Navigating part and supplier obsolescence for nuclear safety-related applications
Nuclear facilities can operate for decades, but the components and suppliers supporting them may not. When safety-related parts become obsolete, finding a suitable replacement is only the beginning. Three potential routes can help organisations maintain safety and reliability.
By Cordon Witherington, P. E., Engineer, Flowserve Corporation
About the author
Cordon Witherington, a North
Carolina native and licensed Professional Engineer, holds a mechanical engineering degree from NC State University. He supports Flowserve’ s Isolation Valve team and is committed to advancing reliable power generation and nuclear energy’ s renewed growth.
Nuclear safety-related equipment is often expected to remain serviceable for decades. Plants depend on spare parts, assemblies, and components that must meet established design, quality, environmental, and seismic requirements. Yet the supply chains supporting those components are continually changing. Manufacturers discontinue products, revise designs, relocate facilities, merge with other companies, change names, or decide that maintaining a nuclear quality programme is no longer practical. These changes can make it difficult to procure a historically supplied item as nuclear safety-related, even when the part itself still appears to be available. The core issue is not simply finding a replacement. The challenge is demonstrating that a replacement part, supplier, or manufacturing method will support the required safety-related function without introducing unacceptable risk. In many cases, customers require components that align with historical drawings, code years, specifications, and environmental or seismic qualification reports. Obsolescence can take several forms. A product may no longer be manufactured because demand has declined, production costs have increased, or a supplier has rationalised its product line. A manufacturer may revise a part, and even small changes in geometry, material, or performance can make the revised item non-identical to the original. A supplier may also discontinue the quality program that previously allowed it to provide items as nuclear safety-related. When these conditions arise, nuclear organisations typically have three primary paths forward: 1) Source a commercial item and perform commercial grade dedication; 2) Identify an“ equivalent” item from a qualified supplier; or 3) Reverse engineer the obsolete item.
The appropriate path depends on the item’ s complexity, supplier capabilities, qualification requirements, and the potential effect on the parent equipment.
Option 1: Source commercially and perform commercial grade dedication
The first option is to procure an identical item from a commercial supplier and dedicate it for use in a nuclear safety-related application. This approach may be appropriate when the item is available in the commercial market but cannot be obtained from a supplier qualified to 10CFR50 Appendix B or another applicable nuclear quality programme. Commercial grade dedication should not be treated as a simplified procurement process. It requires a structured evaluation of the item’ s safety function and the critical characteristics that provide reasonable assurance the item will perform that function. A primary consideration is item complexity. Geometrical complexity can create difficulties when critical features are internal, inaccessible, or require specialised tools for verification. Organisations should determine whether they have the measuring and testing equipment required and that all critical geometry is accessible when considering dedicating and item’ s geometric properties. This can become particularly tricky in the case of pre-assembled components. Material complexity presents another challenge. A dedication plan may require destructive testing to validate material composition or physical properties. The organisation must determine whether a test specimen is required and demonstrate that a commercial supplier can maintain lot / batch traceability. In some cases, parts may consist of proprietary chemical compositions; how will you verify a material if its composition is not publicly available?
60 Valve World November 2026 www. valve-world. net