A major manufacturer in the nuclear industry is reporting a potential “substantial safety hazard” with control rods used at dozens of reactors around the country, including in Mississippi, according to a report made public Wednesday by the federal Nuclear Regulatory Commission.

GE Hitachi Nuclear Energy said it discovered cracking and “material distortion,” and would recommend that the reactors using its Marathon control rod blades replace them more frequently.

“The design life if not revised, could result in significant control blade cracking and could, if not corrected, create a substantial safety hazard and is considered a reportable condition,” the company said.

Grand Gulf Nuclear Power Station in Claiborne County uses reactors that require Marathon rods. “We have been monitoring the blades since GE Hitachi made the report to the NRC last year,” Mike Bowling of Entergy Nuclear in Jackson said. “Our plan is to continue with the rigorous inspection regimen and replace the rods.”