WHEN GREGORY B. JACZKO began his tenure as the chairman of the Nuclear Regulatory Commission (NRC) in 2009, the agency was largely invisible to the public, for all the right reasons. Its professional staff was widely recognized as world-class, to the point that analysts held it up as a model for other government energy regulators to emulate, and it was quietly preparing to oversee the first expansion of this nation’s nuclear fleet in decades.

Then came the drama. Mr. Jaczko helped President Obama and Senate Majority Leader Harry M. Reid (D-Nev.) kill the Yucca Mountain nuclear waste storage facility while freezing other commissioners out of the process. All of the commissioners later rose up against their chairman, alleging erratic behavior and abuse of staff. The NRC’s inspector general also got involved, detailing complaints about Mr. Jaczko’s aggressive style and use of procedure to manipulate colleagues into supporting his preferences. Another, possibly more scathing inspector general’s report is due anytime now.

That’s why Mr. Jaczko’s resignation from the NRC on Monday is for the best. Even if not every allegation against him bears out, his presence had become a distraction at an agency that will get only more important in coming years.

Nuclear reactors produce electricity at all times of day (unlike wind or solar power) and emit almost no greenhouse gases (unlike coal- or gas-fired power plants), which means they are likely to play a significant role in fighting global warming. But they can also be expensive, in no small part because of extensive safety requirements during permitting and construction. Rigorous safety standards are essential, but regulatory delay costs money, and a dysfunctional NRC does not inspire confidence among power-plant operators that the commission will move at an appropriate pace.

The new chairman should recommit the NRC to applying an updated approval system to a second generation of reactors, with the goal of streamlining approval where possible. The new system, for example, allows the commission to pre-approve a few standard reactor designs from which operators can then choose, cutting down the time needed for each application. Also on the horizon is the possibility of innovative reactor designs that would require a nimble response from the NRC. And it must address nuclear waste in the wake of the Yucca Mountain policy failure.

First, though, the Senate needs to do its job. The president on Thursday nominated a successor to Mr. Jaczko, nuclear-waste expert Allison M. Macfarlane. Lawmakers must thoroughly — but promptly — consider her, as well as Kristine L. Svinicki, a Republican commissioner Mr. Obama recently renominated. It’s time to end the drama.