Fabrication Roadmap as an Example for Small Modular Reactors

Small Modular Reactors (SMRs) are being designed to achieve many of the same goals as Generation IV reactors in much smaller individual package sizes. The experience with developing a fabrication roadmap to Generation IV reactors can be transferred as guidance for fabrication design of SMRs. Some areas where fabrication process development needs to come early in the sequence are materials for fast neutron areas, connections of thick to thin for combinations of pressure containment and fluid flow, fabrication with planned coating of internal surfaces, and materials that push beyond existing upper temperature limits. For instance, the Next Generation Nuclear Plant (NGNP) shifted to lower peak temperatures as the enormity of the materials qualification task for the originally planned peak temperatures became apparent. Materials replacements for long lifetime were needed in NGNP even when the peak temperature was lowered, with some like silicon carbide composite fuel rods not expected to be available for initial production. Several new welding techniques such as short-circuit transfer, narrow groove, tandem gas metal arc, hybrid laser-gas metal arc, and friction stir are also available. These techniques offer improved weld quality and higher productivity in assembly operations. Other fabrication considerations, such as qualification of joining methods, long life mechanical components, and dissimilar material joints will be discussed.