Toshiba Corp. said Thursday a buildup of material found inside a plant of its U.S. unit, Westinghouse Electric Co., contained an amount of uranium three times higher than the facility's internally set limit.

There were no safety consequences or any health or environmental impacts from the accumulation of the material, the company said.

The nuclear fuel plant in Columbia, South Carolina, has been under scrutiny by the U.S. Nuclear Regulatory Commission since August after the material was found during a regular maintenance check in late May.

The material built up inside a device for filtering out particles and gases during the process of turning uranium mass into powder, it said.

The major Japanese nuclear fuel maker said Westinghouse has been conducting regular inspections and cleanups but its management was insufficient.

Westinghouse faces sanctions from the NRC over the issue.