The Nuclear Regulatory Commission's most recent round of inspections at the U.S. Energy Department's mixed oxide fuel facility yielded four notices of violation for mostly minor infractions, according to a copy of the report made public Tuesday.

Inspectors, who conducted extensive reviews at the construction site from July 1 to Sept. 30, also noted many programs -- including the placement of concrete and steel -- were adequate.

The $4.8 million MOX facility, scheduled to open at Savannah River Site in 2016, is designed to dispose of 34 metric tons of surplus weapons-grade plutonium by using small amounts to make fuel for commercial reactors.

The inspections evaluated construction of principal structures and included quality assurance activities related to design verification and documentation control; problem identification, resolution and corrective actions; structural steel and support activities; structural concrete activities; and geotechnical foundation activities, the report said.

All were "performed in a safe and quality related manner and in accordance with procedures and work packages."

The four violations identified by the NRC were assigned a priority level of IV -- the least serious on the agency's scale:

- An inadequate design change related to the improper relocation of wall penetrations above a wall pier.

- An inadequate procedural guidance for documentation of methods and results of design verification reviews related to design drawing revisions and engineering change requests.

- Inadequate technical justifications were found in an engineering change request.

- Undocumented work activities did not show a coupler had been removed from column or that a quality control inspection was no longer valid.

Among the other findings:

- Geotechnical backfill procedures and specifications were adequate and records associated with these activities were properly maintained.

- Observed rebar and embedded plates were properly installed; cleanliness was adequate; concrete testing activities were adequate; and concrete placement activities were appropriate.

- Field preparation of concrete test cylinders and temporary storage of the cylinders were acceptable.