* Criticized for abrasive management style
* Jaczko says decision unrelated to criticism
* Wanted to give ample time to find replacement
* NRC writing tough new post-Fukushima safety rules
WASHINGTON, May 21 (Reuters) - Gregory Jaczko, chairman of the U.S. Nuclear Regulatory Commission, said on Monday that he would resign, following a year of intense criticism over his abrasive management style.
A series of reports and congressional hearings have painted Jaczko as a bully who had reduced some senior female employees to tears - accusations that have overshadowed new rules he championed in the wake of the 2011 earthquake and tsunami that devastated Japan's Fukushima Daiichi nuclear complex.
Jaczko, 41, has consistently dismissed and denied the reports. He said announcing his decision to step down more than a year before his term expired was "not at all" related to the accusations but rather publicly signals his intention not to pursue a second term as chairman.
"I just wanted to provide the best opportunity for a successor to be brought on board and to give the president and the Senate maximum opportunity to do that," Jaczko told Reuters, noting he will stay in his job until his replacement is confirmed by the Senate.
The White House plans to nominate a new chairman soon, a spokesman said.
Jaczko said the negative headlines have not taken a toll on him or his family. "I've learned to separate and not take personally the kinds of things that people have said," he said.
"It's rare in life to have the opportunities I've had as chairman and I relish every moment of it. If that means being in the middle of some difficult issues with Congress, then that's just part of the job and something I will continue to deal with," he said.
ACCUSATIONS OVERSHADOW CHANGES
Having cast himself as a reformer at an agency where change typically happens at a glacial pace, Jaczko was long an irritant for the nuclear power industry, which fears the new regulations could drive up costs at the same time that cheap natural gas heightens competition.
The head of the Nuclear Energy Institute, a lobby group, acknowledged in a statement that the industry had differences with Jaczko but wished him well and urged the White House to name a new chairman quickly.
Republicans, with an eye to elections in November, were quick to cheer the departure of Jaczko, a Democrat, and also want a replacement soon.
"The only thing surprising about his resignation is the fact that the Obama administration has remained silent for more than a year after allegations of Jaczko's offensive behavior surfaced," said Mitch McConnell, Republican leader in the U.S. Senate.
The selection of a replacement could happen in tandem with the reconfirmation of a Republican commissioner, Kristine Svinicki, whose term expires next month.
Jaczko's replacement likely will be someone more open to "consensus building," said Ed Batts, a partner at law firm DLA Piper.
"It would seem likely that his successor ... will be from a more conventional background, either a technocrat or academic, and perhaps less of a dynamic personality," Batts said.
"DECENT GUY BUT HE WAS TOO DIRECT"
Jaczko got his start in Washington as a young, socially conscious physicist helping his then-boss Harry Reid, now Senate majority leader, block a plan to store radioactive waste under Nevada's Yucca Mountain.
Jaczko, a Democrat, had served at the NRC for almost eight years, and was appointed to the chairman role by President Barack Obama.
"He was a decent guy but he was too direct," said Najmedin Meshkati, an engineering professor at the University of Southern California. "To run the NRC he needed to be much more diplomatic, much more circumspect."
The resignation comes as the nuclear agency overhauls safety rules for the nation's 104 nuclear plants, owned by companies such as Exelon and Entergy Corp.
It also recently approved licenses for the first new U.S. plants in more than 30 years, owned by Southern Co and Scana Corp.
Jaczko cast the lone dissenting vote against the new licenses, drawing ire from the industry and Republicans.
UNCOMFORTABLE HEARINGS ON THE HILL
The four other commissioners at the NRC - two Democrats and two Republicans - took the unprecedented step last year of complaining to the White House about Jaczko.
Uncomfortable congressional hearings followed with the commissioners detailing their concerns and Republicans grilling Jaczko.
At the time, Bill Daley, then White House chief of staff, expressed his support for Jaczko and urged the commissioners to get along, perhaps with help from a mediator.
But the rancor did not fade. Republicans helped revive the story when the White House was slow to renominate Svinicki this spring. House Republicans had a hearing planned for next week expected to focus on Jaczko's tactics.
The inner turmoil at the NRC first attracted public scrutiny a year ago when the agency's inspector general, an internal watchdog, released a report that described Jaczko as someone who often lost his temper and used threats and intimidation to try to get his way.
The NRC's inspector general is expected to release a follow-up report about Jaczko's leadership style soon, although the timing and content of the report is not clear.
Jaczko told Reuters he had not seen the report and said he would not see it until it is final.
Jaczko's defenders said the accusations have been amplified by opponents to distract the agency from its reforms.
"These attempts to make a slender, balding particle physicist appear to be careening about the NRC like Mike Tyson with Evander Holyfield's ear in his teeth were always complete nonsense," said Peter Bradford, an adjunct professor at Vermont Law School and a former NRC commissioner.