The head of the Nuclear Regulatory Commission said Thursday he was “mortified” by allegations that he verbally abused women who worked at the agency.

“I have never intentionally berated, threatened, bullied or intimidated any member of the staff,” Gregory Jaczko told a Senate committee. “I have a wife, I have a sister . . . and I have interacted and worked with a tremendous number of people at the agency, including a large number of women.”

Jaczko’s comments came on the second day of congressional hearings into his behavior as leader of the 4,000-employee agency, which oversees safety at the nation’s 104 commercial nuclear reactors.

The four other members of the commission have described Jaczko as an intimidating bully whose actions could compromise nuclear safety. The two Democratic and two Republican commissioners wrote the White House to express “grave concerns” about Jaczko’s actions, which they said created a “chilled work environment.”

Their Oct. 13 letter stopped short of calling for Jaczko to resign but said he “intimidated and bullied” senior career staff, ordered workers to withhold information and ignored the will of the commission’s majority.

The commissioners — Democrats William Magwood and George Apostolakis and Republicans Kristine Svinicki and William Ostendorff — told Congress that women at the NRC felt particularly intimidated by Jaczko.

Jaczko, 41, has led the commission since May 2009. He is a former aide to Senate Majority Leader Harry Reid (D-Nev.).

Magwood told the House Oversight and Government Reform Committee on Wednesday that Jaczko had bullied and belittled at least three female staff members, one of whom told Magwood she was “humiliated” by what Magwood called a “raging verbal assault.”

Jaczko told senators Thursday that he was “shocked and I have to say I was mortified when I heard those statements.”

Svinicki, the only female commissioner, told House investigators that she was so uncomfortable around Jaczko that she asked her chief of staff to “keep watch” over a private meeting with the chairman in Svinicki’s office.

Jaczko said Thursday that at times he can “be passionate, be intense in my questioning” of colleagues and staff members. “And if that has ever, ever led to an emotional reaction by somebody, I would want to know that and I would address it immediately.”

Sen. Barbara Boxer (D-Calif.), chairwoman of the Senate Environment and Public Works Committee, said the allegations against Jaczko were unfounded.

Boxer said Wednesday’s GOP-led House oversight hearing on Jaczko’s behavior amounted to little more than a “witch hunt” that “attempted to assassinate the character of a dedicated public servant.”

“Frankly, I was shocked and appalled,” Boxer said.

Boxer said she asked committee staff to investigate whether Jaczko had mistreated women. The staff reported that a woman at the agency told them Jaczko was “the most fair person” she had ever met, Boxer said.

Boxer called Jaczko a “proven leader” who has advanced important safety reforms at the commission. She accused the other NRC commissioners of “slow-walking needed reforms” prompted by the nuclear crisis in Japan.

“I think this is all about safety, dressed up as something else,” Boxer said.

Commissioners called Boxer’s account offensive and inaccurate and said the main issue was Jaczko’s behavior. “The chairman’s continued outbursts of abusive rage” at NRC staffers and fellow commissioners, were unacceptable, Svinicki said. She and other commissioners blamed Jaczko for what they said was an increasingly tense and unsettled work environment at the NRC.

Jaczko said he has suggested the commissioners talk to a “trusted third party” to improve communications.

White House Chief of Staff Bill Daley said this week that problems at the NRC stem from the commission’s “strong chairman” structure, in which the leader of the five-member panel has far greater powers than the other commissioners.

— Associated Press