Clashes are likely if Macfarlane is confirmed to replace the outgoing Jaczko, including over her criticism of proposals to store high-level nuclear waste at Nevada’s Yucca Mountain.
The Obama administration has sought to cancel the long-planned, long-delayed Yucca project, enraging Republicans.
Inhofe said at the hearing that he has "modest concerns" about Macfarlane, citing a lack of management experience and other concerns.
Macfarlane is appearing before the panel Wednesday along with Kristine Svinicki, a Republican member of the NRC that Obama has nominated for a second term.
The NRC has been a hotbed of controversy under Jaczko, a Democrat who has clashed with the other members of the body that oversees the safety of U.S. nuclear plants.
Jaczko has faced a series of allegations over his management style, strongly dening charges that he verbally abused NRC staff and taking particular umbrage to claims that he targeted women.
Jaczko's defenders say he's being attacked by more pro-industry members and senators over his efforts to boost nuclear safety.
Macfarlane, in her testimony to the committee, suggested that she would seek to end rifts within the NRC if confirmed.
“I will make a strong commitment to collegiality at all levels. An agency endowed with the public trust such as the NRC requires a respectful working environment to assure its integrity,” Macfarlane said.
She praised the people who will be her colleagues on the NRC if she’s confirmed.
“If confirmed, I look forward to working with Commissioner Svinicki and Commissioners [George] Apostolakis, [William] Magwood and [William] Ostendorff. They are all talented individuals engaged in the high calling of public service, and I look forward to forging a collegial relationship with them, if confirmed,” Macfarlane said.
—This post was updated at 11:15 a.m.