Allison Macfarlane began her second term as chairwoman of the Nuclear Regulatory Commission Monday after a delayed confirmation vote in the Senate last week.

California Sen. Barbara Boxer had prevented the confirmation from moving forward, pending the receipt of documents related to the recently closed San Onofre nuclear plant. The confirmation vote took place June 27, three days before the expiration of Macfarlane’s first term.

President Barack Obama nominated her last year to fill the position vacated by Gregory Jaczko. She joined the NRC following her membership on the Blue Ribbon Commission on America’s Nuclear Future. A geologist with a lengthy academic background, Macfarlane previously worked as a professor of environmental science and policy at George Mason University. Her second NRC term is for five years.