The Nuclear Regulatory Commission is investigating why a nuclear expert on an independent panel within the agency resigned this month after citing a "hostile, targeted environment."

Said Abdel-Khalik, former chairman of NRC's Advisory Committee on Reactor Safeguards, sent a letter of resignation to outgoing NRC Chairman Gregory Jaczko on May 13, according to ACRS spokesman Ed Hackett.

The reactor engineer and professor blamed his decision to step down on problems with J. Sam Armijo, the current ACRS chairman, Hackett said. The part-time panel of federal workers has the authority under the Atomic Energy Act to question NRC's decisions on licensing and reactor safety.

Abdel-Khalik did not clarify what issues he had with Armijo, and the NRC's Inspector General is investigating the situation, Hackett said.

Abdel-Khalik had been a member of the ACRS since Armijo succeeded him as chairman in January, Hackett said. He served as the board's chairman from 2010 to 2011 and is a professor at the Georgia Institute of Technology in Atlanta. He is considered a world-renowned expert in the area of reactor engineering and thermal hydraulics, according to the university's website.

Armijo is an adjunct professor of material science and engineering at the University of Nevada, Reno.

Abdel-Khalik's resignation came to light in a letter Rep. Ed Markey (D-Mass.), a nuclear skeptic and Jaczko's former boss, released yesterday (Greenwire, June 4).

Markey said Abdel-Khalik stepped down over "concerns about inappropriate nuclear industry influence" on the panel's activities, adding that whistle-blower retaliation is an agencywide problem at NRC.

But Hackett said he could not confirm Markey's statement. Instead, he said Armijo has conducted his chairmanship of the ACRS consistent with NRC values and with the openness and transparency required under the Federal Advisory Committee Act.

Jaczko ordered NRC staff yesterday to assess whether the commission is promoting a "healthy and transparent dialogue and discussion" on safety issues. NRC has made progress on safety culture initiatives but "must redouble our efforts in this area," according to the agency.

Jaczko also issued a statement thanking Abdel-Khalik for his service, namely in the wake of Japan's nuclear disaster last year.

"I've appreciated his thoughtful and candid advice and I regret that he's leaving," Jaczko said. "He has provided a great service to this agency and to the American people, especially with his leadership of the ACRS during its participation in the NRC follow-up to the Fukushima accident."