Washington (CNN) -- Allison Macfarlane was sworn in as commissioner of the Nuclear Regulatory Commission on Monday, replacing controversial NRC commissioner Gregory Jaczko, who abruptly resigned in May.
Macfarlane becomes the 15th person to head up the regulatory agency tasked with overseeing U.S. nuclear reactors and nuclear safety.
"I am grateful to the president for nominating me and to the Senate for confirming my selection," Macfarlane said in a statement issued after the private ceremony.
Macfarlane, 48, holds a doctorate from the Massachusetts Institute of Technology and was an associate professor at George Mason University when President Barack Obama nominated her for the NRC's top job.
With Macfarlane at the helm, the NRC now looks to move beyond the scandals that embroiled Jaczko. In April, he denied allegations that he targeted women and created a hostile work environment. The accusations came amid a political fight between Congress and the White House over who should serve on the five-member commission.
The accusations followed a long-running dispute between Jaczko and the NRC's four other commissioners that erupted last year into public view when letters expressing "grave concerns" about his leadership were posted on a congressional website.
Like Jaczko, Macfarlane is considered an ally to Senate Majority Leader Harry Reid's steadfast opposition to disposing nuclear waste in his home state of Nevada.
Macfarlane's expertise in nuclear waste disposal and criticism of plans to dispose of nuclear waste at the Yucca Mountain Nuclear Repository made her nomination agreeable to Reid.
In her book, "Uncertainty Underground: Yucca Mountain and the Nation's High-Level Nuclear Waste," Macfarlane claims, "although geologic repositories are the best solution to the nuclear waste problem, there are substantial uncertainties in projecting the performance of a geologic repository far into the future."
According to the NRC, Macfarlane is the third woman to lead the agency and the only member with a background in geology to serve on the commission.