Lockheed Martin Utility Services Inc. (LMUS), as the agent for the United States Enrichment Corporation (USEC), was responsible for the operation and maintenance of the Paducah and Portsmouth gaseous diffusion plants. In this capacity, LMUS frequently required engineering design and analysis in support of ongoing operation and maintenance activities.

NAC International performed detailed finite analysis modeling and analyses of the Paducah Tiger Overpack (PTO) during hypothetical accident conditions, as required by 10 CFR 71. The PTO is used for shipping the 48X UF6 cylinder. These analyses were used as the basis for USEC justification to the Nuclear Regulatory Commission for continued shipping operations using the PTO.

Subsequently, LMUS and USEC needed to develop a revised Safety Analysis Report (SAR) for PTO re-certification and contracted with NAC for that work. The initial phase of that project reviewed the licensed SAR and developed draft revisions and supporting documentation for the existing PTO design. NAC also identified technical issues and developed a plan to produce a revised SAR that would meet NRC requirements. In the next phase, the SAR was revised to meet NRC Regulatory Guide 7.9 requirements. Finally, the revised SAR was submitted, and the PTO was successfully re-certified.