Legislators in the House want the head of the Nuclear Regulatory Commission (NRC) to answer questions about the agency’s efforts to decide whether or not to approve the Yucca Mountain nuclear waste site in Nevada.

Reps. Fred Upton (R-Mich.) and John Shimkus (R-Ill.), the heads of the Energy and Commerce Committee and its subcommittee on the Environment and the Economy, asked Allison Macfarlane on Friday to appear before the subcommittee at a hearing in September.

They want her to answer questions about the status of the NRC’s review of the dump site, which a federal appeals court last week ordered it to resume.

“Our country has invested 30 years and $15 billion in determining whether Yucca Mountain would be a safe repository,” they wrote in a letter to the NRC. “The NRC is this nation’s nuclear safety regulator and its reputation for independence and objectivity rests on its transparency in this matter. As such, NRC’s objective, scientific findings regarding the safety of Yucca Mountain would provide the public an independent, authoritative assessment of this important project.”