site.

NNSA Administrator Thoomas D'Agostino, who has spent more than five years at the agency helm as undersecretary for nuclear security in the Department of Energy, said in a statement late last week that he was leaving federal service to spend more time with his family. He has served in government for more than three decades.

"I have an ... important commitment to my wife and family and I am a strong believer that organizations are healthier when leadership changes on a periodic basis," D'Agostino said in a statement. "The time is right for this change."

Earlier this year, three elderly peace activists broke into the Y-12 National Security Complex at Oak Ridge, Tenn., a critical nuclear weapons site.

But NNSA's parent, the Department of Energy, is stressing that D'Agostino's departure has nothing to do with the incident. Investigators have aimed their criticism at security contractors (Greenwire, Nov. 1). Energy Secretary Steven Chu praised D'Agostino's work.

"Under his watch, we have eliminated or secured hundreds of nuclear weapons worth of nuclear materials," Chu said in a statement. "We have reduced the number of deployed warheads to the lowest level since the 1950s -- an approximate reduction of 85 percent from the darkest days of the Cold War -- while successfully maintaining the safety, security, and effectiveness of a shrinking stockpile."

D'Agostino's retirement is effective Jan. 18. NNSA Deputy Administrator Neile Miller will take on his duties until the administration finds and the Senate confirms a replacement.

Also departing from the Energy Department is Deputy Assistant Secretary for Clean Coal James Wood. Wood spent more than three decades in the power sector, including a stint as CEO of Babcock Power Inc. He was in charge of carbon capture and sequestration efforts at DOE for three years.