It’s ironic that just before the media reported the appearance of radioactive bluefin tuna from Japan off the California coast, Gregory Jaczko, chairman of the Nuclear Regulatory Commission since 2009, stepped down.

Jaczko’s action followed a hot barrage of requests for his resignation from Republicans and from NRC commissioners who are supportive of the nuclear industry. The reason given is that Jaczko was, or so it’s alleged, autocratic and abusive, sometimes even controlling the flow of information to the commissioners to suit his own ends.

But Jaczko’s resignation is worth a longer look. The holder of a doctorate in particle physics from the University of Wisconsin, Jaczko came into politics with a Congressional Science Fellowship that paid him to work with U.S. Rep. Ed Markey of Massachusetts. He became an NRC commissioner in 2005 and was a vocal advocate for public safety, pushing, in the wake of the 9/11 attacks, for new requirements that nuclear power plants be built to withstand collisions with airplanes.

As chairman of the NRC, Jaczko cast the lone vote on the Commission against the construction of new nuclear reactors in Georgia and South Carolina, the first new reactors to be built in the U.S. in more than 30 years, because they were not required to meet new, post-Fukushima safety standards. He opposed the construction of the Yucca Mountain nuclear waste storage facility. In a matter affecting Western Massachusetts and southern Vermont, he refused to go along with commissioners who wanted to involve the federal Department of Justice in a suit to force the state of Vermont to approve relicensing of the Vermont Yankee nuclear power plant near Brattleboro.

Late last month, when the NRC voted to relicense the Pilgrim nuclear plant in Plymouth, Mass. before all reviews of its operations were completed, Jaczko cast the only dissenting vote.

And after the nuclear disaster at Fukushima last year, Jaczko pushed aggressively for new safety regulations for nuclear power plants in this country—expensive regulations from the industry’s point of view. His adversaries on the Commission claimed that after Fukushima, Jaczko became particularly intractable and determined to do things his own way.

(Worth noticing is that a company formed by one of those adversaries, Commissioner Bill Magwood, did consulting work for TEPCO, the firm that owns the Japanese nuclear reactors that melted down; Magwood said in Congressional hearings that his connection with that company didn’t influence his view of matters under the purview of the NRC.)

It’s true that Jaczko’s adversaries included Democrats on the Commission as well as Republicans; Magwood, for example, is a Democrat. But former NRC commissioner Peter Bradford told the New York Times that in Washington there is a “nuclear party” that “transcends” the Republican and Democratic parties, and that Jaczko has “never been a member of the nuclear party.” Allison Macfarlane, an associate professor of environmental science and policy at George Mason University in Virginia who has written a book on technical problems with the Yucca Mountain waste storage project, has been nominated by President Obama to replace Jaczko.