Gregory Jaczko, the outgoing chairman of the Nuclear Regulatory Commission, was unapologetic today for his role in multiple agency spats and said the commission made better decisions under his leadership.

Jaczko, who will officially step down as the NRC chairman tomorrow, indicated at the Platts Energy Podium that he had some regrets about his frayed relationships with his colleagues. Four commissioners -- two Republicans and two Democrats -- complained to the White House last year that Jaczko verbally abused staffers and withheld information.

But Jaczko today said the commission benefited from his decisionmaking after a magnitude-9 earthquake and tsunami crippled three nuclear reactors at Japan's Fukushima Daiichi complex.

"I believe, in the end, that the commission made better decisions because of the leadership that I demonstrated during Fukushima and the aftermath and the changes that we needed to make," he said. "Those were not always popular."

Jaczko also denied that complaints about his management style prompted him to step down and said he planned all along to resign before his term expired in June 2013.

Announcing his intention to step down early allowed the White House to pair a new chairwoman -- Allison Macfarlane, a geologist and professor -- with Republican NRC Commissioner Kristine Svinicki, who was confirmed for a second five-year term last week, Jaczko said.

The chairman applauded the staff at the NRC for dedication to nuclear safety -- but outlined his concerns with the agency's work going forward.

Jaczko called on the commission and nuclear industry to accelerate seismic reviews for nuclear power plants. He also criticized power plant operators' focus on preventing disasters rather than mitigating rare catastrophes through better reactor designs.

"One of the things we're seeing right now, particularly in the area of station blackout, is the industry seems to be pushing ... more and more from a mitigation side and less from a prevention side," he said. "I think that's a mistake."

Jaczko also cautioned the commission against analyzing the cost of new safety rules instead of simply requiring plant operators to make changes. The industry, he said, could be using risk assessments as a way to rule out having to deal with very rare accidents, and better analysis and computer modeling should be used to figure out how to deal with those 'low-probability, high-consequence' events, he said.

"It can be very difficult through a cost-benefit analysis to justify making changes when you're dealing with these very unlikely events," he said. "In hindsight, if it happens, it's no longer unlikely and you're now dealing with the consequences."

Jaczko also said the NRC has "wrapped up" its review on the abandoned Yucca Mountain nuclear waste repository in Nevada and doesn't have the money to continue working on the Energy Department's application to construct the site.

Jaczko, 41, who has a doctorate in theoretical particle physics and worked on Capitol Hill for several years before joining the NRC in 2005, said he was going to take time off after leaving the agency but wouldn't provide further details.