The 578-page report follows a draft issued last August and covers, among other things, the mixed oxide fuel facility's ability to protect nuclear materials from theft; the adequacy of environmental studies; and safety features to prevent any criticality within the plant's many processes.

Dozens of accident scenarios were evaluated, according to the report, from which portions were edited for security or proprietary technology reasons.

Those analyses included fires, leaks, explosions, acid spills, tornadoes and earthquakes. Radiation hazards from explosions were calculated out more than six miles to the Savannah River Site boundaries.

"The NRC staff concludes that the applicant's descriptions, specifications, commitments, and analyses provide an adequate basis for safety and safeguards of facility operations and that operation of the facility does not pose an undue risk to worker and public health and safety," the inspectors wrote.

Although defense facilities are often exempt from NRC oversight, the MOX project requires licensing because of its mission, which is to manufacture fuel to be used in commercial nuclear power reactors.

By using surplus plutonium to make that fuel, the weapons-grade material is permanently disposed of in a manner in which it cannot be exploited by terrorists.

NRC spokesman Joey Ledford said that the issuance of the MOX project's Safety Evaluation Report is a major step in the process but that final licensing decisions are still several years away.

In the meantime, he added, the Atomic Safety & Licensing Board will continue its evaluation of the project's application and on-site construction inspection programs will remain in place.

"A license will be issued only if the commission verifies the applicant has properly constructed principal structures, systems and components," Ledford said.

The MOX program is part of an agreement between the U.S. and the Russian Federation to dismantle thousands of Cold War-era nuclear weapons by using the plutonium from warheads to manufacture fuel for civilian nuclear power reactors.

The facility would -- over time -- combine 34 metric tons of weapon-grade plutonium with larger volumes of uranium oxides to make the mixed oxide, or MOX, fuel.

Scheduled to open in late 2016, it is the only MOX fuel fabrication facility being built in the U.S.