Radioisotope Power Systems

The Radioisotope Power Systems Program at ORNL has a nearly 50-year history of materials development (refractory metal alloys and carbon bonded carbon fiber) and the fabrication of unique components for the Department of Energy, NASA and other government agencies. In addition to production activities, the Program provides a wide range of capabilities that span the entire sphere of alloy design, production, mechanical property testing, component testing and qualification. Manufacturing equipment and expertise exist to cast metal alloy ingots and process them into finished metal shapes by extrusion, rolling, forming, machining, assembly, and welding. Nondestructive examination and quality systems are employed throughout the process to ensure customer requirements are maintained. Areas of expertise can be grouped into the four following areas: 

• Alloy Design, Production and Processing
• Component Manufacture
• Testing and Evaluation
• Quality Systems, Dimensional Inspection, NDE, and Material Characterization Techniques

An entire array of nondestructive testing capabilities is available for the evaluation of alloys and structures including radiography, liquid penetrant, visual, ultrasonic, and thermal imaging.

Alloy Design, Production and Processing

Specialty alloys are produced in development or small production size lots using powder processing, electron beam melting, inert gas arc melting, and vacuum arc remelting. Extensive experience exists for the production of reactive, refractory, and precious metal alloys. An example of a high performance alloy developed and produced at ORNL is the iridium DOP-26 alloy. This platinum group alloy is used to encapsulate radioactive materials for NASA deep space missions. The alloy was designed for high-temperature strength and ductility to survive impact damage from potential accident scenarios. Other examples of developmental alloys are refractory alloys for the friction stir welding tool for welding heat resistant alloys. Further processing of ingots is accomplished by extruding, rolling, and heat treating to produce finished sheet and/or foils.

• Vacuum Arc Remelting
• Vacuum Electron Beam Melting
• Extruding
• Heat treating
• Rolling
• Sintering
• Zone melting

Component Manufacturing

A wide array of room temperature and high temperature manufacturing equipment is employed to produce final shapes or components. A unique carbon bonded carbon fiber (CBCF) insulating material is produced at ORNL to provide reentry protection for nuclear fuel clads in radioisotope thermoelectric generators. Facilities are maintained for vacuum molding, high temperature carbonization and machining of insulating components. ORNL has experience in forming and machining many alloys including steels, superalloys, refractory and precious metals. Other processing technologies employed are air, vacuum, hydrogen, and inert atmosphere heat treating, diffusion bonding and powder sintering. One component made using these processes is a high temperature precious metal filter. ORNL has vast experience in welding and brazing technology including arc processes, laser, electron beam, and friction stir welding. Surface modification of alloys and components is performed by laser and plasma arc lamps.

• Forming
• Heat treating and sintering
• Machining
• Arc, electron beam, friction stir and laser welding
• Inert-gas glove box welding
• High temperature carbonization
• Surface modification