On June 4, 2013, the NRC issued a Notice of Violation (NOV) associated with a White Significance Determination Process (SDP) finding and a Severity Level III violation to Tennessee Valley Authority (TVA). The White finding, a violation of Technical Specification (TS) 6.8.1, Procedures and Programs, involved the failure of Sequoyah personnel to establish an adequate Abnormal Condition Procedure to implement its flood mitigation strategy. Specifically, prior to September 30, 2009, AOP-N.03, "External Flooding," was inadequate to mitigate the effects of a Probable Maximum Flood (PMF) event, in that earthen dams located upstream of the facility could potentially overtop, causing a subsequent breach and resulting in onsite flooding and the submergence of critical equipment. The Severity Level III violation of 10 CFR 50.72(b)(3)(ii)(B) involved the failure of Sequoyah personnel to report within eight hours an unanalyzed condition that significantly degraded plant safety. Specifically, on December 30, 2009, Sequoyah personnel failed to notify the NRC upon confirmation that a postulated Probable Maximum Flood (PMF) level would exceed the current licensing basis and the design basis PMF flooding event would result in overtopping of critical earthen dam structures upstream of the Sequoyah facility.