Federal regulators are poised to cite two Tennessee Valley Authority nuclear plants for having inadequate procedures to deal with certain flood conditions prior to the modification of upstream dams in 2009.

Watts Bar nuclear plant. Source: TVAThe Nuclear Regulatory Commission reassessed flood predictions on the Tennessee River in 2008 as part of its license review for two new units proposed at TVA's Bellefonte plant. In documents released Friday, the Nuclear Regulatory Commission asserted that TVA assessed new flood data and determined that certain conditions could result in a dam failure upstream from the Sequoyah and Watts Bar plants. In the months that followed, TVA raised the dams using HESCO barriers filled with gravel to ensure their height exceeded the new flood predictions. But prior to their installation, the federal utility did not account for the possible dam breach in its emergency planning to protect critical equipment at the plants, the NRC inspection reports allege.

The regulatory body issued preliminary yellow findings related to the investigation, including findings that TVA did not report the unanalyzed conditions to the NRC, as required, until February of this year. A yellow finding is the second most severe issued by the agency.