On December 21, 2020, the NRC issued a Notice of Violation to NAC International (Certificate Holder) for a Severity Level III and a Severity Level IV violation. NAC failed to comply with the requirements of 10 CFR 72.48(c)(2)(viii), “Changes, tests, and experiments,” and 10 CFR 72.146(c), “Design control.” The violations involved a design change for NAC’s MAGNASTOR dry cask storage system. The certificate holder failed to utilize a methodology as specified in the MAGNASTOR Final Safety Analysis Report (FSAR); and, failed to obtain an amendment to use a different methodology. In response, NAC re-performed the spent fuel cask tip-over analysis using the appropriate methodology and obtained satisfactory results. NAC also implemented corrective actions to enhance its design control and 72.48 screening processes.