SI provides engineering services for on-site high-level waste storage systems. Clients served include BNFL, Westinghouse, Transnuclear West, Transnuclear East, Holtec and NAC for design/analysis of their respective systems. SI has been a major contributor to the industry’s on-site spent fuel storage activities. SI developed flaw evaluation and acceptance criteria for the multi-assembly sealed basket (MSB) closure welds for the Sierra Nuclear VSC-24 systems, in support of the Palisades, ANO, and Point Beach plants. SI also developed a method for ultrasonic testing (UT) of these closure welds using our proprietary time of flight diffraction system, and, to the best of our knowledge, we are the only company that has successfully applied UT to these types of dry storage systems (DFS). SI assists utilities in preparing licensing presentations and submittals on these issues.

SI has provided engineering services to the Yucca Mountain Project (YMP) since 1998. SI analyzed the Alloy 22 waste package (WP) weld residual stresses, suggested low residual stress welding processes and mitigation techniques, identified the expected cracking probabilities and geometries and calculated crack leak rates.

SI performed finite element analysis and fracture mechanics for the WP closure weld and determined the threshold stress for stress corrosion cracking (SCC). SI has also provided guidance for the Alloy 22 corrosion test program and provided recommendations related to a long-term corrosion mitigaiton and monitoring system for the WP to EPRI. An evaluation was also performed to determine the long-term effect of Alloy 22 general corrosion on the compressive residual stress induced on the WP outside surface due to water quenching. This evaluation determined if quenching of the WP would result in lifetime resistance to SCC.

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