A security-related problem found at the Prairie Island nuclear plant requires additional inspections.
The Nuclear Regulatory Commission will release little information about its finding because it's a security-related issue.
In a statement, Xcel Energy said security and safety are the company's highest priorities, and will decide within the next month whether to appeal the NRC finding.
Last October, an NRC inspection revealed an undisclosed issue that called for more attention. The agency says Xcel Energy "corrected or compensated for the deficiencies, and the plant was in compliance with requirements before the inspector left the site."
It is common for the Nuclear Regulatory Commission to withhold information about security at nuclear plants.
Prairie Island is already subject to extra inspections because of problems with its backup power supply for safety equipment.