If the Senate confirms President Obama's choice to be the next chair of the Nuclear Regulatory Commission—George Mason University professor Allison M. Macfarlane—she would join the panel as it faces a host of challenges.

The NRC has 10 license applications pending for 16 new nuclear reactors and is determining what new requirements it may set for U.S. nuclear powerplants in the wake of last year's Fukushima Daiichi nuclear disaster in Japan.

If approved, Macfarlane, nominated on May 24, would replace Gregory B. Jaczko, NRC chairman since 2009, who announced on May 21 he planned to resign when a successor is confirmed. Jaczko, a Democrat and former aide to Senate Majority Leader Harry Reid (D-Nev.), has been the focus of controversy.

Last October, in a highly unusual move, NRC's other four commissioners—two Democrats and two Republicans—wrote to then-White House Chief of Staff William Daley expressing "grave concerns" about Jaczko's "leadership and management practices." In the letter, which became public in December, the four officials contended that Jaczko's actions "are causing serious damage" to the NRC. Jaczko, testifying with the other commissioners at congressional hearings, said he is passionate about nuclear safety but denied allegations he bullied NRC staffers or withheld information from other commissioners.

Macfarlane was a member of a blue-ribbon panel that in January recommended ways to deal with U.S. nuclear waste disposal. Since 2006, she has been an associate professor of environmental science and policy at George Mason University in Fairfax, Va.